            CIS Ubuntu Linux 22.04
            LTS Benchmark
        v3.0.0 - 10-30-2025




Internal Only - General
            Terms of Use
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            Table of Contents
            Terms of Use ................................................................................................................. 1
            Table of Contents .......................................................................................................... 2
            Overview ...................................................................................................................... 11
              Important Usage Information ...............................................................................................11
                Key Stakeholders ................................................................................................................................. 11
                Apply the Correct Version of a Benchmark ...................................................................................... 12
                Exceptions ............................................................................................................................................ 12
                Remediation ......................................................................................................................................... 13
                Summary ............................................................................................................................................... 13
              Target Technology Details ...................................................................................................14
              Intended Audience................................................................................................................14
              Consensus Guidance ...........................................................................................................15
              Typographical Conventions .................................................................................................16
            Recommendation Definitions ..................................................................................... 17
              Title ........................................................................................................................................17
              Assessment Status...............................................................................................................17
                Automated ............................................................................................................................................ 17
                Manual ................................................................................................................................................... 17
              Profile ....................................................................................................................................17
              Description ............................................................................................................................17
              Rationale Statement .............................................................................................................17
              Impact Statement ..................................................................................................................18
              Audit Procedure ....................................................................................................................18
              Remediation Procedure........................................................................................................18
              Default Value .........................................................................................................................18
              References ............................................................................................................................18
              CIS Critical Security Controls® (CIS Controls®) ..................................................................18
              Additional Information..........................................................................................................18
              Profile Definitions .................................................................................................................19
              Acknowledgements ..............................................................................................................20
            Recommendations ...................................................................................................... 21
              1 Initial Setup ........................................................................................................................21
                1.1 Filesystem ...................................................................................................................................... 21
                  1.1.1 Configure Filesystem Kernel Modules ................................................................................... 22
                         1.1.1.1 Ensure cramfs kernel module is not available (Automated) ......................................... 23
                         1.1.1.2 Ensure freevxfs kernel module is not available (Automated) ....................................... 26


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                         1.1.1.3 Ensure hfs kernel module is not available (Automated) ............................................... 29
                         1.1.1.4 Ensure hfsplus kernel module is not available (Automated) ........................................ 32
                         1.1.1.5 Ensure jffs2 kernel module is not available (Automated) ............................................. 35
                         1.1.1.6 Ensure overlay kernel module is not available (Automated) ........................................ 38
                         1.1.1.7 Ensure squashfs kernel module is not available (Automated) ..................................... 41
                         1.1.1.8 Ensure udf kernel module is not available (Automated) ............................................... 44
                         1.1.1.9 Ensure usb-storage kernel module is not available (Automated) ................................. 47
                         1.1.1.10 Ensure unused filesystems kernel modules are not available (Manual) .................... 51
                         1.1.1.11 Ensure firewire-core kernel module is not available (Automated) .............................. 58
                  1.1.2 Configure Filesystem Partitions ............................................................................................. 61
                    1.1.2.1 Configure /tmp .................................................................................................................... 62
                         1.1.2.1.1 Ensure /tmp is tmpfs or a separate partition (Automated) ......................................... 63
                         1.1.2.1.2 Ensure nodev option set on /tmp partition (Automated) ............................................ 66
                         1.1.2.1.3 Ensure nosuid option set on /tmp partition (Automated) ........................................... 68
                         1.1.2.1.4 Ensure noexec option set on /tmp partition (Automated) .......................................... 70
                    1.1.2.2 Configure /dev/shm ............................................................................................................ 72
                         1.1.2.2.1 Ensure /dev/shm is tmpfs or a separate partition (Automated) ................................. 73
                         1.1.2.2.2 Ensure nodev option set on /dev/shm partition (Automated) .................................... 75
                         1.1.2.2.3 Ensure nosuid option set on /dev/shm partition (Automated) .................................... 77
                         1.1.2.2.4 Ensure noexec option set on /dev/shm partition (Automated) ................................... 79
                    1.1.2.3 Configure /home ................................................................................................................. 81
                         1.1.2.3.1 Ensure separate partition exists for /home (Automated) ........................................... 82
                         1.1.2.3.2 Ensure nodev option set on /home partition (Automated) ......................................... 84
                         1.1.2.3.3 Ensure nosuid option set on /home partition (Automated) ........................................ 86
                    1.1.2.4 Configure /var ..................................................................................................................... 88
                         1.1.2.4.1 Ensure separate partition exists for /var (Automated) ............................................... 89
                         1.1.2.4.2 Ensure nodev option set on /var partition (Automated) ............................................. 91
                         1.1.2.4.3 Ensure nosuid option set on /var partition (Automated) ............................................ 93
                    1.1.2.5 Configure /var/tmp .............................................................................................................. 95
                         1.1.2.5.1 Ensure separate partition exists for /var/tmp (Automated) ........................................ 96
                         1.1.2.5.2 Ensure nodev option set on /var/tmp partition (Automated) ...................................... 98
                         1.1.2.5.3 Ensure nosuid option set on /var/tmp partition (Automated) ................................... 100
                         1.1.2.5.4 Ensure noexec option set on /var/tmp partition (Automated) .................................. 102
                    1.1.2.6 Configure /var/log ............................................................................................................. 104
                         1.1.2.6.1 Ensure separate partition exists for /var/log (Automated) ....................................... 105
                         1.1.2.6.2 Ensure nodev option set on /var/log partition (Automated) ..................................... 107
                         1.1.2.6.3 Ensure nosuid option set on /var/log partition (Automated) .................................... 109
                         1.1.2.6.4 Ensure noexec option set on /var/log partition (Automated) ................................... 111
                    1.1.2.7 Configure /var/log/audit ................................................................................................... 113
                         1.1.2.7.1 Ensure separate partition exists for /var/log/audit (Automated) .............................. 114
                         1.1.2.7.2 Ensure nodev option set on /var/log/audit partition (Automated) ............................ 116
                         1.1.2.7.3 Ensure nosuid option set on /var/log/audit partition (Automated) ............................ 118
                         1.1.2.7.4 Ensure noexec option set on /var/log/audit partition (Automated)........................... 120
                1.2 Package Management ................................................................................................................. 122
                  1.2.1 Configure Package Repositories .......................................................................................... 123
                         1.2.1.1 Ensure GPG keys are configured (Manual) ................................................................ 124
                         1.2.1.2 Ensure package manager repositories are configured (Manual) ............................... 127
                  1.2.2 Configure Package Updates ................................................................................................. 129
                         1.2.2.1 Ensure updates, patches, and additional security software are installed (Manual) ... 130
                1.3 Mandatory Access Control ......................................................................................................... 132
                  1.3.1 Configure AppArmor.............................................................................................................. 133
                         1.3.1.1 Ensure the apparmor packages are installed (Automated) ........................................ 134
                         1.3.1.2 Ensure AppArmor is enabled (Automated) ................................................................. 136
                         1.3.1.3 Ensure all AppArmor Profiles are not disabled (Automated) ...................................... 138
                         1.3.1.4 Ensure all AppArmor Profiles are enforcing (Automated) .......................................... 140
                1.4 Configure Bootloader .................................................................................................................. 142


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                       1.4.1 Ensure bootloader password is set (Automated) ........................................................... 143
                       1.4.2 Ensure access to bootloader config is configured (Automated) .................................... 146
                1.5 Configure Additional Process Hardening ................................................................................. 148
                       1.5.1 Ensure randomize_va_space is configured (Automated) .............................................. 149
                       1.5.2 Ensure ptrace_scope is configured (Automated) .......................................................... 154
                       1.5.3 Ensure suid_dumpable is configured (Automated)........................................................ 159
                       1.5.4 Ensure core file size is configured (Automated) ............................................................ 163
                       1.5.5 Ensure prelink is not installed (Automated) ................................................................... 165
                       1.5.6 Ensure Automatic Error Reporting is configured (Automated) ...................................... 166
                1.6 Configure Command Line Warning Banners ............................................................................ 168
                       1.6.1 Ensure /etc/motd is configured (Automated) ................................................................. 169
                       1.6.2 Ensure /etc/issue is configured (Automated) ................................................................. 172
                       1.6.3 Ensure /etc/issue.net is configured (Automated) ........................................................... 174
                       1.6.4 Ensure access to /etc/motd is configured (Automated) ................................................. 176
                       1.6.5 Ensure access to /etc/issue is configured (Automated)................................................. 178
                       1.6.6 Ensure access to /etc/issue.net is configured (Automated) .......................................... 180
                1.7 Configure GNOME Display Manager .......................................................................................... 182
                       1.7.1 Ensure GDM is removed (Automated) .......................................................................... 183
                       1.7.2 Ensure GDM login banner is configured (Automated) ................................................... 185
                       1.7.3 Ensure GDM disable-user-list option is enabled (Automated) ...................................... 188
                       1.7.4 Ensure GDM screen locks when the user is idle (Automated) ...................................... 191
                       1.7.5 Ensure GDM screen locks cannot be overridden (Automated) ..................................... 194
                       1.7.6 Ensure GDM automatic mounting of removable media is disabled (Automated) .......... 196
                       1.7.7 Ensure GDM disabling automatic mounting of removable media is not overridden
                       (Automated) ............................................................................................................................ 198
                       1.7.8 Ensure GDM autorun-never is enabled (Automated) .................................................... 200
                       1.7.9 Ensure GDM autorun-never is not overridden (Automated) .......................................... 202
                       1.7.10 Ensure XDMCP is not enabled (Automated) ............................................................... 204
                       1.7.11 Ensure Xwayland is configured (Automated) .............................................................. 207
              2 Services............................................................................................................................209
                2.1 Configure Server Services .......................................................................................................... 210
                       2.1.1 Ensure autofs services are not in use (Automated) ....................................................... 211
                       2.1.2 Ensure avahi daemon services are not in use (Automated) .......................................... 214
                       2.1.3 Ensure dhcp server services are not in use (Automated).............................................. 217
                       2.1.4 Ensure dns server services are not in use (Automated)................................................ 220
                       2.1.5 Ensure dnsmasq services are not in use (Automated) .................................................. 222
                       2.1.6 Ensure ftp server services are not in use (Automated) ................................................. 224
                       2.1.7 Ensure ldap server services are not in use (Automated)............................................... 227
                       2.1.8 Ensure message access server services are not in use (Automated) .......................... 229
                       2.1.9 Ensure network file system services are not in use (Automated) .................................. 232
                       2.1.10 Ensure nis server services are not in use (Automated) ............................................... 234
                       2.1.11 Ensure print server services are not in use (Automated) ............................................ 237
                       2.1.12 Ensure rpcbind services are not in use (Automated)................................................... 240
                       2.1.13 Ensure rsync services are not in use (Automated) ...................................................... 243
                       2.1.14 Ensure samba file server services are not in use (Automated) ................................... 245
                       2.1.15 Ensure snmp services are not in use (Automated) ...................................................... 247
                       2.1.16 Ensure tftp server services are not in use (Automated) .............................................. 250
                       2.1.17 Ensure web proxy server services are not in use (Automated) ................................... 253
                       2.1.18 Ensure web server services are not in use (Automated) ............................................. 255
                       2.1.19 Ensure xinetd services are not in use (Automated) ..................................................... 258
                       2.1.20 Ensure X window server services are not in use (Automated) .................................... 261
                       2.1.21 Ensure mail transfer agents are configured for local-only mode (Automated) ............ 263
                       2.1.22 Ensure only approved services are listening on a network interface (Manual) ........... 266
                2.2 Configure Client Services ........................................................................................................... 268
                       2.2.1 Ensure nis client is not installed (Automated) ................................................................ 269



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                         2.2.2 Ensure rsh client is not installed (Automated) ............................................................... 271
                         2.2.3 Ensure talk client is not installed (Automated) ............................................................... 273
                         2.2.4 Ensure telnet client is not installed (Automated) ........................................................... 275
                         2.2.5 Ensure ldap client is not installed (Automated) ............................................................. 277
                         2.2.6 Ensure ftp client is not installed (Automated) ................................................................ 279
                2.3 Configure Time Synchronization ............................................................................................... 281
                  2.3.1 Ensure time synchronization is in use................................................................................. 282
                         2.3.1.1 Ensure a single time synchronization daemon is in use (Automated) ........................ 283
                  2.3.2 Configure systemd-timesyncd.............................................................................................. 287
                         2.3.2.1 Ensure systemd-timesyncd configured with authorized timeserver (Automated) ...... 289
                         2.3.2.2 Ensure systemd-timesyncd is enabled and running (Automated) .............................. 293
                  2.3.3 Configure chrony ................................................................................................................... 295
                         2.3.3.1 Ensure chrony is configured with authorized timeserver (Automated) ....................... 296
                         2.3.3.2 Ensure chrony is running as user _chrony (Automated) ............................................ 300
                         2.3.3.3 Ensure chrony is enabled and running (Automated) .................................................. 302
                2.4 Job Schedulers ............................................................................................................................ 304
                  2.4.1 Configure cron ........................................................................................................................ 305
                         2.4.1.1 Ensure cron daemon is enabled and active (Automated) .......................................... 306
                         2.4.1.2 Ensure access to /etc/crontab is configured (Automated) .......................................... 308
                         2.4.1.3 Ensure access to /etc/cron.hourly is configured (Automated) .................................... 310
                         2.4.1.4 Ensure access to /etc/cron.daily is configured (Automated) ...................................... 312
                         2.4.1.5 Ensure access to /etc/cron.weekly is configured (Automated) ................................... 314
                         2.4.1.6 Ensure access to /etc/cron.monthly is configured (Automated) ................................. 316
                         2.4.1.7 Ensure access to /etc/cron.yearly is configured (Automated) .................................... 318
                         2.4.1.8 Ensure access to /etc/cron.d is configured (Automated) ............................................ 319
                         2.4.1.9 Ensure access to crontab is configured (Automated) ................................................. 321
                  2.4.2 Configure at ............................................................................................................................ 325
                         2.4.2.1 Ensure access to at is configured (Automated) .......................................................... 326
              3 Network ............................................................................................................................329
                3.1 Configure Network Devices ........................................................................................................ 330
                         3.1.1 Ensure IPv6 status is identified (Manual) ...................................................................... 331
                         3.1.2 Ensure wireless interfaces are not available (Automated) ............................................ 333
                         3.1.3 Ensure bluetooth services are not in use (Automated).................................................. 336
                3.2 Configure Network Kernel Modules ........................................................................................... 339
                         3.2.1 Ensure dccp kernel module is not available (Automated) ............................................. 340
                         3.2.2 Ensure tipc kernel module is not available (Automated) ............................................... 343
                         3.2.3 Ensure rds kernel module is not available (Automated) ................................................ 346
                         3.2.4 Ensure sctp kernel module is not available (Automated) .............................................. 349
                3.3 Configure Network Kernel Parameters ...................................................................................... 352
                  3.3.1 Configure IPv4 parameters ................................................................................................... 353
                         3.3.1.1 Ensure net.ipv4.ip_forward is configured (Automated) .............................................. 354
                         3.3.1.2 Ensure net.ipv4.conf.all.forwarding is configured (Automated) .................................. 358
                         3.3.1.3 Ensure net.ipv4.conf.default.forwarding is configured (Automated) ........................... 363
                         3.3.1.4 Ensure net.ipv4.conf.all.send_redirects is configured (Automated) ........................... 368
                         3.3.1.5 Ensure net.ipv4.conf.default.send_redirects is configured (Automated) .................... 373
                         3.3.1.6 Ensure net.ipv4.icmp_ignore_bogus_error_responses is configured (Automated) ... 378
                         3.3.1.7 Ensure net.ipv4.icmp_echo_ignore_broadcasts is configured (Automated) .............. 382
                         3.3.1.8 Ensure net.ipv4.conf.all.accept_redirects is configured (Automated) ........................ 386
                         3.3.1.9 Ensure net.ipv4.conf.default.accept_redirects is configured (Automated) ................. 390
                         3.3.1.10 Ensure net.ipv4.conf.all.secure_redirects is configured (Automated) ...................... 394
                         3.3.1.11 Ensure net.ipv4.conf.default.secure_redirects is configured (Automated) ............... 398
                         3.3.1.12 Ensure net.ipv4.conf.all.rp_filter is configured (Automated) ..................................... 402
                         3.3.1.13 Ensure net.ipv4.conf.default.rp_filter is configured (Automated) .............................. 406
                         3.3.1.14 Ensure net.ipv4.conf.all.accept_source_route is configured (Automated) ............... 410
                         3.3.1.15 Ensure net.ipv4.conf.default.accept_source_route is configured (Automated) ........ 414



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                         3.3.1.16 Ensure net.ipv4.conf.all.log_martians is configured (Automated) ............................ 418
                         3.3.1.17 Ensure net.ipv4.conf.default.log_martians is configured (Automated) ..................... 422
                         3.3.1.18 Ensure net.ipv4.tcp_syncookies is configured (Automated) ..................................... 426
                  3.3.2 Configure IPv6 parameters ................................................................................................... 430
                         3.3.2.1 Ensure net.ipv6.conf.all.forwarding is configured (Automated) .................................. 431
                         3.3.2.2 Ensure net.ipv6.conf.default.forwarding is configured (Automated) ........................... 435
                         3.3.2.3 Ensure net.ipv6.conf.all.accept_redirects is configured (Automated) ........................ 439
                         3.3.2.4 Ensure net.ipv6.conf.default.accept_redirects is configured (Automated) ................. 443
                         3.3.2.5 Ensure net.ipv6.conf.all.accept_source_route is configured (Automated) ................. 447
                         3.3.2.6 Ensure net.ipv6.conf.default.accept_source_route is configured (Automated) .......... 451
                         3.3.2.7 Ensure net.ipv6.conf.all.accept_ra is configured (Automated) ................................... 455
                         3.3.2.8 Ensure net.ipv6.conf.default.accept_ra is configured (Automated) ............................ 459
              4 Host Based Firewall .........................................................................................................463
                4.1 Configure Uncomplicated Firewall ............................................................................................. 464
                       4.1.1 Ensure ufw is installed (Automated) .............................................................................. 465
                       4.1.2 Ensure ufw service is configured (Automated) .............................................................. 467
                       4.1.3 Ensure ufw incoming default is configured (Automated) ............................................... 470
                       4.1.4 Ensure ufw outgoing default is configured (Automated) ................................................ 472
                       4.1.5 Ensure ufw routed default is configured (Automated) ................................................... 474
              5 Access Control ................................................................................................................475
                5.1 Configure SSH Server ................................................................................................................. 476
                         5.1.1 Ensure access to /etc/ssh/sshd_config is configured (Automated) ............................... 478
                         5.1.2 Ensure access to SSH private host key files is configured (Automated)....................... 481
                         5.1.3 Ensure access to SSH public host key files is configured (Automated) ........................ 485
                         5.1.4 Ensure sshd access is configured (Automated) ............................................................ 489
                         5.1.5 Ensure sshd Banner is configured (Automated) ............................................................ 492
                         5.1.6 Ensure sshd Ciphers are configured (Automated) ........................................................ 494
                         5.1.7 Ensure sshd ClientAliveInterval and ClientAliveCountMax are configured (Automated)
                         ................................................................................................................................................ 497
                         5.1.8 Ensure sshd DisableForwarding is enabled (Automated) ............................................. 500
                         5.1.9 Ensure sshd GSSAPIAuthentication is disabled (Automated) ...................................... 503
                         5.1.10 Ensure sshd HostbasedAuthentication is disabled (Automated) ................................. 505
                         5.1.11 Ensure sshd IgnoreRhosts is enabled (Automated) .................................................... 507
                         5.1.12 Ensure sshd KexAlgorithms is configured (Automated) .............................................. 509
                         5.1.13 Ensure sshd LoginGraceTime is configured (Automated) ........................................... 512
                         5.1.14 Ensure sshd LogLevel is configured (Automated) ....................................................... 514
                         5.1.15 Ensure sshd MACs are configured (Automated) ......................................................... 516
                         5.1.16 Ensure sshd MaxAuthTries is configured (Automated) ............................................... 519
                         5.1.17 Ensure sshd MaxSessions is configured (Automated) ................................................ 521
                         5.1.18 Ensure sshd MaxStartups is configured (Automated) ................................................. 523
                         5.1.19 Ensure sshd PermitEmptyPasswords is disabled (Automated) .................................. 525
                         5.1.20 Ensure sshd PermitRootLogin is disabled (Automated) .............................................. 527
                         5.1.21 Ensure sshd PermitUserEnvironment is disabled (Automated) .................................. 529
                         5.1.22 Ensure sshd UsePAM is enabled (Automated) ........................................................... 531
                5.2 Configure privilege escalation ................................................................................................... 533
                         5.2.1 Ensure sudo is installed (Automated) ............................................................................ 534
                         5.2.2 Ensure sudo commands use pty (Automated) .............................................................. 536
                         5.2.3 Ensure sudo log file exists (Automated) ........................................................................ 538
                         5.2.4 Ensure users must provide password for escalation (Automated) ................................ 540
                         5.2.5 Ensure re-authentication for privilege escalation is not disabled globally (Automated) 542
                         5.2.6 Ensure sudo timestamp_timeout is configured (Automated) ......................................... 544
                         5.2.7 Ensure access to the su command is restricted (Automated) ....................................... 546
                5.3 Pluggable Authentication Modules ............................................................................................ 548
                  5.3.1 Configure PAM software packages ...................................................................................... 549
                         5.3.1.1 Ensure latest version of pam is installed (Automated) ............................................... 550


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                         5.3.1.2 Ensure latest version of libpam-modules is installed (Automated) ............................. 552
                         5.3.1.3 Ensure latest version of libpam-pwquality is installed (Automated) ........................... 553
                  5.3.2 Configure pam-auth-update profiles .................................................................................... 555
                         5.3.2.1 Ensure pam_unix module is enabled (Automated)..................................................... 556
                         5.3.2.2 Ensure pam_faillock module is enabled (Automated) ................................................ 558
                         5.3.2.3 Ensure pam_pwquality module is enabled (Automated) ............................................ 561
                         5.3.2.4 Ensure pam_pwhistory module is enabled (Automated) ............................................ 564
                  5.3.3 Configure PAM Arguments ................................................................................................... 567
                    5.3.3.1 Configure pam_faillock module ...................................................................................... 568
                         5.3.3.1.1 Ensure password failed attempts lockout is configured (Automated)...................... 569
                         5.3.3.1.2 Ensure password unlock time is configured (Automated) ....................................... 571
                         5.3.3.1.3 Ensure password failed attempts lockout includes root account (Automated) ........ 573
                    5.3.3.2 Configure pam_pwquality module .................................................................................. 576
                         5.3.3.2.1 Ensure password number of changed characters is configured (Automated) ........ 578
                         5.3.3.2.2 Ensure minimum password length is configured (Automated) ................................ 581
                         5.3.3.2.3 Ensure password complexity is configured (Manual) .............................................. 584
                         5.3.3.2.4 Ensure password same consecutive characters is configured (Automated) ........... 588
                         5.3.3.2.5 Ensure password maximum sequential characters is configured (Automated) ...... 591
                         5.3.3.2.6 Ensure password dictionary check is enabled (Automated) .................................... 594
                         5.3.3.2.7 Ensure password quality checking is enforced (Automated) ................................... 597
                         5.3.3.2.8 Ensure password quality is enforced for the root user (Automated) ....................... 599
                    5.3.3.3 Configure pam_pwhistory module ................................................................................. 602
                         5.3.3.3.1 Ensure password history remember is configured (Automated) ............................. 603
                         5.3.3.3.2 Ensure password history is enforced for the root user (Automated) ....................... 605
                         5.3.3.3.3 Ensure pam_pwhistory includes use_authtok (Automated) .................................... 607
                    5.3.3.4 Configure pam_unix module ........................................................................................... 609
                         5.3.3.4.1 Ensure pam_unix does not include nullok (Automated) .......................................... 610
                         5.3.3.4.2 Ensure pam_unix does not include remember (Automated) ................................... 613
                         5.3.3.4.3 Ensure pam_unix includes a strong password hashing algorithm (Automated) ..... 615
                         5.3.3.4.4 Ensure pam_unix includes use_authtok (Automated) ............................................. 619
                5.4 User Accounts and Environment ............................................................................................... 621
                  5.4.1 Configure shadow password suite parameters .................................................................. 622
                         5.4.1.1 Ensure password expiration is configured (Automated) ............................................. 623
                         5.4.1.2 Ensure minimum password days is configured (Manual) ........................................... 626
                         5.4.1.3 Ensure password expiration warning days is configured (Automated) ....................... 629
                         5.4.1.4 Ensure strong password hashing algorithm is configured (Automated) ..................... 631
                         5.4.1.5 Ensure inactive password lock is configured (Automated) ......................................... 633
                         5.4.1.6 Ensure all users last password change date is in the past (Automated) .................... 635
                  5.4.2 Configure root and system accounts and environment .................................................... 636
                         5.4.2.1 Ensure root is the only UID 0 account (Automated) ................................................... 637
                         5.4.2.2 Ensure root is the only GID 0 account (Automated) ................................................... 638
                         5.4.2.3 Ensure group root is the only GID 0 group (Automated) ............................................ 640
                         5.4.2.4 Ensure root account access is controlled (Automated) .............................................. 641
                         5.4.2.5 Ensure root path integrity (Automated) ....................................................................... 643
                         5.4.2.6 Ensure root user umask is configured (Automated) ................................................... 646
                         5.4.2.7 Ensure system accounts do not have a valid login shell (Automated) ....................... 649
                         5.4.2.8 Ensure accounts without a valid login shell are locked (Automated) ......................... 651
                  5.4.3 Configure user default environment .................................................................................... 653
                         5.4.3.1 Ensure nologin is not listed in /etc/shells (Automated) ............................................... 654
                         5.4.3.2 Ensure default user shell timeout is configured (Automated) ..................................... 656
                         5.4.3.3 Ensure default user umask is configured (Automated) .............................................. 660
              6 Logging and Auditing ......................................................................................................664
                6.1 System Logging ........................................................................................................................... 665
                  6.1.1 Configure journald ................................................................................................................. 666
                    6.1.1.1 Configure systemd-journald service .............................................................................. 667



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                         6.1.1.1.1 Ensure journald service is active (Automated) ........................................................ 668
                         6.1.1.1.2 Ensure journald log file access is configured (Manual) ........................................... 670
                         6.1.1.1.3 Ensure journald log file rotation is configured (Manual) .......................................... 673
                         6.1.1.1.4 Ensure journald ForwardToSyslog is disabled (Automated) ................................... 675
                         6.1.1.1.5 Ensure journald Storage is configured (Automated)................................................ 679
                         6.1.1.1.6 Ensure journald Compress is configured (Automated) ............................................ 683
                    6.1.1.2 Configure systemd-journal-remote................................................................................. 687
                         6.1.1.2.1 Ensure systemd-journal-remote is installed (Automated) ........................................ 688
                         6.1.1.2.2 Ensure systemd-journal-upload authentication is configured (Manual)................... 690
                         6.1.1.2.3 Ensure systemd-journal-upload is enabled and active (Automated) ....................... 693
                         6.1.1.2.4 Ensure systemd-journal-remote service is not in use (Automated) ......................... 695
                  6.1.2 Configure rsyslog................................................................................................................... 697
                         6.1.2.1 Ensure rsyslog is installed (Automated) ..................................................................... 698
                         6.1.2.2 Ensure rsyslog service is enabled and active (Automated) ........................................ 700
                         6.1.2.3 Ensure journald is configured to send logs to rsyslog (Automated) ........................... 702
                         6.1.2.4 Ensure rsyslog log file creation mode is configured (Automated) .............................. 706
                         6.1.2.5 Ensure rsyslog logging is configured (Manual) ........................................................... 708
                         6.1.2.6 Ensure rsyslog is configured to send logs to a remote log host (Manual) .................. 710
                         6.1.2.7 Ensure rsyslog is not configured to receive logs from a remote client (Automated) .. 712
                         6.1.2.8 Ensure logrotate is configured (Manual) ..................................................................... 714
                  6.1.3 Configure Logfiles.................................................................................................................. 716
                         6.1.3.1 Ensure access to all logfiles has been configured (Automated) ................................. 717
                6.2 System Auditing ........................................................................................................................... 722
                  6.2.1 Configure auditd Service ....................................................................................................... 724
                         6.2.1.1 Ensure auditd packages are installed (Automated) .................................................... 725
                         6.2.1.2 Ensure auditd service is enabled and active (Automated) ......................................... 727
                         6.2.1.3 Ensure auditing for processes that start prior to auditd is enabled (Automated) ....... 729
                         6.2.1.4 Ensure audit_backlog_limit is configured (Automated) .............................................. 731
                  6.2.2 Configure Data Retention ...................................................................................................... 733
                         6.2.2.1 Ensure audit log storage size is configured (Automated) ........................................... 734
                         6.2.2.2 Ensure audit logs are not automatically deleted (Automated) .................................... 736
                         6.2.2.3 Ensure system is disabled when audit logs are full (Automated) ............................... 737
                         6.2.2.4 Ensure system warns when audit logs are low on space (Automated) ...................... 740
                  6.2.3 Configure auditd Rules .......................................................................................................... 743
                         6.2.3.1 Ensure changes to system administration scope (sudoers) is collected (Automated)744
                         6.2.3.2 Ensure actions as another user are always logged (Automated) ............................... 746
                         6.2.3.3 Ensure events that modify the sudo log file are collected (Automated) ..................... 750
                         6.2.3.4 Ensure events that modify date and time information are collected (Automated) ...... 753
                         6.2.3.5 Ensure events that modify the system's network environment are collected
                         (Automated) ............................................................................................................................ 757
                         6.2.3.6 Ensure use of privileged commands are collected (Automated) ................................ 761
                         6.2.3.7 Ensure unsuccessful file access attempts are collected (Automated) ....................... 765
                         6.2.3.8 Ensure events that modify user/group information are collected (Automated) .......... 769
                         6.2.3.9 Ensure discretionary access control permission modification events are collected
                         (Automated) ............................................................................................................................ 773
                         6.2.3.10 Ensure successful file system mounts are collected (Automated) ........................... 778
                         6.2.3.11 Ensure session initiation information is collected (Automated) ................................ 782
                         6.2.3.12 Ensure login and logout events are collected (Automated) ...................................... 785
                         6.2.3.13 Ensure file deletion events by users are collected (Automated) .............................. 788
                         6.2.3.14 Ensure events that modify the system's Mandatory Access Controls are collected
                         (Automated) ............................................................................................................................ 792
                         6.2.3.15 Ensure successful and unsuccessful attempts to use the chcon command are
                         collected (Automated) ............................................................................................................. 795
                         6.2.3.16 Ensure successful and unsuccessful attempts to use the setfacl command are
                         collected (Automated) ............................................................................................................. 799



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                         6.2.3.17 Ensure successful and unsuccessful attempts to use the chacl command are
                         collected (Automated) ............................................................................................................. 803
                         6.2.3.18 Ensure successful and unsuccessful attempts to use the usermod command are
                         collected (Automated) ............................................................................................................. 807
                         6.2.3.19 Ensure kernel module loading unloading and modification is collected (Automated)
                          ................................................................................................................................................ 811
                         6.2.3.20 Ensure the audit configuration is immutable (Automated) ........................................ 816
                         6.2.3.21 Ensure the running and on disk configuration is the same (Manual) ....................... 818
                  6.2.4 Configure auditd File Access ................................................................................................ 820
                         6.2.4.1 Ensure audit log files mode is configured (Automated) .............................................. 821
                         6.2.4.2 Ensure audit log files owner is configured (Automated) ............................................. 824
                         6.2.4.3 Ensure audit log files group owner is configured (Automated) ................................... 826
                         6.2.4.4 Ensure the audit log file directory mode is configured (Automated) ........................... 828
                         6.2.4.5 Ensure audit configuration files mode is configured (Automated) .............................. 830
                         6.2.4.6 Ensure audit configuration files owner is configured (Automated) ............................. 832
                         6.2.4.7 Ensure audit configuration files group owner is configured (Automated) ................... 834
                         6.2.4.8 Ensure audit tools mode is configured (Automated)................................................... 836
                         6.2.4.9 Ensure audit tools owner is configured (Automated) .................................................. 838
                         6.2.4.10 Ensure audit tools group owner is configured (Automated) ..................................... 839
                6.3 Configure Filesystem Integrity Checking .................................................................................. 841
                         6.3.1 Ensure AIDE is installed (Automated) ........................................................................... 842
                         6.3.2 Ensure filesystem integrity is regularly checked (Automated) ....................................... 844
                         6.3.3 Ensure cryptographic mechanisms are used to protect the integrity of audit tools
                         (Automated) ............................................................................................................................ 847
              7 System Maintenance .......................................................................................................851
                7.1 Configure system file and directory access ............................................................................. 852
                       7.1.1 Ensure access to /etc/passwd is configured (Automated) ............................................. 853
                       7.1.2 Ensure access to /etc/passwd- is configured (Automated) ........................................... 855
                       7.1.3 Ensure access to /etc/group is configured (Automated) ................................................ 857
                       7.1.4 Ensure access to /etc/group- is configured (Automated)............................................... 859
                       7.1.5 Ensure access to /etc/shadow is configured (Automated) ............................................ 861
                       7.1.6 Ensure access to /etc/shadow- is configured (Automated) ........................................... 863
                       7.1.7 Ensure access to /etc/gshadow is configured (Automated) .......................................... 865
                       7.1.8 Ensure access to /etc/gshadow- is configured (Automated) ......................................... 867
                       7.1.9 Ensure access to /etc/shells is configured (Automated) ................................................ 869
                       7.1.10 Ensure access to /etc/security/opasswd is configured (Automated) ........................... 871
                       7.1.11 Ensure world writable files and directories are secured (Automated) ......................... 873
                       7.1.12 Ensure no files or directories without an owner and a group exist (Automated) ......... 877
                       7.1.13 Ensure SUID and SGID files are reviewed (Manual) ................................................... 880
                7.2 Local User and Group Settings .................................................................................................. 883
                       7.2.1 Ensure accounts in /etc/passwd use shadowed passwords (Automated) .................... 884
                       7.2.2 Ensure /etc/shadow password fields are not empty (Automated) ................................. 886
                       7.2.3 Ensure all groups in /etc/passwd exist in /etc/group (Automated) ................................. 888
                       7.2.4 Ensure shadow group is empty (Automated) ................................................................ 890
                       7.2.5 Ensure no duplicate UIDs exist (Automated) ................................................................. 892
                       7.2.6 Ensure no duplicate GIDs exist (Automated) ................................................................ 894
                       7.2.7 Ensure no duplicate user names exist (Automated) ...................................................... 896
                       7.2.8 Ensure no duplicate group names exist (Automated).................................................... 898
                       7.2.9 Ensure local interactive user home directories are configured (Automated) ................. 900
                       7.2.10 Ensure local interactive user dot files access is configured (Automated) ................... 905
            Appendix: Summary Table ....................................................................................... 910
            Appendix: CIS Controls v7 IG 1 Mapped Recommendations ................................ 926
            Appendix: CIS Controls v7 IG 2 Mapped Recommendations ................................ 930


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            Appendix: CIS Controls v7 IG 3 Mapped Recommendations ................................ 938
            Appendix: CIS Controls v7 Unmapped Recommendations ................................... 947
            Appendix: CIS Controls v8 IG 1 Mapped Recommendations ................................ 948
            Appendix: CIS Controls v8 IG 2 Mapped Recommendations ................................ 953
            Appendix: CIS Controls v8 IG 3 Mapped Recommendations ................................ 961
            Appendix: CIS Controls v8 Unmapped Recommendations ................................... 970
            Appendix: Change History ....................................................................................... 971




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            Overview
            All CIS Benchmarks™ (Benchmarks) focus on technical configuration settings used to
            maintain and/or increase the security of the addressed technology, and they should be
            used in conjunction with other essential cyber hygiene tasks like:
                 •   Monitoring the base operating system and applications for vulnerabilities and
                     quickly updating with the latest security patches.
                 •   End-point protection (Antivirus software, Endpoint Detection and Response
                     (EDR), etc.).
                 •   Logging and monitoring user and system activity.

            In the end, the Benchmarks are designed to be a key component of a comprehensive
            cybersecurity program.

            Important Usage Information
            All Benchmarks are available free for non-commercial use from the CIS Website. They
            can be used to manually assess and remediate systems and applications. In lieu of
            manual assessment and remediation, there are several tools available to assist with
            assessment:
                 •   CIS Configuration Assessment Tool (CIS-CAT® Pro Assessor)
                 •   CIS Benchmarks™ Certified 3rd Party Tooling

            These tools make the hardening process much more scalable for large numbers of
            systems and applications.

               NOTE:      Some tooling focuses only on the Benchmark Recommendations that can
                          be fully automated (skipping ones marked Manual). It is important that ALL
                          Recommendations (Automated and Manual) be addressed since all are
                          important for properly securing systems and are typically in scope for
                          audits.

            Key Stakeholders
            Cybersecurity is a collaborative effort, and cross functional cooperation is imperative
            within an organization to discuss, test, and deploy Benchmarks in an effective and
            efficient way. The Benchmarks are developed to be best practice configuration
            guidelines applicable to a wide range of use cases. In some organizations, exceptions
            to specific Recommendations will be needed, and this team should work to prioritize the
            problematic Recommendations based on several factors like risk, time, cost, and labor.
            These exceptions should be properly categorized and documented for auditing
            purposes.




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            Apply the Correct Version of a Benchmark
            Benchmarks are developed and tested for a specific set of products and versions and
            applying an incorrect Benchmark to a system can cause the resulting pass/fail score to
            be incorrect. This is due to the assessment of settings that do not apply to the target
            systems. To assure the correct Benchmark is being assessed:
                 •   Deploy the Benchmark applicable to the way settings are managed in the
                     environment: An example of this is the Microsoft Windows family of
                     Benchmarks, which have separate Benchmarks for Group Policy, Intune, and
                     Stand-alone systems based upon how system management is deployed.
                     Applying the wrong Benchmark in this case will give invalid results.

                 •   Use the most recent version of a Benchmark: This is true for all Benchmarks,
                     but especially true for cloud technologies. Cloud technologies change frequently
                     and using an older version of a Benchmark may have invalid methods for
                     auditing and remediation.

            Exceptions
            The guidance items in the Benchmarks are called recommendations and not
            requirements, and exceptions to some of them are expected and acceptable. The
            Benchmarks strive to be a secure baseline, or starting point, for a specific technology,
            with known issues identified during Benchmark development are documented in the
            Impact section of each Recommendation. In addition, organizational, system specific
            requirements, or local site policy may require changes as well, or an exception to a
            Recommendation or group of Recommendations (e.g. A Benchmark could Recommend
            that a Web server not be installed on the system, but if a system's primary purpose is to
            function as a Webserver, there should be a documented exception to this
            Recommendation for that specific server).

            In the end, exceptions to some Benchmark Recommendations are common and
            acceptable, and should be handled as follows:
                 •   The reasons for the exception should be reviewed cross-functionally and be well
                     documented for audit purposes.
                 •   A plan should be developed for mitigating, or eliminating, the exception in the
                     future, if applicable.
                 •   If the organization decides to accept the risk of this exception (not work toward
                     mitigation or elimination), this should be documented for audit purposes.

            It is the responsibility of the organization to determine their overall security policy, and
            which settings are applicable to their unique needs based on the overall risk profile for
            the organization.




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            Remediation
            CIS has developed Build Kits for many technologies to assist in the automation of
            hardening systems. Build Kits are designed to correspond to Benchmark's
            “Remediation” section, which provides the manual remediation steps necessary to make
            that Recommendation compliant to the Benchmark.

                  When remediating systems (changing configuration settings on
                  deployed systems as per the Benchmark's Recommendations),
                      please approach this with caution and test thoroughly.

            The following is a reasonable remediation approach to follow:
               • CIS Build Kits, or internally developed remediation methods should never be
                   applied to production systems without proper testing.
               • Proper testing consists of the following:
                   o Understand the configuration (including installed applications) of the targeted
                      systems. Various parts of the organization may need different configurations
                      (e.g., software developers vs standard office workers).
                   o Read the Impact section of the given Recommendation to help determine if
                      there might be an issue with the targeted systems.
                   o Test the configuration changes with representative lab system(s). If issues
                      arise during testing, they can be resolved prior to deploying to any production
                      systems.
                   o When testing is complete, initially deploy to a small sub-set of production
                      systems and monitor closely for issues. If there are issues, they can be
                      resolved prior to deploying more broadly.
                   o When the initial deployment above is completes successfully, iteratively
                      deploy to additional systems and monitor closely for issues. Repeat this
                      process until the full deployment is complete.
            Summary
            Using the Benchmarks Certified tools, working as a team with key stakeholders, being
            selective with exceptions, and being careful with remediation deployment, it is possible
            to harden large numbers of deployed systems in a cost effective, efficient, and safe
            manner.

               NOTE: As previously stated, the PDF versions of the CIS Benchmarks™ are
                     available for free, non-commercial use on the CIS Website. All other formats
                     of the CIS Benchmarks™ (MS Word, Excel, and Build Kits) are available for
                     CIS SecureSuite® members.

                          CIS-CAT® Pro is also available to CIS SecureSuite® members.




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            Target Technology Details
            This document provides prescriptive guidance for establishing a secure configuration
            posture for Ubuntu Linux 22.04 LTS running on x86_64 platforms.
            This guide was developed and tested against Ubuntu 22.04.5 LTS
            The guidance within broadly assumes that operations are being performed as the root
            user, and executed under the default Bash version for the applicable distribution.
            Operations performed using sudo instead of the root user, or executed under another
            shell, may produce unexpected results, or fail to make the intended changes to the
            system. Non-root users may not be able to access certain areas of the system,
            especially after remediation has been performed. It is advisable to verify root users
            path integrity and the integrity of any programs being run prior to execution of
            commands and scripts included in this benchmark.
            The default prompt for the root user is #, and as such all sample commands will have #
            as an additional indication that it is to be executed as root.
            To obtain the latest version of this guide, please visit https://workbench.cisecurity.org. If
            you have questions, comments, or have identified ways to improve this guide, please
            write us at feedback@cisecurity.org.


            Intended Audience
            This benchmark is intended for system and application administrators, security
            specialists, auditors, help desk, and platform deployment personnel who plan to
            develop, deploy, assess, or secure solutions that incorporate Ubuntu Linux 22.04 LTS
            on x86_64 platforms.




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            Consensus Guidance
            This CIS Benchmark™ was created using a consensus review process comprised of a
            global community of subject matter experts. The process combines real world
            experience with data-based information to create technology specific guidance to assist
            users to secure their environments. Consensus participants provide perspective from a
            diverse set of backgrounds including consulting, software development, audit and
            compliance, security research, operations, government, and legal.
            Each CIS Benchmark undergoes two phases of consensus review. The first phase
            occurs during initial Benchmark development. During this phase, subject matter experts
            convene to discuss, create, and test working drafts of the Benchmark. This discussion
            occurs until consensus has been reached on Benchmark recommendations. The
            second phase begins after the Benchmark has been published. During this phase, all
            feedback provided by the Internet community is reviewed by the consensus team for
            incorporation in the Benchmark. If you are interested in participating in the consensus
            process, please visit https://workbench.cisecurity.org/.




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            Typographical Conventions
            The following typographical conventions are used throughout this guide:
              Convention                             Meaning
                                                     Used for blocks of code, command, and
               Stylized Monospace font               script examples. Text should be interpreted
                                                     exactly as presented.
                                                     Used for inline code, commands, UI/Menu
              Monospace font                         selections or examples. Text should be
                                                     interpreted exactly as presented.
                                                     Text set in angle brackets denote a variable
              <Monospace font in brackets>
                                                     requiring substitution for a real value.
                                                     Used to reference other relevant settings,
                                                     CIS Benchmarks and/or Benchmark
              Italic font
                                                     Communities. Also, used to denote the title
                                                     of a book, article, or other publication.
                                                     Additional information or caveats things like
                                                     Notes, Warnings, or Cautions (usually just
              Bold font
                                                     the word itself and the rest of the text
                                                     normal).




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            Recommendation Definitions
            The following defines the various components included in a CIS recommendation as
            applicable. If any of the components are not applicable it will be noted, or the
            component will not be included in the recommendation.

            Title
            Concise description for the recommendation's intended configuration.

            Assessment Status
            An assessment status is included for every recommendation. The assessment status
            indicates whether the given recommendation can be automated or requires manual
            steps to implement. Both statuses are equally important and are determined and
            supported as defined below:

            Automated
            Represents recommendations for which assessment of a technical control can be fully
            automated and validated to a pass/fail state. Recommendations will include the
            necessary information to implement automation.

            Manual
            Represents recommendations for which assessment of a technical control cannot be
            fully automated and requires all or some manual steps to validate that the configured
            state is set as expected. The expected state can vary depending on the environment.

            Profile
            A collection of recommendations for securing a technology or a supporting platform.
            Most benchmarks include at least a Level 1 and Level 2 Profile. Level 2 extends Level 1
            recommendations and is not a standalone profile. The Profile Definitions section in the
            benchmark provides the definitions as they pertain to the recommendations included for
            the technology.

            Description
            Detailed information pertaining to the setting with which the recommendation is
            concerned. In some cases, the description will include the recommended value.

            Rationale Statement
            Detailed reasoning for the recommendation to provide the user a clear and concise
            understanding on the importance of the recommendation.



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            Impact Statement
            Any security, functionality, or operational consequences that can result from following
            the recommendation.

            Audit Procedure
            Systematic instructions for determining if the target system complies with the
            recommendation.

            Remediation Procedure
            Systematic instructions for applying recommendations to the target system to bring it
            into compliance according to the recommendation.

            Default Value
            Default value for the given setting in this recommendation, if known. If not known, either
            not configured or not defined will be applied.

            References
            Additional documentation relative to the recommendation.

            CIS Critical Security Controls® (CIS Controls®)
            The mapping between a recommendation and the CIS Controls is organized by CIS
            Controls version, Safeguard, and Implementation Group (IG). The Benchmark in its
            entirety addresses the CIS Controls safeguards of (v7) “5.1 - Establish Secure
            Configurations” and (v8) '4.1 - Establish and Maintain a Secure Configuration Process”
            so individual recommendations will not be mapped to these safeguards.

            Additional Information
            Supplementary information that does not correspond to any other field but may be
            useful to the user.




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            Profile Definitions
            The following configuration profiles are defined by this Benchmark:
               • Level 1 - Server

                     Items in this profile intend to:

                          o   be practical and prudent;
                          o   provide a clear security benefit; and
                          o   not inhibit the utility of the technology beyond acceptable means.

                     This profile is intended for servers.

                 •   Level 2 - Server

                     This profile extends the "Level 1 - Server" profile. Items in this profile exhibit one
                     or more of the following characteristics:

                          o   are intended for environments or use cases where security is paramount.
                          o   acts as defense in depth measure.
                          o   may negatively inhibit the utility or performance of the technology.

                     This profile is intended for servers.

                 •   Level 1 - Workstation

                     Items in this profile intend to:

                          o   be practical and prudent;
                          o   provide a clear security benefit; and
                          o   not inhibit the utility of the technology beyond acceptable means.

                     This profile is intended for workstations.

                 •   Level 2 - Workstation

                     This profile extends the "Level 1 - Workstation" profile. Items in this profile exhibit
                     one or more of the following characteristics:

                          o   are intended for environments or use cases where security is paramount.
                          o   acts as defense in depth measure.
                          o   may negatively inhibit the utility or performance of the technology.

                     This profile is intended for workstations.




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            Acknowledgements
            This Benchmark exemplifies the great things a community of users, vendors, and
            subject matter experts can accomplish through consensus collaboration. The CIS
            community thanks the entire consensus team with special recognition to the following
            individuals who contributed greatly to the creation of this guide:
            This benchmark is based upon previous Linux benchmarks published and would not be
            possible without the contributions provided over the history of all of these benchmarks.
            The CIS community thanks everyone who has contributed to the Linux benchmarks.

            Contributor
            Ron Colvin
            Dave Billing
            Dominic Pace
            Koen Laevens
            Mark Birch
            Thomas Sjögren
            James Trigg
            Matthew Burket
            Marcus Burghardt
            Graham Eames
            Robert McSulla
            Chad Streck
            Ryan Jaynes
            Cory Sherman
            Simon John
            Steve Cobrin
            Justin Brown
            Mike Cross
            Kleber Leal
            Laurent Mesure

            Editor
            Jonathan Lewis Christopherson
            Eric Pinnell
            Randie Bejar
            Gokhan Lus
            Trevor Wood




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            Recommendations
            1 Initial Setup
            Items in this section are advised for all systems but may be difficult or require extensive
            preparation after the initial setup of the system.

            1.1 Filesystem

            The file system is generally a built-in layer used to handle the data management of the
            storage.




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            1.1.1 Configure Filesystem Kernel Modules

            Several uncommon filesystem types are supported under Linux. Removing support for
            unneeded filesystem types reduces the local attack surface of the system. If a
            filesystem type is not needed it should be disabled. Native Linux file systems are
            designed to ensure that built-in security controls function as expected. Non-native
            filesystems can lead to unexpected consequences to both the security and functionality
            of the system and should be used with caution. Many filesystems are created for niche
            use cases and are not maintained and supported as the operating systems are updated
            and patched. Users of non-native filesystems should ensure that there is attention and
            ongoing support for them, especially in light of frequent operating system changes.
            Standard network connectivity and Internet access to cloud storage may make the use
            of non-standard filesystem formats to directly attach heterogeneous devices much less
            attractive.
            Note: This should not be considered a comprehensive list of filesystems. You may wish
            to consider additions to those listed here for your environment. For the current available
            file system modules on the system see ls /usr/lib/modules/**/kernel/fs | sort
            -u.
            Start up scripts
            Kernel modules loaded directly via insmod will ignore what is configured in the relevant
            /etc/modprobe.d/*.conf files. If modules are still being loaded after a reboot whilst
            having the correctly configured blacklist and install command, check for insmod
            entries in start up scripts such as .bashrc.
            Return values
            Using /bin/false as the command in disabling a particular module serves two
            purposes; to convey the meaning of the entry to the user and cause a non-zero return
            value. The latter can be tested for in scripts. Please note that insmod will ignore what is
            configured in the relevant configuration files. The preferred way to load modules is with
            modprobe.




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            1.1.1.1 Ensure cramfs kernel module is not available (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The cramfs filesystem type is a compressed read-only Linux filesystem embedded in
            small footprint systems. A cramfs image can be used without having to first
            decompress the image.
            Rationale:
            Removing support for unneeded filesystem types reduces the local attack surface of the
            system. If this filesystem type is not needed, disable it.
            Audit:
            Verify the cramfs kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the cramfs kernel module is available on
                    the system:

            #!/usr/bin/env bash

            {
                 l_mod_name="cramfs" l_mod_type="fs"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the cramfs kernel module is not available on the system and no
            further audit steps are required.

            Note: Some systems may include the cramfs filesystem as part of the kernel opposed
            to being available as a kernel module. In this case, the above audit will not return
            anything. This is also considered a passing state.

            If anything is returned by the above script:




                                                                                               Page 23

Internal Only - General
                 2. verify the cramfs kernel module is not loaded and not loadable by performing the
                    following:

            Run the following command to verify the cramfs kernel module is not loaded:
            # lsmod | grep 'cramfs'
            Nothing should be returned.
            Run the following command to verify the cramfs kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+cramfs\b'
            Verify the output includes:
            blacklist cramfs
             -AND EITHER-
            install cramfs /bin/false
             -OR-
            install cramfs /bin/true
            Example output:
            blacklist cramfs
            install cramfs /bin/false

            Remediation:
            Unload and disable the cramfs kernel module.

                 1. Run the following commands to unload the cramfs kernel module:

            # modprobe -r cramfs 2>/dev/null
            # rmmod cramfs 2>/dev/null

                 2. Perform the following to disable the cramfs kernel module:

            Create a file ending in .conf with install cramfs /bin/false in the
            /etc/modprobe.d/ directory.
            Example:
            # printf '%s\n' "" "install cramfs /bin/false" >> /etc/modprobe.d/60-
            cramfs.conf
            Create a file ending in .conf with blacklist cramfs in the /etc/modprobe.d/
            directory.
            Example:
            # printf '%s\n' "" "blacklist cramfs" >> /etc/modprobe.d/60-cramfs.conf




                                                                                             Page 24

Internal Only - General
            References:

                 1. CCI-000381
                 2. NIST SP 800-53: CM-7 a
                 3. NIST SP 800-53A :: CM-7.1 (ii)
                 4. STIG ID: RHEL-08-040025 | RULE ID: SV-230498r1069314 | CAT III
                 5. STIG ID: OL08-00-040025 | RULE ID: SV-248833r958478 | CAT III
                 6. STIG ID: RHEL-09-231195 | RULE ID: SV-257880r1044951 | CAT III
                 7. STIG ID: ALMA-09-029940 | RULE ID: SV-269344r1050226 | CAT II
                 8. STIG ID: OL09-00-000045 | RULE ID: SV-271448r1091056 | CAT III

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●      ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●      ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                       Page 25

Internal Only - General
            1.1.1.2 Ensure freevxfs kernel module is not available
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The freevxfs filesystem type is a free version of the Veritas type filesystem. This is the
            primary filesystem type for HP-UX operating systems.
            Rationale:
            Removing support for unneeded filesystem types reduces the local attack surface of the
            system. If this filesystem type is not needed, disable it.
            Audit:
            Verify the freevxfs kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the freevxfs kernel module is available
                    on the system:

            #!/usr/bin/env bash

            {
                 l_mod_name="freevxfs" l_mod_type="fs"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the freevxfs kernel module is not available on the system and
            no further audit steps are required.

            Note: Some systems may include the freevxfs filesystem as part of the kernel
            opposed to being available as a kernel module. In this case, the above audit will not
            return anything. This is also considered a passing state.

            If anything is returned by the above script:




                                                                                               Page 26

Internal Only - General
                 2. Verify the freevxfs kernel module is not loaded and not loadable by performing
                    the following:

            Run the following command to verify the freevxfs kernel module is not loaded:
            # lsmod | grep 'freevxfs'
            Nothing should be returned.
            Run the following command to verify the freevxfs kernel module is not loadable:
            modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+freevxfs\b'
            Verify the output includes:
            blacklist freevxfs
             -AND-
            install freevxfs /bin/false
             -OR-
            install freevxfs /bin/true
            Example output:
            blacklist freevxfs
            install freevxfs /bin/false

            Remediation:
            Unload and disable the freevxfs kernel module.

                 1. Run the following commands to unload the freevxfs kernel module:

            # modprobe -r freevxfs 2>/dev/null
            # rmmod freevxfs 2>/dev/null

                 2. Perform the following to disable the freevxfs kernel module:

            Create a file ending in .conf with install freevxfs /bin/false in the
            /etc/modprobe.d/ directory.
            Example:
            # printf '%s\n' "" "install freevxfs /bin/false" >> /etc/modprobe.d/60-
            freevxfs.conf
            Create a file ending in .conf with blacklist freevxfs in the /etc/modprobe.d/
            directory.
            Example:
            # printf '%s\n' "" "blacklist freevxfs" >> /etc/modprobe.d/60-freevxfs.conf

            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)



                                                                                            Page 27

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●      ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●      ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                       Page 28

Internal Only - General
            1.1.1.3 Ensure hfs kernel module is not available (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The hfs filesystem type is a hierarchical filesystem that allows you to mount Mac OS
            filesystems.
            Rationale:
            Removing support for unneeded filesystem types reduces the local attack surface of the
            system. If this filesystem type is not needed, disable it.
            Audit:
            Verify the hfs kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the hfs kernel module is available on the
                    system:

            #!/usr/bin/env bash

            {
                 l_mod_name="hfs" l_mod_type="fs"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the hfs kernel module is not available on the system and no
            further audit steps are required.
            Note: Some systems may include the hfs filesystem as part of the kernel opposed to
            being available as a kernel module. In this case, the above audit will not return anything.
            This is also considered a passing state.
            If anything is returned by the above script:




                                                                                                Page 29

Internal Only - General
                 2. Verify the hfs kernel module is not loaded and not loadable by performing the
                    following:

            Run the following command to verify the hfs kernel module is not loaded:
            # lsmod | grep 'hfs'
            Nothing should be returned.
            Run the following command to verify the hfs kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+hfs\b'
            Verify the output includes:
            blacklist hfs
             -AND-
            install hfs /bin/false
             -OR-
            install hfs /bin/true
            Example output:
            blacklist hfs
            install hfs /bin/false

            Remediation:
            Unload and disable the hfs kernel module.

                 1. Run the following commands to unload the hfs kernel module:

            modprobe -r hfs 2>/dev/null
            rmmod hfs 2>/dev/null

                 2. Perform the following to disable the hfs kernel module:

            Create a file ending in .conf with install hfs /bin/false in the /etc/modprobe.d/
            directory.
            Example:
            # printf '%s\n' "" "install hfs /bin/false" >> /etc/modprobe.d/60-hfs.conf
            Create a file ending in .conf with blacklist hfs in the /etc/modprobe.d/ directory.
            Example:
            printf '%s\n' "" "blacklist hfs" >> /etc/modprobe.d/60-hfs.conf

            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)




                                                                                             Page 30

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●      ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●      ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                       Page 31

Internal Only - General
            1.1.1.4 Ensure hfsplus kernel module is not available (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The hfsplus filesystem type is a hierarchical filesystem designed to replace hfs that
            allows you to mount Mac OS filesystems.
            Rationale:
            Removing support for unneeded filesystem types reduces the local attack surface of the
            system. If this filesystem type is not needed, disable it.
            Audit:
            Verify the hfsplus kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the hfsplus kernel module is available on
                    the system:

            #!/usr/bin/env bash

            {
                 l_mod_name="hfsplus" l_mod_type="fs"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the hfsplus kernel module is not available on the system and no
            further audit steps are required.
            Note: Some systems may include the hfsplus filesystem as part of the kernel opposed
            to being available as a kernel module. In this case, the above audit will not return
            anything. This is also considered a passing state.
            If anything is returned by the above script:




                                                                                               Page 32

Internal Only - General
                 2. Verify the hfsplus kernel module is not loaded and not loadable by performing
                    the following:

            Run the following command to verify the hfsplus kernel module is not loaded:
            # lsmod | grep 'hfsplus'
            Nothing should be returned.
            Run the following command to verify the hfsplus kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+hfsplus\b'
            Verify the output includes:
            blacklist hfsplus
             -AND-
            install hfsplus /bin/false
             -OR-
            install hfsplus /bin/true
            Example output:
            blacklist hfsplus
            install hfsplus /bin/false

            Remediation:
            Unload and disable the hfsplus kernel module.

                 1. Run the following commands to unload the hfsplus kernel module:

            # modprobe -r hfsplus 2>/dev/null
            # rmmod hfsplus 2>/dev/null

                 2. Perform the following to disable the hfsplus kernel module:

            Create a file ending in .conf with install hfsplus /bin/false in the
            /etc/modprobe.d/ directory.
            Example:
            # printf '%s\n' "" "install hfsplus /bin/false" >> /etc/modprobe.d/60-
            hfsplus.conf
            Create a file ending in .conf with blacklist hfsplus in the /etc/modprobe.d/
            directory.
            Example:
            # printf '%s\n' "" "blacklist hfsplus" >> /etc/modprobe.d/60-hfsplus.conf

            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)



                                                                                             Page 33

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●      ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●      ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                       Page 34

Internal Only - General
            1.1.1.5 Ensure jffs2 kernel module is not available (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The jffs2 (journaling flash filesystem 2) filesystem type is a log-structured filesystem
            used in flash memory devices.
            Rationale:
            Removing support for unneeded filesystem types reduces the local attack surface of the
            system. If this filesystem type is not needed, disable it.
            Audit:
            Verify the jffs2 kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the jffs2 kernel module is available on
                    the system:

            #!/usr/bin/env bash

            {
                 l_mod_name="jffs2" l_mod_type="fs"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the jffs2 kernel module is not available on the system and no
            further audit steps are required.
            Note: Some systems may include the jffs2 filesystem as part of the kernel opposed to
            being available as a kernel module. In this case, the above audit will not return anything.
            This is also considered a passing state.
            If anything is returned by the above script:




                                                                                               Page 35

Internal Only - General
                 2. Verify the jffs2 kernel module is not loaded and not loadable by performing the
                    following:

            Run the following command to verify the jffs2 kernel module is not loaded:
            lsmod | grep 'jffs2'
            Nothing should be returned.
            Run the following command to verify the jffs2 kernel module is not loadable:
            modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+jffs2\b'
            Verify the output includes:
            blacklist jffs2
             -AND-
            install jffs2 /bin/false
             -OR-
            install jffs2 /bin/true
            Example output:
            blacklist jffs2
            install jffs2 /bin/false

            Remediation:
            Unload and disable the jffs2 kernel module.

                 1. Run the following commands to unload the jffs2 kernel module:

            # modprobe -r jffs2 2>/dev/null
            # rmmod jffs2 2>/dev/null

                 2. Perform the following to disable the jffs2 kernel module:

            Create a file ending in .conf with install jffs2 /bin/false in the
            /etc/modprobe.d/ directory.
            Example:
            # printf '%s\n' "" "install jffs2 /bin/false" >> /etc/modprobe.d/60-
            jffs2.conf
            Create a file ending in .conf with blacklist jffs2 in the /etc/modprobe.d/
            directory.
            Example:
            # printf '%s\n' "" "blacklist jffs2" >> /etc/modprobe.d/60-jffs2.conf

            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)



                                                                                             Page 36

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●      ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●      ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                       Page 37

Internal Only - General
            1.1.1.6 Ensure overlay kernel module is not available (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The Linux overlay kernel module, commonly referred to as Overlayfs, is a union mount
            filesystem. It allows the user to overlay one file system on top of another, and creates a
            single, unified view.
            Rationale:
            The overlay kernel module has known CVE's: CVE-2023-32629, CVE-2023-2640, and
            CVE-2023-0386. Disabling the overlay kernel module reduces the local attack surface
            by removing support for unnecessary filesystem types and mitigates potential risks
            associated with unauthorized execution of setuid files, enhancing the overall system
            security.
            Impact:
            WARNING: If Container applications such as Docker, Kubernetes, Podman, Linux
            Containers (LXC), etc. are in use proceed with caution and consider the impact on
            containerized workloads, as disabling the overlay may severely disrupt
            containerization.
            Audit:
            Verify the overlay kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the overlay kernel module is available on
                    the system:

            #!/usr/bin/env bash

            {
                 l_mod_name="overlayfs" l_mod_type="fs"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the overlay kernel module is not available on the system and no
            further audit steps are required.



                                                                                               Page 38

Internal Only - General
            Note: Some systems may include the overlay kernel module as part of the kernel
            opposed to being available as a kernel module. In this case, the above audit will not
            return anything. This is also considered a passing state.
            If anything is returned by the above script:

                 2. Verify the overlay kernel module is not loaded and not loadable by performing
                    the following:

            Run the following command to verify the overlay kernel module is not loaded:
            # lsmod | grep 'overlay'
            Nothing should be returned
            Run the following command to verify the overlay kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+overlay\b'
            Verify the output includes:
            blacklist overlay
             -AND-
            install overlay /bin/false
             -OR-
            install overlay /bin/true
            Example output:
            blacklist overlay
            install overlay /bin/false

            Remediation:
            Unload and disable the overlay kernel module.

                 1. Run the following commands to unload the overlay kernel module:

            # modprobe -r overlay 2>/dev/null
            # rmmod overlay 2>/dev/null

                 2. Perform the following to disable the overlay kernel module:

            Create a file ending in .conf with install overlay /bin/false in the
            /etc/modprobe.d/ directory
            Example:
            # printf '%s\n' "" "install overlay /bin/false" >> /etc/modprobe.d/60-
            overlay.conf
            Create a file ending in .conf with blacklist overlay in the /etc/modprobe.d/
            directory
            Example:
            # printf '%s\n' "" "blacklist overlay" >> /etc/modprobe.d/60-overlay.conf




                                                                                              Page 39

Internal Only - General
            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)
                 4. https://docs.kernel.org/filesystems/overlayfs.html
                 5. https://wiki.archlinux.org/title/Overlay_filesystem
                 6. https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=overlayfs

            CIS Controls:

               Controls
                                                             Control                                          IG 1 IG 2 IG 3
               Version
                           4.8 Uninstall or Disable Unnecessary Services on
                           Enterprise Assets and Software
                    v8        Uninstall or disable unnecessary services on enterprise assets and software,          ●      ●
                           such as an unused file sharing service, web application module, or service
                           function.

                           9.2 Ensure Only Approved Ports, Protocols and Services
                    v7     Are Running                                                                              ●      ●
                              Ensure that only network ports, protocols, and services listening on a system
                           with validated business needs, are running on each system.




                                                                                                                        Page 40

Internal Only - General
            1.1.1.7 Ensure squashfs kernel module is not available
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The squashfs filesystem type is a compressed read-only Linux filesystem embedded in
            small footprint systems. A squashfs image can be used without having to first
            decompress the image.
            Rationale:
            Removing support for unneeded filesystem types reduces the local attack surface of the
            system. If this filesystem type is not needed, disable it.
            Impact:
            As Snap packages utilize squashfs as a compressed filesystem, disabling squashfs
            will cause Snap packages to fail.
            Snap application packages of software are self-contained and work across a range of
            Linux distributions. This is unlike traditional Linux package management approaches,
            like APT or RPM, which require specifically adapted packages per Linux distribution on
            an application update and delay therefore application deployment from developers to
            their software's end-user. Snaps themselves have no dependency on any external store
            ("App store"), can be obtained from any source and can be therefore used for upstream
            software deployment.




                                                                                           Page 41

Internal Only - General
            Audit:
            Verify the squashfs kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the squashfs kernel module is available
                    on the system:

            #!/usr/bin/env bash

            {
                 l_mod_name="squashfs" l_mod_type="fs"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the squashfs kernel module is not available on the system and
            no further audit steps are required.
            Note: Some systems may include the squashfs filesystem as part of the kernel
            opposed to being available as a kernel module. In this case, the above audit will not
            return anything. This is also considered a passing state.
            If anything is returned by the above script:

                 2. Verify the squashfs kernel module is not loaded and not loadable by performing
                    the following:

            Run the following command to verify the squashfs kernel module is not loaded:
            # lsmod | grep 'squashfs'
            Nothing should be returned.
            Run the following command to verify the squashfs kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+squashfs\b'
            Verify the output includes:
            blacklist squashfs
             -AND-
            install squashfs /bin/false
             -OR-
            install squashfs /bin/true
            Example output:
            blacklist squashfs
            install squashfs /bin/false




                                                                                               Page 42

Internal Only - General
            Remediation:
            Unload and disable the squashfs kernel module.

                 1. Run the following commands to unload the squashfs kernel module:

            # modprobe -r squashfs 2>/dev/null
            # rmmod squashfs 2>/dev/null

                 2. Perform the following to disable the squashfs kernel module:

            Create a file ending in .conf with install squashfs /bin/false in the
            /etc/modprobe.d/ directory.
            Example:
            # printf '%s\n' "" "install squashfs /bin/false" >> /etc/modprobe.d/60-
            squashfs.conf
            Create a file ending in .conf with blacklist squashfs in the /etc/modprobe.d/
            directory.
            Example:
            # printf '%s\n' "" "blacklist squashfs" >> /etc/modprobe.d/60-squashfs.conf

            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)
                 4. STIG ID: ALMA-09-030160 | RULE ID: SV-269346r1050228 | CAT II

            CIS Controls:

               Controls
                                                             Control                                          IG 1 IG 2 IG 3
               Version
                           4.8 Uninstall or Disable Unnecessary Services on
                           Enterprise Assets and Software
                    v8        Uninstall or disable unnecessary services on enterprise assets and software,          ●      ●
                           such as an unused file sharing service, web application module, or service
                           function.

                           9.2 Ensure Only Approved Ports, Protocols and Services
                    v7     Are Running                                                                              ●      ●
                              Ensure that only network ports, protocols, and services listening on a system
                           with validated business needs, are running on each system.




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            1.1.1.8 Ensure udf kernel module is not available (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The udf filesystem type is the universal disk format used to implement ISO/IEC 13346
            and ECMA-167 specifications. This is an open vendor filesystem type for data storage
            on a broad range of media. This filesystem type is necessary to support writing DVDs
            and newer optical disc formats.
            Rationale:
            Removing support for unneeded filesystem types reduces the local attack surface of the
            system. If this filesystem type is not needed, disable it.
            Impact:
            Microsoft Azure requires the usage of udf.
            udf should not be disabled on systems run on Microsoft Azure.

            Audit:
            Verify the udf kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the udf kernel module is available on the
                    system:

            #!/usr/bin/env bash

            {
                 l_mod_name="udf" l_mod_type="fs"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the udf kernel module is not available on the system and no
            further audit steps are required.
            Note: Some systems may include the udf filesystem as part of the kernel opposed to
            being available as a kernel module. In this case, the above audit will not return anything.
            This is also considered a passing state.
            If anything is returned by the above script:


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                 2. Verify the udf kernel module is not loaded and not loadable by performing the
                    following:

            Run the following command to verify the udf kernel module is not loaded:
            # lsmod | grep 'udf'
            Nothing should be returned
            Run the following command to verify the udf kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+udf\b'
            Verify the output includes:
            blacklist udf
             -AND-
            install udf /bin/false
             -OR-
            install udf /bin/true
            Example output:
            blacklist udf
            install udf /bin/false

            Remediation:
            Unload and disable the udf kernel module.

                 1. Run the following commands to unload the udf kernel module:

            # modprobe -r udf 2>/dev/null
            # rmmod udf 2>/dev/null

                 2. Perform the following to disable the udf kernel module:

            Create a file ending in .conf with install udf /bin/false in the /etc/modprobe.d/
            directory
            Example:
            # printf '%s\n' "" "install udf /bin/false" >> /etc/modprobe.d/60-udf.conf
            Create a file ending in .conf with blacklist udf in the /etc/modprobe.d/ directory
            Example:
            # printf '%s\n' "" "blacklist udf" >> /etc/modprobe.d/60-udf.conf

            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)
                 4. STIG ID: ALMA-09-030380 | RULE ID: SV-269348r1050230 | CAT II




                                                                                             Page 45

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            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●      ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●      ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            1.1.1.9 Ensure usb-storage kernel module is not available
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 2 - Workstation
            Description:
            USB storage provides a means to transfer and store files ensuring persistence and
            availability of the files independent of network connection status. Its popularity and utility
            has led to USB-based malware being a simple and common means for network
            infiltration and a first step to establishing a persistent threat within a networked
            environment.
            Rationale:
            Restricting USB access on the system will decrease the physical attack surface for a
            device and diminish the possible vectors to introduce malware.
            Satisfies: SRG-OS-000114-GPOS-00059, SRG-OS-000378-GPOS-00163
            Impact:
            Disabling the usb-storage module will disable any usage of USB storage devices.
            If requirements and local site policy allow the use of such devices, other solutions
            should be configured accordingly instead. One example of a commonly used solution is
            USBGuard.




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            Audit:
            Verify the usb-storage kernel module is not available on the system or has been
            disabled.

                 1. Run the following script to determine if the usb-storage kernel module is
                    available on the system:

            #!/usr/bin/env bash

            {
                 l_mod_name="usb-storage" l_mod_type="drivers"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the usb-storage kernel module is not available on the system
            and no further audit steps are required.
            Note: Some systems may include the usb-storage filesystem as part of the kernel
            opposed to being available as a kernel module. In this case, the above audit will not
            return anything. This is also considered a passing state.
            If anything is returned by the above script:

                 2. Verify the usb-storage kernel module is not loaded and not loadable by
                    performing the following:

            Run the following command to verify the usb-storage kernel module is not loaded:
            # lsmod | grep -P -- 'usb(_|-)storage'
            Nothing should be returned
            Run the following command to verify the usb-storage kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+usb_storage\b'
            Verify the output includes:
            blacklist usb_storage
             -AND-
            install usb_storage /bin/false
             -OR-
            install usb_storage /bin/true
            Example output:
            blacklist usb_storage
            install usb_storage /bin/false




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            Remediation:
            Unload and disable the usb-storage kernel module.

                 1. Run the following commands to unload the usb-storage kernel module:

            # modprobe -r usb-storage 2>/dev/null
            # rmmod usb-storage 2>/dev/null

                 2. Perform the following to disable the usb-storage kernel module:

            Create a file ending in .conf with install usb_storage /bin/false in the
            /etc/modprobe.d/ directory
            Example:
            # printf '%s\n' "" "install usb_storage /bin/false" >> /etc/modprobe.d/60-
            usb-storage.conf
            Create a file ending in .conf with blacklist usb_storage in the /etc/modprobe.d/
            directory
            Example:
            # printf '%s\n' "" "blacklist usb_storage" >> /etc/modprobe.d/60-usb-
            storage.conf

            References:

                 1. CCI-000778 | CCI-001958 | CCI-003959
                 2. NIST SP 800-53 :: IA-3 | NIST SP 800-53 :: CM-7 (9) (b)
                 3. NIST SP 800-53A :: IA-3.1 (ii)
                 4. STIG ID: RHEL-08-040080 | RULE ID: SV-230503r1069316 | CAT II
                 5. STIG ID: OL08-00-040080 | RULE ID: SV-248837r986386 | CAT II
                 6. STIG ID: RHEL-09-291010 | RULE ID: SV-258034r1051267 | CAT II
                 7. STIG ID: ALMA-09-031370 | RULE ID: SV-269357r1050240 | CAT II
                 8. STIG ID: OL09-00-000047 | RULE ID: SV-271450r1092466 | CAT II
                 9. STIG ID: OL09-00-002332 | RULE ID: SV-271702r1091818 | CAT II
                 10. STIG ID: UBTU-22-291010 | RULE ID: SV-260540r986276 | CAT II
                 11. STIG ID: UBTU-24-300039 | RULE ID: SV-270718r1067128 | CAT II
                 12. STIG ID: SLES-15-010480 | RULE ID: SV-234856r958820 | CAT II

            Additional Information:
            An alternative solution to disabling the usb-storage module may be found in USBGuard.
            Use of USBGuard and construction of USB device policies should be done in alignment
            with site policy.




                                                                                          Page 49

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            CIS Controls:

               Controls
                                                             Control                                         IG 1 IG 2 IG 3
               Version

                   v8     10.3 Disable Autorun and Autoplay for Removable Media                               ●    ●      ●
                             Disable autorun and autoplay auto-execute functionality for removable media.

                          13.7 Manage USB Devices
                   v7        If USB storage devices are required, enterprise software should be used that
                          can configure systems to allow the use of specific devices. An inventory of such
                                                                                                                   ●      ●
                          devices should be maintained.




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            1.1.1.10 Ensure unused filesystems kernel modules are not
            available (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Filesystem kernel modules are pieces of code that can be dynamically loaded into the
            Linux kernel to extend its filesystem capabilities, or so-called base kernel, of an
            operating system. Filesystem kernel modules are typically used to add support for new
            hardware (as device drivers), or for adding system calls.
            Rationale:
            While loadable filesystem kernel modules are a convenient method of modifying the
            running kernel, this can be abused by attackers on a compromised system to prevent
            detection of their processes or files, allowing them to maintain control over the system.
            Many rootkits make use of loadable filesystem kernel modules in this way.
            Removing support for unneeded filesystem types reduces the local attack surface of the
            system. If this filesystem type is not needed, disable it. The following filesystem kernel
            modules have known CVE's and should be made unavailable if no dependencies exist:

                 •   ceph - CVE-2022-0670
                 •   cifs - CVE-2022-29869
                 •   exfat CVE-2022-29973
                 •   ext CVE-2022-1184
                 •   fat CVE-2022-22043
                 •   fscache CVE-2022-3630
                 •   fuse CVE-2023-0386
                 •   gfs2 CVE-2023-3212
                 •   nfs_common CVE-2023-6660
                 •   nfsd CVE-2022-43945
                 •   smbfs_common CVE-2022-2585

            Impact:
            This list may be quite extensive and covering all edges cases is difficult. Therefore, it's
            crucial to carefully consider the implications and dependencies before making any
            changes to the filesystem kernel module configurations.




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            Audit:
            Verify filesystem kernel modules that are not in use on the system are disabled. Review
            currently loaded kernel modules to ensure they are needed and conform to local site
            policy.
            Note: The "Audit script" included at the bottom of the "Audit Procedure" will perform the
            steps included below.

                 1. Run the following command to generate a list of filesystem types currently
                    mounted on the system.

            # findmnt -Dkerno fstype | sort -u
            Review the output. These filesystem types should either be excluded from the audit or if
            no longer needed, unmounted and disabled.
            Example output:
            devtmpfs
            ext4
            tmpfs
            vfat

                 2. Run the following script to generate a list of all file system kernel modules
                    currently installed on the system:

            #!/usr/bin/env bash

            {
                 l_search="$(readlink -e /usr/lib/modules/ || readlink -e /lib/modules/)"
                 a_module=()
                 while IFS= read -r -d $'\0' l_module_dir; do
                    if [ ! "$(basename "$l_module_dir")" = "nls" ]; then
                       while IFS= read -r -d $'\0' l_module_file; do
                          l_mname="$(basename "$l_module_file" | cut -d'.' -f1)"
                          if [ -f "$l_module_file" ] && ! grep -Psiq -- '\b'"$l_mname"'\b'
            \
                             <<< "${a_module[*]}"; then
                                a_module+=("$l_mname")
                             fi
                          done < <(find -L "$l_module_dir" -mindepth 1 -maxdepth 1 -type f -
            print0)
                  fi
               done < <(find "$l_search"/**/kernel/fs/ -mindepth 1 -maxdepth 1 -type d !
            -empty -print0)
               printf '%s\n' "" "${a_module[@]}"
            }
            The output is a list of the kernel modules included in the
            /usr/lib/modules/{KERNEL_VERSION}/kernel/fs/ or
            /lib/modules/{KERNEL_VERSION}/kernel/fs/ directories. This list has been sorted
            to be unique values, ignore items in the nls directory, and added to an array called
            a_module.



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                 3. Run the following command to generate a list of modules currently loaded into
                    the kernel:

            # lsmod

                 4. compare the output from the list generated in step 2 to the list of loaded modules
                    generated by the lsmod command in step 3. Any module appearing in both lists
                    is currently loaded into the kernel. Review these to verify they are needed and
                    approved by local site policy
                 5. Run the following command to generate a list of modules that are set to be Deny
                    Listed: blacklist {MODULE_NAME}, and/or set be be not loadable: install
                    {MODULE_NAME} /bin/false or install {MODULE_NAME} /bin/true:

            # modprobe --showconfig | grep -Pi -- '^\h*(blacklist|install)\h+'

                 6. Verify all modules in the output from the list generated in step 2 are both Deny
                    Listed: blacklist {MODULE_NAME} and set to be not loadable: install
                    {MODULE_NAME} /bin/false or install {MODULE_NAME} /bin/true.

            Audit Script:




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            #!/usr/bin/env bash

            {
               a_check=() a_output=() a_module=() a_output2=() a_output3=()
               l_search="$(readlink -e /usr/lib/modules/ || readlink -e /lib/modules/)"
               IFS=$'\n' read -r -d '' -a a_mounted < <(findmnt -Dkerno fstype \
               | sort -u && printf '\0' )
               IFS=$'\n' read -r -d '' -a a_lsmod < <(lsmod | awk '{print $1}' && printf
            '\0' )
               IFS=$'\n' read -r -d '' -a a_showconfig < <(modprobe --showconfig | \
               grep -Pi -- '^\h*(blacklist|install)\h+' && printf '\0')
               while IFS= read -r -d $'\0' l_module_dir; do
                   if [ ! "$(basename "$l_module_dir")" = "nls" ]; then
                      while IFS= read -r -d $'\0' l_module_file; do
                         l_mname="$(basename "$l_module_file" | cut -d'.' -f1)"
                         if [ -f "$l_module_file" ] && ! grep -Psiq -- '\b'"$l_mname"'\b'
            <<< "${a_module[*]}"; then
                            a_module+=("$l_mname")
                         fi
                      done < <(find -L "$l_module_dir" -mindepth 1 -maxdepth 1 -type f -
            print0)
                   fi
               done < <(find "$l_search"/**/kernel/fs/ -mindepth 1 -maxdepth 1 -type d !
            -empty -print0)
               for l_module in "${a_module[@]}"; do
                   if grep -Psoiq -- '\b'"$l_module"'\b' <<< "${a_mounted[*]}"; then
                      a_output+=(" - \"$l_module\"")
                   elif grep -Psoiq -- '\b'"$l_module"'\b' <<< "${a_lsmod[*]}"; then
                      a_output2+=(" - \"$l_module\"")
                   elif ! grep -Psioq -- '\binstall\h+'"${l_module//-/_}"'\h+\H+\b' <<<
            "${a_showconfig[*]}" || \
                   ! grep -Psioq -- '\bblacklist\h+'"${l_module//-/_}"'\b' <<<
            "${a_showconfig[*]}"; then
                      a_output3+=(" - \"$l_module\"")
                   fi
               done
               [ "${#a_output[@]}" -gt 0 ] && printf '%s\n' "" \
               "- There are \"${#a_output[@]}\" kernel modules currently mounted:"
            "${a_output[@]}"
               [ "${#a_output2[@]}" -gt 0 ] && printf '%s\n' "" \
               "- There are \"${#a_output2[@]}\" kernel modules currently loaded:"
            "${a_output2[@]}"
               [ "${#a_output3[@]}" -gt 0 ] && printf '%s\n' "" \
               "- There are \"${#a_output3[@]}\" Kernel modules currently loadable:"
            "${a_output3[@]}"
            }
            WARNING: disabling or denylisting filesystem modules that are in use on the system
            may be FATAL. It is extremely important to thoroughly review this list.




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            Remediation:
            - IF - the module is available in the running kernel:

                 •   Unload the filesystem kernel module from the kernel
                 •   Create a file ending in .conf with install filesystem kernel modules /bin/false
                     in the /etc/modprobe.d/ directory
                 •   Create a file ending in .conf with deny list filesystem kernel modules in the
                     /etc/modprobe.d/ directory

            WARNING: unloading, disabling or denylisting filesystem modules that are in use on the
            system may be FATAL. It is extremely important to thoroughly review the filesystems
            returned by the audit before following the remediation procedure.
            Example of unloading the gfs2kernel module:
            modprobe -r gfs2 2>/dev/null
            rmmod gfs2 2>/dev/null
            Example of fully disabling the gfs2 kernel module:
            printf '%s\n' "" "blacklist gfs2" "install gfs2 /bin/false" >>
            /etc/modprobe.d/gfs2.conf
            Note:

                 •   Disable a kernel module by modifying the command above for each unused
                     filesystem kernel module
                 •   The example gfs2 must be updated with the appropriate module name for the
                     command or example script bellow to run correctly.

            Below is an example script that can be modified to use on various filesystem
            kernel modules manual remediation process:
            Example Script




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            #!/usr/bin/env bash

            {
               a_output2=(); a_output3=(); l_dl="" # Initialize arrays and clear
            variables
               l_mod_name="gfs2" # set module name
               l_mod_type="fs" # set module type
               l_mod_path="$(readlink -f /usr/lib/modules/**/kernel/$l_mod_type ||
            readlink -f /lib/modules/**/kernel/$l_mod_type)"
               f_module_fix()
               {
                  l_dl="y" # Set to ignore duplicate checks
                  a_showconfig=() # Create array with modprobe output
                  while IFS= read -r l_showconfig; do
                      a_showconfig+=("$l_showconfig")
                  done < <(modprobe --showconfig | grep -P --
            '\b(install|blacklist)\h+'"${l_mod_name//-/_}"'\b')
                  if lsmod | grep "$l_mod_name" &> /dev/null; then # Check if the module
            is currently loaded
                      a_output2+=(" - unloading kernel module: \"$l_mod_name\"")
                      modprobe -r "$l_mod_name" 2>/dev/null; rmmod "$l_mod_name"
            2>/dev/null
                  fi
                  if ! grep -Pq -- '\binstall\h+'"${l_mod_name//-
            /_}"'\h+(\/usr)?\/bin\/(true|false)\b' <<< "${a_showconfig[*]}"; then
                      a_output2+=(" - setting kernel module: \"$l_mod_name\" to
            \"$(readlink -f /bin/false)\"")
                      printf '%s\n' "install $l_mod_name $(readlink -f /bin/false)" >>
            /etc/modprobe.d/"$l_mod_name".conf
                  fi
                  if ! grep -Pq -- '\bblacklist\h+'"${l_mod_name//-/_}"'\b' <<<
            "${a_showconfig[*]}"; then
                      a_output2+=(" - denylisting kernel module: \"$l_mod_name\"")
                      printf '%s\n' "blacklist $l_mod_name" >>
            /etc/modprobe.d/"$l_mod_name".conf
                  fi
               }
               for l_mod_base_directory in $l_mod_path; do # Check if the module exists
            on the system
                  if [ -d "$l_mod_base_directory/${l_mod_name/-/\/}" ] && [ -n "$(ls -A
            "$l_mod_base_directory/${l_mod_name/-/\/}")" ]; then
                      a_output3+=(" - \"$l_mod_base_directory\"")
                      [[ "$l_mod_name" =~ overlay ]] && l_mod_name="${l_mod_name::-2}"
                      [ "$l_dl" != "y" ] && f_module_fix
                  else
                      echo -e " - kernel module: \"$l_mod_name\" doesn't exist in
            \"$l_mod_base_directory\""
                  fi
               done
               [ "${#a_output3[@]}" -gt 0 ] && printf '%s\n' "" " -- INFO --" " - module:
            \"$l_mod_name\" exists in:" "${a_output3[@]}"
               [ "${#a_output2[@]}" -gt 0 ] && printf '%s\n' "" "${a_output2[@]}" ||
            printf '%s\n' "" " - No changes needed"
               printf '%s\n' "" " - remediation of kernel module: \"$l_mod_name\"
            complete" ""
            }



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            References:

                 1. https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=filesystem

            CIS Controls:

               Controls
                                                             Control                                          IG 1 IG 2 IG 3
               Version
                           4.8 Uninstall or Disable Unnecessary Services on
                           Enterprise Assets and Software
                    v8        Uninstall or disable unnecessary services on enterprise assets and software,          ●      ●
                           such as an unused file sharing service, web application module, or service
                           function.

                           9.2 Ensure Only Approved Ports, Protocols and Services
                    v7     Are Running                                                                              ●      ●
                              Ensure that only network ports, protocols, and services listening on a system
                           with validated business needs, are running on each system.




                                                                                                                        Page 57

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            1.1.1.11 Ensure firewire-core kernel module is not available
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 2 - Workstation
            Description:
            The IEEE 1394 (FireWire) is a serial bus standard for high-speed real-time
            communication.
            Rationale:
            Disabling FireWire protects the system against exploitation of any flaws in its
            implementation.
            Audit:
            Verify the firewire-core kernel module is not available on the system or has been
            disabled.

                 1. Run the following script to determine if the firewire-core kernel module is
                    available on the system:

            #!/usr/bin/env bash

            {
                 l_mod_name="firewire" l_mod_type="drivers"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the firewire-core kernel module is not available on the system
            and no further audit steps are required.
            Note: Some systems may include the firewire-core filesystem as part of the kernel
            opposed to being available as a kernel module. In this case, the above audit will not
            return anything. This is also considered a passing state.
            If anything is returned by the above script:




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                 2. Verify the firewire-core kernel module is not loaded and not loadable by
                    performing the following:

            Run the following command to verify the firewire-core kernel module is not loaded:
            # lsmod | grep -P -- 'firewire(_|-)core'
            Nothing should be returned
            Run the following command to verify the firewire-core kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+firewire(_|-
            )core\b'
            Verify the output includes:
            blacklist firewire_core
             -AND-
            install firewire_core /bin/false
             -OR-
            install firewire_core /bin/true
            Example output:
            blacklist firewire_core
            install firewire_core /bin/false

            Remediation:
            Unload and disable the firewire-core kernel module.

                 1. Run the following commands to unload the firewire-core kernel module:

            # modprobe -r firewire-core 2>/dev/null
            # rmmod firewire-core 2>/dev/null


                 2. Perform the following to disable the firewire-core kernel module:

            Create a file ending in .conf with install firewire-core /bin/false in the
            /etc/modprobe.d/ directory
            Example:
            # printf '%s\n' "" "install firewire-core /bin/false" >> /etc/modprobe.d/60-
            firewire-core.conf
            Create a file ending in .conf with blacklist firewire-core in the
            /etc/modprobe.d/ directory
            Example:
            # printf '%s\n' "" "blacklist firewire-core" >> /etc/modprobe.d/60-firewire-
            core.conf




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            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)
                 4. STIG ID: RHEL-08-040026 | RULE ID: SV-230499r1069315 | CAT III
                 5. STIG ID: OL08-00-040026 | RULE ID: SV-248834r958478 | CAT III
                 6. STIG ID: RHEL-09-213055 | RULE ID: SV-257806r1044859 | CAT II
                 7. STIG ID: OL09-00-000042 | RULE ID: SV-271445r1091047 | CAT II

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●      ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●      ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                       Page 60

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            1.1.2 Configure Filesystem Partitions

            Directories that are used for system-wide functions can be further protected by placing
            them on separate partitions. This provides protection for resource exhaustion and
            enables the use of mounting options that are applicable to the directory's intended use.
            Users' data can be stored on separate partitions and have stricter mount options. A user
            partition is a filesystem that has been established for use by the users and does not
            contain software for system operations.
            The recommendations in this section are easier to perform during initial system
            installation. If the system is already installed, it is recommended that a full backup be
            performed before repartitioning the system.
            Note:
            -IF- you are repartitioning a system that has already been installed (This may require
            the system to be in single-user mode):

                 •   Mount the new partition to a temporary mountpoint e.g. mount /dev/sda2 /mnt
                 •   Copy data from the original partition to the new partition. e.g. cp -a /var/tmp/*
                     /mnt
                 •   Verify that all data is present on the new partition. e.g. ls -la /mnt
                 •   Unmount the new partition. e.g. umount /mnt
                 •   Remove the data from the original directory that was in the old partition. e.g. rm
                     -Rf /var/tmp/* Otherwise it will still consume space in the old partition that will
                     be masked when the new filesystem is mounted.
                 •   Mount the new partition to the desired mountpoint. e.g. mount /dev/sda2
                     /var/tmp
                 •   Update /etc/fstab with the new mountpoint. e.g. /dev/sda2 /var/tmp xfs
                     defaults,rw,nosuid,nodev,noexec,relatime 0 0




                                                                                                 Page 61

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            1.1.2.1 Configure /tmp
            The /tmp directory is a world-writable directory used to store data used by the system
            and user applications for a short period of time. This data should have no expectation of
            surviving a reboot, as this directory is intended to be emptied after each reboot.




                                                                                              Page 62

Internal Only - General
            1.1.2.1.1 Ensure /tmp is tmpfs or a separate partition (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /tmp directory is a world-writable directory used for temporary storage by all users
            and some applications.
            Note: If an entry for /tmp exists in /etc/fstab it will take precedence over entries in a
            systemd unit file. There is an exception to this when a system is diskless and connected
            to iSCSI, entries in /etc/fstab may not take precedence over a systemd unit file.

            Rationale:
            Making /tmp its own file system allows an administrator to set additional mount options
            such as the noexec option on the mount, making /tmp useless for an attacker to install
            executable code. It would also prevent an attacker from establishing a hard link to a
            system setuid program and wait for it to be updated. Once the program was updated,
            the hard link would be broken, and the attacker would have his own copy of the
            program. If the program happened to have a security vulnerability, the attacker could
            continue to exploit the known flaw.
            This can be accomplished by either mounting tmpfs to /tmp, or creating a separate
            partition for /tmp.

            Impact:
            By design files saved to /tmp should have no expectation of surviving a reboot of the
            system. tmpfs is ram based and all files stored to tmpfs will be lost when the system is
            rebooted.
            If files need to be persistent through a reboot, they should be saved to /var/tmp not
            /tmp.
            Since the /tmp directory is intended to be world-writable, there is a risk of resource
            exhaustion if it is not bound to tmpfs or a separate partition.
            Running out of /tmp space is a problem regardless of what kind of filesystem lies under
            it, but in a configuration where /tmp is not a separate file system it will essentially have
            the whole disk available, as the default installation only creates a single / partition. On
            the other hand, a RAM-based /tmp (as with tmpfs) will almost certainly be much
            smaller, which can lead to applications filling up the filesystem much more easily.
            Another alternative is to create a dedicated partition for /tmp from a separate volume or
            disk. One of the downsides of a disk-based dedicated partition is that it will be slower
            than tmpfs which is RAM-based.




                                                                                                 Page 63

Internal Only - General
            Audit:
            Run the following command and verify the output shows that /tmp is mounted.
            Particular requirements pertaining to mount options are covered in ensuing sections.
            # findmnt -kn /tmp
            Example output:
            /tmp          tmpfs   tmpfs    rw,nosuid,nodev,noexec
            Ensure that systemd will mount the /tmp partition at boot time.
            # systemctl is-enabled tmp.mount
            Example output:
            generated
            Verify output is not masked or disabled.
            Note: By default, systemd will output generated if there is an entry in /etc/fstab for
            /tmp. This just means systemd will use the entry in /etc/fstab instead of its default
            unit file configuration for /tmp.

            Remediation:
            First ensure that systemd is correctly configured to ensure that /tmp will be mounted at
            boot time.
            # systemctl unmask tmp.mount
            For specific configuration requirements of the /tmp mount for your environment, modify
            /etc/fstab.
            Example of using tmpfs with specific mount options:
            tmpfs         /tmp     tmpfs        defaults,rw,nosuid,nodev,noexec,relatime,size=2G   0
            0
            Note: the size=2G is an example of setting a specific size for tmpfs.
            Example of using a volume or disk with specific mount options. The source location of
            the volume or disk will vary depending on your environment:
            <device> /tmp            <fstype>      defaults,nodev,nosuid,noexec   0 0

            References:

                 1. https://www.freedesktop.org/wiki/Software/systemd/APIFileSystems/
                 2. https://www.freedesktop.org/software/systemd/man/systemd-fstab-generator.html
                 3. https://www.kernel.org/doc/Documentation/filesystems/tmpfs.txt
                 4. CCI-000366
                 5. NIST SP 800-53 :: CM-6 b
                 6. NIST SP 800-53A :: CM-6.1 (iv)
                 7. STIG ID: RHEL-08-010543 | RULE ID: SV-230295r1017106 | CAT II
                 8. STIG ID: RHEL-09-231015 | RULE ID: SV-257844r1044918 | CAT II
                 9. STIG ID: ALMA-09-025540 | RULE ID: SV-269305r1050187 | CAT II




                                                                                              Page 64

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            Additional Information:
            /tmp can be configured to use tmpfs.
            tmpfs puts everything into the kernel internal caches and grows and shrinks to
            accommodate the files it contains and is able to swap unneeded pages out to swap
            space. It has maximum size limits which can be adjusted on the fly via mount -o
            remount.
            Since tmpfs lives completely in the page cache and on swap, all tmpfs pages will be
            shown as "Shmem" in /proc/meminfo and "Shared" in free. Notice that these
            counters also include shared memory. The most reliable way to get the count is using
            df and du.
            tmpfs has three mount options for sizing:

                 •    size: The limit of allocated bytes for this tmpfs instance. The default is half of
                      your physical RAM without swap. If you oversize your tmpfs instances the
                      machine will deadlock since the OOM handler will not be able to free that
                      memory.
                 •    nr_blocks: The same as size, but in blocks of PAGE_SIZE.
                 •    nr_inodes: The maximum number of inodes for this instance. The default is half
                      of the number of your physical RAM pages, or (on a machine with highmem) the
                      number of lowmem RAM pages, whichever is the lower.

            These parameters accept a suffix k, m or g and can be changed on remount. The size
            parameter also accepts a suffix % to limit this tmpfs instance to that percentage of your
            physical RAM. The default, when neither size nor nr_blocks is specified, is size=50%.

            CIS Controls:

              Controls
                                                                Control                                          IG 1 IG 2 IG 3
              Version
                           3.3 Configure Data Access Control Lists
                     v8       Configure data access control lists based on a user’s need to know. Apply data
                           access control lists, also known as access permissions, to local and remote file
                                                                                                                  ●    ●      ●
                           systems, databases, and applications.

                           14.6 Protect Information through Access Control Lists
                               Protect all information stored on systems with file system, network share,
                     v7    claims, application, or database specific access control lists. These controls will
                           enforce the principle that only authorized individuals should have access to the
                                                                                                                  ●    ●      ●
                           information based on their need to access the information as a part of their
                           responsibilities.




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            1.1.2.1.2 Ensure nodev option set on /tmp partition (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nodev mount option specifies that the filesystem cannot contain special devices.

            Rationale:
            Since the /tmp filesystem is not intended to support devices, set this option to ensure
            that users cannot create a block or character special devices in /tmp.

            Audit:
            - IF - a separate partition exists for /tmp, verify that the nodev option is set.
            Run the following command to verify that the nodev mount option is set.
            Example:
            # findmnt -kn /tmp | grep -v nodev

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /tmp.
            Edit the /etc/fstab file and add nodev to the fourth field (mounting options) for the
            /tmp partition.
            Example:
            <device> /tmp        <fstype>       defaults,rw,nosuid,nodev,noexec,relatime        0 0
            Run the following command to remount /tmp with the configured options:
            # mount -o remount /tmp

            References:

                 1. CCI-001764
                 2. NIST SP 800-53 :: CM-7 (2)
                 3. STIG ID: RHEL-08-040123 | RULE ID: SV-230511r958804 | CAT II
                 4. STIG ID: RHEL-09-231125 | RULE ID: SV-257866r958804 | CAT II
                 5. STIG ID: ALMA-09-026860 | RULE ID: SV-269317r1050199 | CAT II

            Additional Information:
            See the fstab(5) manual page for more information.



                                                                                                Page 66

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 67

Internal Only - General
            1.1.2.1.3 Ensure nosuid option set on /tmp partition (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nosuid mount option specifies that the filesystem cannot contain setuid files.

            Rationale:
            Since the /tmp filesystem is only intended for temporary file storage, set this option to
            ensure that users cannot create setuid files in /tmp.

            Audit:
            - IF - a separate partition exists for /tmp, verify that the nosuid option is set.
            Run the following command to verify that the nosuid mount option is set.
            Example:
            # findmnt -kn /tmp | grep -v nosuid

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /tmp.
            Edit the /etc/fstab file and add nosuid to the fourth field (mounting options) for the
            /tmp partition.
            Example:
            <device> /tmp        <fstype>       defaults,rw,nosuid,nodev,noexec,relatime         0 0
            Run the following command to remount /tmp with the configured options:
            # mount -o remount /tmp

            References:

                 1. CCI-001764
                 2. NIST SP 800-53 :: CM-7 (2)
                 3. STIG ID: RHEL-08-040124 | RULE ID: SV-230512r958804 | CAT II
                 4. STIG ID: RHEL-09-231135 | RULE ID: SV-257868r958804 | CAT II
                 5. STIG ID: ALMA-09-027080 | RULE ID: SV-269319r1050201 | CAT II

            Additional Information:
            See the fstab(5) manual page for more information.



                                                                                                 Page 68

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 69

Internal Only - General
            1.1.2.1.4 Ensure noexec option set on /tmp partition (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The noexec mount option specifies that the filesystem cannot contain executable
            binaries.
            Rationale:
            Since the /tmp filesystem is only intended for temporary file storage, set this option to
            ensure that users cannot run executable binaries from /tmp.

            Impact:
            Setting the noexec option on /tmp may prevent installation and/or updating of some 3rd
            party software.
            Audit:
            - IF - a separate partition exists for /tmp, verify that the noexec option is set.
            Run the following command to verify that the noexec mount option is set.
            Example:
            # findmnt -kn /tmp | grep -v noexec

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /tmp.
            Edit the /etc/fstab file and add noexec to the fourth field (mounting options) for the
            /tmp partition.
            Example:
            <device> /tmp        <fstype>       defaults,rw,nosuid,nodev,noexec,relatime         0 0
            Run the following command to remount /tmp with the configured options:
            # mount -o remount /tmp




                                                                                                 Page 70

Internal Only - General
            References:

                 1. CCI-001764
                 2. NIST SP 800-53 :: CM-7 (2)
                 3. STIG ID: RHEL-08-040125 | RULE ID: SV-230513r958804 | CAT II
                 4. STIG ID: RHEL-09-231130 | RULE ID: SV-257867r958804 | CAT II
                 5. STIG ID: ALMA-09-026970 | RULE ID: SV-269318r1050200 | CAT II

            Additional Information:
            See the fstab(5) manual page for more information.
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 71

Internal Only - General
            1.1.2.2 Configure /dev/shm
            The /dev/shm directory is a world-writable directory that can function as shared
            memory that facilitates inter process communication (IPC)




                                                                                               Page 72

Internal Only - General
            1.1.2.2.1 Ensure /dev/shm is tmpfs or a separate partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /dev/shm directory is a world-writable directory that can function as shared
            memory that facilitates inter process communication (IPC).
            Rationale:
            Making /dev/shm its own file system allows an administrator to set additional mount
            options such as the noexec option on the mount, making /dev/shm useless for an
            attacker to install executable code. It would also prevent an attacker from establishing a
            hard link to a system setuid program and wait for it to be updated. Once the program
            was updated, the hard link would be broken and the attacker would have his own copy
            of the program. If the program happened to have a security vulnerability, the attacker
            could continue to exploit the known flaw.
            This can be accomplished by mounting tmpfs to /dev/shm.

            Impact:
            Since the /dev/shm directory is intended to be world-writable, there is a risk of resource
            exhaustion if it is not bound to a separate partition.
            /dev/shm utilizing tmpfs can be resized using the size={size} parameter in the
            relevant entry in /etc/fstab.

            Audit:
            - IF - /dev/shm is to be used on the system, run the following command and verify the
            output shows that /dev/shm is mounted. Particular requirements pertaining to mount
            options are covered in ensuing sections.
            # findmnt -kn /dev/shm
            Example output:
            /dev/shm      tmpfs   tmpfs   rw,nosuid,nodev,noexec,relatime,seclabel




                                                                                               Page 73

Internal Only - General
            Remediation:
            For specific configuration requirements of the /dev/shm mount for your environment,
            modify /etc/fstab.
            Example:
            tmpfs   /dev/shm       tmpfs
            defaults,rw,nosuid,nodev,noexec,relatime,size=2G                               0 0

            References:

                 1. https://www.freedesktop.org/wiki/Software/systemd/APIFileSystems/
                 2. https://www.freedesktop.org/software/systemd/man/systemd-fstab-generator.html
                 3. NIST SP 800-53 Rev. 5: CM-7

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 74

Internal Only - General
            1.1.2.2.2 Ensure nodev option set on /dev/shm partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nodev mount option specifies that the filesystem cannot contain special devices.

            Rationale:
            Since the /dev/shm filesystem is not intended to support devices, set this option to
            ensure that users cannot attempt to create special devices in /dev/shm partitions.

            Audit:
            - IF - a separate partition exists for /dev/shm, verify that the nodev option is set.
            # findmnt -kn /dev/shm | grep -v 'nodev'

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /dev/shm.
            Edit the /etc/fstab file and add nodev to the fourth field (mounting options) for the
            /dev/shm partition. See the fstab(5) manual page for more information.
            Example:
            tmpfs /dev/shm       tmpfs       defaults,rw,nosuid,nodev,noexec,relatime           0 0
            Run the following command to remount /dev/shm with the configured options:
            # mount -o remount /dev/shm
            Note: It is recommended to use tmpfs as the device/filesystem type as /dev/shm is
            used as shared memory space by applications.
            References:

                 1. CCI-001764
                 2. NIST SP 800-53 :: CM-7 (2)
                 3. STIG ID: RHEL-08-040120 | RULE ID: SV-230508r958804 | CAT II
                 4. STIG ID: RHEL-09-231110 | RULE ID: SV-257863r958804 | CAT II
                 5. STIG ID: ALMA-09-026530 | RULE ID: SV-269314r1050196 | CAT II




                                                                                                    Page 75

Internal Only - General
            Additional Information:
            Some distributions mount /dev/shm through other means and require /dev/shm to be
            added to /etc/fstab even though it is already being mounted on boot. Others may
            configure /dev/shm in other locations and may override /etc/fstab configuration.
            Consult the documentation appropriate for your distribution.
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 76

Internal Only - General
            1.1.2.2.3 Ensure nosuid option set on /dev/shm partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nosuid mount option specifies that the filesystem cannot contain setuid files.

            Rationale:
            Setting this option on a file system prevents users from introducing privileged programs
            onto the system and allowing non-root users to execute them.
            Audit:
            - IF - a separate partition exists for /dev/shm, verify that the nosuid option is set.
            # findmnt -kn /dev/shm | grep -v 'nosuid'

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /dev/shm.
            Edit the /etc/fstab file and add nosuid to the fourth field (mounting options) for the
            /dev/shm partition. See the fstab(5) manual page for more information.
            Example:
            tmpfs /dev/shm       tmpfs       defaults,rw,nosuid,nodev,noexec,relatime          0 0
            Run the following command to remount /dev/shm with the configured options:
            # mount -o remount /dev/shm
            Note: It is recommended to use tmpfs as the device/filesystem type as /dev/shm is
            used as shared memory space by applications.
            References:

                 1. CCI-001764
                 2. NIST SP 800-53 :: CM-7 (2)
                 3. STIG ID: RHEL-08-040121 | RULE ID: SV-230509r958804 | CAT II
                 4. STIG ID: RHEL-09-231120 | RULE ID: SV-257865r1044946 | CAT II
                 5. STIG ID: ALMA-09-026750 | RULE ID: SV-269316r1050198 | CAT II




                                                                                                 Page 77

Internal Only - General
            Additional Information:
            Some distributions mount /dev/shm through other means and require /dev/shm to be
            added to /etc/fstab even though it is already being mounted on boot. Others may
            configure /dev/shm in other locations and may override /etc/fstab configuration.
            Consult the documentation appropriate for your distribution.
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 78

Internal Only - General
            1.1.2.2.4 Ensure noexec option set on /dev/shm partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The noexec mount option specifies that the filesystem cannot contain executable
            binaries.
            Rationale:
            Setting this option on a file system prevents users from executing programs from shared
            memory. This deters users from introducing potentially malicious software on the
            system.
            Audit:
            - IF - a separate partition exists for /dev/shm, verify that the noexec option is set.
            # findmnt -kn /dev/shm | grep -v 'noexec'

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /dev/shm.
            Edit the /etc/fstab file and add noexec to the fourth field (mounting options) for the
            /dev/shm partition.
            Example:
            tmpfs /dev/shm       tmpfs       defaults,rw,nosuid,nodev,noexec,relatime          0 0
            Run the following command to remount /dev/shm with the configured options:
            # mount -o remount /dev/shm
            Note: It is recommended to use tmpfs as the device/filesystem type as /dev/shm is
            used as shared memory space by applications.
            References:

                 1. CCI-001764
                 2. NIST SP 800-53 :: CM-7 (2)
                 3. STIG ID: RHEL-08-040122 | RULE ID: SV-230510r958804 | CAT II
                 4. STIG ID: RHEL-09-231115 | RULE ID: SV-257864r958804 | CAT II
                 5. STIG ID: ALMA-09-026640 | RULE ID: SV-269315r1050197 | CAT II




                                                                                                 Page 79

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 80

Internal Only - General
            1.1.2.3 Configure /home
            Please note that home directories can be mounted anywhere and are not necessarily
            restricted to /home, nor restricted to a single location, nor is the name restricted in any
            way.
            Finding user home directories can be done by looking in /etc/passwd, looking over the
            mounted file systems with mount or querying the relevant database with getent.
            The following script can be run to find user's home directories:
            #!/usr/bin/env bash

            {
              l_valid_shells="^($(awk -F\/ '$NF != "nologin" {print}' /etc/shells | sed -
            rn '/^\//{s,/,\\\\/,g;p}' | paste -s -d '|' - ))$"
              awk -v pat="$l_valid_shells" -F:
            '($1!~/^(root|halt|sync|shutdown|nfsnobody)$/ && ($3>='"$(awk
            '/^\s*UID_MIN/{print $2}' /etc/login.defs)"' || $3 != 65534) && $(NF) ~ pat)
            {print $1 " - " $6}' /etc/passwd
            }




                                                                                                Page 81

Internal Only - General
            1.1.2.3.1 Ensure separate partition exists for /home (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The /home directory is used to support disk storage needs of local users.

            Rationale:
            The default installation only creates a single / partition. Since the /home directory
            contains user generated data, there is a risk of resource exhaustion. It will essentially
            have the whole disk available to fill up and impact the system as a whole. In addition,
            other operations on the system could fill up the disk unrelated to /home and impact all
            local users.
            Configuring /home as its own file system allows an administrator to set additional mount
            options such as noexec/nosuid/nodev. These options limit an attacker's ability to
            create exploits on the system. In the case of /home options such as
            usrquota/grpquota may be considered to limit the impact that users can have on each
            other with regards to disk resource exhaustion. Other options allow for specific
            behavior. See man mount for exact details regarding filesystem-independent and
            filesystem-specific options.
            As /home contains user data, care should be taken to ensure the security and integrity
            of the data and mount point.
            Impact:
            Resizing filesystems is a common activity in cloud-hosted servers. Separate filesystem
            partitions may prevent successful resizing or may require the installation of additional
            tools solely for the purpose of resizing operations. The use of these additional tools may
            introduce their own security considerations.
            Audit:
            Run the following command and verify output shows /home is mounted:
            # findmnt -kn /home

            /home         /dev/sdb   ext4   rw,nosuid,nodev,relatime,seclabel

            Remediation:
            For new installations, during installation create a custom partition setup and specify a
            separate partition for /home.
            For systems that were previously installed, create a new partition and configure
            /etc/fstab as appropriate.


                                                                                                Page 82

Internal Only - General
            References:

                 1. AJ Lewis, "LVM HOWTO", http://tldp.org/HOWTO/LVM-HOWTO/
                 2. NIST SP 800-53 Rev. 5: CM-7

            Additional Information:
            When modifying /home it is advisable to bring the system to emergency mode (so auditd
            is not running), rename the existing directory, mount the new file system, and migrate
            the data over before returning to multi-user mode.
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 83

Internal Only - General
            1.1.2.3.2 Ensure nodev option set on /home partition (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nodev mount option specifies that the filesystem cannot contain special devices.

            Rationale:
            Since the /home filesystem is not intended to support devices, set this option to ensure
            that users cannot create a block or character special devices in /home.

            Audit:
            - IF - a separate partition exists for /home, verify that the nodev option is set.
            Run the following command to verify that the nodev mount option is set.
            Example:
            # findmnt -kn /home | grep -v nodev
            Nothing should be returned
            Remediation:
            - IF - a separate partition exists for /home.
            Edit the /etc/fstab file and add nodev to the fourth field (mounting options) for the
            /home partition.
            Example:
            <device> /home       <fstype>        defaults,rw,nosuid,nodev,relatime          0 0
            Run the following command to remount /home with the configured options:
            # mount -o remount /home

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2




                                                                                                  Page 84

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 85

Internal Only - General
            1.1.2.3.3 Ensure nosuid option set on /home partition (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nosuid mount option specifies that the filesystem cannot contain setuid files.

            Rationale:
            Since the /home filesystem is only intended for user file storage, set this option to
            ensure that users cannot create setuid files in /home.

            Audit:
            - IF - a separate partition exists for /home, verify that the nosuid option is set.
            Run the following command to verify that the nosuid mount option is set.
            Example:
            # findmnt -kn /home | grep -v nosuid
            Nothing should be returned
            Remediation:
            - IF - a separate partition exists for /home.
            Edit the /etc/fstab file and add nosuid to the fourth field (mounting options) for the
            /home partition.
            Example:
            <device> /home       <fstype>        defaults,rw,nosuid,nodev,relatime         0 0
            Run the following command to remount /home with the configured options:
            # mount -o remount /home

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2




                                                                                                    Page 86

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 87

Internal Only - General
            1.1.2.4 Configure /var
            The /var directory is used by daemons and other system services to temporarily store
            dynamic data. Some directories created by these processes may be world-writable.




                                                                                          Page 88

Internal Only - General
            1.1.2.4.1 Ensure separate partition exists for /var (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The /var directory is used by daemons and other system services to temporarily store
            dynamic data. Some directories created by these processes may be world-writable.
            Rationale:
            The reasoning for mounting /var on a separate partition is as follows.
            The default installation only creates a single / partition. Since the /var directory may
            contain world writable files and directories, there is a risk of resource exhaustion. It will
            essentially have the whole disk available to fill up and impact the system. In addition,
            other operations on the system could fill up the disk unrelated to /var and cause
            unintended behavior across the system as the disk is full. See man auditd.conf for
            details.
            Configuring /var as its own file system allows an administrator to set additional mount
            options such as noexec/nosuid/nodev. These options limit an attacker's ability to
            create exploits on the system. Other options allow for specific behavior. See man mount
            for exact details regarding filesystem-independent and filesystem-specific options.
            An example of exploiting /var may be an attacker establishing a hard-link to a system
            setuid program and waiting for it to be updated. Once the program is updated, the
            hard-link can be broken and the attacker would have their own copy of the program. If
            the program happened to have a security vulnerability, the attacker could continue to
            exploit the known flaw.
            Impact:
            Resizing filesystems is a common activity in cloud-hosted servers. Separate filesystem
            partitions may prevent successful resizing or may require the installation of additional
            tools solely for the purpose of resizing operations. The use of these additional tools may
            introduce their own security considerations.




                                                                                                  Page 89

Internal Only - General
            Audit:
            Run the following command and verify output shows /var is mounted.
            Example:
            # findmnt -kn /var

            /var     /dev/sdb     ext4        rw,nosuid,nodev,relatime,seclabel

            Remediation:
            For new installations, during installation create a custom partition setup and specify a
            separate partition for /var.
            For systems that were previously installed, create a new partition and configure
            /etc/fstab as appropriate.

            References:

                 1. AJ Lewis, "LVM HOWTO", http://tldp.org/HOWTO/LVM-HOWTO/
                 2. NIST SP 800-53 Rev. 5: CM-7
                 3. RHEL 8 STIG Vul ID: V-244529
                 4. RHEL 8 STIG Rule ID: SV-244529r902737

            Additional Information:
            When modifying /var it is advisable to bring the system to emergency mode (so auditd
            is not running), rename the existing directory, mount the new file system, and migrate
            the data over before returning to multi-user mode.
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 90

Internal Only - General
            1.1.2.4.2 Ensure nodev option set on /var partition (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nodev mount option specifies that the filesystem cannot contain special devices.

            Rationale:
            Since the /var filesystem is not intended to support devices, set this option to ensure
            that users cannot create a block or character special devices in /var.

            Audit:
            - IF - a separate partition exists for /var, verify that the nodev option is set.
            Run the following command to verify that the nodev mount option is set.
            Example:
            # findmnt -kn /var | grep -v nodev
            Nothing should be returned
            Remediation:
            - IF - a separate partition exists for /var.
            Edit the /etc/fstab file and add nodev to the fourth field (mounting options) for the
            /var partition.
            Example:
            <device> /var        <fstype>       defaults,rw,nosuid,nodev,relatime          0 0
            Run the following command to remount /var with the configured options:
            # mount -o remount /var

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2




                                                                                                 Page 91

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 92

Internal Only - General
            1.1.2.4.3 Ensure nosuid option set on /var partition (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nosuid mount option specifies that the filesystem cannot contain setuid files.

            Rationale:
            Since the /var filesystem is only intended for variable files such as logs, set this option
            to ensure that users cannot create setuid files in /var.

            Audit:
            - IF - a separate partition exists for /var, verify that the nosuid option is set.
            Run the following command to verify that the nosuid mount option is set.
            Example:
            # findmnt -kn /var | grep -v nosuid
            Nothing should be returned
            Remediation:
            - IF - a separate partition exists for /var.
            Edit the /etc/fstab file and add nosuid to the fourth field (mounting options) for the
            /var partition.
            Example:
            <device> /var        <fstype>       defaults,rw,nosuid,nodev,relatime         0 0
            Run the following command to remount /var with the configured options:
            # mount -o remount /var

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2




                                                                                                 Page 93

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 94

Internal Only - General
            1.1.2.5 Configure /var/tmp
            The /var/tmp directory is a world-writable directory used for temporary storage by all
            users and some applications. Temporary files residing in /var/tmp are to be preserved
            between reboots.




                                                                                            Page 95

Internal Only - General
            1.1.2.5.1 Ensure separate partition exists for /var/tmp
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The /var/tmp directory is a world-writable directory used for temporary storage by all
            users and some applications. Temporary files residing in /var/tmp are to be preserved
            between reboots.
            Rationale:
            The default installation only creates a single / partition. Since the /var/tmp directory is
            world-writable, there is a risk of resource exhaustion. In addition, other operations on
            the system could fill up the disk unrelated to /var/tmp and cause potential disruption to
            daemons as the disk is full.
            Configuring /var/tmp as its own file system allows an administrator to set additional
            mount options such as noexec/nosuid/nodev. These options limit an attacker's ability
            to create exploits on the system.
            Impact:
            Resizing filesystems is a common activity in cloud-hosted servers. Separate filesystem
            partitions may prevent successful resizing or may require the installation of additional
            tools solely for the purpose of resizing operations. The use of these additional tools may
            introduce their own security considerations.
            Audit:
            Run the following command and verify output shows /var/tmp is mounted.
            Example:
            # findmnt -kn /var/tmp

            /var/tmp      /dev/sdb ext4    rw,nosuid,nodev,noexec,relatime,seclabel

            Remediation:
            For new installations, during installation create a custom partition setup and specify a
            separate partition for /var/tmp.
            For systems that were previously installed, create a new partition and configure
            /etc/fstab as appropriate.




                                                                                                Page 96

Internal Only - General
            References:

                 1. AJ Lewis, "LVM HOWTO", http://tldp.org/HOWTO/LVM-HOWTO/
                 2. NIST SP 800-53 Rev. 5: CM-7
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. RHEL 8 STIG Vul ID: V-244529
                 5. RHEL 8 STIG Rule ID: SV-244529r902737

            Additional Information:
            When modifying /var/tmp it is advisable to bring the system to emergency mode (so
            auditd is not running), rename the existing directory, mount the new file system, and
            migrate the data over before returning to multi-user mode.
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 97

Internal Only - General
            1.1.2.5.2 Ensure nodev option set on /var/tmp partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nodev mount option specifies that the filesystem cannot contain special devices.

            Rationale:
            Since the /var/tmp filesystem is not intended to support devices, set this option to
            ensure that users cannot create a block or character special devices in /var/tmp.

            Audit:
            - IF - a separate partition exists for /var/tmp, verify that the nodev option is set.
            Run the following command to verify that the nodev mount option is set.
            Example:
            # findmnt -kn /var/tmp | grep -v nodev

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /var/tmp.
            Edit the /etc/fstab file and add nodev to the fourth field (mounting options) for the
            /var/tmp partition.
            Example:
            <device> /var/tmp         <fstype>      defaults,rw,nosuid,nodev,noexec,relatime            0
            0
            Run the following command to remount /var/tmp with the configured options:
            # mount -o remount /var/tmp

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2
                 3. NIST SP 800-53 Revision 5 :: CM-7 (2)
                 4. RHEL 8 STIG Vul ID: V-230520
                 5. RHEL 8 STIG Rule ID: SV-230520r854061




                                                                                                    Page 98

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●      ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●      ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                          Page 99

Internal Only - General
            1.1.2.5.3 Ensure nosuid option set on /var/tmp partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nosuid mount option specifies that the filesystem cannot contain setuid files.

            Rationale:
            Since the /var/tmp filesystem is only intended for temporary file storage, set this option
            to ensure that users cannot create setuid files in /var/tmp.

            Audit:
            - IF - a separate partition exists for /var/tmp, verify that the nosuid option is set.
            Run the following command to verify that the nosuid mount option is set.
            Example:
            # findmnt -kn /var/tmp | grep -v nosuid

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /var/tmp.
            Edit the /etc/fstab file and add nosuid to the fourth field (mounting options) for the
            /var/tmp partition.
            Example:
            <device> /var/tmp         <fstype>      defaults,rw,nosuid,nodev,noexec,relatime         0
            0
            Run the following command to remount /var/tmp with the configured options:
            # mount -o remount /var/tmp

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2
                 3. NIST SP 800-53 Revision 5 :: CM-7 (2)
                 4. RHEL 8 STIG Vul ID: V-230521
                 5. RHEL 8 STIG STIG ID: RHEL-08-040133




                                                                                                Page 100

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 101

Internal Only - General
            1.1.2.5.4 Ensure noexec option set on /var/tmp partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The noexec mount option specifies that the filesystem cannot contain executable
            binaries.
            Rationale:
            Since the /var/tmp filesystem is only intended for temporary file storage, set this option
            to ensure that users cannot run executable binaries from /var/tmp.

            Audit:
            - IF - a separate partition exists for /var/tmp, verify that the noexec option is set.
            Run the following command to verify that the noexec mount option is set.
            Example:
            # findmnt -kn /var/tmp | grep -v noexec

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /var/tmp.
            Edit the /etc/fstab file and add noexec to the fourth field (mounting options) for the
            /var/tmp partition.
            Example:
            <device> /var/tmp         <fstype>      defaults,rw,nosuid,nodev,noexec,relatime         0
            0
            Run the following command to remount /var/tmp with the configured options:
            # mount -o remount /var/tmp

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2
                 3. NIST SP 800-53 Revision 5 :: CM-7 (2)
                 4. RHEL 8 STIG Vul ID: V-230522
                 5. RHEL 8 STIG Rule ID: SV-230522r854063



                                                                                                Page 102

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 103

Internal Only - General
            1.1.2.6 Configure /var/log
            The /var/log directory is used by system services to store log data.




                                                                                   Page 104

Internal Only - General
            1.1.2.6.1 Ensure separate partition exists for /var/log (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The /var/log directory is used by system services to store log data.

            Rationale:
            The default installation only creates a single / partition. Since the /var/log directory
            contains log files which can grow quite large, there is a risk of resource exhaustion. It
            will essentially have the whole disk available to fill up and impact the system as a whole.
            Configuring /var/log as its own file system allows an administrator to set additional
            mount options such as noexec/nosuid/nodev. These options limit an attackers ability
            to create exploits on the system. Other options allow for specific behavior. See man
            mount for exact details regarding filesystem-independent and filesystem-specific
            options.
            As /var/log contains log files, care should be taken to ensure the security and integrity
            of the data and mount point.
            Impact:
            Resizing filesystems is a common activity in cloud-hosted servers. Separate filesystem
            partitions may prevent successful resizing, or may require the installation of additional
            tools solely for the purpose of resizing operations. The use of these additional tools may
            introduce their own security considerations.
            Audit:
            Run the following command and verify output shows /var/log is mounted:
            # findmnt -kn /var/log

            /var/log /dev/sdb ext4       rw,nosuid,nodev,noexec,relatime,seclabel

            Remediation:
            For new installations, during installation create a custom partition setup and specify a
            separate partition for /var/log .
            For systems that were previously installed, create a new partition and configure
            /etc/fstab as appropriate.




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            References:

                 1. AJ Lewis, "LVM HOWTO", http://tldp.org/HOWTO/LVM-HOWTO/
                 2. NIST SP 800-53 Rev. 5:: CM-6 b CM-7
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. RHEL 8 STIG Vul ID: V-230293
                 5. RHEL 8 STIG Rule ID: SV-230293r902720

            Additional Information:
            When modifying /var/log it is advisable to bring the system to emergency mode (so
            auditd is not running), rename the existing directory, mount the new file system, and
            migrate the data over before returning to multiuser mode.
            CIS Controls:

                Controls
                                                             Control                                         IG 1 IG 2 IG 3
                Version
                            8.3 Ensure Adequate Audit Log Storage
                     v8        Ensure that logging destinations maintain adequate storage to comply with      ●    ●    ●
                            the enterprise’s audit log management process.

                            6.4 Ensure adequate storage for logs
                     v7        Ensure that all systems that store logs have adequate storage space for the         ●    ●
                            logs generated.




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            1.1.2.6.2 Ensure nodev option set on /var/log partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nodev mount option specifies that the filesystem cannot contain special devices.

            Rationale:
            Since the /var/log filesystem is not intended to support devices, set this option to
            ensure that users cannot create a block or character special devices in /var/log.

            Audit:
            - IF - a separate partition exists for /var/log, verify that the nodev option is set.
            Run the following command to verify that the nodev mount option is set.
            Example:
            # findmnt -kn /var/log | grep -v nodev

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /var/log.
            Edit the /etc/fstab file and add nodev to the fourth field (mounting options) for the
            /var/log partition.
            Example:
            <device> /var/log         <fstype>      defaults,rw,nosuid,nodev,noexec,relatime             0
            0
            Run the following command to remount /var/log with the configured options:
            # mount -o remount /var/log

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2
                 3. NIST SP 800-53 Revision 5 :: CM-7 (2)
                 4. RHEL 8 STIG Vul ID: V-230514
                 5. RHEL 8 STIG Rule ID: SV-230514r854055




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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 108

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            1.1.2.6.3 Ensure nosuid option set on /var/log partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nosuid mount option specifies that the filesystem cannot contain setuid files.

            Rationale:
            Since the /var/log filesystem is only intended for log files, set this option to ensure
            that users cannot create setuid files in /var/log.

            Audit:
            - IF - a separate partition exists for /var/log, verify that the nosuid option is set.
            Run the following command to verify that the nosuid mount option is set.
            Example:
            # findmnt -kn /var/log | grep -v nosuid

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /var/log.
            Edit the /etc/fstab file and add nosuid to the fourth field (mounting options) for the
            /var/log partition.
            Example:
            <device> /var/log         <fstype>      defaults,rw,nosuid,nodev,noexec,relatime          0
            0
            Run the following command to remount /var/log with the configured options:
            # mount -o remount /var/log

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2
                 3. NIST SP 800-53 Revision 5 :: CM-7 (2)
                 4. RHEL 8 STIG Vul ID: V-230515
                 5. RHEL 8 STIG Rule ID: SV-230515r854056




                                                                                                Page 109

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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 110

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            1.1.2.6.4 Ensure noexec option set on /var/log partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The noexec mount option specifies that the filesystem cannot contain executable
            binaries.
            Rationale:
            Since the /var/log filesystem is only intended for log files, set this option to ensure
            that users cannot run executable binaries from /var/log.

            Audit:
            - IF - a separate partition exists for /var/log, verify that the noexec option is set.
            Run the following command to verify that the noexec mount option is set.
            Example:
            # findmnt -kn /var/log | grep -v noexec

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /var/log.
            Edit the /etc/fstab file and add noexec to the fourth field (mounting options) for the
            /var/log partition.
            Example:
            <device> /var/log         <fstype>      defaults,rw,nosuid,nodev,noexec,relatime          0
            0
            Run the following command to remount /var/log with the configured options:
            # mount -o remount /var/log

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2
                 3. NIST SP 800-53 Revision 5 :: CM-7 (2)
                 4. RHEL 8 STIG Vul ID: V-230516
                 5. RHEL 8 STIG Rule ID: SV-230516r854057



                                                                                                Page 111

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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 112

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            1.1.2.7 Configure /var/log/audit
            The auditing daemon, auditd, stores log data in the /var/log/audit directory.




                                                                                        Page 113

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            1.1.2.7.1 Ensure separate partition exists for /var/log/audit
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The auditing daemon, auditd, stores log data in the /var/log/audit directory.

            Rationale:
            The default installation only creates a single / partition. Since the /var/log/audit
            directory contains the audit.log file which can grow quite large, there is a risk of
            resource exhaustion. It will essentially have the whole disk available to fill up and impact
            the system as a whole. In addition, other operations on the system could fill up the disk
            unrelated to /var/log/audit and cause auditd to trigger its space_left_action as
            the disk is full. See man auditd.conf for details.
            Configuring /var/log/audit as its own file system allows an administrator to set
            additional mount options such as noexec/nosuid/nodev. These options limit an
            attacker's ability to create exploits on the system. Other options allow for specific
            behavior. See man mount for exact details regarding filesystem-independent and
            filesystem-specific options.
            As /var/log/audit contains audit logs, care should be taken to ensure the security
            and integrity of the data and mount point.
            Impact:
            Resizing filesystems is a common activity in cloud-hosted servers. Separate filesystem
            partitions may prevent successful resizing or may require the installation of additional
            tools solely for the purpose of resizing operations. The use of these additional tools may
            introduce their own security considerations.
            Audit:
            Run the following command and verify output shows /var/log/audit is mounted:
            # findmnt -kn /var/log/audit

            /var/log/audit /dev/sdb ext4        rw,nosuid,nodev,noexec,relatime,seclabel




                                                                                               Page 114

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            Remediation:
            For new installations, during installation create a custom partition setup and specify a
            separate partition for /var/log/audit.
            For systems that were previously installed, create a new partition and configure
            /etc/fstab as appropriate.

            References:

                 1. AJ Lewis, "LVM HOWTO", http://tldp.org/HOWTO/LVM-HOWTO/
                 2. NIST SP 800-53 Rev. 5: CM-7 CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. RHEL 8 STIG Vul ID: V-230294
                 5. RHEL 8 STIG Rule ID: SV-230294r627750

            Additional Information:
            When modifying /var/log/audit it is advisable to bring the system to emergency
            mode (so auditd is not running), rename the existing directory, mount the new file
            system, and migrate the data over before returning to multi-user mode.
            CIS Controls:

                Controls
                                                             Control                                         IG 1 IG 2 IG 3
                Version
                            8.3 Ensure Adequate Audit Log Storage
                     v8        Ensure that logging destinations maintain adequate storage to comply with      ●    ●    ●
                            the enterprise’s audit log management process.

                            6.4 Ensure adequate storage for logs
                     v7        Ensure that all systems that store logs have adequate storage space for the         ●    ●
                            logs generated.




                                                                                                                   Page 115

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            1.1.2.7.2 Ensure nodev option set on /var/log/audit partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nodev mount option specifies that the filesystem cannot contain special devices.

            Rationale:
            Since the /var/log/audit filesystem is not intended to support devices, set this option
            to ensure that users cannot create a block or character special devices in
            /var/log/audit.

            Audit:
            - IF - a separate partition exists for /var/log/audit, verify that the nodev option is set.
            Run the following command to verify that the nodev mount option is set.
            Example:
            # findmnt -kn /var/log/audit | grep -v nodev

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /var/log/audit.
            Edit the /etc/fstab file and add nodev to the fourth field (mounting options) for the
            /var/log/audit partition.
            Example:
            <device> /var/log/audit    <fstype>
            defaults,rw,nosuid,nodev,noexec,relatime         0 0
            Run the following command to remount /var/log/audit with the configured options:
            # mount -o remount /var/log/audit

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Revision 5 :: CM-7 (2)
                 3. STIG ID: RHEL-08-040129 | RULE ID: SV-230517r958804 | CAT II
                 4. STIG ID: RHEL-09-231175 | RULE ID: SV-257876r958804 | CAT II
                 5. STIG ID: ALMA-09-027190 | RULE ID: SV-269320r1050202 | CAT II



                                                                                               Page 116

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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 117

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            1.1.2.7.3 Ensure nosuid option set on /var/log/audit partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nosuid mount option specifies that the filesystem cannot contain setuid files.

            Rationale:
            Since the /var/log/audit filesystem is only intended for variable files such as logs,
            set this option to ensure that users cannot create setuid files in /var/log/audit.

            Audit:
            - IF - a separate partition exists for /var/log/audit, verify that the nosuid option is
            set.
            Run the following command to verify that the nosuid mount option is set.
            Example:
            # findmnt -kn /var/log/audit | grep -v nosuid

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /var/log/audit.
            Edit the /etc/fstab file and add nosuid to the fourth field (mounting options) for the
            /var/log/audit partition.
            Example:
            <device> /var/log/audit    <fstype>
            defaults,rw,nosuid,nodev,noexec,relatime        0 0
            Run the following command to remount /var/log/audit with the configured options:
            # mount -o remount /var/log/audit

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2
                 3. NIST SP 800-53 Revision 5 :: CM-7 (2)
                 4. STIG ID: RHEL-08-040130 | RULE ID: SV-230518r958804 | CAT II
                 5. STIG ID: RHEL-09-231170 | RULE ID: SV-257875r958804 | CAT II



                                                                                              Page 118

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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 119

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            1.1.2.7.4 Ensure noexec option set on /var/log/audit partition
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The noexec mount option specifies that the filesystem cannot contain executable
            binaries.
            Rationale:
            Since the /var/log/audit filesystem is only intended for audit logs, set this option to
            ensure that users cannot run executable binaries from /var/log/audit.

            Audit:
            - IF - a separate partition exists for /var/log/audit, verify that the noexec option is
            set.
            Run the following command to verify that the noexec mount option is set.
            Example:
            # findmnt -kn /var/log/audit | grep -v noexec

            Nothing should be returned

            Remediation:
            - IF - a separate partition exists for /var/log/audit.
            Edit the /etc/fstab file and add noexec to the fourth field (mounting options) for the
            /var/log/audit partition.
            Example:
            <device> /var/log/audit    <fstype>
            defaults,rw,nosuid,nodev,noexec,relatime        0 0
            Run the following command to remount /var/log/audit with the configured options:
            # mount -o remount /var/log/audit

            References:

                 1. See the fstab(5) manual page for more information.
                 2. NIST SP 800-53 Rev. 5: AC-3, MP-2
                 3. NIST SP 800-53 Revision 5 :: CM-7 (2)
                 4. STIG ID: RHEL-08-040131 | RULE ID: SV-230519r958804 | CAT II
                 5. STIG ID: RHEL-09-231165 | RULE ID: SV-257874r958804 | CAT II


                                                                                              Page 120

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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 121

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            1.2 Package Management

            Patch management procedures may vary widely between enterprises. Large enterprises
            may choose to install a local updates server that can be used in place of their
            distributions servers, whereas a single deployment of a system may prefer to get
            updates directly. Updates can be performed automatically or manually, depending on
            the site's policy for patch management. Organizations may prefer to test patches
            against their environment on a non-production system before rolling out to production.
            Outdated software is vulnerable to cyber criminals and hackers. Software updates help
            reduce the risk to your organization. The release of software update notes often reveals
            the patched exploitable entry points to the public. Public knowledge of these exploits
            can make your organization more vulnerable to malicious actors attempting to gain
            entry to your system's data.
            Software updates often offer new and improved features and speed enhancements.
            For the purpose of this benchmark, the requirement is to ensure that a patch
            management process is defined and maintained, the specifics of which are left to the
            organization.




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            1.2.1 Configure Package Repositories

            Patch management procedures may vary widely between enterprises. Large enterprises
            may choose to install a local updates server that can be used in place of their
            distributions servers, whereas a single deployment of a system may prefer to get
            updates directly. Updates can be performed automatically or manually, depending on
            the site's policy for patch management. Organizations may prefer to test patches
            against their environment on a non-production system before rolling out to production.
            Outdated software is vulnerable to cyber criminals and hackers. Software updates help
            reduce the risk to your organization. The release of software update notes often reveals
            the patched exploitable entry points to the public. Public knowledge of these exploits
            can leave your organization more vulnerable to malicious actors attempting to gain
            access to your system's data.
            Note: Creation of an appropriate patch management policy is left to the organization.




                                                                                            Page 123

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            1.2.1.1 Ensure GPG keys are configured (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Most package managers implement GPG key signing to verify package integrity during
            installation.
            Rationale:
            It is important to ensure that updates are obtained from a valid source to protect against
            spoofing that could lead to the inadvertent installation of malware on the system.




                                                                                              Page 124

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            Audit:
            Verify GPG keys are configured correctly for your package manager:
            # apt-key list
            Note:

                 •   apt-key list is deprecated. Manage keyring files in trusted.gpg.d instead
                     (see apt-key(8)).
                 •   With the deprecation of apt-key it is recommended to use the Signed-By option
                     in sources.list to require a repository to pass apt-secure(8) verification with a
                     certain set of keys rather than all trusted keys apt has configured.

            - OR -

                 1. Run the following script and verify GPG keys are configured correctly for your
                    package manager:

            #! /usr/bin/env bash

            {
               for file in /etc/apt/trusted.gpg.d/*.{gpg,asc}
            /etc/apt/sources.list.d/*.{gpg,asc} ; do
                  if [ -f "$file" ]; then
                     echo -e "File: $file"
                     gpg --list-packets "$file" 2>/dev/null | awk '/keyid/ &&
            !seen[$NF]++ {print "keyid:", $NF}'
                     gpg --list-packets "$file" 2>/dev/null | awk '/Signed-By:/ {print
            "signed-by:", $NF}'
                     echo -e
                  fi
               done
            }

                 2. REVIEW and VERIFY to ensure that GPG keys are configured correctly for your
                    package manager IAW site policy.

            Remediation:
            Update your package manager GPG keys in accordance with site policy.
            References:

                 1. NIST SP 800-53 Rev. 5: SI-2
                 2. https://manpages.debian.org/stretch/apt/sources.list.5.en.html




                                                                                              Page 125

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            CIS Controls:

               Controls
                                                            Control                                         IG 1 IG 2 IG 3
               Version
                          7.3 Perform Automated Operating System Patch
                    v8    Management                                                                         ●    ●    ●
                             Perform operating system updates on enterprise assets through automated
                          patch management on a monthly, or more frequent, basis.

                          7.4 Perform Automated Application Patch Management
                    v8      Perform application updates on enterprise assets through automated patch         ●    ●    ●
                          management on a monthly, or more frequent, basis.

                          3.4 Deploy Automated Operating System Patch
                          Management Tools
                    v7       Deploy automated software update tools in order to ensure that the operating    ●    ●    ●
                          systems are running the most recent security updates provided by the software
                          vendor.

                          3.5 Deploy Automated Software Patch Management
                          Tools
                    v7       Deploy automated software update tools in order to ensure that third-party      ●    ●    ●
                          software on all systems is running the most recent security updates provided by
                          the software vendor.




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            1.2.1.2 Ensure package manager repositories are configured
            (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Systems need to have package manager repositories configured to ensure they receive
            the latest patches and updates.
            Rationale:
            If a system's package repositories are misconfigured important patches may not be
            identified or a rogue repository could introduce compromised software.
            Audit:
            Run the following command and verify package repositories are configured correctly:
            # apt-cache policy

            Remediation:
            Configure your package manager repositories according to site policy.
            References:

                 1. NIST SP 800-53 Rev. 5: SI-2




                                                                                          Page 127

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            CIS Controls:

               Controls
                                                            Control                                         IG 1 IG 2 IG 3
               Version
                          7.3 Perform Automated Operating System Patch
                    v8    Management                                                                         ●    ●    ●
                             Perform operating system updates on enterprise assets through automated
                          patch management on a monthly, or more frequent, basis.

                          7.4 Perform Automated Application Patch Management
                    v8      Perform application updates on enterprise assets through automated patch         ●    ●    ●
                          management on a monthly, or more frequent, basis.

                          3.4 Deploy Automated Operating System Patch
                          Management Tools
                    v7       Deploy automated software update tools in order to ensure that the operating    ●    ●    ●
                          systems are running the most recent security updates provided by the software
                          vendor.

                          3.5 Deploy Automated Software Patch Management
                          Tools
                    v7       Deploy automated software update tools in order to ensure that third-party      ●    ●    ●
                          software on all systems is running the most recent security updates provided by
                          the software vendor.




                                                                                                                  Page 128

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            1.2.2 Configure Package Updates




                                              Page 129

Internal Only - General
            1.2.2.1 Ensure updates, patches, and additional security software
            are installed (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Periodically patches are released for included software either due to security flaws or to
            include additional functionality.
            Rationale:
            Newer patches may contain security enhancements that would not be available through
            the latest full update. As a result, it is recommended that the latest software patches be
            used to take advantage of the latest functionality. As with any software installation,
            organizations need to determine if a given update meets their requirements and verify
            the compatibility and supportability of any additional software against the update
            revision that is selected.
            Audit:
            Verify there are no updates or patches to install:
            # apt update
            # apt -s upgrade

            Remediation:
            Run the following commands to update all packages following local site policy guidance
            on applying updates and patches:
            Run the following command to update the system with the available patches and
            updates:
            # apt update
            Run one of the following commands to apply the updates and patches:
            # apt upgrade
            - OR -
            # apt dist-upgrade
            Note: When running the command apt dist-upgrade that apt has a "smart" conflict
            resolution system, and it will attempt to upgrade the most important packages at the
            expense of less important ones if necessary. So, dist-upgrade command may remove
            some packages.
            References:

                 1. NIST SP 800-53 Rev. 5: SI-2


                                                                                              Page 130

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            Additional Information:
            Site policy may mandate a testing period before installation onto production systems for
            available updates.

                 •    upgrade - is used to install the newest versions of all packages currently installed
                      on the system from the sources enumerated in /etc/apt/sources.list. Packages
                      currently installed with new versions available are retrieved and upgraded; under
                      no circumstances are currently installed packages removed, or packages not
                      already installed retrieved and installed. New versions of currently installed
                      packages that cannot be upgraded without changing the install status of another
                      package will be left at their current version. An update must be performed first so
                      that apt knows that new versions of packages are available.
                 •    dist-upgrade - in addition to performing the function of upgrade, also intelligently
                      handles changing dependencies with new versions of packages; apt has a
                      "smart" conflict resolution system, and it will attempt to upgrade the most
                      important packages at the expense of less important ones if necessary. So, dist-
                      upgrade command may remove some packages. The /etc/apt/sources.list file
                      contains a list of locations from which to retrieve desired package files. See also
                      apt_preferences(5) for a mechanism for overriding the general settings for
                      individual packages.

            CIS Controls:

               Controls
                                                               Control                                         IG 1 IG 2 IG 3
               Version
                             7.3 Perform Automated Operating System Patch
                     v8      Management                                                                         ●    ●    ●
                                Perform operating system updates on enterprise assets through automated
                             patch management on a monthly, or more frequent, basis.

                             7.4 Perform Automated Application Patch Management
                     v8        Perform application updates on enterprise assets through automated patch         ●    ●    ●
                             management on a monthly, or more frequent, basis.

                             3.4 Deploy Automated Operating System Patch
                             Management Tools
                     v7         Deploy automated software update tools in order to ensure that the operating    ●    ●    ●
                             systems are running the most recent security updates provided by the software
                             vendor.

                             3.5 Deploy Automated Software Patch Management
                             Tools
                     v7         Deploy automated software update tools in order to ensure that third-party      ●    ●    ●
                             software on all systems is running the most recent security updates provided by
                             the software vendor.




                                                                                                                     Page 131

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            1.3 Mandatory Access Control

            Mandatory Access Control (MAC) provides an additional layer of access restrictions to
            processes on top of the base Discretionary Access Controls. By restricting how
            processes can access files and resources on a system the potential impact from
            vulnerabilities in the processes can be reduced.
            Impact: Mandatory Access Control limits the capabilities of applications and daemons
            on a system, while this can prevent unauthorized access the configuration of MAC can
            be complex and difficult to implement correctly preventing legitimate access from
            occurring.




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            1.3.1 Configure AppArmor

            AppArmor provides a Mandatory Access Control (MAC) system that greatly augments
            the default Discretionary Access Control (DAC) model. Under AppArmor MAC rules are
            applied by file paths instead of by security contexts as in other MAC systems. As such it
            does not require support in the filesystem and can be applied to network mounted
            filesystems for example. AppArmor security policies define what system resources
            applications can access and what privileges they can do so with. This automatically
            limits the damage that the software can do to files accessible by the calling user. The
            user does not need to take any action to gain this benefit. For an action to occur, both
            the traditional DAC permissions must be satisfied as well as the AppArmor MAC rules.
            The action will not be allowed if either one of these models does not permit the action.
            In this way, AppArmor rules can only make a system's permissions more restrictive and
            secure.
            References:

                 1. AppArmor Documentation: http://wiki.apparmor.net/index.php/Documentation
                 2. Ubuntu AppArmor Documentation: https://help.ubuntu.com/community/AppArmor
                 3. SUSE AppArmor Documentation:
                    https://www.suse.com/documentation/apparmor/




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            1.3.1.1 Ensure the apparmor packages are installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            AppArmor provides Mandatory Access Controls.
            Rationale:
            Without a Mandatory Access Control system installed only the default Discretionary
            Access Control system will be available.
            Audit:
            Run the following command to verify that apparmor is installed:
            # dpkg-query -s apparmor &>/dev/null && echo "apparmor is installed"

            apparmor is installed
            Run the following command to verify that apparmor-utils is installed:
            # dpkg-query -s apparmor-utils &>/dev/null && echo "apparmor-utils is
            installed"

            apparmor-utils is installed

            Remediation:
            Run the following command to install apparmor and apparmor-utils:
            # apt install apparmor apparmor-utils

            References:

                 1. NIST SP 800-53 Rev. 5: AC-3




                                                                                           Page 134

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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




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            1.3.1.2 Ensure AppArmor is enabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            AppArmor is a kernel enhancement to confine programs to a limited set of resources.
            AppArmor is enabled by default.
            Note: This recommendation is designed around the grub bootloader, if LILO or another
            bootloader is in use in your environment enact equivalent settings.
            Rationale:
            AppArmor is a security mechanism and disabling it is not recommended.

            Audit:
            Run the following command to verify that AppArmor has not been disabled:
            # grep "^\s*linux" /boot/grub/grub.cfg | grep "apparmor=0"
            Nothing should be returned.
            Remediation:
            Edit /etc/default/grub of file in /etc/default/grub.d and remove the apparmor=0
            parameters to the GRUB_CMDLINE_LINUX= line
            Run the following commands to update the grub2 configuration and reboot the system:
            # update-grub
            # reboot

            References:

                 1. NIST SP 800-53 Rev. 5: AC-3




                                                                                          Page 136

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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




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            1.3.1.3 Ensure all AppArmor Profiles are not disabled
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            AppArmor profiles define what resources applications are able to access.
            Rationale:
            Security configuration requirements vary from site to site. Some sites may mandate a
            policy that is stricter than the default policy, which is perfectly acceptable. This item is
            intended to ensure that any policies that exist on the system are activated.
            Audit:
            Run the following command and verify that profiles are loaded, and are in either enforce
            or complain mode:
            # apparmor_status | grep profiles
            Review output and ensure that profiles are loaded, and in either enforce or complain
            mode:
            37 profiles are loaded.
            35 profiles are in enforce mode.
            2 profiles are in complain mode.
            4 processes have profiles defined.
            Run the following command and verify no processes are unconfined
            # apparmor_status | grep processes
            Review the output and ensure no processes are unconfined:
            4 processes have profiles defined.
            4 processes are in enforce mode.
            0 processes are in complain mode.
            0 processes are unconfined but have a profile defined.

            Remediation:
            Run the following command to set all profiles to enforce mode:
            # aa-enforce /etc/apparmor.d/*
            - OR -
            Run the following command to set all profiles to complain mode:
            # aa-complain /etc/apparmor.d/*
            Note: Any unconfined processes may need to have a profile created or activated for
            them and then be restarted



                                                                                                  Page 138

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            References:

                 1. NIST SP 800-53 Rev. 5: AC-3

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




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            1.3.1.4 Ensure all AppArmor Profiles are enforcing (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            AppArmor profiles define what resources applications are able to access.
            Rationale:
            Security configuration requirements vary from site to site. Some sites may mandate a
            policy that is stricter than the default policy, which is perfectly acceptable. This item is
            intended to ensure that any policies that exist on the system are activated.
            Audit:
            Run the following commands and verify that profiles are loaded and are not in complain
            mode:
            # apparmor_status | grep profiles
            Review output and ensure that profiles are loaded, and in enforce mode:
            34 profiles are loaded.
            34 profiles are in enforce mode.
            0 profiles are in complain mode.
            2 processes have profiles defined.
            Run the following command and verify that no processes are unconfined:
            apparmor_status | grep processes
            Review the output and ensure no processes are unconfined:
            2 processes have profiles defined.
            2 processes are in enforce mode.
            0 processes are in complain mode.
            0 processes are unconfined but have a profile defined.

            Remediation:
            Run the following command to set all profiles to enforce mode:
            # aa-enforce /etc/apparmor.d/*
            Note: Any unconfined processes may need to have a profile created or activated for
            them and then be restarted
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3




                                                                                                  Page 140

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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 141

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            1.4 Configure Bootloader

            The recommendations in this section focus on securing the bootloader and settings
            involved in the boot process directly.




                                                                                          Page 142

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            1.4.1 Ensure bootloader password is set (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Setting the boot loader password will require that anyone rebooting the system must
            enter a password before being able to set command line boot parameters
            Rationale:
            Requiring a boot password upon execution of the boot loader will prevent an
            unauthorized user from entering boot parameters or changing the boot partition. This
            prevents users from weakening security (e.g. turning off AppArmor at boot time).
            Impact:
            If password protection is enabled, only the designated superuser can edit a GRUB 2
            menu item by pressing "e" or access the GRUB 2 command line by pressing "c"
            If GRUB 2 is set up to boot automatically to a password-protected menu entry the user
            has no option to back out of the password prompt to select another menu entry. Holding
            the SHIFT key will not display the menu in this case. The user must enter the correct
            username and password. If unable to do so, the configuration files will have to be edited
            via a LiveCD or other means to fix the problem
            You can add --unrestricted to the menu entries to allow the system to boot without
            entering a password. A password will still be required to edit menu items.
            More Information: https://help.ubuntu.com/community/Grub2/Passwords
            Audit:
            Run the following commands and verify output matches:
            # grep "^set superusers" /boot/grub/grub.cfg

            set superusers="<username>"
            # awk -F. '/^\s*password/ {print $1"."$2"."$3}' /boot/grub/grub.cfg

            password_pbkdf2 <username> grub.pbkdf2.sha512




                                                                                             Page 143

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            Remediation:
            Create an encrypted password with grub-mkpasswd-pbkdf2:
            # grub-mkpasswd-pbkdf2 --iteration-count=600000 --salt=64

            Enter password: <password>
            Reenter password: <password>
            PBKDF2 hash of your password is <encrypted-password>
            Add the following into a custom /etc/grub.d configuration file:
            set superusers="<username>"
            password_pbkdf2 <username> <encrypted-password>
            The superuser/user information and password should not be contained in the
            /etc/grub.d/00_header file as this file could be overwritten in a package update.
            If there is a requirement to be able to boot/reboot without entering the password, edit
            /etc/grub.d/10_linux and add --unrestricted to the line CLASS=
            Example:
            CLASS="--class gnu-linux --class gnu --class os --unrestricted"
            Run the following command to update the grub2 configuration:
            # update-grub

            Default Value:
            This recommendation is designed around the grub bootloader, if LILO or another
            bootloader is in use in your environment enact equivalent settings.
            Replace /boot/grub/grub.cfg with the appropriate grub configuration file for your
            environment.
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3
                 2. NIST SP 800-53A :: AC-3.1

            Additional Information:
            Changes to /etc/grub.d/10_linux may be overwritten during updates to the grub-
            common package. You should review any changes to this file before rebooting otherwise
            the system may unexpectedly prompt for a password on the next boot.




                                                                                              Page 144

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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




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            1.4.2 Ensure access to bootloader config is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The grub configuration file contains information on boot settings and passwords for
            unlocking boot options.
            Rationale:
            Setting the permissions to read and write for root only prevents non-root users from
            seeing the boot parameters or changing them. Non-root users who read the boot
            parameters may be able to identify weaknesses in security upon boot and be able to
            exploit them.
            Audit:
            Run the following command and verify Uid and Gid are both 0/root and Access is
            0600 or more restrictive.
            # stat -Lc 'Access: (%#a/%A)         Uid: ( %u/ %U) Gid: ( %g/ %G)'
            /boot/grub/grub.cfg

            Access: (0600/-rw-------)        Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            Run the following commands to set permissions on your grub configuration:
            # chown root:root /boot/grub/grub.cfg
            # chmod u-x,go-rwx /boot/grub/grub.cfg

            Default Value:
            Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3

            Additional Information:
            This recommendation is designed around the grub bootloader, if LILO or another
            bootloader is in use in your environment enact equivalent settings.
            Replace /boot/grub/grub.cfg with the appropriate grub configuration file for your
            environment


                                                                                            Page 146

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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 147

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            1.5 Configure Additional Process Hardening




                                                         Page 148

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            1.5.1 Ensure randomize_va_space is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Address space layout randomization (ASLR) is an exploit mitigation technique which
            randomly arranges the address space of key data areas of a process.
            Rationale:
            Randomly placing virtual memory regions will make it difficult to write memory page
            exploits as the memory placement will be consistently shifting.




                                                                                           Page 149

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            Audit:
            Verify kernel.randomize_va_space is set to 2.

                 1. Run the following command to verify kernel.randomize_va_space is set to 2 in
                    the running configuration:

            # sysctl kernel.randomize_va_space
            Verify output is:
            kernel.randomize_va_space = 2`

                 2. Run the following script to verify kernel.randomize_va_space is set to 2 in a
                    sysctl conf file being used by systemd sysctl:

            #!/usr/bin/env bash

            {
                l_parameter_name="kernel.randomize_va_space"
            l_grep="${l_parameter_name//./\\.}" a_output=()
                l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl || readlink -e
            /usr/lib/systemd/systemd-sysctl)"
                l_ufwscf="$([ -f /etc/default/ufw ] && awk -F= '/^\s*IPT_SYSCTL=/ {print
            $2}' /etc/default/ufw)"
                l_opt="$(grep -Psoi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_ufwscf" | tail -n
            1)"
                l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                [ -n "$l_option_value" ] && a_output+=(" - UFW set: \"$l_parameter_name\"
            to: \"$l_option_value\" in: \"$l_file\"")
                while IFS= read -r l_file; do
                   l_file="${l_file//# /}"
                   l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                   l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                   [ -n "$l_option_value" ] && a_output+=(" - \"$l_parameter_name\" is set
            to: \"$l_option_value\" in: \"$l_file\"")
                done < <("$l_systemdsysctl" --cat-config | tac | grep -Pio
            '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "kernel.randomize_va_space" is set to: "2" in: "/etc/sysctl.d/60-
            kernel_sysctl.conf"




                                                                                            Page 150

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            Note:

                 •   If the UFW set value is displayed, and is the correct value, this is considered a
                     passing state. If this value is incorrect, it must be updated in the file shown in the
                     audit script output.
                 •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                             correct value, this is considered a passing state. If the file listed is not in
                             the /etc/sysctl.d/ directory, it is highly recommended to follow the
                             remediation procedure to create a .conf file in the /etc/sysctl.d/
                             directory with the correct setting to prevent a potential change due to an
                             update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                             should be modified to correct or comment out the incorrect value to
                             minimize the potential of the incorrect value being used by systemd
                             sysctl do to system configuration changes.




                                                                                                   Page 151

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            Remediation:

                 1. Review all files ending in .conf in the /etc/sysctl.d directory and comment
                    out or remove all kernel.randomize_va_space lines that are not
                    kernel.randomize_va_spacee=2.

            Example script:
            #!/usr/bin/env bash

            {
               l_option="kernel.randomize_va_space" l_grep="${l_option//./\\.}"
            l_value="2"
               while IFS= read -r -d $'\0' l_file; do
                  grep -Poi '\h*'"$l_option"'\h*=\h*\H+\b' "$l_file" \
                  | grep -Pivq '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                  sed -ri '/^\s*kernel.yama.ptrace_scope\s*=/s/^/# /' "$l_file"
               done < <(find /etc/sysctl.d/ -type f -name '*.conf' -print0)
            }

                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            kernel.randomize_va_space = 2
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "kernel.randomize_va_space = 2" >> /etc/sysctl.d/60-
            kernel_sysctl.conf

                 3. Run the following command to load all system configuration filles:

            # sysctl --system

            Default Value:
            kernel.randomize_va_space = 2
            References:

                 1. CCI-002824
                 2. NIST SP 800-53 :: SI-16
                 3. STIG ID: RHEL-08-010430 | RULE ID: SV-230280r1017093 | CAT II
                 4. STIG ID: RHEL-09-213070 | RULE ID: SV-257809r1044866 | CAT II
                 5. STIG ID: ALMA-09-044900 | RULE ID: SV-269452r1050335 | CAT II
                 6. STIG ID: UBTU-22-213020 | RULE ID: SV-260474r958928 | CAT II
                 7. STIG ID: UBTU-24-700310 | RULE ID: SV-270772r1066805 | CAT II
                 8. STIG ID: SLES-15-010550 | RULE ID: SV-234862r958928 | CAT II




                                                                                             Page 152

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            CIS Controls:

              Controls
                                                              Control                                             IG 1 IG 2 IG 3
              Version
                          10.5 Enable Anti-Exploitation Features
                             Enable anti-exploitation features on enterprise assets and software, where
                   v8     possible, such as Microsoft® Data Execution Prevention (DEP), Windows®                        ●    ●
                          Defender Exploit Guard (WDEG), or Apple® System Integrity Protection (SIP) and
                          Gatekeeper™.

                          8.3 Enable Operating System Anti-Exploitation Features/
                          Deploy Anti-Exploit Technologies
                   v7        Enable anti-exploitation features such as Data Execution Prevention (DEP) or
                          Address Space Layout Randomization (ASLR) that are available in an operating
                                                                                                                        ●    ●
                          system or deploy appropriate toolkits that can be configured to apply protection to a
                          broader set of applications and executables.




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            1.5.2 Ensure ptrace_scope is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The ptrace() system call provides a means by which one process (the "tracer") may
            observe and control the execution of another process (the "tracee"), and examine and
            change the tracee's memory and registers.
            The sysctl settings (writable only with CAP_SYS_PTRACE) are:

                 •   0 - classic ptrace permissions: a process can PTRACE_ATTACH to any other
                     process running under the same uid, as long as it is dumpable (i.e. did not
                     transition uids, start privileged, or have called prctl(PR_SET_DUMPABLE...)
                     already). Similarly, PTRACE_TRACEME is unchanged.
                 •   1 - restricted ptrace: a process must have a predefined relationship with the
                     inferior it wants to call PTRACE_ATTACH on. By default, this relationship is that
                     of only its descendants when the above classic criteria is also met. To change
                     the relationship, an inferior can call prctl(PR_SET_PTRACER, debugger, ...) to
                     declare an allowed debugger PID to call PTRACE_ATTACH on the inferior.
                     Using PTRACE_TRACEME is unchanged.
                 •   2 - admin-only attach: only processes with CAP_SYS_PTRACE may use ptrace
                     with PTRACE_ATTACH, or through children calling PTRACE_TRACEME.
                 •   3 - no attach: no processes may use ptrace with PTRACE_ATTACH nor via
                     PTRACE_TRACEME. Once set, this sysctl value cannot be changed.

            Rationale:
            If one application is compromised, it would be possible for an attacker to attach to other
            running processes (e.g. Bash, Firefox, SSH sessions, GPG agent, etc) to extract
            additional credentials and continue to expand the scope of their attack.
            Enabling restricted mode will limit the ability of a compromised process to
            PTRACE_ATTACH on other processes running under the same user. With restricted
            mode, ptrace will continue to work with root user.




                                                                                               Page 154

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            Audit:
            Verify kernel.yama.ptrace_scope is set to a value of: 1, 2, or 3.

                 1. Run the following command to verify kernel.yama.ptrace_scope is set to a
                    value of: 1, 2, or 3 in the running configuration:

            # sysctl kernel.yama.ptrace_scope
            Example output:
            kernel.yama.ptrace_scope = 1

                 2. Run the following script to verify kernel.yama.ptrace_scope is set to a value
                    of: 1, 2, or 3 in a sysctl conf file being used by systemd sysctl:

            #!/usr/bin/env bash

            {
                l_parameter_name="kernel.yama.ptrace_scope"
            l_grep="${l_parameter_name//./\\.}" a_output=()
                l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl || readlink -e
            /usr/lib/systemd/systemd-sysctl)"
                l_ufwscf="$([ -f /etc/default/ufw ] && awk -F= '/^\s*IPT_SYSCTL=/ {print
            $2}' /etc/default/ufw)"
                l_opt="$(grep -Psoi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_ufwscf" | tail -n
            1)"
                l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                [ -n "$l_option_value" ] && a_output+=(" - UFW set: \"$l_parameter_name\"
            to: \"$l_option_value\" in: \"$l_file\"")
                while IFS= read -r l_file; do
                   l_file="${l_file//# /}"
                   l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                   l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                   [ -n "$l_option_value" ] && a_output+=(" - \"$l_parameter_name\" is set
            to: \"$l_option_value\" in: \"$l_file\"")
                done < <("$l_systemdsysctl" --cat-config | tac | grep -Pio
            '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
            - "kernel.yama.ptrace_scope" is set to: "1" in: "/etc/sysctl.d/60-
            kernel_sysctl.conf"




                                                                                           Page 155

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            Note:

                 •   If the UFW set value is displayed, and is the correct value, this is considered a
                     passing state. If this value is incorrect, it must be updated in the file shown in the
                     audit script output.
                 •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                             correct value, this is considered a passing state. If the file listed is not in
                             the /etc/sysctl.d/ directory, it is highly recommended to follow the
                             remediation procedure to create a .conf file in the /etc/sysctl.d/
                             directory with the correct setting to prevent a potential change due to an
                             update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                             should be modified to correct or comment out the incorrect value to
                             minimize the potential of the incorrect value being used by systemd
                             sysctl do to system configuration changes.




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            Remediation:

                 1. Review all files ending in .conf in the /etc/sysctl.d directory and comment
                    out or remove all kernel.yama.ptrace_scope lines that are not
                    kernel.yama.ptrace_scope=1, kernel.yama.ptrace_scope=2, or
                    kernel.yama.ptrace_scope=3.

            Example script:
            #!/usr/bin/env bash

            {
               l_option="kernel.yama.ptrace_scope" l_grep="${l_option//./\\.}"
            l_value="(1|2|3)"
               while IFS= read -r -d $'\0' l_file; do
                  grep -Poi '\h*'"$l_option"'\h*=\h*\H+\b' "$l_file" \
                  | grep -Pivq '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                  sed -ri '/^\s*kernel.yama.ptrace_scope\s*=/s/^/# /' "$l_file"
               done < <(find /etc/sysctl.d/ -type f -name '*.conf' -print0)
            }

                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            kernel.yama.ptrace_scope = 1
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "kernel.yama.ptrace_scope = 1" >> /etc/sysctl.d/60-
            kernel_sysctl.conf
            Note: The example uses kernel.yama.ptrace_scope = 1 but value may be set to 1,
            2, or 3

                 3. Run the following command to load all system configuration filles:

            # sysctl --system

            Default Value:
            kernel.yama.ptrace_scope = 0
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040282 | RULE ID: SV-230546r1017308 | CAT II
                 5. STIG ID: RHEL-09-213080 | RULE ID: SV-257811r1044872 | CAT II
                 6. STIG ID: ALMA-09-040940 | RULE ID: SV-269424r1050307 | CAT II



                                                                                             Page 157

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            Additional Information:
            Ptrace is very rarely used by regular applications and is mostly used by debuggers such
            as gdb and strace.

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            1.5.3 Ensure suid_dumpable is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            fs.suid_dumpable governs whether a privileged process (with the setuid bit) can
            generate a core dump, regardless of other configurations.
            fs.suid_dumpable values:

                 •   0 (default) - Any process that has changed privilege levels (like SUID programs)
                     or is execute-only will not dump core.
                 •   1 (debug) - All processes dump core if possible. The core dump is owned by the
                     current user and security is not applied. This is primarily intended for system
                     debugging.
                 •   2 (suidsafe) - Any binary that normally wouldn't be dumped is dumped, but only if
                     the core_pattern is set to a pipe handler or a fully qualified path. This mode is
                     suitable for administrators debugging in a production environment.

            Rationale:
            core dumps may contain sensitive in-memory data like password hashes or keys. An
            attacker could potentially exploit this to gain access to such data.




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            Audit:

                 1. Run the following script to verify fs.suid_dumpable is set to 0 in the running
                    configuration:

            # sysctl fs.suid_dumpable
            Verify output is:
            fs.suid_dumpable = 0

                 2. Run the following script to verify fs.suid_dumpable is set to 0 in a sysctl conf
                    file being used by systemd sysctl:

            #!/usr/bin/env bash

            {
                l_parameter_name="fs.suid_dumpable" l_grep="${l_parameter_name//./\\.}"
            a_output=()
                l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl || readlink -e
            /usr/lib/systemd/systemd-sysctl)"
                l_ufwscf="$([ -f /etc/default/ufw ] && awk -F= '/^\s*IPT_SYSCTL=/ {print
            $2}' /etc/default/ufw)"
                l_opt="$(grep -Psoi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_ufwscf" | tail -n
            1)"
                l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                [ -n "$l_option_value" ] && a_output+=(" - UFW set: \"$l_parameter_name\"
            to: \"$l_option_value\" in: \"$l_file\"")
                while IFS= read -r l_file; do
                   l_file="${l_file//# /}"
                   l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                   l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                   [ -n "$l_option_value" ] && a_output+=(" - \"$l_parameter_name\" is set
            to: \"$l_option_value\" in: \"$l_file\"")
                done < <("$l_systemdsysctl" --cat-config | tac | grep -Pio
            '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "fs.suid_dumpable" is set to: "0" in: "/etc/sysctl.d/60-
            kernel_sysctl.conf"




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            Note:

                 •   If the UFW set value is displayed, and is the correct value, this is considered a
                     passing state. If this value is incorrect, it must be updated in the file shown in the
                     audit script output.
                 •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                             correct value, this is considered a passing state. If the file listed is not in
                             the /etc/sysctl.d/ directory, it is highly recommended to follow the
                             remediation procedure to create a .conf file in the /etc/sysctl.d/
                             directory with the correct setting to prevent a potential change due to an
                             update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                             should be modified to correct or comment out the incorrect value to
                             minimize the potential of the incorrect value being used by systemd
                             sysctl do to system configuration changes.

            Remediation:

                 1. Review all files ending in .conf in the /etc/sysctl.d directory and comment
                    out or remove all fs.suid_dumpable lines that are not fs.suid_dumpable=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="fs.suid_dumpable" l_grep="${l_option//./\\.}" l_value="0"
                 while IFS= read -r -d $'\0' l_file; do
                    grep -Poi '\h*'"$l_option"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*kernel.yama.ptrace_scope\s*=/s/^/# /' "$l_file"
                 done < <(find /etc/sysctl.d/ -type f -name '*.conf' -print0)
            }

                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            fs.suid_dumpable = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "fs.suid_dumpable = 0" >> /etc/sysctl.d/60-
            kernel_sysctl.conf

                 3. Run the following command to load all system configuration filles:

            # sysctl --system




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            Default Value:
            fs.suid_dumpable = 0
            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 162

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            1.5.4 Ensure core file size is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            core - limits the core file size
            hard - for enforcing hard resource limits. These limits are set by the superuser and
            enforced by the Kernel. The user cannot raise their requirement of system resources
            above such values.
            Rationale:
            Setting a hard limit on core dumps prevents users from overriding the soft variable.
            A core dump includes a memory image taken at the time the operating system
            terminates an application. The memory image could contain sensitive data and is
            generally useful only for developers trying to debug problems.
            Audit:
            Run the following command to verify a hard limit for core is set to 0 for all users *:
            # grep -Psi -- '^\h*\*\h+hard\h+core\b' /etc/security/limits.conf
            /etc/security/limits.d/*
            Example output:
            /etc/security/limits.d/60-limits.conf:* hard core 0
            Verify no line are returned with a value greater than 0.

            Remediation:

                 1. Run the following command to comment out any entries that include a hard
                    value for core greater than 0 in /etc/security/limits.conf and and file in
                    the /etc/security/limits.d/ directory.

            Example:
            # sed -ri '/^\s*[#\n\r]+\s+hard\s+core\h+([1-9][0-9]*)/s/^/# /'
            /etc/security/limits.conf /etc/security/limits.d/*

                 2. Create or edit a file in /etc/security/limits.d/ and add the following line:

            * hard core 0
            Example:
            # printf '%s\n' "" "* hard core 0" >> /etc/security/limits.d/60-limits.conf




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            Default Value:
            None
            References:

                 1. limits.conf(5)
                 2. CCI-000366
                 3. NIST SP 800-53 :: CM-6 b
                 4. NIST SP 800-53A :: CM-6.1 (iv)
                 5. STIG ID: RHEL-08-010673 | RULE ID: SV-230313r1069304 | CAT II
                 6. STIG ID: RHEL-09-213095 | RULE ID: SV-257814r991589 | CAT II
                 7. STIG ID: ALMA-09-044900 | RULE ID: SV-269452r1050335 | CAT II

            CIS Controls:

                 Controls Version                     Control        IG 1 IG 2 IG 3

                          v8         0.0 Explicitly Not Mapped
                                       Explicitly Not Mapped

                          v7         0.0 Explicitly Not Mapped
                                       Explicitly Not Mapped




                                                                                      Page 164

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            1.5.5 Ensure prelink is not installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            prelink is a program that modifies ELF shared libraries and ELF dynamically linked
            binaries in such a way that the time needed for the dynamic linker to perform relocations
            at startup significantly decreases.
            Rationale:
            The prelinking feature can interfere with the operation of AIDE, because it changes
            binaries. Prelinking can also increase the vulnerability of the system if a malicious user
            is able to compromise a common library such as libc.
            Audit:
            Verify prelink is not installed:
            # dpkg-query -s prelink &>/dev/null && echo "prelink is installed"
            Nothing should be returned.
            Remediation:
            Run the following command to restore binaries to normal:
            # prelink -ua
            Uninstall prelink using the appropriate package manager or manual installation:
            # apt purge prelink

            References:

                 1. NIST SP 800-53 Rev. 5: CM-6, CM-1, CM-3

            CIS Controls:

               Controls
                                                              Control                                      IG 1 IG 2 IG 3
               Version

                    v8     3.14 Log Sensitive Data Access                                                             ●
                              Log sensitive data access, including modification and disposal.

                           14.9 Enforce Detail Logging for Access or Changes to
                           Sensitive Data
                    v7         Enforce detailed audit logging for access to sensitive data or changes to              ●
                           sensitive data (utilizing tools such as File Integrity Monitoring or Security
                           Information and Event Monitoring).




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            1.5.6 Ensure Automatic Error Reporting is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Apport Error Reporting Service automatically generates crash reports for
            debugging
            Rationale:
            Apport collects potentially sensitive data, such as core dumps, stack traces, and log
            files. They can contain passwords, credit card numbers, serial numbers, and other
            private material.
            Audit:
            Run the following command to verify that the Apport Error Reporting Service is not
            enabled:
            # dpkg-query -s apport &> /dev/null && grep -Psi --
            '^\h*enabled\h*=\h*[^0]\b' /etc/default/apport
            Nothing should be returned
            Run the following command to verify that the apport service is not active:
            # systemctl is-active apport.service | grep '^active'
            Nothing should be returned
            Remediation:
            Edit /etc/default/apport and add or edit the enabled parameter to equal 0:
            enabled=0
            Run the following commands to stop and mask the apport service
            # systemctl stop apport.service
            # systemctl mask apport.service
            - OR -
            Run the following command to remove the apport package:
            # apt purge apport

            Default Value:
            enabled=1




                                                                                             Page 166

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            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 167

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            1.6 Configure Command Line Warning Banners

            Presenting a warning message prior to the normal user login may assist in the
            prosecution of trespassers on the computer system. Changing some of these login
            banners also has the side effect of hiding OS version information and other detailed
            system information from attackers attempting to target specific exploits at a system.
            Guidelines published by the US Department of Defense require that warning messages
            include at least the name of the organization that owns the system, the fact that the
            system is subject to monitoring and that such monitoring is in compliance with local
            statutes, and that use of the system implies consent to such monitoring. It is important
            that the organization's legal counsel review the content of all messages before any
            system modifications are made, as these warning messages are inherently site-specific.
            More information (including citations of relevant case law) can be found at
            http://www.justice.gov/criminal/cybercrime/
            The /etc/motd, /etc/issue, and /etc/issue.net files govern warning banners for
            standard command line logins for both local and remote users.
            Note: The text provided in the remediation actions for these items is intended as an
            example only. Please edit to include the specific text for your organization as approved
            by your legal department.




                                                                                            Page 168

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            1.6.1 Ensure /etc/motd is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The contents of the /etc/motd file are displayed to users after login and function as a
            message of the day for authenticated users.
            Unix-based systems have typically displayed information about the OS release and
            patch level upon logging in to the system. This information can be useful to developers
            who are developing software for a particular OS platform. If mingetty(8) supports the
            following options, they display operating system information: \m - machine architecture
            \r - operating system release \s - operating system name \v - operating system
            version
            Rationale:
            Warning messages inform users who are attempting to login to the system of their legal
            status regarding the system and must include the name of the organization that owns
            the system and any monitoring policies that are in place. Displaying OS and patch level
            information in login banners also has the side effect of providing detailed system
            information to attackers attempting to target specific exploits of a system. Authorized
            users can easily get this information by running the " uname -a " command once they
            have logged in.




                                                                                            Page 169

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            Audit:
            Run the following script to verify MOTD files do not contain system information:
            #!/usr/bin/env bash

            {
               l_output="" l_output2=""
               a_files=()
               for l_file in /etc/motd{,.d/*}; do
                  if grep -Psqi -- "(\\\v|\\\r|\\\m|\\\s|\b$(grep ^ID= /etc/os-release |
            cut -d= -f2 | sed -e 's/"//g')\b)" "$l_file"; then
                     l_output2="$l_output2\n - File: \"$l_file\" includes system
            information"
                  else
                     a_files+=("$l_file")
                  fi
               done
               if [ "${#a_files[@]}" -gt 0 ]; then
                  echo -e "\n- ** Please review the following files and verify their
            contents follow local site policy **\n"
                  printf '%s\n' "${a_files[@]}"
               elif [ -z "$l_output2" ]; then
                  echo -e "- ** No MOTD files with any size were found. Please verify
            this conforms to local site policy ** -"
               fi
               if [ -z "$l_output2" ]; then
                  l_output=" - No MOTD files include system information"
                  echo -e "\n- Audit Result:\n ** PASS **\n$l_output\n"
               else
                  echo -e "\n- Audit Result:\n ** FAIL **\n - Reason(s) for audit
            failure:\n$l_output2\n"
               fi
            }
            Review any files returned and verify that they follow local site policy




                                                                                               Page 170

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            Remediation:
            Edit the file found in /etc/motd.d/* with the appropriate contents according to your
            site policy, remove any instances of \m , \r , \s , \v or references to the OS platform
            - OR -
            - IF - the motd is not used, this file can be removed.
            Run the following command to remove the motd file:
            # rm /etc/motd
            Run the following script and review and/or update all returned files' contents to:

                 •   Remove all system information (\v, \r; \m, \s)
                 •   Remove any refence to the operating system
                 •   Ensure contents follow local site policy

            #!/usr/bin/env bash

            {
               a_files=()
               for l_file in /etc/motd{,.d/*}; do
                  if grep -Psqi -- "(\\\v|\\\r|\\\m|\\\s|\b$(grep ^ID= /etc/os-release |
            cut -d= -f2 | sed -e 's/"//g')\b)" "$l_file"; then
                     echo -e "\n - File: \"$l_file\" includes system information. Edit
            this file to remove these entries"
                  else
                  a_files+=("$l_file")
                  fi
               done
               if [ "${#a_files[@]}" -gt 0 ]; then
                  echo -e "\n- ** Please review the following files and verify their
            contents follow local site policy **\n"
                  printf '%s\n' "${a_files[@]}"
               fi
            }

            References:

                 1. NIST SP 800-53 Rev. 5: CM-6, CM-1, CM-3

            CIS Controls:

                 Controls Version                        Control             IG 1 IG 2 IG 3

                          v8            0.0 Explicitly Not Mapped
                                          Explicitly Not Mapped

                          v7            0.0 Explicitly Not Mapped
                                          Explicitly Not Mapped




                                                                                                 Page 171

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            1.6.2 Ensure /etc/issue is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The contents of the /etc/issue file are displayed to users prior to login for local
            terminals.
            Unix-based systems have typically displayed information about the OS release and
            patch level upon logging in to the system. This information can be useful to developers
            who are developing software for a particular OS platform. If mingetty(8) supports the
            following options, they display operating system information: \m - machine architecture
            \r - operating system release \s - operating system name \v - operating system
            version - or the operating system's name
            Rationale:
            Warning messages inform users who are attempting to login to the system of their legal
            status regarding the system and must include the name of the organization that owns
            the system and any monitoring policies that are in place. Displaying OS and patch level
            information in login banners also has the side effect of providing detailed system
            information to attackers attempting to target specific exploits of a system. Authorized
            users can easily get this information by running the " uname -a " command once they
            have logged in.
            Audit:
            Run the following command and verify that the contents match site policy:
            # cat /etc/issue
            Run the following command and verify no results are returned:
            # grep -Psi "(\\\v|\\\r|\\\m|\\\s|\b$(grep '^ID=' /etc/os-release | cut -d= -
            f2 | sed -e 's/"//g')\b)" /etc/issue

            Remediation:
            Edit the /etc/issue file with the appropriate contents according to your site policy,
            remove any instances of \m , \r , \s , \v or references to the OS platform
            Example:
            # echo "Authorized users only. All activity may be monitored and reported." >
            /etc/issue

            References:

                 1. NIST SP 800-53 Rev. 5: CM-6, CM-1, CM-3


                                                                                              Page 172

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            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 173

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            1.6.3 Ensure /etc/issue.net is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The contents of the /etc/issue.net file are displayed to users prior to login for remote
            connections from configured services.
            Unix-based systems have typically displayed information about the OS release and
            patch level upon logging in to the system. This information can be useful to developers
            who are developing software for a particular OS platform. If mingetty(8) supports the
            following options, they display operating system information: \m - machine architecture
            \r - operating system release \s - operating system name \v - operating system
            version
            Rationale:
            Warning messages inform users who are attempting to login to the system of their legal
            status regarding the system and must include the name of the organization that owns
            the system and any monitoring policies that are in place. Displaying OS and patch level
            information in login banners also has the side effect of providing detailed system
            information to attackers attempting to target specific exploits of a system. Authorized
            users can easily get this information by running the " uname -a " command once they
            have logged in.
            Audit:
            Run the following command and verify that the contents match site policy:
            # cat /etc/issue.net
            Run the following command and verify no results are returned:
            # grep -Psi "(\\\v|\\\r|\\\m|\\\s|\b$(grep '^ID=' /etc/os-release | cut -d= -
            f2 | sed -e 's/"//g')\b)" /etc/issue.net

            Remediation:
            Edit the /etc/issue.net file with the appropriate contents according to your site policy,
            remove any instances of \m , \r , \s , \v or references to the OS platform
            Example:
            # echo "Authorized users only. All activity may be monitored and reported." >
            /etc/issue.net

            References:

                 1. NIST SP 800-53 Rev. 5: CM-6, CM-1, CM-3


                                                                                             Page 174

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            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




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            1.6.4 Ensure access to /etc/motd is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The contents of the /etc/motd file are displayed to users after login and function as a
            message of the day for authenticated users.
            Rationale:
            - IF - the /etc/motd file does not have the correct access configured, it could be
            modified by unauthorized users with incorrect or misleading information.
            Audit:
            Run the following command and verify that if /etc/motd exists, Access is 644 or more
            restrictive, Uid and Gid are both 0/root:
            # [ -e /etc/motd ] && stat -Lc 'Access: (%#a/%A)         Uid: ( %u/ %U) Gid: { %g/
            %G)' /etc/motd

            Access: (0644/-rw-r--r--)      Uid: ( 0/ root) Gid: ( 0/ root)
              -- OR --
            Nothing is returned

            Remediation:
            Run the following commands to set mode, owner, and group on /etc/motd:
            # chown root:root $(readlink -e /etc/motd)
            # chmod u-x,go-wx $(readlink -e /etc/motd)
            - OR -
            Run the following command to remove the /etc/motd file:
            # rm /etc/motd

            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2




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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




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            1.6.5 Ensure access to /etc/issue is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The contents of the /etc/issue file are displayed to users prior to login for local
            terminals.
            Rationale:
            - IF - the /etc/issue file does not have the correct access configured, it could be
            modified by unauthorized users with incorrect or misleading information.
            Audit:
            Run the following command and verify Access is 644 or more restrictive and Uid and
            Gid are both 0/root:
            # stat -Lc 'Access: (%#a/%A)         Uid: ( %u/ %U) Gid: { %g/ %G)' /etc/issue

            Access: (0644/-rw-r--r--)        Uid: ( 0/ root) Gid: { 0/ root)

            Remediation:
            Run the following commands to set mode, owner, and group on /etc/issue:
            # chown root:root $(readlink -e /etc/issue)
            # chmod u-x,go-wx $(readlink -e /etc/issue)

            Default Value:
            Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2




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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




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            1.6.6 Ensure access to /etc/issue.net is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The contents of the /etc/issue.net file are displayed to users prior to login for remote
            connections from configured services.
            Rationale:
            - IF - the /etc/issue.net file does not have the correct access configured, it could be
            modified by unauthorized users with incorrect or misleading information.
            Audit:
            Run the following command and verify Access is 644 or more restrictive and Uid and
            Gid are both 0/root:
            # stat -Lc 'Access: (%#a/%A)         Uid: ( %u/ %U) Gid: { %g/ %G)' /etc/issue.net

            Access: (0644/-rw-r--r--)        Uid: ( 0/ root)       Gid: ( 0/ root)

            Remediation:
            Run the following commands to set mode, owner, and group on /etc/issue.net:
            # chown root:root $(readlink -e /etc/issue.net)
            # chmod u-x,go-wx $(readlink -e /etc/issue.net)

            Default Value:
            Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2




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            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




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            1.7 Configure GNOME Display Manager

            The GNOME Display Manager (GDM) is a program that manages graphical display
            servers and handles graphical user logins.
            This subsection requires user profiles to already exist on the system. A profile is a list of
            configuration databases.
            Sample profile:
            user-db:user
            system-db:local
            system-db:site
            Configuring a single user and multiple system databases allows for layering of
            preferences. Settings from the user database file take precedence over the settings in
            the local database file, and the local database file in turn takes precedence over the site
            database file.
            Note:

                 •   - IF - GDM is not installed on the system, this section can be skipped
                 •   The Remediation Procedure commands in this section MUST be done from a
                     command window on a graphical desktop or an error will be returned.




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            1.7.1 Ensure GDM is removed (Automated)
            Profile Applicability:

            • Level 2 - Server
            Description:
            The GNOME Display Manager (GDM) is a program that manages graphical display
            servers and handles graphical user logins.
            Rationale:
            If a Graphical User Interface (GUI) is not required, it should be removed to reduce the
            attack surface of the system.
            Impact:
            Removing the GNOME Display manager will remove the Graphical User Interface (GUI)
            from the system.
            Audit:
            Run the following command and verify gdm3 is not installed:
            # dpkg-query -s gdm3 &>/dev/null && echo "gdm3 is installed"
            Nothing should be returned
            Remediation:
            Run the following commands to uninstall gdm3 and remove unused dependencies:
            # apt purge gdm3
            # apt autoremove gdm3

            References:

                 1. NIST SP 800-53 Rev. 5: CM-11




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            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            1.7.2 Ensure GDM login banner is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            GDM is the GNOME Display Manager which handles graphical login for GNOME based
            systems.
            Rationale:
            Warning messages inform users who are attempting to login to the system of their legal
            status regarding the system and must include the name of the organization that owns
            the system and any monitoring policies that are in place.
            Audit:
            Run the following command to verify that a user profile exists:
            # grep -Psi "user-db|system-db" /etc/dconf/profile/*/*

            /etc/dconf/profile/gdm:user-db:user
            /etc/dconf/profile/gdm:system-db:local
            Run the following commands to verify that the text banner on the login screen is
            enabled and set:
            # gsettings get org.gnome.login-screen banner-message-enable
            true
            # gsettings get org.gnome.login-screen banner-message-text
            'Authorized uses only. All activity may be monitored and reported'




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            Remediation:
            - IF - A user profile is already created run the following commands to set and enable the
            text banner message on the login screen:
            # gsettings set org.gnome.login-screen banner-message-text 'Authorized uses
            only. All activity may be monitored and reported'
            # gsettings set org.gnome.login-screen banner-message-enable true
            Note:

                 •   banner-message-text may be set in accordance with local site policy
                 •   gsettings commands in this section MUST be done from a command window
                     on a graphical desktop or an error will be returned.
                 •   The system must be restarted after all gsettings configurations have been set
                     in order for CIS-CAT Assessor to appropriately assess.

            - OR/IF - A user profile does not exist:

                 1. Create or edit the gdm profile in the /etc/dconf/profile/gdm with the following
                    lines:

            user-db:user
            system-db:gdm
            file-db:/usr/share/gdm/greeter-dconf-defaults
            Note: gdm is the name of a dconf database.

                 2. Create a gdm keyfile for machine-wide settings in /etc/dconf/db/gdm.d/01-
                    banner-message:

            [org/gnome/login-screen]
            banner-message-enable=true
            banner-message-text='Type the banner message here.'


                 3. Update the system databases

            # dconf update
            Note:

                 •   Users must log out and back in again before the system-wide settings take effect.
                 •   There is no character limit for the banner message. gnome-shell autodetects
                     longer stretches of text and enters two column mode.
                 •   The banner message cannot be read from an external file.

            Default Value:
            disabled




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            References:

                 1. https://help.gnome.org/admin/system-admin-guide/stable/login-banner.html.en
                 2. NIST SP 800-53 Rev. 5: CM-1,CM-2, CM-6, CM-7, IA-5

            Additional Information:
            Additional options and sections may appear in the /etc/dconf/db/gdm.d/01-banner-
            message file.
            If a different GUI login service is in use, consult your documentation and apply an
            equivalent banner.




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            1.7.3 Ensure GDM disable-user-list option is enabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            GDM is the GNOME Display Manager which handles graphical login for GNOME based
            systems.
            The disable-user-list option controls if a list of users is displayed on the login
            screen
            Rationale:
            Displaying the user list eliminates half of the Userid/Password equation that an
            unauthorized person would need to log on.
            Audit:
            Run the following command to verify that a user profile exists:
            # grep -Psi "user-db|system-db" /etc/dconf/profile/*/*

            /etc/dconf/profile/local:user-db:user
            /etc/dconf/profile/local:system-db:local
            Run the following command and to verify that the disable-user-list option is
            enabled:
            # gsettings get org.gnome.login-screen disable-user-list
            true




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            Remediation:
            - IF - A user profile exists run the following command to enable the disable-user-
            list:
            # gsettings set org.gnome.login-screen disable-user-list true
            Note:

                 •   gsettings commands in this section MUST be done from a command window
                     on a graphical desktop or an error will be returned.
                 •   The system must be restarted after all gsettings configurations have been set
                     in order for CIS-CAT Assessor to appropriately assess.

            - OR/IF - A user profile does not exist:

                 1. Create or edit the gdm profile in /etc/dconf/profile/gdm with the following
                    lines:

            user-db:user
            system-db:gdm
            file-db:/usr/share/gdm/greeter-dconf-defaults
            Note: gdm is the name of a dconf database.

                 2. Create a gdm keyfile for machine-wide settings in /etc/dconf/db/gdm.d/00-
                    login-screen:

            [org/gnome/login-screen]
            # Do not show the user list
            disable-user-list=true

                 3. Update the system databases:

            # dconf update
            Note: When the user profile is created or changed, the user will need to log out and log
            in again before the changes will be applied.
            Default Value:
            false
            References:

                 1. https://help.gnome.org/admin/system-admin-guide/stable/login-userlist-
                    disable.html.en
                 2. NIST SP 800-53 Rev. 5: CM-1,CM-2, CM-6, CM-7, IA-5




                                                                                             Page 189

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            Additional Information:
            If a different GUI login service is in use and required on the system, consult your
            documentation to disable displaying the user list




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            1.7.4 Ensure GDM screen locks when the user is idle
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            GNOME Desktop Manager can make the screen lock automatically whenever the user
            is idle for some amount of time.
            Rationale:
            Setting a lock-out value reduces the window of opportunity for unauthorized user access
            to another user's session that has been left unattended.
            Audit:
            Run the following command to verify that a user profile exists:
            # grep -Psi "user-db|system-db" /etc/dconf/profile/*/*

            /etc/dconf/profile/local:user-db:user
            /etc/dconf/profile/local:system-db:local
            Run the following commands to verify that the screen locks when the user is idle:
            # gsettings get org.gnome.desktop.screensaver lock-delay
            uint32 5
            # gsettings get org.gnome.desktop.session idle-delay
            uint32 900
            # gsettings get org.gnome.desktop.screensaver lock-enabled
            true
            Notes:

                 •   lock-delay=uint32 {n} - should be 5 seconds or less and follow local site
                     policy
                 •   idle-delay=uint32 {n} - Should be 900 seconds (15 minutes) or less, not 0
                     (disabled) and follow local site policy
                 •   lock-enabled - must be set to true for screen locks to lock when the user is
                     idle




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            Remediation:
            - IF - A user profile is already created run the following commands to enable screen
            locks when the user is idle:
            # gsettings set org.gnome.desktop.screensaver lock-delay 5
            # gsettings set org.gnome.desktop.session idle-delay 900
            # gsettings set org.gnome.desktop.screensaver lock-enabled true
            Note:

                 •   gsettings commands in this section MUST be done from a command window
                     on a graphical desktop or an error will be returned.
                 •   The system must be restarted after all gsettings configurations have been set
                     in order for CIS-CAT Assessor to appropriately assess.

            - OR/IF- A user profile does not exist:

                 1. Create or edit the user profile in the /etc/dconf/profile/ and verify it includes
                    the following:

            user-db:user
            system-db:{NAME_OF_DCONF_DATABASE}
            Note: local is the name of a dconf database used in the examples.

                 2. Create the directory /etc/dconf/db/local.d/ if it doesn't already exist:
                 3. Create the key file /etc/dconf/db/local.d/00-screensaver to provide
                    information for the local database:

            Example key file:
            # Specify the dconf path
            [org/gnome/desktop/session]

            # Number of seconds of inactivity before the screen goes blank
            # Set to 0 seconds if you want to deactivate the screensaver.
            idle-delay=uint32 180

            # Specify the dconf path
            [org/gnome/desktop/screensaver]

            # Number of seconds after the screen is blank before locking the screen
            lock-delay=uint32 0

            # Ensure screen locks after inactivity
            lock-enabled=true
            Note: You must include the uint32 along with the integer key values as shown.

                 4. Run the following command to update the system databases:

            # dconf update




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                 5. Users must log out and back in again before the system-wide settings take effect.

            References:

                 1. https://help.gnome.org/admin/system-admin-guide/stable/desktop-
                    lockscreen.html.en

            CIS Controls:

              Controls
                                                              Control                                           IG 1 IG 2 IG 3
              Version
                          4.3 Configure Automatic Session Locking on Enterprise
                          Assets
                   v8         Configure automatic session locking on enterprise assets after a defined period    ●    ●    ●
                          of inactivity. For general purpose operating systems, the period must not exceed
                          15 minutes. For mobile end-user devices, the period must not exceed 2 minutes.

                   v7     16.11 Lock Workstation Sessions After Inactivity                                       ●    ●    ●
                             Automatically lock workstation sessions after a standard period of inactivity.




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            1.7.5 Ensure GDM screen locks cannot be overridden
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            GNOME Desktop Manager can lock down specific settings by using the lockdown mode
            in dconf to prevent users from changing specific settings.
            To lock down a dconf key or subpath, create a locks subdirectory in the keyfile directory.
            The files inside this directory contain a list of keys or subpaths to lock. Just as with the
            keyfiles, you may add any number of files to this directory.
            Rationale:
            Setting a lock-out value reduces the window of opportunity for unauthorized user access
            to another user's session that has been left unattended.
            Without locking down the system settings, user settings take precedence over the
            system settings.
            Audit:
            Run the following commands to verify that the screen lock cannot be overridden:
            # grep -Psi "idle-delay|lock-delay|lock-enabled" /etc/dconf/db/*/locks/*

            /org/gnome/desktop/session/idle-delay
            /org/gnome/desktop/screensaver/lock-delay
            /org/gnome/desktop/screensaver/lock-enabled




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            Remediation:

                 1. To prevent the user from overriding these settings, create the file
                    /etc/dconf/db/local.d/locks/00-screensaver with the following content:

            # Lock desktop screensaver settings
            /org/gnome/desktop/session/idle-delay
            /org/gnome/desktop/screensaver/lock-delay
            /org/gnome/desktop/screensaver/lock-enabled

                 2. Update the system databases:

            # dconf update
            Note:

                 •    A user profile must exist in order to apply locks. If a user profile does not exist
                      review the remediation steps in the previous recommendation.
                 •    Users must log out and back in again before the system-wide settings take effect.

            References:

                 1. https://help.gnome.org/admin/system-admin-guide/stable/desktop-
                    lockscreen.html.en
                 2. https://help.gnome.org/admin/system-admin-guide/stable/dconf-lockdown.html.en
                 3. NIST SP 800-53 Rev. 5: CM-11

            CIS Controls:

              Controls
                                                                Control                                           IG 1 IG 2 IG 3
              Version
                            4.3 Configure Automatic Session Locking on Enterprise
                            Assets
                     v8         Configure automatic session locking on enterprise assets after a defined period    ●    ●    ●
                            of inactivity. For general purpose operating systems, the period must not exceed
                            15 minutes. For mobile end-user devices, the period must not exceed 2 minutes.

                     v7     16.11 Lock Workstation Sessions After Inactivity                                       ●    ●    ●
                               Automatically lock workstation sessions after a standard period of inactivity.




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            1.7.6 Ensure GDM automatic mounting of removable media is
            disabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 2 - Workstation
            Description:
            By default GNOME automatically mounts removable media when inserted as a
            convenience to the user.
            Rationale:
            With automounting enabled anyone with physical access could attach a USB drive or
            disc and have its contents available in system even if they lacked permissions to mount
            it themselves.
            Impact:
            The use of portable hard drives is very common for workstation users. If your
            organization allows the use of portable storage or media on workstations and physical
            access controls to workstations is considered adequate there is little value add in
            turning off automounting.
            Audit:
            Run the following command to verify that a user profile exists:
            # grep -Psi "user-db|system-db" /etc/dconf/profile/*/*

            /etc/dconf/profile/local:user-db:user
            /etc/dconf/profile/local:system-db:local
            Run the following commands to verify automatic mounting is disabled:
            # gsettings get org.gnome.desktop.media-handling automount
            false
            # gsettings get org.gnome.desktop.media-handling automount-open
            false




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            Remediation:
            - IF - A user profile exists run the following commands to ensure automatic mounting is
            disabled:
            # gsettings set org.gnome.desktop.media-handling automount false
            # gsettings set org.gnome.desktop.media-handling automount-open false
            Note:

                 •     gsettings commands in this section MUST be done from a command window
                       on a graphical desktop or an error will be returned.
                 •     The system must be restarted after all gsettings configurations have been set
                       in order for CIS-CAT Assessor to appropriately assess.

            - OR/IF - A user profile does not exist:

                 1. Create a file /etc/dconf/db/local.d/00-media-automount with following
                    content:

            [org/gnome/desktop/media-handling]
            automount=false
            automount-open=false


                 2. After creating the file, apply the changes using below command :

            # dconf update
            Note: Users must log out and back in again before the system-wide settings take effect.
            References:

                 1. https://access.redhat.com/solutions/20107
                 2. NIST SP 800-53 Rev. 5: CM-1,CM-2, CM-6, CM-7, IA-5

            CIS Controls:

                     Controls
                                                                Control                                     IG 1 IG 2 IG 3
                     Version
                                  10.3 Disable Autorun and Autoplay for Removable
                          v8      Media                                                                      ●    ●    ●
                                    Disable autorun and autoplay auto-execute functionality for removable
                                  media.

                          v7      8.5 Configure Devices Not To Auto-run Content                              ●    ●    ●
                                     Configure devices to not auto-run content from removable media.




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            1.7.7 Ensure GDM disabling automatic mounting of removable
            media is not overridden (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 2 - Workstation
            Description:
            By default GNOME automatically mounts removable media when inserted as a
            convenience to the user.
            By using the lockdown mode in dconf, you can prevent users from changing specific
            settings. To lock down a dconf key or subpath, create a locks subdirectory in the keyfile
            directory. The files inside this directory contain a list of keys or subpaths to lock. Just as
            with the keyfiles, you may add any number of files to this directory.
            Rationale:
            With automounting enabled anyone with physical access could attach a USB drive or
            disc and have its contents available in system even if they lacked permissions to mount
            it themselves.
            Impact:
            The use of portable hard drives is very common for workstation users
            Audit:
            Run the following command to verify automount=false and automount-open=false is
            correctly configured to ensure automatic mounting of removable media is not
            overridden:
            # grep -Psi "automount" /etc/dconf/db/*/locks/*

            /etc/dconf/db/local.d/locks/00-media-automount:automount=false
            /etc/dconf/db/local.d/locks/00-media-automount:automount-open=false




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            Remediation:

                 1. To prevent the user from overriding these settings, create the file
                    /etc/dconf/db/local.d/locks/00-media-automount with the following
                    content:

            [org/gnome/desktop/media-handling]
            automount=false
            automount-open=false

                 2. Update the systems databases:

            # dconf update
            Note:

                 •   A user profile must exist in order to apply locks. If a user profile does not exist
                     review the remediation steps in the previous recommendation.
                 •   Users must log out and back in again before the system-wide settings take effect.

            References:

                 1. https://help.gnome.org/admin/system-admin-guide/stable/dconf-lockdown.html.en
                 2. NIST SP 800-53 Rev. 5: CM-1,CM-2, CM-6, CM-7, IA-5
                 3. https://manpages.ubuntu.com/manpages/trusty/man1/gsettings.1.html
                 4. https://access.redhat.com/solutions/20107




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            1.7.8 Ensure GDM autorun-never is enabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The autorun-never setting allows the GNOME Desktop Display Manager to disable
            autorun through GDM.
            Rationale:
            Malware on removable media may taking advantage of Autorun features when the
            media is inserted into a system and execute.
            Audit:
            Run the following command to verify that a user profile exists:
            # grep -Psi "user-db|system-db" /etc/dconf/profile/*/*

            /etc/dconf/profile/local:user-db:user
            /etc/dconf/profile/local:system-db:local
            Run the following command to verify that autorun-never is set to true for GDM:
            # gsettings get org.gnome.desktop.media-handling autorun-never
            true




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            Remediation:
            - IF - A user profile exist run the following command to set autorun-never to true for
            GDM users:
            # gsettings set org.gnome.desktop.media-handling autorun-never true
            Note:

                 •     gsettings commands in this section MUST be done from a command window
                       on a graphical desktop or an error will be returned.
                 •     The system must be restarted after all gsettings configurations have been set
                       in order for CIS-CAT Assessor to appropriately assess.

            - OR/IF - A user profile does not exist:

                 1. create the file /etc/dconf/db/local.d/locks/00-media-autorun with the
                    following content:

            [org/gnome/desktop/media-handling]
            autorun-never=true


                 2. Update the systems databases:

            # dconf update
            Note: Users must log out and back in again before the system-wide settings take effect.
            Default Value:
            false
            References:

                 1. NIST SP 800-53 Rev. 5: CM-1,CM-2, CM-6, CM-7, IA-5

            CIS Controls:

                     Controls
                                                                Control                                     IG 1 IG 2 IG 3
                     Version
                                  10.3 Disable Autorun and Autoplay for Removable
                          v8      Media                                                                      ●    ●    ●
                                    Disable autorun and autoplay auto-execute functionality for removable
                                  media.

                          v7      8.5 Configure Devices Not To Auto-run Content                              ●    ●    ●
                                     Configure devices to not auto-run content from removable media.




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            1.7.9 Ensure GDM autorun-never is not overridden (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The autorun-never setting allows the GNOME Desktop Display Manager to disable
            autorun through GDM.
            By using the lockdown mode in dconf, you can prevent users from changing specific
            settings.
            To lock down a dconf key or subpath, create a locks subdirectory in the keyfile directory.
            The files inside this directory contain a list of keys or subpaths to lock. Just as with the
            keyfiles, you may add any number of files to this directory.
            Rationale:
            Malware on removable media may taking advantage of Autorun features when the
            media is inserted into a system and execute.
            Audit:
            Run the following command to verify that autorun-never=true cannot be overridden:
            # grep -Psi "autorun-never" /etc/dconf/db/*/locks/*

            /etc/dconf/db/local.d/locks/00-media-autorun:autorun-never=true

            Remediation:

                 1. To prevent the user from overriding these settings, create the file
                    /etc/dconf/db/local.d/locks/00-media-autorun with the following content:

            [org/gnome/desktop/media-handling]
            autorun-never=true

                 2. Update the systems databases:

            # dconf update
            Note:

                 •   A user profile must exist in order to apply locks. If a user profile does not exist
                     review the remediation steps in the previous recommendation.
                 •   Users must log out and back in again before the system-wide settings take effect.




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            References:

                 1. NIST SP 800-53 Rev. 5: CM-1,CM-2, CM-6, CM-7, IA-5

            CIS Controls:

                  Controls
                                                             Control                                     IG 1 IG 2 IG 3
                  Version
                               10.3 Disable Autorun and Autoplay for Removable
                          v8   Media                                                                      ●    ●    ●
                                 Disable autorun and autoplay auto-execute functionality for removable
                               media.

                          v7   8.5 Configure Devices Not To Auto-run Content                              ●    ●    ●
                                  Configure devices to not auto-run content from removable media.




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            1.7.10 Ensure XDMCP is not enabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            X Display Manager Control Protocol (XDMCP) is designed to provide authenticated
            access to display management services for remote displays
            Rationale:
            XDMCP is inherently insecure.

                 •   XDMCP is not a ciphered protocol. This may allow an attacker to capture
                     keystrokes entered by a user
                 •   XDMCP is vulnerable to man-in-the-middle attacks. This may allow an attacker to
                     steal the credentials of legitimate users by impersonating the XDMCP server.

            Audit:
            Run the following script and verify the output:
            #!/usr/bin/env bash

            {
               while IFS= read -r l_file; do
                  awk '/\[xdmcp\]/{ f = 1;next } /\[/{ f = 0 } f {if
            (/^\s*Enable\s*=\s*true/) print "The file: \"'"$l_file"'\" includes: \"" $0
            "\" in the \"[xdmcp]\" block"}' "$l_file"
               done < <(grep -Psil -- '^\h*\[xdmcp\]'
            /etc/{gdm3,gdm}/{custom,daemon}.conf)
            }
            Nothing should be returned




                                                                                            Page 204

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            Remediation:
            Edit all files returned by the audit and remove or comment out the Enable=true line in
            the [xdmcp] block:
            Example file:
            # GDM configuration storage
            #
            # See /usr/share/gdm/gdm.schemas for a list of available options.

            [daemon]
            # Uncomment the line below to force the login screen to use Xorg
            #WaylandEnable=false

            #    Enabling automatic login
            #    AutomaticLoginEnable = true
            #    AutomaticLogin = user1

            # Enabling timed login
            # TimedLoginEnable = true
            # TimedLogin = user1
            # TimedLoginDelay = 10

            [security]

            [xdmcp]
            # Enable=true <- **This line should be removed or commented out**

            [chooser]

            [debug]
            # Uncomment the line below to turn on debugging
            # More verbose logs
            # Additionally lets the X server dump core if it crashes
            # Enable=true

            Default Value:
            false
            References:

                 1. NIST SP 800-53 Rev. 5: SI-4




                                                                                           Page 205

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            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            1.7.11 Ensure Xwayland is configured (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Xwayland is a compatibility layer that allows legacy X11 applications to run within a
            Wayland environment. It's effectively an X server that runs as a Wayland client,
            enabling existing X11 software to be displayed on a Wayland compositor.
            Rationale:
            Wayland's security benefits from not relying on X11's network listener. Without X11,
            there's no network listener, making it harder for malicious actors to exploit vulnerabilities
            in X11. However, enabling Xwayland (running X11 applications on Wayland) introduces
            X11's security concerns.
            All X vulnerabilities apply to Xwayland, including keylogging, but they only affect X
            windows and interactions with them.
            Malware can potentially exploit Xwayland vulnerabilities to keylog or intercept other
            input events
            Impact:
            Many applications haven't been ported to Wayland yet, and Xwayland makes it possible
            to run these applications without requiring a full switch back to X11. Disabling Xwayland
            functionality may cause these applications to fail.
            Audit:
            Run the following command to verify Xwayland is not enabled:
            # sed -n '/\[daemon\]/,/\[/p' /etc/gdm/custom.conf | grep -Psi
            '^\h*waylandenable\b'
            Verify output includes:
            WaylandEnable=false




                                                                                                Page 207

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            Remediation:
            Edit the file /etc/gdm/custom.conf and uncomment or add the following line in the
            [daemon] block:
            WaylandEnable=false
            Example:
            # GDM configuration storage

            [daemon]
            WaylandEnable=false

            [security]

            [xdmcp]

            [chooser]

            [debug]
            # Uncomment the line below to turn on debugging
            #Enable=true

            Default Value:
            Enabled
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 208

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            2 Services
            While applying system updates and patches helps correct known vulnerabilities, one of
            the best ways to protect the system against as yet unreported vulnerabilities is to
            disable all services that are not required for normal system operation. This prevents the
            exploitation of vulnerabilities discovered at a later date. If a service is not enabled, it
            cannot be exploited. The actions in this section of the document provide guidance on
            some services which can be safely disabled and under which circumstances, greatly
            reducing the number of possible threats to the resulting system. Additionally, some
            services which should remain enabled but with secure configuration are covered as well
            as insecure service clients.




                                                                                               Page 209

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            2.1 Configure Server Services

            This section describes services that are installed on systems that specifically need to
            run these services. If any of these services are not required, it is recommended that the
            package be removed.
            - IF - the package is required for a dependency:

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy
                 •   Stop and mask the service and/or socket to reduce the potential attack surface

            The following commands can be used to stop and mask the service and socket:
            # systemctl stop <service_name>.socket <service_name>.service
            # systemctl mask <service_name>.socket <service_name>.service
            Note: This should not be considered a comprehensive list of services not required for
            normal system operation. You may wish to consider additions to those listed here for
            your environment




                                                                                             Page 210

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            2.1.1 Ensure autofs services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 2 - Workstation
            Description:
            autofs allows automatic mounting of devices, typically including CD/DVDs and USB
            drives.
            Rationale:
            With automounting enabled anyone with physical access could attach a USB drive or
            disc and have its contents available in the filesystem even if they lacked permissions to
            mount it themselves.
            Impact:
            The use of portable hard drives is very common for workstation users. If your
            organization allows the use of portable storage or media on workstations and physical
            access controls to workstations is considered adequate there is little value add in
            turning off automounting.
            There may be packages that are dependent on the autofs package. If the autofs
            package is removed, these dependent packages will be removed as well. Before
            removing the autofs package, review any dependent packages to determine if they are
            required on the system.
            - IF - a dependent package is required: stop and mask the autofs.service leaving the
            autofs package installed.




                                                                                              Page 211

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            Audit:
            As a preference autofs should not be installed unless other packages depend on it.
            Run the following command to verify autofs is not installed:
            # dpkg-query -s autofs &>/dev/null && echo "autofs is installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify autofs.service is not enabled:
            # systemctl is-enabled autofs.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify the autofs.service is not active:
            # systemctl is-active autofs.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy

            Remediation:
            Run the following commands to stop autofs.service and remove the autofs
            package:
            # systemctl stop autofs.service
            # apt purge autofs
            - OR -
            - IF - the autofs package is required as a dependency:
            Run the following commands to stop and mask autofs.service:
            # systemctl stop autofs.service
            # systemctl mask autofs.service

            References:

                 1. NIST SP 800-53 Rev. 5: SI-3, MP-7
                 2. RHEL 8 STIG Vul ID: V-230502
                 3. RHEL 8 STIG Rule ID: SV-230502r627750




                                                                                             Page 212

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            Additional Information:
            This control should align with the tolerance of the use of portable drives and optical
            media in the organization. On a server, requiring an admin to manually mount media
            can be part of defense-in-depth to reduce the risk of unapproved software or information
            being introduced or proprietary software or information being exfiltrated. If admins
            commonly use flash drives and Server access has sufficient physical controls, requiring
            manual mounting may not increase security.
            CIS Controls:

                  Controls
                                                             Control                                     IG 1 IG 2 IG 3
                  Version
                               10.3 Disable Autorun and Autoplay for Removable
                          v8   Media                                                                      ●    ●    ●
                                 Disable autorun and autoplay auto-execute functionality for removable
                               media.

                          v7   8.5 Configure Devices Not To Auto-run Content                              ●    ●    ●
                                  Configure devices to not auto-run content from removable media.




                                                                                                               Page 213

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            2.1.2 Ensure avahi daemon services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 2 - Workstation
            Description:
            Avahi is a free zeroconf implementation, including a system for multicast DNS/DNS-SD
            service discovery. Avahi allows programs to publish and discover services and hosts
            running on a local network with no specific configuration. For example, a user can plug
            a computer into a network and Avahi automatically finds printers to print to, files to look
            at and people to talk to, as well as network services running on the machine.
            Rationale:
            Automatic discovery of network services is not normally required for system
            functionality. It is recommended to remove this package to reduce the potential attack
            surface.
            Impact:
            There may be packages that are dependent on the avahi package. If the avahi
            package is removed, these dependent packages will be removed as well. Before
            removing the avahi package, review any dependent packages to determine if they are
            required on the system.
            - IF - a dependent package is required: stop and mask the avahi-daemon.socket and
            avahi-daemon.service leaving the avahi package installed.




                                                                                               Page 214

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            Audit:
            Run the following command to verify avahi-daemon is not installed:
            # dpkg-query -s avahi-daemon &>/dev/null && echo "avahi-daemon is installed"
            Nothing should be returned.
            - OR -
            - IF - the avahi package is required as a dependency:
            Run the following command to verify avahi-daemon.socket and avahi-
            daemon.service are not enabled:
            # systemctl is-enabled avahi-daemon.socket avahi-daemon.service 2>/dev/null |
            grep 'enabled'

            Nothing should be returned
            Run the following command to verify avahi-daemon.socket and avahi-
            daemon.service are not active:
            # systemctl is-active avahi-daemon.socket avahi-daemon.service 2>/dev/null |
            grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy

            Remediation:
            Run the following commands to stop avahi-daemon.socket and avahi-
            daemon.service, and remove the avahi-daemon package:
            # systemctl stop avahi-daemon.socket avahi-daemon.service
            # apt purge avahi-daemon
            - OR -
            - IF - the avahi-daemon package is required as a dependency:
            Run the following commands to stop and mask the avahi-daemon.socket and avahi-
            daemon.service:
            # systemctl stop avahi-daemon.socket avahi-daemon.service
            # systemctl mask avahi-daemon.socket avahi-daemon.service

            References:

                 1. NIST SP 800-53 Rev. 5: SI-4




                                                                                             Page 215

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            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 216

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            2.1.3 Ensure dhcp server services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Dynamic Host Configuration Protocol (DHCP) is a service that allows machines to
            be dynamically assigned IP addresses. There are two versions of the DHCP protocol
            DHCPv4 and DHCPv6. At startup the server may be started for one or the other via the -4
            or -6 arguments.

            Rationale:
            Unless a system is specifically set up to act as a DHCP server, it is recommended that
            this package be removed to reduce the potential attack surface.
            Impact:
            There may be packages that are dependent on the isc-dhcp-server package. If the
            isc-dhcp-server package is removed, these dependent packages will be removed as
            well. Before removing the isc-dhcp-server package, review any dependent packages
            to determine if they are required on the system.
            - IF - a dependent package is required: stop and mask the isc-dhcp-server.service
            and isc-dhcp-server6.service leaving the isc-dhcp-server package installed.




                                                                                           Page 217

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            Audit:
            Run the following commands to verify isc-dhcp-server is not installed:
            # dpkg-query -s isc-dhcp-server &>/dev/null && echo "isc-dhcp-server is
            installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify isc-dhcp-server.service and isc-dhcp-
            server6.service are not enabled:
            # systemctl is-enabled isc-dhcp-server.service isc-dhcp-server6.service
            2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify isc-dhcp-server.service and isc-dhcp-
            server6.service are not active:
            # systemctl is-active isc-dhcp-server.service isc-dhcp-server6.service
            2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy

            Remediation:
            Run the following commands to stop isc-dhcp-server.service and isc-dhcp-
            server6.service and remove the isc-dhcp-server package:
            # systemctl stop isc-dhcp-server.service isc-dhcp-server6.service
            # apt purge isc-dhcp-server
            - OR -
            - IF - the isc-dhcp-server package is required as a dependency:
            Run the following commands to stop and mask isc-dhcp-server.service and isc-
            dhcp-server6.service:
            # systemctl stop isc-dhcp-server.service isc-dhcp-server6.service
            # systemctl mask isc-dhcp-server isc-dhcp-server6.service

            References:

                 1. More detailed documentation on DHCP is available at
                    http://www.isc.org/software/dhcp.
                 2. NIST SP 800-53 Rev. 5: CM-7




                                                                                             Page 218

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            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 219

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            2.1.4 Ensure dns server services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Domain Name System (DNS) is a hierarchical naming system that maps names to
            IP addresses for computers, services and other resources connected to a network.
            Note: bind9 is the package and bind.service is the alias for named.service.

            Rationale:
            Unless a system is specifically designated to act as a DNS server, it is recommended
            that the package be deleted to reduce the potential attack surface.
            Impact:
            There may be packages that are dependent on the bind9 package. If the bind9
            package is removed, these dependent packages will be removed as well. Before
            removing the bind9 package, review any dependent packages to determine if they are
            required on the system.
            - IF - a dependent package is required: stop and mask named.service leaving the
            bind9 package installed.

            Audit:
            Run the following command to verify bind9 is not installed:
            # dpkg-query -s bind9 &>/dev/null && echo "bind9 is installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify named.service is not enabled:
            # systemctl is-enabled named.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify the named.service is not active:
            # systemctl is-active named.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy


                                                                                             Page 220

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            Remediation:
            Run the following commands to stop named.service and remove the bind9 package:
            # systemctl stop named.service
            # apt purge bind9
            - OR -
            - IF - the bind9 package is required as a dependency:
            Run the following commands to stop and mask bind9.service:
            # systemctl stop named.service
            # systemctl mask named.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 221

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            2.1.5 Ensure dnsmasq services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            dnsmasq is a lightweight tool that provides DNS caching, DNS forwarding and DHCP
            (Dynamic Host Configuration Protocol) services.
            Rationale:
            Unless a system is specifically designated to act as a DNS caching, DNS forwarding
            and/or DHCP server, it is recommended that the package be removed to reduce the
            potential attack surface.
            Impact:
            There may be packages that are dependent on the dnsmasq package. If the dnsmasq
            package is removed, these dependent packages will be removed as well. Before
            removing the dnsmasq package, review any dependent packages to determine if they
            are required on the system.
            - IF - a dependent package is required: stop and mask the dnsmasq.service leaving
            the dnsmasq package installed.

            Audit:
            Run one of the following commands to verify dnsmasq is not installed:
            # dpkg-query -s dnsmasq &>/dev/null && echo "dnsmasq is installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify dnsmasq.service is not enabled:
            # systemctl is-enabled dnsmasq.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify the dnsmasq.service is not active:
            # systemctl is-active dnsmasq.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy



                                                                                             Page 222

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            Remediation:
            Run the following commands to stop dnsmasq.service and remove dnsmasq package:
            # systemctl stop dnsmasq.service
            # apt purge dnsmasq
            - OR -
            - IF - the dnsmasq package is required as a dependency:
            Run the following commands to stop and mask the dnsmasq.service:
            # systemctl stop dnsmasq.service
            # systemctl mask dnsmasq.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 223

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            2.1.6 Ensure ftp server services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The File Transfer Protocol (FTP) provides networked computers with the ability to
            transfer files. vsftpd is the Very Secure File Transfer Protocol Daemon.

            Rationale:
            FTP does not protect the confidentiality of data or authentication credentials. It is
            recommended SFTP be used if file transfer is required. Unless there is a need to run
            the system as a FTP server (for example, to allow anonymous downloads), it is
            recommended that the package be deleted to reduce the potential attack surface.
            Impact:
            There may be packages that are dependent on the vsftpd package. If the vsftpd
            package is removed, these dependent packages will be removed as well. Before
            removing the vsftpd package, review any dependent packages to determine if they are
            required on the system.
            - IF - a dependent package is required: stop and mask the vsftpd.service leaving the
            vsftpd package installed.




                                                                                            Page 224

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            Audit:
            Run the following command to verify vsftpd is not installed:
            # dpkg-query -l | awk '{print $2}' | grep -E '^ftp|^tnftp' &>/dev/null &&
            echo "ftp is installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify vsftpd service is not enabled:
            # systemctl is-enabled vsftpd.service 2>/dev/null | grep 'enabled'
            Nothing should be returned.
            Run the following command to verify the vsftpd service is not active:
            # systemctl is-active vsftpd.service 2>/dev/null | grep '^active'
            Nothing should be returned.
            Note:

                 •   Other ftp server packages may exist. They should also be audited, if not required
                     and authorized by local site policy
                 •   If the package is required for a dependency:
                          o Ensure the dependent package is approved by local site policy
                          o Ensure stopping and masking the service and/or socket meets local site
                             policy

            Remediation:
            Run the following commands to stop vsftpd.service and remove the vsftpd
            package:
            # systemctl stop vsftpd.service
            # apt purge vsftpd
            - OR -
            - IF - the vsftpd package is required as a dependency:
            Run the following commands to stop and mask the vsftpd.service:
            # systemctl stop vsftpd.service
            # systemctl mask vsftpd.service
            Note: Other ftp server packages may exist. If not required and authorized by local site
            policy, they should also be removed. If the package is required for a dependency, the
            service should be stopped and masked.
            References:

                 1. NIST SP 800-53 Rev. 5: CM-7




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            Additional Information:
            Additional FTP servers also exist and should be audited.
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            2.1.7 Ensure ldap server services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Lightweight Directory Access Protocol (LDAP) was introduced as a replacement for
            NIS/YP. It is a service that provides a method for looking up information from a central
            database.
            Rationale:
            If the system will not need to act as an LDAP server, it is recommended that the
            software be removed to reduce the potential attack surface.
            Impact:
            There may be packages that are dependent on the slapd package. If the slapd
            package is removed, these dependent packages will be removed as well. Before
            removing the slapd package, review any dependent packages to determine if they are
            required on the system.
            - IF - a dependent package is required: stop and mask the slapd.service leaving the
            slapd package installed.

            Audit:
            Run the following command to verify slapd is not installed:
            # dpkg-query -s slapd &>/dev/null && echo "slapd is installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify slapd.service is not enabled:
            # systemctl is-enabled slapd.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify slapd.service is not active:
            # systemctl is-active slapd.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy



                                                                                               Page 227

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            Remediation:
            Run the following commands to stop slapd.service and remove the slapd package:
            # systemctl stop slapd.service
            # apt purge slapd
            - OR -
            - IF - the slapd package is required as a dependency:
            Run the following commands to stop and mask slapd.service:
            # systemctl stop slapd.service
            # systemctl mask slapd.service

            References:

                 1. For more detailed documentation on OpenLDAP, go to the project homepage at
                    http://www.openldap.org.
                 2. NIST SP 800-53 Rev. 5: CM-7

            CIS Controls:

               Controls
                                                             Control                                          IG 1 IG 2 IG 3
               Version
                           4.8 Uninstall or Disable Unnecessary Services on
                           Enterprise Assets and Software
                    v8        Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                           such as an unused file sharing service, web application module, or service
                           function.

                           9.2 Ensure Only Approved Ports, Protocols and Services
                    v7     Are Running                                                                              ●    ●
                              Ensure that only network ports, protocols, and services listening on a system
                           with validated business needs, are running on each system.




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            2.1.8 Ensure message access server services are not in use
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            dovecot-imapd and dovecot-pop3d are an open source IMAP and POP3 server for
            Linux based systems.
            Rationale:
            Unless POP3 and/or IMAP servers are to be provided by this system, it is
            recommended that the package be removed to reduce the potential attack surface.
            Note: Several IMAP/POP3 servers exist and can use other service names. These
            should also be audited and the packages removed if not required.
            Impact:
            There may be packages that are dependent on dovecot-imapd and/or dovecot-pop3d
            packages. If dovecot-imapd and dovecot-pop3d packages are removed, these
            dependent packages will be removed as well. Before removing dovecot-imapd and/or
            dovecot-pop3d packages, review any dependent packages to determine if they are
            required on the system.
            - IF - a dependent package is required: stop and mask dovecot.socket and
            dovecot.service leaving dovecot-imapd and/or dovecot-pop3d packages installed.




                                                                                        Page 229

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            Audit:
            Run the following command to verify dovecot-imapd and dovecot-pop3d are not
            installed:
            # dpkg-query -s dovecot-imapd &>/dev/null && echo "dovecot-imapd is
            installed"
            Nothing should be returned.
            # dpkg-query -s dovecot-pop3d &>/dev/null && echo "dovecot-pop3d is
            installed"
            Nothing should be returned.
            - OR -
            - IF - a package is installed and is required for dependencies:
            Run the following commands to verify dovecot.socket and dovecot.service are not
            enabled:
            # systemctl is-enabled dovecot.socket dovecot.service 2>/dev/null | grep
            'enabled'

            Nothing should be returned
            Run the following command to verify dovecot.socket and dovecot.service are not
            active:
            # systemctl is-active dovecot.socket dovecot.service 2>/dev/null | grep
            '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy




                                                                                             Page 230

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            Remediation:
            Run one of the following commands to remove dovecot-imapd and dovecot-pop3d:
            Run the following commands to stop dovecot.socket and dovecot.service, and
            remove the dovecot-imapd and dovecot-pop3d packages:
            # systemctl stop dovecot.socket dovecot.service
            # apt purge dovecot-imapd dovecot-pop3d
            - OR -
            - IF - a package is installed and is required for dependencies:
            Run the following commands to stop and mask dovecot.socket and
            dovecot.service:
            # systemctl stop dovecot.socket dovecot.service
            # systemctl mask dovecot.socket dovecot.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7

            Additional Information:
            Several IMAP/POP3 servers exist and can use other service names. courier-imap
            and cyrus-imap are example services that provide a mail server. These and other
            services should also be audited.
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            2.1.9 Ensure network file system services are not in use
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Network File System (NFS) is one of the first and most widely distributed file
            systems in the UNIX environment. It provides the ability for systems to mount file
            systems of other servers through the network.
            Rationale:
            If the system does not export NFS shares, it is recommended that the nfs-kernel-
            server package be removed to reduce the remote attack surface.

            Impact:
            There may be packages that are dependent on the nfs-kernel-server package. If the
            nfs-kernel-server package is removed, these dependent packages will be removed
            as well. Before removing the nfs-kernel-server package, review any dependent
            packages to determine if they are required on the system.
            - IF - a dependent package is required: stop and mask the nfs-server.service
            leaving the nfs-kernel-server package installed.

            Audit:
            Run the following command to verify nfs-kernel-server is not installed:
            # dpkg-query -s nfs-kernel-server &>/dev/null && echo "nfs-kernel-server is
            installed"
            Nothing should be returned.
            - OR -
            - IF - package is required for dependencies:
            Run the following command to verify that the nfs-server.service is not enabled:
            # systemctl is-enabled nfs-server.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify the nfs-server.service is not active:
            # systemctl is-active nfs-server.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency
               • Ensure the dependent package is approved by local site policy
               • Ensure stopping and masking the service and/or socket meets local site policy


                                                                                             Page 232

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            Remediation:
            Run the following command to stop nfs-server.service and remove nfs-kernel-
            server package:
            # systemctl stop nfs-server.service
            # apt purge nfs-kernel-server
            - OR -
            - IF - the nfs-kernel-server package is required as a dependency:
            Run the following commands to stop and mask the nfs-server.service:
            # systemctl stop nfs-server.service
            # systemctl mask nfs-server.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-6, CM-7

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            2.1.10 Ensure nis server services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Network Information Service (NIS) (formally known as Yellow Pages) is a client-
            server directory service protocol for distributing system configuration files. The NIS
            server is a collection of programs that allow for the distribution of configuration files. The
            NIS client (ypbind) was used to bind a machine to an NIS server and receive the
            distributed configuration files.
            Rationale:
            ypserv.service is inherently an insecure system that has been vulnerable to DOS
            attacks, buffer overflows and has poor authentication for querying NIS maps. NIS
            generally has been replaced by such protocols as Lightweight Directory Access
            Protocol (LDAP). It is recommended that ypserv.service be removed and other, more
            secure services be used
            Impact:
            There may be packages that are dependent on the ypserv package. If the ypserv
            package is removed, these dependent packages will be removed as well. Before
            removing the ypserv package, review any dependent packages to determine if they are
            required on the system.
            - IF - a dependent package is required: stop and mask the ypserv.service leaving the
            ypserv package installed.




                                                                                                 Page 234

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            Audit:
            Run the following command to verify ypserv is not installed:
            # dpkg-query -s ypserv &>/dev/null && echo "ypserv is installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify ypserv.service is not enabled:
            # systemctl is-enabled ypserv.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify ypserv.service is not active:
            # systemctl is-active ypserv.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy

            Remediation:
            Run the following commands to stop ypserv.service and remove ypserv package:
            # systemctl stop ypserv.service
            # apt purge ypserv
            - OR -
            - IF - the ypserv package is required as a dependency:
            Run the following commands to stop and mask ypserv.service:
            # systemctl stop ypserv.service
            # systemctl mask ypserv.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7




                                                                                             Page 235

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 236

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            2.1.11 Ensure print server services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 2 - Workstation
            Description:
            The Common Unix Print System (CUPS) provides the ability to print to both local and
            network printers. A system running CUPS can also accept print jobs from remote
            systems and print them to local printers. It also provides a web based remote
            administration capability.
            Rationale:
            If the system does not need to print jobs or accept print jobs from other systems, it is
            recommended that CUPS be removed to reduce the potential attack surface.
            Impact:
            Removing the cups package, or disabling cups.socket and/or cups.service will
            prevent printing from the system, a common task for workstation systems.
            There may be packages that are dependent on the cups package. If the cups package
            is removed, these dependent packages will be removed as well. Before removing the
            cups package, review any dependent packages to determine if they are required on the
            system.
            - IF - a dependent package is required: stop and mask cups.socket and
            cups.service leaving the cups package installed.




                                                                                               Page 237

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            Audit:
            Run the following command to verify cups is not Installed:
            # dpkg-query -s cups &>/dev/null && echo "cups is installed"
            Nothing should be returned.
            - OR -
            - IF - the cups package is required as a dependency:
            Run the following command to verify the cups.socket and cups.service are not
            enabled:
            # systemctl is-enabled cups.socket cups.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify the cups.socket and cups.service are not
            active:
            # systemctl is-active cups.socket cups.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy

            Remediation:
            Run the following commands to stop cups.socket and cups.service, and remove the
            cups package:
            # systemctl stop cups.socket cups.service
            # apt purge cups
            - OR -
            - IF - the cups package is required as a dependency:
            Run the following commands to stop and mask the cups.socket and cups.service:
            # systemctl stop cups.socket cups.service
            # systemctl mask cups.socket cups.service

            References:

                 1. http://www.cups.org
                 2. NIST SP 800-53 Rev. 5: CM-7




                                                                                             Page 238

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 239

Internal Only - General
            2.1.12 Ensure rpcbind services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The rpcbind utility maps RPC services to the ports on which they listen. RPC
            processes notify rpcbind when they start, registering the ports they are listening on and
            the RPC program numbers they expect to serve. The client system then contacts
            rpcbind on the server with a particular RPC program number. The rpcbind.service
            redirects the client to the proper port number so it can communicate with the requested
            service.
            Portmapper is an RPC service, which always listens on tcp and udp 111, and is used to
            map other RPC services (such as nfs, nlockmgr, quotad, mountd, etc.) to their
            corresponding port number on the server. When a remote host makes an RPC call to
            that server, it first consults with portmap to determine where the RPC server is listening.
            Rationale:
            A small request (~82 bytes via UDP) sent to the Portmapper generates a large
            response (7x to 28x amplification), which makes it a suitable tool for DDoS attacks. If
            rpcbind is not required, it is recommended to remove rpcbind package to reduce the
            potential attack surface.
            Impact:
            Many of the libvirt packages used by Enterprise Linux virtualization, and the nfs-utils
            package used for The Network File System (NFS), are dependent on the rpcbind
            package. If the rpcbind package is removed, these dependent packages will be
            removed as well. Before removing the rpcbind package, review any dependent
            packages to determine if they are required on the system.
            - IF - a dependent package is required: stop and mask the rpcbind.socket and
            rpcbind.service leaving the rpcbind package installed.




                                                                                              Page 240

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            Audit:
            Run the following command to verify rpcbind package is not installed:
            # dpkg-query -s rpcbind &>/dev/null && echo "rpcbind is installed"
            Nothing should be returned.
            - OR -
            - IF - the rpcbind package is required as a dependency:
            Run the following command to verify rpcbind.socket and rpcbind.service are not
            enabled:
            # systemctl is-enabled rpcbind.socket rpcbind.service 2>/dev/null | grep
            'enabled'

            Nothing should be returned
            Run the following command to verify rpcbind.socket and rpcbind.service are not
            active:
            # systemctl is-active rpcbind.socket rpcbind.service 2>/dev/null | grep
            '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy

            Remediation:
            Run the following commands to stop rpcbind.socket and rpcbind.service, and
            remove the rpcbind package:
            # systemctl stop rpcbind.socket rpcbind.service
            # apt purge rpcbind
            - OR -
            - IF - the rpcbind package is required as a dependency:
            Run the following commands to stop and mask the rpcbind.socket and
            rpcbind.service:
            # systemctl stop rpcbind.socket rpcbind.service
            # systemctl mask rpcbind.socket rpcbind.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-6, CM-7




                                                                                             Page 241

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 242

Internal Only - General
            2.1.13 Ensure rsync services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The rsync service can be used to synchronize files between systems over network
            links.
            Rationale:
            rsync.service presents a security risk as the rsync protocol is unencrypted.
            The rsync package should be removed to reduce the attack area of the system.

            Impact:
            There may be packages that are dependent on the rsync package. If the rsync
            package is removed, these dependent packages will be removed as well. Before
            removing the rsync package, review any dependent packages to determine if they are
            required on the system.
            - IF - a dependent package is required: stop and mask rsync.service leaving the
            rsync package installed.

            Audit:
            Run the following command to verify rsync is not installed:
            # dpkg-query -s rsync &>/dev/null && echo "rsync is installed"
            Nothing should be returned.
            - OR -
            - IF - the rsync package is required as a dependency:
            Run the following command to verify rsync.service is not enabled:
            # systemctl is-enabled rsync.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify rsync.service is not active:
            # systemctl is-active rsync.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy



                                                                                             Page 243

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            Remediation:
            Run the following commands to stop rsync.service, and remove the rsync package:
            # systemctl stop rsync.service
            # apt purge rsync
            - OR -
            - IF - the rsync package is required as a dependency:
            Run the following commands to stop and mask rsync.service:
            # systemctl stop rsync.service
            # systemctl mask rsync.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 244

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            2.1.14 Ensure samba file server services are not in use
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Samba daemon allows system administrators to configure their Linux systems to
            share file systems and directories with Windows desktops. Samba will advertise the file
            systems and directories via the Server Message Block (SMB) protocol. Windows
            desktop users will be able to mount these directories and file systems as letter drives on
            their systems.
            Rationale:
            If there is no need to mount directories and file systems to Windows systems, then this
            service should be deleted to reduce the potential attack surface.
            Impact:
            There may be packages that are dependent on the samba package. If the samba
            package is removed, these dependent packages will be removed as well. Before
            removing the samba package, review any dependent packages to determine if they are
            required on the system.
            - IF - a dependent package is required: stop and mask the smbd.service leaving the
            samba package installed.




                                                                                              Page 245

Internal Only - General
            Audit:
            Run the following command to verify samba is not installed:
            # dpkg-query -s samba &>/dev/null && echo "samba is installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify smbd.service is not enabled:
            # systemctl is-enabled smbd.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify the smbd.service is not active:
            # systemctl is-active smbd.service 2>/dev/null | grep '^active'

            Nothing should be returned

            Remediation:
            Run the following commands to stop smbd.service and remove samba package:
            # systemctl stop smbd.service
            # apt purge samba
            - OR -
            - IF - the samba package is required as a dependency:
            Run the following commands to stop and mask the smbd.service:
            # systemctl stop smbd.service
            # systemctl mask smbd.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-6, CM-7

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 246

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            2.1.15 Ensure snmp services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Simple Network Management Protocol (SNMP) is a widely used protocol for monitoring
            the health and welfare of network equipment, computer equipment and devices like
            UPSs.
            Net-SNMP is a suite of applications used to implement SNMPv1 (RFC 1157), SNMPv2
            (RFCs 1901-1908), and SNMPv3 (RFCs 3411-3418) using both IPv4 and IPv6.
            Support for SNMPv2 classic (a.k.a. "SNMPv2 historic" - RFCs 1441-1452) was dropped
            with the 4.0 release of the UCD-snmp package.
            The Simple Network Management Protocol (SNMP) server is used to listen for SNMP
            commands from an SNMP management system, execute the commands or collect the
            information and then send results back to the requesting system.
            Rationale:
            The SNMP server can communicate using SNMPv1, which transmits data in the clear
            and does not require authentication to execute commands. SNMPv3 replaces the
            simple/clear text password sharing used in SNMPv2 with more securely encoded
            parameters. If the the SNMP service is not required, the snmpd package should be
            removed to reduce the attack surface of the system.
            Note: If SNMP is required:

                 •   The server should be configured for SNMP v3 only. User Authentication and
                     Message Encryption should be configured.
                 •   If SNMP v2 is absolutely necessary, modify the community strings' values.

            Impact:
            There may be packages that are dependent on the snmpd package. If the snmpd
            package is removed, these packages will be removed as well.
            Before removing the snmpd package, review any dependent packages to determine if
            they are required on the system. If a dependent package is required, stop and mask the
            snmpd.service leaving the snmpd package installed.




                                                                                          Page 247

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            Audit:
            Run the following command to verify snmpd is not installed:
            # dpkg-query -s snmpd &>/dev/null && echo "snmpd is installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify the snmpd.service is not enabled:
            # systemctl is-enabled snmpd.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify the snmpd.service is not active:
            # systemctl is-active snmpd.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy

            Remediation:
            Run the following commands to stop snmpd.service and remove the snmpd package:
            # systemctl stop snmpd.service
            # apt purge snmpd
            - OR - If the package is required for dependencies:
            Run the following commands to stop and mask the snmpd.service:
            # systemctl stop snmpd.service
            # systemctl mask snmpd.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7




                                                                                             Page 248

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 249

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            2.1.16 Ensure tftp server services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Trivial File Transfer Protocol (TFTP) is a simple protocol for exchanging files between
            two TCP/IP machines. TFTP servers allow connections from a TFTP Client for sending
            and receiving files.
            Rationale:
            Unless there is a need to run the system as a TFTP server, it is recommended that the
            package be removed to reduce the potential attack surface.
            TFTP does not have built-in encryption, access control or authentication. This makes it
            very easy for an attacker to exploit TFTP to gain access to files
            Impact:
            TFTP is often used to provide files for network booting such as for PXE based
            installation of servers.
            There may be packages that are dependent on the tftpd-hpa package. If the tftpd-
            hpa package is removed, these dependent packages will be removed as well. Before
            removing the tftpd-hpa package, review any dependent packages to determine if they
            are required on the system.
            - IF - a dependent package is required: stop and mask tftpd-hpa.service leaving the
            tftpd-hpa package installed.




                                                                                            Page 250

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            Audit:
            Run the following command to verify tftpd-hpa is not installed:
            # dpkg-query -s tftpd-hpa &>/dev/null && echo "tftpd-hpa is installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify tftpd-hpa.service is not enabled:
            # systemctl is-enabled tftpd-hpa.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify the tftpd-hpa.service is not active:
            # systemctl is-active tftpd-hpa.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy

            Remediation:
            Run the following commands to stop tftpd-hpa.service, and remove the tftpd-hpa
            package:
            # systemctl stop tftpd-hpa.service
            # apt purge tftpd-hpa
            - OR -
            - IF - the tftpd-hpa package is required as a dependency:
            Run the following commands to stop and mask tftpd-hpa.service:
            # systemctl stop tftpd-hpa.service
            # systemctl mask tftpd-hpa.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7




                                                                                             Page 251

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 252

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            2.1.17 Ensure web proxy server services are not in use
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Squid is a standard proxy server used in many distributions and environments.
            Rationale:
            Unless a system is specifically set up to act as a proxy server, it is recommended that
            the squid package be removed to reduce the potential attack surface.
            Note: Several HTTP proxy servers exist. These should be checked and removed unless
            required.
            Impact:
            There may be packages that are dependent on the squid package. If the squid
            package is removed, these dependent packages will be removed as well. Before
            removing the squid package, review any dependent packages to determine if they are
            required on the system.
            - IF - a dependent package is required: stop and mask the squid.service leaving the
            squid package installed.

            Audit:
            Run the following command to verify squid is not installed:
            # dpkg-query -s squid &>/dev/null && echo "squid is installed"
            Nothing should be returned.
            - OR -
            - IF - the package is required for dependencies:
            Run the following command to verify squid.service is not enabled:
            # systemctl is-enabled squid.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify the squid.service is not active:
            # systemctl is-active squid.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency
               • Ensure the dependent package is approved by local site policy
               • Ensure stopping and masking the service and/or socket meets local site policy



                                                                                            Page 253

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            Remediation:
            Run the following commands to stop squid.service and remove the squid package:
            # systemctl stop squid.service
            # apt purge squid
            - OR - If the squid package is required as a dependency:
            Run the following commands to stop and mask the squid.service:
            # systemctl stop squid.service
            # systemctl mask squid.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7

            Additional Information:
            Several HTTP proxy servers exist. These and other services should be checked
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 254

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            2.1.18 Ensure web server services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Web servers provide the ability to host web site content.
            Rationale:
            Unless there is a local site approved requirement to run a web server service on the
            system, web server packages should be removed to reduce the potential attack surface.
            Impact:
            Removal of a web server's package, or changing the state of its service and/or socket,
            will prevent the server from hosting web services.
            - IF - a web server package is required for a dependency, any related service or socket
            should be stopped and masked.
            Note: If the remediation steps to mask a service are followed and that package is not
            installed on the system, the service and/or socket will still be masked. If the package is
            installed due to an approved requirement to host a web server, the associated service
            and/or socket would need to be unmasked before it could be enabled and/or started.




                                                                                               Page 255

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            Audit:
            Run the following command to verify apache2 is not installed:
            # dpkg-query -s apache2 &>/dev/null && echo "apache2 is installed"
            Nothing should be returned.
            Run the following command to verify nginx is not installed:
            # dpkg-query -s nginx &>/dev/null && echo "nginx is installed"
            Nothing should be returned.
            - OR -
            - IF - a package is installed and is required for dependencies:
            - IF - the httpd package is required for dependencies:
            Run the following command to verify httpd.socket and httpd.service
            UnitFileState is not enabled and ActiveState is not active:
            # systemctl show httpd.socket httpd.service -p UnitFileState,ActiveState |
            grep -Pi '=(enabled|active)'

            Nothing should be returned
            - IF - the nginx package is required for dependencies:
            Run the following command to verify nginx.service UnitFileState is not enabled
            and ActiveState is not active:
            # systemctl show nginx.service -p UnitFileState,ActiveState | grep -Pi
            '=(enabled|active)'

            Nothing should be returned
            Note:

                 •   Other web server packages may exist. They should also be audited, if not
                     required and authorized by local site policy
                 •   If the package is required for a dependency:
                          o Ensure the dependent package is approved by local site policy
                          o Ensure stopping and masking the service and/or socket meets local site
                             policy




                                                                                            Page 256

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            Remediation:
            Run the following commands to stop httpd.socket, httpd.service and remove the
            apache2 package:
            # systemctl stop apache2.socket apache2.service
            # apt purge apache2
            Run the following commands to stop nginx.service and remove the nginx package:
            # systemctl stop nginx.service
            # apt purge nginx
            - OR -
            - IF - a package is installed and is required for dependencies:
            - IF - the httpd package is required for dependencies:
            Run the following commands to stop and mask httpd.socket and httpd.service:
            # systemctl stop httpd.socket httpd.service
            # systemctl mask httpd.socket httpd.service
            - IF - the nginx package is required for dependencies:
            Run the following commands to stop and mask nginx.service:
            # systemctl stop nginx.service
            # systemctl mask nginx.service
            Note: Other web server packages may exist. If not required and authorized by local site
            policy, they should also be removed. If the package is required for a dependency, the
            service and socket should be stopped and masked.
            References:

                 1. NIST SP 800-53 :: CM-7

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 257

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            2.1.19 Ensure xinetd services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The eXtended InterNET Daemon (xinetd) is an open source super daemon that
            replaced the original inetd daemon. The xinetd daemon listens for well known
            services and dispatches the appropriate daemon to properly respond to service
            requests.
            Rationale:
            If there are no xinetd services required, it is recommended that the package be
            removed to reduce the attack surface are of the system.
            Note: If an xinetd service or services are required, ensure that any xinetd service not
            required is stopped and masked
            Impact:
            There may be packages that are dependent on the xinetd package. If the xinetd
            package is removed, these dependent packages will be removed as well. Before
            removing the xinetd package, review any dependent packages to determine if they are
            required on the system.
            -IF- a dependent package is required: stop and mask xinetd.service leaving the xinetd
            package installed.




                                                                                           Page 258

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            Audit:
            Run the following command to verify the xinetd package is not installed:
            # dpkg-query -s xinetd &>/dev/null && echo "xinetd is installed"
            Nothing should be returned.
            -OR-
            -IF- the xinetd package is required as a dependency:
            Run the following command to verify xinetd.service is not enabled:
            # systemctl is-enabled xinetd.service 2>/dev/null | grep 'enabled'

            Nothing should be returned
            Run the following command to verify xinetd.service is not active:
            # systemctl is-active xinetd.service 2>/dev/null | grep '^active'

            Nothing should be returned
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy

            Remediation:
            Run the following commands to stop xinetd.service, and remove the xinetd
            package:
            # systemctl stop xinetd.service
            # apt purge xinetd
            -OR-
            -IF- the xinetd package is required as a dependency:
            Run the following commands to stop and mask the xinetd.service:
            # systemctl stop xinetd.service
            # systemctl mask xinetd.service

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7




                                                                                             Page 259

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 260

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            2.1.20 Ensure X window server services are not in use
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            Description:
            The X Window System provides a Graphical User Interface (GUI) where users can have
            multiple windows in which to run programs and various add on. The X Windows system
            is typically used on workstations where users login, but not on servers where users
            typically do not login.
            Rationale:
            Unless your organization specifically requires graphical login access via X Windows,
            remove it to reduce the potential attack surface.
            Impact:
            If a Graphical Desktop Manager (GDM) is in use on the system, there may be a
            dependency on the xorg-x11-server-common package. If the GDM is required and
            approved by local site policy, the package should not be removed.
            Many Linux systems run applications which require a Java runtime. Some Linux Java
            packages have a dependency on specific X Windows xorg-x11-fonts. One workaround
            to avoid this dependency is to use the "headless" Java packages for your specific Java
            runtime.
            Audit:
            - IF - a Graphical Desktop Manager or X-Windows server is not required and approved
            by local site policy:
            Run the following command to Verify X Windows Server is not installed.
            dpkg-query -s xserver-common &>/dev/null && echo "xserver-common is
            installed"
            Nothing should be returned
            Remediation:
            - IF - a Graphical Desktop Manager or X-Windows server is not required and approved
            by local site policy:
            Run the following command to remove the X Windows Server package:
            # apt purge xserver-common

            References:

                 1. NIST SP 800-53 Rev. 5: CM-11


                                                                                           Page 261

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                         IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,         ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          2.6 Address unapproved software
                    v7       Ensure that unauthorized software is either removed or the inventory is         ●    ●    ●
                          updated in a timely manner




                                                                                                                  Page 262

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            2.1.21 Ensure mail transfer agents are configured for local-only
            mode (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Mail Transfer Agents (MTA), such as sendmail and Postfix, are used to listen for
            incoming mail and transfer the messages to the appropriate user or mail server. If the
            system is not intended to be a mail server, it is recommended that the MTA be
            configured to only process local mail.
            Rationale:
            The software for all Mail Transfer Agents is complex and most have a long history of
            security issues. While it is important to ensure that the system can process local mail
            messages, it is not necessary to have the MTA's daemon listening on a port unless the
            server is intended to be a mail server that receives and processes mail from other
            systems.
            Impact:
            This recommendation is designed around the postfix mail server. Depending on your
            environment you may have an alternative MTA installed such as exim4 or sendmail. If
            this is the case consult the documentation for your installed MTA to configure the
            recommended state.




                                                                                            Page 263

Internal Only - General
            Audit:
            Run the following script to verify that the MTA is not listening on any non-loopback
            address ( 127.0.0.1 or ::1 )
            #!/usr/bin/env bash

            {
               a_output=(); a_output2=(); a_port_list=("25" "465" "587")
               for l_port_number in "${a_port_list[@]}"; do
                  if ss -plntu | grep -P -- ':'"$l_port_number"'\b' | grep -Pvq --
            '\h+(127\.0\.0\.1|\[?::1\]?):'"$l_port_number"'\b'; then
                     a_output2+=(" - Port \"$l_port_number\" is listening on a non-
            loopback network interface")
                  else
                     a_output+=(" - Port \"$l_port_number\" is not listening on a non-
            loopback network interface")
                  fi
               done
               if command -v postconf &> /dev/null; then
                  l_interfaces="$(postconf -n inet_interfaces)"
               elif command -v exim &> /dev/null; then
                  l_interfaces="$(exim -bP local_interfaces)"
               elif command -v sendmail &> /dev/null; then
                  l_interfaces="$(grep -i "O DaemonPortOptions=" /etc/mail/sendmail.cf |
            grep -oP '(?<=Addr=)[^,+]+' | grep -v '^127\.0\.0\.1$')"
               fi
               if [ -n "$l_interfaces" ]; then
                  if grep -Pqi '\ball\b' <<< "$l_interfaces"; then
                     a_output2+=(" - MTA is bound to all network interfaces")
                  elif ! grep -Pqi '(inet_interfaces\h*=\h*)?(0\.0\.0\.0|::1|loopback-
            only)' <<< "$l_interfaces"; then
                     a_output2+=(" - MTA is bound to a network interface" "
            \"$l_interfaces\"")
                  else
                     a_output+=(" - MTA is not bound to a non loopback network interface"
            "   \"$l_interfaces\"")
                  fi
               else
                  a_output+=(" - MTA not detected or in use")
               fi
               if [ "${#a_output2[@]}" -le 0 ]; then
                  printf '%s\n' "" "- Audit Result:" " ** PASS **" "${a_output[@]}"
               else
                  printf '%s\n' "" "- Audit Result:" " ** FAIL **" " * Reasons for
            audit failure *" "${a_output2[@]}" ""
                  [ "${#a_output[@]}" -gt 0 ] && printf '%s\n' "- Correctly set:"
            "${a_output[@]}"
               fi
            }




                                                                                             Page 264

Internal Only - General
            Remediation:
            Edit /etc/postfix/main.cf and add the following line to the RECEIVING MAIL
            section. If the line already exists, change it to look like the line below:
            inet_interfaces = loopback-only
            Run the following command to restart postfix:
            # systemctl restart postfix
            Note:

                 •    This recommendation is designed around the postfix mail server.
                 •    Depending on your environment you may have an alternative MTA installed such
                      as exim4 or sendmail. If this is the case consult the documentation for your
                      installed MTA to configure the recommended state.

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                     v8        Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                     v7     Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 265

Internal Only - General
            2.1.22 Ensure only approved services are listening on a network
            interface (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            A network port is identified by its number, the associated IP address, and the type of the
            communication protocol such as TCP or UDP.
            A listening port is a network port on which an application or process listens on, acting as
            a communication endpoint.
            Each listening port can be open or closed (filtered) using a firewall. In general terms, an
            open port is a network port that accepts incoming packets from remote locations.
            Rationale:
            Services listening on the system pose a potential risk as an attack vector. These
            services should be reviewed, and if not required, the service should be stopped, and the
            package containing the service should be removed. If required packages have a
            dependency, the service should be stopped and masked to reduce the attack surface of
            the system.
            Impact:
            There may be packages that are dependent on the service's package. If the service's
            package is removed, these dependent packages will be removed as well. Before
            removing the service's package, review any dependent packages to determine if they
            are required on the system.
            - IF - a dependent package is required: stop and mask the <service_name>.socket
            and <service_name>.service leaving the service's package installed.

            Audit:
            Run the following command:
            # ss -plntu
            Review the output to ensure:

                 •   All services listed are required on the system and approved by local site policy.
                 •   Both the port and interface the service is listening on are approved by local site
                     policy.
                 •   If a listed service is not required:
                         o Remove the package containing the service
                         o - IF - the service's package is required for a dependency, stop and mask
                              the service and/or socket


                                                                                                 Page 266

Internal Only - General
            Remediation:
            Run the following commands to stop the service and remove the package containing
            the service:
            # systemctl stop <service_name>.socket <service_name>.service
            # apt purge <package_name>
            - OR - If required packages have a dependency:
            Run the following commands to stop and mask the service and socket:
            # systemctl stop <service_name>.socket <service_name>.service
            # systemctl mask <service_name>.socket <service_name>.service
            Note: replace <service_name> with the appropriate service name.

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 267

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            2.2 Configure Client Services

            A number of insecure services exist. While disabling the servers prevents a local attack
            against these services, it is advised to remove their clients unless they are required.
            Note: This should not be considered a comprehensive list of insecure service clients.
            You may wish to consider additions to those listed here for your environment.




                                                                                             Page 268

Internal Only - General
            2.2.1 Ensure nis client is not installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Network Information Service (NIS), formerly known as Yellow Pages, is a client-
            server directory service protocol used to distribute system configuration files. The NIS
            client was used to bind a machine to an NIS server and receive the distributed
            configuration files.
            Rationale:
            The NIS service is inherently an insecure system that has been vulnerable to DOS
            attacks, buffer overflows and has poor authentication for querying NIS maps. NIS
            generally has been replaced by such protocols as Lightweight Directory Access
            Protocol (LDAP). It is recommended that the service be removed.
            Impact:
            Many insecure service clients are used as troubleshooting tools and in testing
            environments. Uninstalling them can inhibit capability to test and troubleshoot. If they
            are required it is advisable to remove the clients after use to prevent accidental or
            intentional misuse.
            Audit:
            Verify nis is not installed. Use the following command to provide the needed
            information:
            # dpkg-query -s nis &>/dev/null && echo "nis is installed"
            Nothing should be returned.
            Remediation:
            Uninstall nis:
            # apt purge nis

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7, CM-11




                                                                                               Page 269

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            CIS Controls:

               Controls
                                                            Control                                         IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,         ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          2.6 Address unapproved software
                    v7       Ensure that unauthorized software is either removed or the inventory is         ●    ●    ●
                          updated in a timely manner




                                                                                                                  Page 270

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            2.2.2 Ensure rsh client is not installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The rsh-client package contains the client commands for the rsh services.

            Rationale:
            These legacy clients contain numerous security exposures and have been replaced with
            the more secure SSH package. Even if the server is removed, it is best to ensure the
            clients are also removed to prevent users from inadvertently attempting to use these
            commands and therefore exposing their credentials. Note that removing the rsh-
            client package removes the clients for rsh , rcp and rlogin .

            Impact:
            Many insecure service clients are used as troubleshooting tools and in testing
            environments. Uninstalling them can inhibit capability to test and troubleshoot. If they
            are required it is advisable to remove the clients after use to prevent accidental or
            intentional misuse.
            Audit:
            Verify rsh-client is not installed. Use the following command to provide the needed
            information:
            # dpkg-query -s rsh-client &>/dev/null && echo "rsh-client is installed"
            Nothing should be returned.
            Remediation:
            Uninstall rsh:
            # apt purge rsh-client

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7




                                                                                               Page 271

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            2.2.3 Ensure talk client is not installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The talk software makes it possible for users to send and receive messages across
            systems through a terminal session. The talk client, which allows initialization of talk
            sessions, is installed by default.
            Rationale:
            The software presents a security risk as it uses unencrypted protocols for
            communication.
            Impact:
            Many insecure service clients are used as troubleshooting tools and in testing
            environments. Uninstalling them can inhibit capability to test and troubleshoot. If they
            are required it is advisable to remove the clients after use to prevent accidental or
            intentional misuse.
            Audit:
            Verify talk is not installed. The following command may provide the needed
            information:
            # dpkg-query -s talk &>/dev/null && echo "talk is installed"
            Nothing should be returned.
            Remediation:
            Uninstall talk:
            # apt purge talk

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7




                                                                                               Page 273

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            2.2.4 Ensure telnet client is not installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The telnet package contains the telnet client, which allows users to start
            connections to other systems via the telnet protocol.
            Rationale:
            The telnet protocol is insecure and unencrypted. The use of an unencrypted
            transmission medium could allow an unauthorized user to steal credentials. The ssh
            package provides an encrypted session and stronger security and is included in most
            Linux distributions.
            Impact:
            Many insecure service clients are used as troubleshooting tools and in testing
            environments. Uninstalling them can inhibit capability to test and troubleshoot. If they
            are required it is advisable to remove the clients after use to prevent accidental or
            intentional misuse.
            Audit:
            Verify telnet is not installed. Use the following command to provide the needed
            information:
            # dpkg-query -s telnet &>/dev/null && echo "telnet is installed"
            Nothing should be returned.
            Remediation:
            Uninstall telnet:
            # apt purge telnet

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7, CM-11




                                                                                               Page 275

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            2.2.5 Ensure ldap client is not installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Lightweight Directory Access Protocol (LDAP) was introduced as a replacement for
            NIS/YP. It is a service that provides a method for looking up information from a central
            database.
            Rationale:
            If the system will not need to act as an LDAP client, it is recommended that the software
            be removed to reduce the potential attack surface.
            Impact:
            Removing the LDAP client will prevent or inhibit using LDAP for authentication in your
            environment.
            Audit:
            Verify that ldap-utils is not installed. Use the following command to provide the
            needed information:
            # dpkg-query -s ldap-utils &>/dev/null && echo "ldap-utils is installed"
            Nothing should be returned.
            Remediation:
            Uninstall ldap-utils:
            # apt purge ldap-utils

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7




                                                                                             Page 277

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 278

Internal Only - General
            2.2.6 Ensure ftp client is not installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            tnftp an enhanced FTP client, is the user interface to the Internet standard File
            Transfer Protocol. The program allows a user to transfer files to and from a remote
            network site.
            Rationale:
            Unless there is a need to run the system using Internet standard File Transfer Protocol
            (for example, to allow anonymous downloads), it is recommended that the package be
            removed to reduce the potential attack surface.
            Audit:
            Verify tnftp & ftp is not installed. Use the following command to provide the needed
            information:
            # dpkg-query -l | awk '{print $2}' | grep -E '^ftp|^tnftp' &>/dev/null &&
            echo "ftp is installed"
            Nothing should be returned.
            Remediation:
            Run the following commands to uninstall tnftp & ftp:
            # apt purge ftp
            # apt purge tnftp

            References:

                 1. NIST SP 800-53 Rev. 5: CM-7, CM-11




                                                                                            Page 279

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




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            2.3 Configure Time Synchronization

            It is recommended that systems be configured to synchronize their time using a service
            such as systemd-timesyncd, or chrony.
            Virtual systems may be configured to receive their time synchronization from their host
            system.
            The host system must be configured to synchronize its time from an authoritative source
            to be considered compliant with this section.
            Any "physical" clock present on a system should be synchronized from an authoritative
            time source.
            Only one time synchronization method should be in use on the system
            Notes: Only the section related to the time synchronization method in use on the
            system should be followed, all other time synchronization recommendations should be
            skipped




                                                                                           Page 281

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            2.3.1 Ensure time synchronization is in use

            It is recommended that physical systems and virtual guests lacking direct access to the
            physical host's clock be configured to synchronize their time using a service such as
            systemd-timesyncd, or chrony.




                                                                                            Page 282

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            2.3.1.1 Ensure a single time synchronization daemon is in use
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            System time should be synchronized between all systems in an environment. This is
            typically done by establishing an authoritative time server or set of servers and having
            all systems synchronize their clocks to them.
            Note:

                 •   On virtual systems where host based time synchronization is available
                     consult your virtualization software documentation and verify that host
                     based synchronization is in use and follows local site policy. In this
                     scenario, this section should be skipped
                 •   Only one time synchronization method should be in use on the system.
                     Configuring multiple time synchronization methods could lead to unexpected or
                     unreliable results

            Rationale:
            Time synchronization is important to support time sensitive security mechanisms and
            ensures log files have consistent time records across the enterprise, which aids in
            forensic investigations.
            Audit:
            On physical systems, and virtual systems where host based time synchronization is not
            available.
            One of the two time synchronization daemons should be available; chrony or systemd-
            timesyncd
            Run the following script to verify that a single time synchronization daemon is available
            on the system:




                                                                                              Page 283

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            #!/usr/bin/env bash

            {
                l_output="" l_output2=""
                service_not_enabled_chk()
                {
                    l_out2=""
                    if systemctl is-enabled "$l_service_name" 2>/dev/null | grep -q 'enabled';
            then
                        l_out2="$l_out2\n - Daemon: \"$l_service_name\" is enabled on the system"
                    fi
                    if systemctl is-active "$l_service_name" 2>/dev/null | grep -q '^active'; then
                        l_out2="$l_out2\n - Daemon: \"$l_service_name\" is active on the system"
                    fi
                }
                l_service_name="systemd-timesyncd.service" # Check systemd-timesyncd daemon
                service_not_enabled_chk
                if [ -n "$l_out2" ]; then
                    l_timesyncd="y"
                    l_out_tsd="$l_out2"
                else
                    l_timesyncd="n"
                    l_out_tsd="\n - Daemon: \"$l_service_name\" is not enabled and not active on
            the system"
                fi
                l_service_name="chrony.service" # Check chrony
                service_not_enabled_chk
                if [ -n "$l_out2" ]; then
                    l_chrony="y"
                    l_out_chrony="$l_out2"
                else
                    l_chrony="n"
                    l_out_chrony="\n - Daemon: \"$l_service_name\" is not enabled and not active
            on the system"
                fi
                l_status="$l_timesyncd$l_chrony"
                case "$l_status" in
                    yy)
                        l_output2=" - More than one time sync daemon is in use on the
            system$l_out_tsd$l_out_chrony"
                        ;;
                    nn)
                        l_output2=" - No time sync daemon is in use on the
            system$l_out_tsd$l_out_chrony"
                        ;;
                    yn|ny)
                        l_output=" - Only one time sync daemon is in use on the
            system$l_out_tsd$l_out_chrony"
                        ;;
                    *)
                        l_output2=" - Unable to determine time sync daemon(s) status"
                        ;;
                esac

                if [ -z "$l_output2" ]; then
                    echo -e "\n- Audit Result:\n   ** PASS **\n$l_output\n"
                else
                    echo -e "\n- Audit Result:\n   ** FAIL **\n - * Reasons for audit failure *
            :\n$l_output2\n"
                fi
            }




                                                                                           Page 284

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            Note: Follow the guidance in the subsection for the time synchronization daemon
            available on the system and skip the other time synchronization daemon subsection.
            Remediation:
            On physical systems, and virtual systems where host based time synchronization is not
            available.
            Select one of the two time synchronization daemons; chrony (1) or systemd-
            timesyncd (2) and following the remediation procedure for the selected daemon.
            Note: enabling more than one synchronization daemon could lead to unexpected or
            unreliable results:

                 1. chrony

            Run the following command to install chrony:
            # apt install chrony
            Run the following commands to stop and mask the systemd-timesyncd daemon:
            # systemctl stop systemd-timesyncd.service

            # systemctl mask systemd-timesyncd.service
            Note:

                 •   Subsection: Configure chrony should be followed
                 •   Subsection: Configure systemd-timesyncd should be skipped

                 2. systemd-timesyncd

            Run the following command to remove the chrony package:
            # apt purge chrony
            # apt autoremove chrony
            Note:

                 •   Subsection: Configure systemd-timesyncd should be followed
                 •   Subsection: Configure chrony should be skipped

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3, AU-12




                                                                                          Page 285

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                        IG 1 IG 2 IG 3
               Version
                          8.4 Standardize Time Synchronization
                    v8       Standardize time synchronization. Configure at least two synchronized time           ●    ●
                          sources across enterprise assets, where supported.

                          6.1 Utilize Three Synchronized Time Sources
                    v7        Use at least three synchronized time sources from which all servers and
                          network devices retrieve time information on a regular basis so that timestamps
                                                                                                                  ●    ●
                          in logs are consistent.




                                                                                                                  Page 286

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            2.3.2 Configure systemd-timesyncd

            systemd-timesyncd is a daemon that has been added for synchronizing the system
            clock across the network. It implements an SNTP client. In contrast to NTP
            implementations such as chrony or the NTP reference server this only implements a
            client side, and does not bother with the full NTP complexity, focusing only on querying
            time from one remote server and synchronizing the local clock to it. The daemon runs
            with minimal privileges, and has been hooked up with networkd to only operate when
            network connectivity is available. The daemon saves the current clock to disk every time
            a new NTP sync has been acquired, and uses this to possibly correct the system clock
            early at bootup, in order to accommodate for systems that lack an RTC such as the
            Raspberry Pi and embedded devices, and make sure that time monotonically
            progresses on these systems, even if it is not always correct. To make use of this
            daemon a new system user and group "systemd-timesync" needs to be created on
            installation of systemd.
            The default configuration is set during compilation, so configuration is only needed
            when it is necessary to deviate from those defaults. Initially, the main configuration file
            in /etc/systemd/ contains commented out entries showing the defaults as a guide to the
            administrator. Local overrides can be created by editing this file or by creating drop-ins,
            as described below. Using drop-ins for local configuration is recommended over
            modifications to the main configuration file.
            In addition to the "main" configuration file, drop-in configuration snippets are read from
            /usr/lib/systemd/*.conf.d/, /usr/local/lib/systemd/*.conf.d/, and
            /etc/systemd/*.conf.d/. Those drop-ins have higher precedence and override the
            main configuration file. Files in the *.conf.d/ configuration subdirectories are sorted by
            their filename in lexicographic order, regardless of in which of the subdirectories they
            reside. When multiple files specify the same option, for options which accept just a
            single value, the entry in the file sorted last takes precedence, and for options which
            accept a list of values, entries are collected as they occur in the sorted files.
            When packages need to customize the configuration, they can install drop-ins under
            /usr/. Files in /etc/ are reserved for the local administrator, who may use this logic to
            override the configuration files installed by vendor packages. Drop-ins have to be used
            to override package drop-ins, since the main configuration file has lower precedence. It
            is recommended to prefix all filenames in those subdirectories with a two-digit number
            and a dash, to simplify the ordering of the files.
            To disable a configuration file supplied by the vendor, the recommended way is to place
            a symlink to /dev/null in the configuration directory in /etc/, with the same filename as
            the vendor configuration file.
            Note:

                 •   The recommendations in this section only apply if timesyncd is in use on the
                     system
                 •   The systemd-timesyncd service specifically implements only SNTP.
                        o This minimalistic service will set the system clock for large offsets or
                           slowly adjust it for smaller deltas

                                                                                              Page 287

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                          o More complex use cases are not covered by systemd-timesyncd
                 •   If chrony is used, systemd-timesyncd should be stopped and masked, and
                     this section skipped
                 •   One, and only one, time synchronization method should be in use on the
                     system




                                                                                     Page 288

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            2.3.2.1 Ensure systemd-timesyncd configured with authorized
            timeserver (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            NTP=

                 •   A space-separated list of NTP server host names or IP addresses. During
                     runtime this list is combined with any per-interface NTP servers acquired from
                     systemd-networkd.service(8). systemd-timesyncd will contact all configured
                     system or per-interface servers in turn, until one responds. When the empty
                     string is assigned, the list of NTP servers is reset, and all prior assignments will
                     have no effect. This setting defaults to an empty list.

            FallbackNTP=

                 •   A space-separated list of NTP server host names or IP addresses to be used as
                     the fallback NTP servers. Any per-interface NTP servers obtained from systemd-
                     networkd.service(8) take precedence over this setting, as do any servers set via
                     NTP= above. This setting is hence only relevant if no other NTP server
                     information is known. When the empty string is assigned, the list of NTP servers
                     is reset, and all prior assignments will have no effect. If this option is not given, a
                     compiled-in list of NTP servers is used.

            Rationale:
            Time synchronization is important to support time sensitive security mechanisms and to
            ensure log files have consistent time records across the enterprise to aid in forensic
            investigations
            Audit:
            Run the following command to verify the NTP and/or FallbackNTP option is set to local
            site approved authoritative time server(s):




                                                                                                    Page 289

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output=() a_output2=() a_output3=() a_out=() a_out2=() a_parlist=("NTP=[^#\n\r]+"
            "FallbackNTP=[^#\n\r]+")
               l_analyze_cmd="$(readlink -f /bin/systemd-analyze)"
            l_systemd_config_file="/etc/systemd/timesyncd.conf"
               f_config_file_parameter_chk()
               {
                  l_used_parameter_setting=""
                  while IFS= read -r l_file; do
                     l_file="$(tr -d '# ' <<< "$l_file")"
                     l_used_parameter_setting="$(grep -PHs -- '^\h*'"$l_parameter_name"'\b' "$l_file" | tail
            -n 1)"
                     [ -n "$l_used_parameter_setting" ] && break
                  done < <($l_analyze_cmd cat-config "$l_systemd_config_file" | tac | grep -Pio
            '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  if [ -n "$l_used_parameter_setting" ]; then
                     while IFS=: read -r l_file_name l_file_parameter; do
                        while IFS="=" read -r l_file_parameter_name l_file_parameter_value; do
                           if grep -Pq -- "$l_parameter_value" <<< "$l_file_parameter_value"; then
                              a_out+=(" - Parameter: \"${l_file_parameter_name// /}\"" \
                              "    correctly set to: \"${l_file_parameter_value// /}\"" \
                              "    in the file: \"$l_file_name\"")
                           else
                              a_out2+=(" - Parameter: \"${l_file_parameter_name// /}\"" \
                              "    incorrectly set to: \"${l_file_parameter_value// /}\"" \
                              "    in the file: \"$l_file_name\"" \
                              "    Should be set to: \"$l_value_out\"")
                           fi
                        done <<< "$l_file_parameter"
                     done <<< "$l_used_parameter_setting"
                  else
                     a_out2+=(" - Parameter: \"$l_parameter_name\" is not set in an included file" \
                     "   *** Note: \"$l_parameter_name\" May be set in a file that's ignored by load
            procedure ***")
                  fi
               }
               while IFS="=" read -r l_parameter_name l_parameter_value; do # Assess and check parameters
                  l_parameter_name="${l_parameter_name// /}"; l_parameter_value="${l_parameter_value// /}"
                  l_value_out="${l_parameter_value//-/ through }"; l_value_out="${l_value_out//|/ or }"
                  l_value_out="$(tr -d '(){}' <<< "$l_value_out")"
                  f_config_file_parameter_chk
               done < <(printf '%s\n' "${a_parlist[@]}")
               if [ "${#a_out[@]}" -gt 0 ]; then
                  a_output+=("${a_out[@]}"); [ "${#a_out2[@]}" -gt 0 ] && a_output3+=(" ** INFO: **"
            "${a_out2[@]}")
               else
                  a_output2+=("${a_out2[@]}")
               fi
               if [ "${#a_output2[@]}" -le 0 ]; then
                  printf '%s\n' "" "- Audit Result:" " ** PASS **" "${a_output[@]}" ""
                  [ "${#a_output3[@]}" -gt 0 ] && printf '%s\n' "${a_output3[@]}"
               else
                  printf '%s\n' "" "- Audit Result:" " ** FAIL **" " - Reason(s) for audit failure:"
            "${a_output2[@]}"
                  [ "${#a_output[@]}" -gt 0 ] && printf '%s\n' "" "- Correctly set:" "${a_output[@]}" ""
               fi
            }
            Note: Please ensure the output for NTP and/or FallbackNTP is in accordance with local
            site policy. The timeservers in the example output are provided as an example of
            possible timeservers and they may not follow local site policy.




                                                                                                    Page 290

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            Remediation:
            Set NTP and/or FallbackNTP parameters to local site approved authoritative time
            server(s) in /etc/systemd/timesyncd.conf or a file in
            /etc/systemd/timesyncd.conf.d/ ending in .conf in the [Time] section:
            Example file:
            [Time]
            NTP=time.nist.gov # Uses the generic name for NIST's time servers
            FallbackNTP=time-a-g.nist.gov time-b-g.nist.gov time-c-g.nist.gov # Space
            separated list of NIST time servers
            Example script to create systemd drop-in configuration file:
            #!/usr/bin/env bash

            {
               a_settings=("NTP=time.nist.gov" "FallbackNTP=time-a-g.nist.gov time-b-
            g.nist.gov time-c-g.nist.gov")
               [ ! -d /etc/systemd/timesyncd.conf.d/ ] && mkdir
            /etc/systemd/timesyncd.conf.d/
               if grep -Psq -- '^\h*\[Time\]' /etc/systemd/timesyncd.conf.d/60-
            timesyncd.conf; then
                  printf '%s\n' "" "${a_settings[@]}" >>
            /etc/systemd/timesyncd.conf.d/60-timesyncd.conf
               else
                  printf '%s\n' "" "[Time]" "${a_settings[@]}" >>
            /etc/systemd/timesyncd.conf.d/60-timesyncd.conf
               fi
            }
            Note: If this setting appears in a canonically later file, or later in the same file, the
            setting will be overwritten
            Run to following command to update the parameters in the service:
            # systemctl reload-or-restart systemd-timesyncd

            Default Value:
            #NTP=
            #FallbackNTP=
            References:

                 1. https://www.freedesktop.org/software/systemd/man/timesyncd.conf.html
                 2. https://tf.nist.gov/tf-cgi/servers.cgi
                 3. NIST SP 800-53 Rev. 5: AU-7, AU-8




                                                                                                    Page 291

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            CIS Controls:

               Controls
                                                             Control                                        IG 1 IG 2 IG 3
               Version
                          8.4 Standardize Time Synchronization
                    v8       Standardize time synchronization. Configure at least two synchronized time           ●    ●
                          sources across enterprise assets, where supported.

                          6.1 Utilize Three Synchronized Time Sources
                    v7        Use at least three synchronized time sources from which all servers and
                          network devices retrieve time information on a regular basis so that timestamps
                                                                                                                  ●    ●
                          in logs are consistent.




                                                                                                                  Page 292

Internal Only - General
            2.3.2.2 Ensure systemd-timesyncd is enabled and running
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            systemd-timesyncd is a daemon that has been added for synchronizing the system
            clock across the network
            Rationale:
            systemd-timesyncd needs to be enabled and running in order to synchronize the system
            to a timeserver.
            Time synchronization is important to support time sensitive security mechanisms and to
            ensure log files have consistent time records across the enterprise to aid in forensic
            investigations
            Audit:
            - IF - systemd-timesyncd is in use on the system, run the following commands:
            Run the following command to verify that the systemd-timesyncd service is enabled:
            # systemctl is-enabled systemd-timesyncd.service

            enabled
            Run the following command to verify that the systemd-timesyncd service is active:
            # systemctl is-active systemd-timesyncd.service

            active

            Remediation:
            - IF - systemd-timesyncd is in use on the system, run the following commands:
            Run the following command to unmask systemd-timesyncd.service:
            # systemctl unmask systemd-timesyncd.service
            Run the following command to enable and start systemd-timesyncd.service:
            # systemctl --now enable systemd-timesyncd.service
            - OR -
            If another time synchronization service is in use on the system, run the following
            command to stop and mask systemd-timesyncd:
            # systemctl --now mask systemd-timesyncd.service




                                                                                                 Page 293

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            References:

                 1. NIST SP 800-53 Rev. 5: AU-7, AU-8

            CIS Controls:

               Controls
                                                             Control                                        IG 1 IG 2 IG 3
               Version
                          8.4 Standardize Time Synchronization
                    v8       Standardize time synchronization. Configure at least two synchronized time           ●    ●
                          sources across enterprise assets, where supported.

                          6.1 Utilize Three Synchronized Time Sources
                    v7        Use at least three synchronized time sources from which all servers and
                          network devices retrieve time information on a regular basis so that timestamps
                                                                                                                  ●    ●
                          in logs are consistent.




                                                                                                                  Page 294

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            2.3.3 Configure chrony

            chrony is a daemon which implements the Network Time Protocol (NTP) and is
            designed to synchronize system clocks across a variety of systems and use a source
            that is highly accurate.
            chrony can be configured to be a client and/or a server.
            More information on chrony can be found at: http://chrony.tuxfamily.org/.
            Note:

                 •   If systemd-timesyncd is being used, chrony should be removed and this
                     section skipped
                 •   Only one time synchronization method should be in use on the system




                                                                                         Page 295

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            2.3.3.1 Ensure chrony is configured with authorized timeserver
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:

                 •   server
                          o   The server directive specifies an NTP server which can be used as a time
                              source. The client-server relationship is strictly hierarchical: a client might
                              synchronize its system time to that of the server, but the server’s system
                              time will never be influenced by that of a client.
                          o   This directive can be used multiple times to specify multiple servers.
                          o   The directive is immediately followed by either the name of the server, or
                              its IP address.
                 •   pool
                          o   The syntax of this directive is similar to that for the server directive, except
                              that it is used to specify a pool of NTP servers rather than a single NTP
                              server. The pool name is expected to resolve to multiple addresses which
                              might change over time.
                          o   This directive can be used multiple times to specify multiple pools.
                          o   All options valid in the server directive can be used in this directive too.

            Rationale:
            Time synchronization is important to support time sensitive security mechanisms and to
            ensure log files have consistent time records across the enterprise to aid in forensic
            investigations




                                                                                                     Page 296

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            Audit:
            - IF - chrony is in use on the system, run the following script to ensure chrony is
            configured with an authorized timeserver:
            #!/usr/bin/env bash

            {
               a_output=() a_output2=() a_config_files=("/etc/chrony/chrony.conf")
               l_include='(confdir|sourcedir)' l_parameter_name='(server|pool)'
            l_parameter_value='.+'
               while IFS= read -r l_conf_loc; do
                  l_dir="" l_ext=""
                  if [ -d "$l_conf_loc" ]; then
                      l_dir="$l_conf_loc" l_ext="*"
                  elif grep -Psq '\/\*\.([^#/\n\r]+)?\h*$' <<< "$l_conf_loc" || [ -f
            "$(readlink -f "$l_conf_loc")" ]; then
                      l_dir="$(dirname "$l_conf_loc")" l_ext="$(basename "$l_conf_loc")"
                  fi
                  if [[ -n "$l_dir" && -n "$l_ext" ]]; then
                      while IFS= read -r -d $'\0' l_file_name; do
                         [ -f "$(readlink -f "$l_file_name")" ] &&
            a_config_files+=("$(readlink -f "$l_file_name")")
                      done < <(find -L "$l_dir" -type f -name "$l_ext" -print0
            2>/dev/null)
                  fi
               done < <(awk '$1~/^\s*'"$l_include"'$/{print $2}' "${a_config_files[*]}"
            2>/dev/null)
               for l_file in "${a_config_files[@]}"; do
                  l_parameter_line="$(grep -Psi
            '^\h*'"$l_parameter_name"'(\h+|\h*:\h*)'"$l_parameter_value"'\b' "$l_file")"
                  [ -n "$l_parameter_line" ] && a_output+=(" - Parameter: \"$(tr -d '()'
            <<< ${l_parameter_name//|/ or })\"" \
                  "     Exists in the file: \"$l_file\" as:" "$l_parameter_line")
               done
               [ "${#a_output[@]}" -le "0" ] && a_output2+=(" - Parameter: \"$(tr -d
            '()' <<< ${l_parameter_name//|/ or })\"" \
               "     Does not exist in the chrony configuration")
               if [ "${#a_output2[@]}" -le 0 ]; then
                  printf '%s\n' "" "- Audit Result:" " ** PASS **" "${a_output[@]}" ""
               else
                  printf '%s\n' "" "- Audit Result:" " ** FAIL **" " - Reason(s) for
            audit failure:" "${a_output2[@]}"
               fi
            }




                                                                                              Page 297

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            Remediation:
            Edit /etc/chrony/chrony.conf or a file ending in .sources in
            /etc/chrony/sources.d/ and add or edit server or pool lines as appropriate
            according to local site policy:
            Edit the Chrony configuration and add or edit the server and/or pool lines returned by
            the Audit Procedure as appropriate according to local site policy
            <[server|pool]> <[remote-server|remote-pool]>
            Example script to add a drop-in configuration for the pool directive:
            #!/usr/bin/env bash

            {
                 [ ! -d "/etc/chrony/sources.d/" ] && mkdir /etc/chrony/sources.d/
                 printf '%s\n' "" "#The maxsources option is unique to the pool directive"
            \
               "pool time.nist.gov iburst maxsources 4" >> /etc/chrony/sources.d/60-
            sources.sources
               chronyc reload sources &>/dev/null
            }
            Example script to add a drop-in configuration for the server directive:
            #!/usr/bin/env bash

            {
               [ ! -d "/etc/chrony/sources.d/" ] && mkdir /etc/chrony/sources.d/
               printf '%s\n' "" "server time-a-g.nist.gov iburst" "server 132.163.97.3
            iburst" \
               "server time-d-b.nist.gov iburst" >> /etc/chrony/sources.d/60-
            sources.sources
               chronyc reload sources &>/dev/null
            }
            Run the following command to reload the chronyd config:
            # systemctl reload-or-restart chronyd

            References:

                 1. chrony.conf(5) Manual Page
                 2. https://tf.nist.gov/tf-cgi/servers.cgi
                 3. NIST SP 800-53 Rev. 5: AU-3, AU-12

            Additional Information:
            If pool and/or server directive(s) are set in a sources file in /etc/chrony/sources.d,
            the line:
            sourcedir /etc/chrony/sources.d
            must be present in /etc/chrony/chrony.conf




                                                                                             Page 298

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            CIS Controls:

               Controls
                                                             Control                                        IG 1 IG 2 IG 3
               Version
                          8.4 Standardize Time Synchronization
                    v8       Standardize time synchronization. Configure at least two synchronized time           ●    ●
                          sources across enterprise assets, where supported.

                          6.1 Utilize Three Synchronized Time Sources
                    v7        Use at least three synchronized time sources from which all servers and
                          network devices retrieve time information on a regular basis so that timestamps
                                                                                                                  ●    ●
                          in logs are consistent.




                                                                                                                  Page 299

Internal Only - General
            2.3.3.2 Ensure chrony is running as user _chrony (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The chrony package is installed with a dedicated user account _chrony. This account
            is granted the access required by the chronyd service

            Rationale:
            The chronyd service should run with only the required privlidges

            Audit:
            - IF - chrony is in use on the system, run the following command to verify the chronyd
            service is being run as the _chrony user:
            # ps -ef | awk '(/[c]hronyd/ && $1!="_chrony") { print $1 }'
            Nothing should be returned
            Remediation:
            Add or edit the user line to /etc/chrony/chrony.conf or a file ending in .conf in
            /etc/chrony/conf.d/:
            user _chrony
            - OR -
            If another time synchronization service is in use on the system, run the following
            command to remove chrony from the system:
            # apt purge chrony
            # apt autoremove chrony

            Default Value:
            user _chrony
            References:

                 1. NIST SP 800-53 Rev. 5: AU-8




                                                                                                 Page 300

Internal Only - General
            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 301

Internal Only - General
            2.3.3.3 Ensure chrony is enabled and running (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            chrony is a daemon for synchronizing the system clock across the network
            Rationale:
            chrony needs to be enabled and running in order to synchronize the system to a
            timeserver.
            Time synchronization is important to support time sensitive security mechanisms and to
            ensure log files have consistent time records across the enterprise to aid in forensic
            investigations
            Audit:
            - IF - chrony is in use on the system, run the following commands:
            Run the following command to verify that the chrony service is enabled:
            # systemctl is-enabled chrony.service

            enabled
            Run the following command to verify that the chrony service is active:
            # systemctl is-active chrony.service

            active

            Remediation:
            - IF - chrony is in use on the system, run the following commands:
            Run the following command to unmask chrony.service:
            # systemctl unmask chrony.service
            Run the following command to enable and start chrony.service:
            # systemctl --now enable chrony.service
            - OR -
            If another time synchronization service is in use on the system, run the following
            command to remove chrony:
            # apt purge chrony
            # apt autoremove chrony

            References:

                 1. NIST SP 800-53 Rev. 5: AU-8

                                                                                                 Page 302

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                        IG 1 IG 2 IG 3
               Version
                          8.4 Standardize Time Synchronization
                    v8       Standardize time synchronization. Configure at least two synchronized time           ●    ●
                          sources across enterprise assets, where supported.

                          6.1 Utilize Three Synchronized Time Sources
                    v7        Use at least three synchronized time sources from which all servers and
                          network devices retrieve time information on a regular basis so that timestamps
                                                                                                                  ●    ●
                          in logs are consistent.




                                                                                                                  Page 303

Internal Only - General
            2.4 Job Schedulers

            A job scheduler is used to execute jobs, commands, or shell scripts, at fixed times,
            dates, or intervals




                                                                                             Page 304

Internal Only - General
            2.4.1 Configure cron

            cron is a time based job scheduler
            - IF - cron is not installed on the system, this sub section can be skipped
            Note: Other methods such as systemd timers exist for scheduling jobs. If an alternate
            method is in use, it should be secured in accordance with local site policy




                                                                                          Page 305

Internal Only - General
            2.4.1.1 Ensure cron daemon is enabled and active (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The cron daemon is used to execute batch jobs on the system.

            Rationale:
            While there may not be user jobs that need to be run on the system, the system does
            have maintenance jobs that may include security monitoring that have to run, and cron
            is used to execute them.
            Audit:
            - IF - cron is installed on the system:
            Run the following command to verify cron is enabled:
            # systemctl list-unit-files | awk '$1~/^crond?\.service/{print $2}'

            enabled
            Run the following command to verify that cron is active:
            # systemctl list-units | awk '$1~/^crond?\.service/{print $3}'

            active

            Remediation:
            - IF - cron is installed on the system:
            Run the following commands to unmask, enable, and start cron:
            # systemctl unmask "$(systemctl list-unit-files | awk
            '$1~/^crond?\.service/{print $1}')"
            # systemctl --now enable "$(systemctl list-unit-files | awk
            '$1~/^crond?\.service/{print $1}')"

            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5




                                                                                          Page 306

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            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 307

Internal Only - General
            2.4.1.2 Ensure access to /etc/crontab is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/crontab file is used by cron to control its own jobs. The commands in this
            item make sure that root is the user and group owner of the file and that only the owner
            can access the file.
            Rationale:
            This file contains information on what system jobs are run by cron. Write access to
            these files could provide unprivileged users with the ability to elevate their privileges.
            Read access to these files could provide users with the ability to gain insight on system
            jobs that run on the system and could provide them a way to gain unauthorized
            privileged access.
            Audit:
            - IF - cron is installed on the system:
            Run the following command and verify Uid and Gid are both 0/root and Access does
            not grant permissions to group or other :
            # stat -Lc 'Access: (%a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/crontab

            Access: (600/-rw-------) Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            - IF - cron is installed on the system:
            Run the following commands to set ownership and permissions on /etc/crontab:
            # chown root:root /etc/crontab
            # chmod og-rwx /etc/crontab

            Default Value:
            Access: (644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2




                                                                                              Page 308

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 309

Internal Only - General
            2.4.1.3 Ensure access to /etc/cron.hourly is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            This directory contains system cron jobs that need to run on an hourly basis. The files
            in this directory cannot be manipulated by the crontab command, but are instead
            edited by system administrators using a text editor. The commands below restrict
            read/write and search access to user and group root, preventing regular users from
            accessing this directory.
            Rationale:
            Granting write access to this directory for non-privileged users could provide them the
            means for gaining unauthorized elevated privileges. Granting read access to this
            directory could give an unprivileged user insight in how to gain elevated privileges or
            circumvent auditing controls.
            Audit:
            - IF - cron is installed on the system:
            Run the following command and verify Uid and Gid are both 0/root and Access does
            not grant permissions to group or other:
            # stat -Lc 'Access: (%a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/cron.hourly/

            Access: (700/drwx------) Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            - IF - cron is installed on the system:
            Run the following commands to set ownership and permissions on the
            /etc/cron.hourly directory:
            # chown root:root /etc/cron.hourly/
            # chmod og-rwx /etc/cron.hourly/

            Default Value:
            Access: (755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2



                                                                                             Page 310

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 311

Internal Only - General
            2.4.1.4 Ensure access to /etc/cron.daily is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/cron.daily directory contains system cron jobs that need to run on a daily
            basis. The files in this directory cannot be manipulated by the crontab command, but
            are instead edited by system administrators using a text editor. The commands below
            restrict read/write and search access to user and group root, preventing regular users
            from accessing this directory.
            Rationale:
            Granting write access to this directory for non-privileged users could provide them the
            means for gaining unauthorized elevated privileges. Granting read access to this
            directory could give an unprivileged user insight in how to gain elevated privileges or
            circumvent auditing controls.
            Audit:
            - IF - cron is installed on the system:
            Run the following command and verify Uid and Gid are both 0/root and Access does
            not grant permissions to group or other:
            # stat -Lc 'Access: (%a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/cron.daily/

            Access: (700/drwx------) Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            - IF - cron is installed on the system:
            Run the following commands to set ownership and permissions on the
            /etc/cron.daily directory:
            # chown root:root /etc/cron.daily/
            # chmod og-rwx /etc/cron.daily/

            Default Value:
            Access: (755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2




                                                                                             Page 312

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 313

Internal Only - General
            2.4.1.5 Ensure access to /etc/cron.weekly is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/cron.weekly directory contains system cron jobs that need to run on a
            weekly basis. The files in this directory cannot be manipulated by the crontab
            command but are instead edited by system administrators using a text editor. The
            commands below restrict read/write and search access to user and group root,
            preventing regular users from accessing this directory.
            Rationale:
            Granting write access to this directory for non-privileged users could provide them the
            means for gaining unauthorized elevated privileges. Granting read access to this
            directory could give an unprivileged user insight in how to gain elevated privileges or
            circumvent auditing controls.
            Audit:
            - IF - cron is installed on the system:
            Run the following command and verify Uid and Gid are both 0/root and Access does
            not grant permissions to group or other:
            # stat -Lc 'Access: (%a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/cron.weekly/

            Access: (700/drwx------) Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            - IF - cron is installed on the system:
            Run the following commands to set ownership and permissions on the
            /etc/cron.weekly directory:
            # chown root:root /etc/cron.weekly/
            # chmod og-rwx /etc/cron.weekly/

            Default Value:
            Access: (755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2



                                                                                             Page 314

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 315

Internal Only - General
            2.4.1.6 Ensure access to /etc/cron.monthly is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/cron.monthly directory contains system cron jobs that need to run on a
            monthly basis. The files in this directory cannot be manipulated by the crontab
            command but are instead edited by system administrators using a text editor. The
            commands below restrict read/write and search access to user and group root,
            preventing regular users from accessing this directory.
            Rationale:
            Granting write access to this directory for non-privileged users could provide them the
            means for gaining unauthorized elevated privileges. Granting read access to this
            directory could give an unprivileged user insight in how to gain elevated privileges or
            circumvent auditing controls.
            Audit:
            - IF - cron is installed on the system:
            Run the following command and verify Uid and Gid are both 0/root and Access does
            not grant permissions to group or other:
            # stat -Lc 'Access: (%a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/cron.monthly/

            Access: (700/drwx------) Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            - IF - cron is installed on the system:
            Run the following commands to set ownership and permissions on the
            /etc/cron.monthly directory:
            # chown root:root /etc/cron.monthly/
            # chmod og-rwx /etc/cron.monthly/

            Default Value:
            Access: (755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2



                                                                                             Page 316

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 317

Internal Only - General
            2.4.1.7 Ensure access to /etc/cron.yearly is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/cron.yearly directory contains system cron jobs that need to run on an
            annual basis. The files in this directory cannot be manipulated by the crontab command
            but are instead edited by system administrators using a text editor. The commands
            below restrict read/write and search access to user and group root, preventing regular
            users from accessing this directory.
            Rationale:
            Granting write access to this directory for non-privileged users could provide them the
            means for gaining unauthorized elevated privileges. Granting read access to this
            directory could give an unprivileged user insight in how to gain elevated privileges or
            circumvent auditing controls.
            Audit:
            - IF - cron is installed on the system:
            Run the following command and verify Uid and Gid are both 0/root and Access does
            not grant permissions to group or other:
            # stat -Lc 'Access: (%a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/cron.yearly/

            Access: (700/drwx------) Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            - IF - cron is installed on the system:
            Run the following commands to set ownership and permissions on the
            /etc/cron.yearly directory:
            # chown root:root /etc/cron.yearly/
            # chmod og-rwx /etc/cron.yearly/

            Default Value:
            Access: (755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2



                                                                                             Page 318

Internal Only - General
            2.4.1.8 Ensure access to /etc/cron.d is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/cron.d directory contains system cron jobs that need to run in a similar
            manner to the hourly, daily weekly and monthly jobs from /etc/crontab, but require
            more granular control as to when they run. The files in this directory cannot be
            manipulated by the crontab command but are instead edited by system administrators
            using a text editor. The commands below restrict read/write and search access to user
            and group root, preventing regular users from accessing this directory.
            Rationale:
            Granting write access to this directory for non-privileged users could provide them the
            means for gaining unauthorized elevated privileges. Granting read access to this
            directory could give an unprivileged user insight in how to gain elevated privileges or
            circumvent auditing controls.
            Audit:
            - IF - cron is installed on the system:
            Run the following command and verify Uid and Gid are both 0/root and Access does
            not grant permissions to group or other:
            # stat -Lc 'Access: (%a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/cron.d/

            Access: (700/drwx------) Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            - IF - cron is installed on the system:
            Run the following commands to set ownership and permissions on the /etc/cron.d
            directory:
            # chown root:root /etc/cron.d/
            # chmod og-rwx /etc/cron.d/

            Default Value:
            Access: (755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2



                                                                                             Page 319

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 320

Internal Only - General
            2.4.1.9 Ensure access to crontab is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            crontab is the program used to install, deinstall, or list the tables used to drive the cron
            daemon. Each user can have their own crontab, and though files are created, they are
            not intended to be edited directly.
            If the /etc/cron.allow file exists, then you must be listed (one user per line) therein in
            order to be allowed to use this command. If the /etc/cron.allow file does not exist but
            the /etc/cron.deny file does exist, then you must not be listed in the /etc/cron.deny
            file in order to use this command.
            If neither of these files exists, then depending on site-dependent configuration
            parameters, only the super user will be allowed to use this command, or all users will be
            able to use this command.
            If both files exist then /etc/cron.allow takes precedence. Which means that
            /etc/cron.deny is not considered and your user must be listed in /etc/cron.allow
            in order to be able to use the crontab.
            Regardless of the existence of any of these files, the root administrative user is always
            allowed to setup a crontab.
            The files /etc/cron.allow and /etc/cron.deny, if they exist, must be either world-
            readable, or readable by group crontab. If they are not, then cron will deny access to
            all users until the permissions are fixed.
            There is one file for each user's crontab. Users are not allowed to edit the file directly to
            ensure that only users allowed by the system to run periodic tasks can add them, and
            only syntactically correct crontabs will be written. This is enforced by having the
            directory writable only by the crontab group and configuring crontab command with the
            setgid bid set for that specific group.
            Note:

                 •   The files /etc/cron.allow and /etc/cron.deny, if they exist, only controls
                     administrative access to the crontab command for scheduling and modifying cron
                     jobs
                 •   If you are using SELinux or AppArmor, these security modules may prevent
                     crontab access. Check the audit logs for any related permission denied entries
                     and adjust your policies if necessary.




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Internal Only - General
            Rationale:
            On many systems, only the system administrator is authorized to schedule cron jobs.
            Using the cron.allow file to control who can run cron jobs enforces this policy. It is
            easier to manage an allow list than a deny list. In a deny list, you could potentially add a
            user ID to the system and forget to add it to the deny files.
            Impact:
            When the /etc/cron.allow file exists, a user must be listed, one user per line, in the
            /etc/cron.allow file in order to be allowed to use the crontab command.

            Audit:
            - IF - cron is installed on the system:
            Run the following command to verify /etc/cron.allow:

                 •   Exists
                 •   Is mode 0640 or more restrictive
                 •   Is owned by the user root
                 •   Is group owned by the group root - OR - the group crontab

            # stat -Lc 'Access: (%a/%A) Owner: (%U) Group: (%G)' /etc/cron.allow
            Verify the returned value is:
            Access: (640/-rw-r-----) Owner: (root) Group: (root)
            - OR -
            Access: (640/-rw-r-----) Owner: (root) Group: (crontab)
            Run the following command to verify either cron.deny doesn't exist or is:

                 •   Mode 0640 or more restrictive
                 •   Owned by the user root
                 •   Is group owned by the group root - OR - the group crontab

            # [ -e "/etc/cron.deny" ] && stat -Lc 'Access: (%a/%A) Owner: (%U) Group:
            (%G)' /etc/cron.deny
            Verify either nothing is returned - OR - returned value is one of the following:
            Access: (640/-rw-r-----) Owner: (root) Group: (root)
            - OR -
            Access: (640/-rw-r-----) Owner: (root) Group: (crontab)
            Note: On systems where cron is configured to use the group crontab, if the group
            crontab is not set as the owner of cron.allow, then cron will deny access to all users
            and you will see an error similar to:
            You (<USERNAME>) are not allowed to use this program (crontab)
            See crontab(1) for more information




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Internal Only - General
            Remediation:
            - IF - cron is installed on the system:
            Run the following script to:

                 •   Create /etc/cron.allow if it doesn't exist
                 •   Change owner to user root
                 •   Change group owner to group root - OR - group crontab if it exists
                 •   Change mode to 640 or more restrictive

            #!/usr/bin/env bash

            {
                 [ ! -e "/etc/cron.allow" ] && touch /etc/cron.allow
                 chmod u-x,g-wx,o-rwx /etc/cron.allow
                 if grep -Pq -- '^\h*crontab\:' /etc/group; then
                    chown root:crontab /etc/cron.allow
                 else
                    chown root:root /etc/cron.allow
                 fi
            }
            - IF - /etc/cron.deny exists, run the following script to:

                 •   Change owner to user root
                 •   Change group owner to group root - OR - group crontab if it exists
                 •   Change mode to 640 or more restrictive

            #!/usr/bin/env bash

            {
                 if [ -e "/etc/cron.deny" ]; then
                    chmod u-x,g-wx,o-rwx /etc/cron.deny
                    if grep -Pq -- '^\h*crontab\:' /etc/group; then
                       chown root:crontab /etc/cron.deny
                    else
                       chown root:root /etc/cron.deny
                    fi
                 fi
            }




                                                                                          Page 323

Internal Only - General
            Note:

                 •    When the /etc/cron.allow file exists, a user must be listed, one user per
                      line, in the /etc/cron.allow file in order to be allowed to use the crontab
                      command.
                 •    If both /etc/cron.allow and /etc/cron.deny exist, /etc/cron.allow takes
                      precedence. Which means that /etc/cron.deny is not considered and users
                      must be listed in /etc/cron.allow in order to use the crontab.
                 •    If the /etc/cron.allow file does not exist but the /etc/cron.deny file does
                      exist, then you must not be listed in the /etc/cron.deny file in order to use the
                      crontab command.
                 •    Regardless of the existence of any of these files, the root administrative user is
                      always allowed to setup a crontab.
                 •    On systems where cron is configured to use the group crontab, if the group
                      crontab is not set as the owner of /etc/cron.allow, then cron will deny access
                      to all users but root, and you will see an error similar to:

            You (<USERNAME>) are not allowed to use this program (crontab)
            See crontab(1) for more information

            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2

            CIS Controls:

              Controls
                                                                Control                                          IG 1 IG 2 IG 3
              Version
                           3.3 Configure Data Access Control Lists
                     v8       Configure data access control lists based on a user’s need to know. Apply data
                           access control lists, also known as access permissions, to local and remote file
                                                                                                                  ●    ●    ●
                           systems, databases, and applications.

                           14.6 Protect Information through Access Control Lists
                               Protect all information stored on systems with file system, network share,
                     v7    claims, application, or database specific access control lists. These controls will
                           enforce the principle that only authorized individuals should have access to the
                                                                                                                  ●    ●    ●
                           information based on their need to access the information as a part of their
                           responsibilities.




                                                                                                                       Page 324

Internal Only - General
            2.4.2 Configure at

            at is a command-line utility used to schedule a job for later execution
            Note: if at is not installed on the system, this section can be skipped




                                                                                      Page 325

Internal Only - General
            2.4.2.1 Ensure access to at is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            at allows fairly complex time specifications, extending the POSIX.2 standard. It accepts
            times of the form HH:MM to run a job at a specific time of day. (If that time is already
            past, the next day is assumed.) You may also specify midnight, noon, or teatime (4pm)
            and you can have a time-of-day suffixed with AM or PM for running in the morning or
            the evening. You can also say what day the job will be run, by giving a date in the form
            month-name day with an optional year, or giving a date of the form MMDD[CC]YY,
            MM/DD/[CC]YY, DD.MM.[CC]YY or [CC]YY-MM-DD. The specification of a date must
            follow the specification of the time of day. You can also give times like now + count
            time-units, where the time-units can be minutes, hours, days, or weeks and you can tell
            at to run the job today by suffixing the time with today and to run the job tomorrow by
            suffixing the time with tomorrow.
            The /etc/at.allow and /etc/at.deny files determine which user can submit
            commands for later execution via at or batch. The format of the files is a list of
            usernames, one on each line. Whitespace is not permitted. If the file /etc/at.allow
            exists, only usernames mentioned in it are allowed to use at. If /etc/at.allow does
            not exist, /etc/at.deny is checked, every username not mentioned in it is then allowed
            to use at. An empty /etc/at.deny means that every user may use at. If neither file
            exists, only the superuser is allowed to use at.
            Rationale:
            On many systems, only the system administrator is authorized to schedule at jobs.
            Using the at.allow file to control who can run at jobs enforces this policy. It is easier
            to manage an allow list than a deny list. In a deny list, you could potentially add a user
            ID to the system and forget to add it to the deny files.




                                                                                                Page 326

Internal Only - General
            Audit:
            - IF - at is installed on the system:
            Run the following command to verify /etc/at.allow:

                 •   Exists
                 •   Is mode 0640 or more restrictive
                 •   Is owned by the user root
                 •   Is group owned by the group daemon or group root

            # stat -Lc 'Access: (%a/%A) Owner: (%U) Group: (%G)' /etc/at.allow

            Access: (640/-rw-r-----) Owner: (root) Group: (daemon)
            -OR-
            Access: (640/-rw-r-----) Owner: (root) Group: (root)
            Verify mode is 640 or more restrictive, owner is root, and group is daemon or root
            Run the following command to verify at.deny doesn't exist, -OR- is:

                 •   Mode 0640 or more restrictive
                 •   Owned by the user root
                 •   Group owned by the group daemon or group root

            # [ -e "/etc/at.deny" ] && stat -Lc 'Access: (%a/%A) Owner: (%U) Group: (%G)'
            /etc/at.deny

            Access: (640/-rw-r-----) Owner: (root) Group: (daemon)
            -OR-
            Access: (640/-rw-r-----) Owner: (root) Group: (root)
            -OR-
            Nothing is returned
            If a value is returned, verify mode is 640 or more restrictive, owner is root, and group is
            daemon or root




                                                                                               Page 327

Internal Only - General
            Remediation:
            - IF - at is installed on the system:
            Run the following script to:

                 •    /etc/at.allow:
                          o Create the file if it doesn't exist
                          o Change owner or user root
                          o If group daemon exists, change to group daemon, else change group to
                              root
                          o Change mode to 640 or more restrictive
                 •    - IF - /etc/at.deny exists:
                          o Change owner or user root
                          o If group daemon exists, change to group daemon, else change group to
                              root
                          o Change mode to 640 or more restrictive

            #!/usr/bin/env bash

            {
                 grep -Pq -- '^daemon\b' /etc/group && l_group="daemon" || l_group="root"
                 [ ! -e "/etc/at.allow" ] && touch /etc/at.allow
                 chown root:"$l_group" /etc/at.allow
                 chmod u-x,g-wx,o-rwx /etc/at.allow
                 [ -e "/etc/at.deny" ] && chown root:"$l_group" /etc/at.deny
                 [ -e "/etc/at.deny" ] && chmod u-x,g-wx,o-rwx /etc/at.deny
            }

            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2

            CIS Controls:

                Controls
                                                                Control                                          IG 1 IG 2 IG 3
                Version
                           3.3 Configure Data Access Control Lists
                     v8       Configure data access control lists based on a user’s need to know. Apply data
                           access control lists, also known as access permissions, to local and remote file
                                                                                                                  ●    ●    ●
                           systems, databases, and applications.

                           14.6 Protect Information through Access Control Lists
                               Protect all information stored on systems with file system, network share,
                     v7    claims, application, or database specific access control lists. These controls will
                           enforce the principle that only authorized individuals should have access to the
                                                                                                                  ●    ●    ●
                           information based on their need to access the information as a part of their
                           responsibilities.




                                                                                                                       Page 328

Internal Only - General
            3 Network
            This section provides guidance on for securing the network configuration of the system




                                                                                           Page 329

Internal Only - General
            3.1 Configure Network Devices

            To reduce the attack surface of a system, unused devices should be disabled.
            Note: This should not be considered a comprehensive list, you may wish to consider
            additions to those listed here for your environment.




                                                                                         Page 330

Internal Only - General
            3.1.1 Ensure IPv6 status is identified (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Internet Protocol Version 6 (IPv6) is the most recent version of Internet Protocol (IP). It's
            designed to supply IP addressing and additional security to support the predicted
            growth of connected devices. IPv6 is based on 128-bit addressing and can support 340
            undecillion, which is 340,282,366,920,938,463,463,374,607,431,768,211,456 unique
            addresses.
            Features of IPv6

                 •   Hierarchical addressing and routing infrastructure
                 •   Statefull and Stateless configuration
                 •   Support for quality of service (QoS)
                 •   An ideal protocol for neighboring node interaction

            Rationale:
            IETF RFC 4038 recommends that applications are built with an assumption of dual
            stack. It is recommended that IPv6 be enabled and configured in accordance with
            Benchmark recommendations.
            - IF - dual stack and IPv6 are not used in your environment, IPv6 may be disabled to
            reduce the attack surface of the system, and recommendations pertaining to IPv6 can
            be skipped.
            Note: It is recommended that IPv6 be enabled and configured unless this is against
            local site policy
            Impact:
            IETF RFC 4038 recommends that applications are built with an assumption of dual
            stack.
            When enabled, IPv6 will require additional configuration to reduce risk to the system.




                                                                                                Page 331

Internal Only - General
            Audit:
            Run the following script to identify if IPv6 is enabled on the system:
            #!/usr/bin/env bash

            {
               l_output=""
               ! grep -Pqs -- '^\h*0\b' /sys/module/ipv6/parameters/disable &&
            l_output="- IPv6 is not enabled"
               if sysctl net.ipv6.conf.all.disable_ipv6 | grep -Pqs --
            "^\h*net\.ipv6\.conf\.all\.disable_ipv6\h*=\h*1\b" && \
                  sysctl net.ipv6.conf.default.disable_ipv6 | grep -Pqs --
            "^\h*net\.ipv6\.conf\.default\.disable_ipv6\h*=\h*1\b"; then
                  l_output="- IPv6 is not enabled"
               fi
               [ -z "$l_output" ] && l_output="- IPv6 is enabled"
               echo -e "\n$l_output\n"
            }

            Remediation:
            Enable or disable IPv6 in accordance with system requirements and local site policy
            Default Value:
            IPv6 is enabled
            References:

                 1. NIST SP 800-53 Rev. 5: CM-7

            Additional Information:
            Having more addresses has grown in importance with the expansion of smart devices
            and connectivity. IPv6 provides more than enough globally unique IP addresses for
            every networked device currently on the planet, helping ensure providers can keep pace
            with the expected proliferation of IP-based devices.
            CIS Controls:

                Controls
                                                             Control                                          IG 1 IG 2 IG 3
                Version
                           4.8 Uninstall or Disable Unnecessary Services on
                           Enterprise Assets and Software
                    v8        Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                           such as an unused file sharing service, web application module, or service
                           function.

                           9.2 Ensure Only Approved Ports, Protocols and Services
                    v7     Are Running                                                                              ●    ●
                              Ensure that only network ports, protocols, and services listening on a system
                           with validated business needs, are running on each system.




                                                                                                                    Page 332

Internal Only - General
            3.1.2 Ensure wireless interfaces are not available (Automated)
            Profile Applicability:

            • Level 1 - Server
            Description:
            Wireless networking is used when wired networks are unavailable.
            Rationale:
            -IF- wireless is not to be used, wireless devices can be disabled to reduce the potential
            attack surface.
            Impact:
            Many if not all laptop workstations and some desktop workstations will connect via
            wireless requiring these interfaces be enabled.
            Audit:
            Run the following script to verify no wireless interfaces are active on the system:




                                                                                                  Page 333

Internal Only - General
            #!/usr/bin/env bash

            {
               l_output="" l_output2=""
               module_chk()
               {
                  # Check how module will be loaded
                  l_loadable="$(modprobe -n -v "$l_mname")"
                  if grep -Pq -- '^\h*install \/bin\/(true|false)' <<< "$l_loadable";
            then
                     l_output="$l_output\n - module: \"$l_mname\" is not loadable:
            \"$l_loadable\""
                  else
                     l_output2="$l_output2\n - module: \"$l_mname\" is loadable:
            \"$l_loadable\""
                  fi
                  # Check is the module currently loaded
                  if ! lsmod | grep "$l_mname" > /dev/null 2>&1; then
                     l_output="$l_output\n - module: \"$l_mname\" is not loaded"
                  else
                     l_output2="$l_output2\n - module: \"$l_mname\" is loaded"
                  fi
                  # Check if the module is deny listed
                  if modprobe --showconfig | grep -Pq -- "^\h*blacklist\h+$l_mname\b";
            then
                     l_output="$l_output\n - module: \"$l_mname\" is deny listed in:
            \"$(grep -Pl -- "^\h*blacklist\h+$l_mname\b" /etc/modprobe.d/*)\""
                  else
                     l_output2="$l_output2\n - module: \"$l_mname\" is not deny listed"
                  fi
               }
               if [ -n "$(find /sys/class/net/*/ -type d -name wireless)" ]; then
                  l_dname=$(for driverdir in $(find /sys/class/net/*/ -type d -name
            wireless | xargs -0 dirname); do basename "$(readlink -f
            "$driverdir"/device/driver/module)";done | sort -u)
                  for l_mname in $l_dname; do
                     module_chk
                  done
               fi
               # Report results. If no failures output in l_output2, we pass
               if [ -z "$l_output2" ]; then
                  echo -e "\n- Audit Result:\n ** PASS **"
                  if [ -z "$l_output" ]; then
                     echo -e "\n - System has no wireless NICs installed"
                  else
                     echo -e "\n$l_output\n"
                  fi
               else
                  echo -e "\n- Audit Result:\n ** FAIL **\n - Reason(s) for audit
            failure:\n$l_output2\n"
                  [ -n "$l_output" ] && echo -e "\n- Correctly set:\n$l_output\n"
               fi
            }




                                                                                  Page 334

Internal Only - General
            Remediation:
            Run the following command to disable any wireless interfaces:
            # find /lib/modules/`uname -r`/kernel/drivers/net/wireless -name '*.ko' -
            printf 'install %f /bin/false\nblacklist %f\n\n' | sed 's/\.ko//1' >>
            /etc/modprobe.d/blacklist-wireless.conf
            Note: the *.conf file in /etc/modprobe.d/ in the above command can renamed as
            needed.
            References:

                 1. NIST SP 800-53 Rev. 5: CM-7

            CIS Controls:

               Controls
                                                             Control                                        IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                   v8        Uninstall or disable unnecessary services on enterprise assets and software,         ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          15.4 Disable Wireless Access on Devices if Not Required
                   v7        Disable wireless access on devices that do not have a business purpose for                ●
                          wireless access.

                          15.5 Limit Wireless Access on Client Devices
                   v7        Configure wireless access on client machines that do have an essential
                          wireless business purpose, to allow access only to authorized wireless networks
                                                                                                                       ●
                          and to restrict access to other wireless networks.




                                                                                                                  Page 335

Internal Only - General
            3.1.3 Ensure bluetooth services are not in use (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 2 - Workstation
            Description:
            Bluetooth is a short-range wireless technology standard that is used for exchanging
            data between devices over short distances. It employs UHF radio waves in the ISM
            bands, from 2.402 GHz to 2.48 GHz. It is mainly used as an alternative to wire
            connections.
            Rationale:
            An attacker may be able to find a way to access or corrupt your data. One example of
            this type of activity is bluesnarfing, which refers to attackers using a Bluetooth
            connection to steal information off of your Bluetooth device. Also, viruses or other
            malicious code can take advantage of Bluetooth technology to infect other devices. If
            you are infected, your data may be corrupted, compromised, stolen, or lost.
            Impact:
            Many personal electronic devices (PEDs) use Bluetooth technology. For example, you
            may be able to operate your computer with a wireless keyboard. Disabling Bluetooth will
            prevent these devices from connecting to the system.
            There may be packages that are dependent on the bluez package. If the bluez
            package is removed, these dependent packages will be removed as well. Before
            removing the bluez package, review any dependent packages to determine if they are
            required on the system.
            -IF- a dependent package is required: stop and mask bluetooth.service leaving the
            bluez package installed.




                                                                                           Page 336

Internal Only - General
            Audit:
            Run the following command to verify the bluez package is not installed:
            # dpkg-query -s bluez &>/dev/null && echo "bluez is installed"
            Nothing should be returned.
            - OR -
            - IF - the bluez package is required as a dependency:
            Run the following command to verify bluetooth.service is not enabled:
            # systemctl is-enabled bluetooth.service 2>/dev/null | grep 'enabled'
            Nothing should be returned.
            Run the following command to verify bluetooth.service is not active:
            # systemctl is-active bluetooth.service 2>/dev/null | grep '^active'
            Nothing should be returned.
            Note: If the package is required for a dependency

                 •   Ensure the dependent package is approved by local site policy
                 •   Ensure stopping and masking the service and/or socket meets local site policy

            Remediation:
            Run the following commands to stop bluetooth.service, and remove the bluez
            package:
            # systemctl stop bluetooth.service
            # apt purge bluez
            - OR -
            - IF - the bluez package is required as a dependency:
            Run the following commands to stop and mask bluetooth.service:
            # systemctl stop bluetooth.service
            # systemctl mask bluetooth.service
            Note: A reboot may be required
            References:

                 1. https://www.cisa.gov/tips/st05-015
                 2. NIST SP 800-53 Rev. 5: CM-7




                                                                                             Page 337

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 338

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            3.2 Configure Network Kernel Modules

            The Linux kernel modules support several network protocols that are not commonly
            used. If these protocols are not needed, it is recommended that they be disabled in the
            kernel.
            Note: This should not be considered a comprehensive list of uncommon network
            protocols, you may wish to consider additions to those listed here for your environment.




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            3.2.1 Ensure dccp kernel module is not available (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Datagram Congestion Control Protocol (DCCP) is a transport layer protocol that
            supports streaming media and telephony. DCCP provides a way to gain access to
            congestion control, without having to do it at the application layer, but does not provide
            in-sequence delivery.
            Rationale:
            Removing support for unneeded protocols reduces the local attack surface of the
            system. If this protocol is not needed, disable it.
            Audit:
            Verify the dccp kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the dccp kernel module is available on the
                    system:

            #!/usr/bin/env bash

            {
                 l_mod_name="dccp" l_mod_type="net"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the dccp kernel module is not available on the system and no
            further audit steps are required.
            Note: Some systems may include the dccp filesystem as part of the kernel opposed to
            being available as a kernel module. In this case, the above audit will not return anything.
            This is also considered a passing state.
            If anything is returned by the above script:




                                                                                               Page 340

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                 2. verify the dccp kernel module is not loaded and not loadable by performing the
                    following:

            Run the following command to verify the dccp kernel module is not loaded:
            # lsmod | grep 'dccp'
            Nothing should be returned
            Run the following command to verify the dccp kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+dccp\b'
            Verify the output includes:
            blacklist dccp
             -AND-
            install dccp /bin/false
             -OR-
            install dccp /bin/true
            Example output:
            blacklist dccp
            install dccp /bin/false

            Remediation:
            Unload and disable the dccp kernel module.

                 1. Run the following commands to unload the dccp kernel module:

            # modprobe -r dccp 2>/dev/null
            # rmmod dccp 2>/dev/null

                 2. Perform the following to disable the dccp kernel module:

            Create a file ending in .conf with install dccp /bin/false in the
            /etc/modprobe.d/ directory
            Example:
            # printf '\n%s\n' "install dccp /bin/false" >> /etc/modprobe.d/60-dccp.conf
            Create a file ending in .conf with blacklist dccp in the /etc/modprobe.d/ directory
            Example:
            # printf '\n%s\n' "blacklist dccp" >> /etc/modprobe.d/60-dccp.conf

            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)




                                                                                            Page 341

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 342

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            3.2.2 Ensure tipc kernel module is not available (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Transparent Inter-Process Communication (TIPC) protocol is designed to provide
            communication between cluster nodes.
            Rationale:
            Removing support for unneeded protocols reduces the local attack surface of the
            system. If this protocol is not needed, disable it.
            Audit:
            Verify the tipc kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the tipc kernel module is available on the
                    system:

            #!/usr/bin/env bash

            {
                 l_mod_name="tipc" l_mod_type="net"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the tipc kernel module is not available on the system and no
            further audit steps are required.
            Note: Some systems may include the tipc filesystem as part of the kernel opposed to
            being available as a kernel module. In this case, the above audit will not return anything.
            This is also considered a passing state.
            If anything is returned by the above script:

                 2. verify the tipc kernel module is not loaded and not loadable by performing the
                    following:

            Run the following command to verify the tipc kernel module is not loaded:
            # lsmod | grep 'tipc'
            Nothing should be returned

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            Run the following command to verify the tipc kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+tipc\b'
            Verify the output includes:
            blacklist tipc
             -AND-
            install tipc /bin/false
             -OR-
            install tipc /bin/true
            Example output:
            blacklist tipc
            install tipc /bin/false

            Remediation:
            Unload and disable the tipc kernel module.

                 1. Run the following commands to unload the tipc kernel module:

            # modprobe -r tipc 2>/dev/null
            # rmmod tipc 2>/dev/null

                 2. Perform the following to disable the tipc kernel module:

            Create a file ending in .conf with install tipc /bin/false in the
            /etc/modprobe.d/ directory
            Example:
            # printf '\n%s\n' "install tipc /bin/false" >> /etc/modprobe.d/60-tipc.conf
            Create a file ending in .conf with blacklist tipc in the /etc/modprobe.d/ directory
            Example:
            # printf '\n%s\n' "blacklist tipc" >> /etc/modprobe.d/60-tipc.conf

            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)
                 4. STIG ID: RHEL-08-040024 | RULE ID: SV-230497r1069313 | CAT III
                 5. STIG ID: OL08-00-040024 | RULE ID: SV-248832r958478 | CAT III
                 6. STIG ID: RHEL-09-213065 | RULE ID: SV-257808r1044865 | CAT II
                 7. STIG ID: ALMA-09-030270 | RULE ID: SV-269347r1050229 | CAT II
                 8. STIG ID: OL09-00-000044 | RULE ID: SV-271447r1092464 | CAT II




                                                                                          Page 344

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            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 345

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            3.2.3 Ensure rds kernel module is not available (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Reliable Datagram Sockets (RDS) protocol is a transport layer protocol designed to
            provide low-latency, high-bandwidth communications between cluster nodes. It was
            developed by the Oracle Corporation.
            Rationale:
            Removing support for unneeded protocols reduces the local attack surface of the
            system. If this protocol is not needed, disable it.
            Audit:
            Verify the rds kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the rds kernel module is available on the
                    system:

            #!/usr/bin/env bash

            {
                 l_mod_name="rds" l_mod_type="net"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the rds kernel module is not available on the system and no
            further audit steps are required.
            Note: Some systems may include the rds filesystem as part of the kernel opposed to
            being available as a kernel module. In this case, the above audit will not return anything.
            This is also considered a passing state.
            If anything is returned by the above script:




                                                                                               Page 346

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                 2. verify the rds kernel module is not loaded and not loadable by performing the
                    following:

            Run the following command to verify the rds kernel module is not loaded:
            # lsmod | grep 'rds'
            Nothing should be returned
            Run the following command to verify the rds kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+rds\b'
            Verify the output includes:
            blacklist rds
             -AND-
            install rds /bin/false
             -OR-
            install rds /bin/true
            Example output:
            blacklist rds
            install rds /bin/false

            Remediation:
            Unload and disable the rds kernel module.

                 1. Run the following commands to unload the rds kernel module:

            # modprobe -r rds 2>/dev/null
            # rmmod rds 2>/dev/null

                 2. Perform the following to disable the rds kernel module:

            Create a file ending in .conf with install rds /bin/false in the /etc/modprobe.d/
            directory
            Example:
            # printf '\n%s\n' "install rds /bin/false" >> /etc/modprobe.d/60-rds.conf
            Create a file ending in .conf with blacklist rds in the /etc/modprobe.d/ directory
            Example:
            # printf '\n%s\n' "blacklist rds" >> /etc/modprobe.d/60-rds.conf

            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)




                                                                                             Page 347

Internal Only - General
            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 348

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            3.2.4 Ensure sctp kernel module is not available (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Stream Control Transmission Protocol (SCTP) is a transport layer protocol used to
            support message oriented communication, with several streams of messages in one
            connection. It serves a similar function as TCP and UDP, incorporating features of both.
            It is message-oriented like UDP, and ensures reliable in-sequence transport of
            messages with congestion control like TCP.
            Rationale:
            Removing support for unneeded protocols reduces the local attack surface of the
            system. If this protocol is not needed, disable it.
            Audit:
            Verify the sctp kernel module is not available on the system or has been disabled.

                 1. Run the following script to determine if the sctp kernel module is available on the
                    system:

            #!/usr/bin/env bash

            {
                 l_mod_name="sctp" l_mod_type="net"
                 while IFS= read -r l_mod_path; do
                    if [ -d "$l_mod_path/${l_mod_name//-/\/}" ] && \
                    [ -n "$(ls -A "$l_mod_path/${l_mod_name//-/\/}")" ]; then
                       printf '%s\n' "$l_mod_name exists in $l_mod_path"
                    fi
                 done < <(readlink -e /usr/lib/modules/**/kernel/$l_mod_type \
                 || readlink -e /lib/modules/**/kernel/$l_mod_type)
            }
            If nothing is returned, the sctp kernel module is not available on the system and no
            further audit steps are required.
            Note: Some systems may include the sctp filesystem as part of the kernel opposed to
            being available as a kernel module. In this case, the above audit will not return anything.
            This is also considered a passing state.
            If anything is returned by the above script:




                                                                                              Page 349

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                 2. verify the sctp kernel module is not loaded and not loadable by performing the
                    following:

            Run the following command to verify the sctp kernel module is not loaded:
            # lsmod | grep 'sctp'
            Nothing should be returned
            Run the following command to verify the sctp kernel module is not loadable:
            # modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+sctp\b'
            Verify the output includes:
            blacklist sctp
             -AND-
            install sctp /bin/false
             -OR-
            install sctp /bin/true
            Example output:
            blacklist sctp
            install sctp /bin/false

            Remediation:
            Unload and disable the sctp kernel module.

                 1. Run the following commands to unload the sctp kernel module:

            # modprobe -r sctp 2>/dev/null
            # rmmod sctp 2>/dev/null

                 2. Perform the following to disable the sctp kernel module:

            Create a file ending in .conf with install sctp /bin/false in the
            /etc/modprobe.d/ directory
            Example:
            # printf '\n%s\n' "install sctp /bin/false" >> /etc/modprobe.d/60-sctp.conf
            Create a file ending in .conf with blacklist sctp in the /etc/modprobe.d/ directory
            Example:
            # printf '\n%s\n' "blacklist sctp" >> /etc/modprobe.d/60-sctp.conf




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            References:

                 1. CCI-000381
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (ii)
                 4. STIG ID: RHEL-08-040023 | RULE ID: SV-230496r1069312 | CAT III
                 5. STIG ID: OL08-00-040023 | RULE ID: SV-248831r991589 | CAT II
                 6. STIG ID: RHEL-09-213060 | RULE ID: SV-257807r1044862 | CAT II
                 7. STIG ID: ALMA-09-030050 | RULE ID: SV-269345r1050227 | CAT II
                 8. STIG ID: OL09-00-000043 | RULE ID: SV-271446r1091050 | CAT II

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 351

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            3.3 Configure Network Kernel Parameters

            This section contains Recommendations covering kernel parameters effecting network
            stack.
            Note:

                 •   Some of the Recommendations in this section's subsections are not applicable if
                     the system is a router. These Recommendations include a note in their
                     description.
                 •   sysctl settings are defined through files in /usr/local/lib, /usr/lib/, /lib/,
                     /run/, and /etc/
                 •   Files are typically placed in the sysctl.d directory within the parent directory
                 •   The paths where sysctl preload files usually exist
                         o /run/sysctl.d/*.conf
                         o /etc/sysctl.d/*.conf
                         o /usr/local/lib/sysctl.d/*.conf
                         o /usr/lib/sysctl.d/*.conf
                         o /lib/sysctl.d/*.conf
                         o /etc/sysctl.conf
                 •   Files must have the ".conf" extension
                 •   Vendors settings usually live in /usr/lib/ or /usr/local/lib/
                 •   To override a whole file, create a new file with the same name in
                     /etc/sysctl.d/ and put new settings there.
                 •   To override only specific settings, add a file with a lexically later name in
                     /etc/sysctl.d/ and put new settings there.
                 •   The command /usr/lib/systemd/systemd-sysctl --cat-config produces
                     output containing The system's loaded kernel parameters and the files they're
                     configured in:
                         o Entries listed latter in the file take precedence over the same settings
                            listed earlier in the file
                         o Files containing kernel parameters that are over-ridden by other files with
                            the same name will not be listed
                         o On systems running UncomplicatedFirewall, the kernel parameters may
                            be set or over-written. This will not be visible in the output of the command
                 •   On systems with Uncomplicated Firewall, additional settings may be configured
                     in /etc/ufw/sysctl.conf
                         o The settings in /etc/ufw/sysctl.conf will override settings other
                            settings and will not be visible in the output of the
                            /usr/lib/systemd/systemd-sysctl --cat-config command
                         o This behavior can be changed by updating the IPT_SYSCTL parameter in
                            /etc/default/ufw




                                                                                                 Page 352

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            3.3.1 Configure IPv4 parameters

            net.ipv4 kernel parameters control various aspects of the IPv4 network stack. These
            parameters effect functions to include routing, TCP, and security.




                                                                                         Page 353

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            3.3.1.1 Ensure net.ipv4.ip_forward is configured (Automated)
            Profile Applicability:

            • Level 1 - Workstation
            • Level 2 - Server
            Description:
            The net.ipv4.ip_forward flag tells the system whether it can forward IPv4 packets or
            not.
            Note:

                 •   If this system is a router this recommendation is not applicable.
                 •   If net.ipv4.conf.all.forwarding=0 and
                     net.ipv4.conf.default.forwarding=0 are configured, this recommendation
                     may be skipped.

            Rationale:
            Routing protocol daemons are typically used on routers to exchange network topology
            information with other routers. If this software is used when not required, system
            network information may be unnecessarily transmitted across the network.
            Setting net.ipv4.ip_forward to 0 ensures that a system with multiple interfaces (for
            example, a hard proxy), will not be able to forward IPv4 packets.
            Impact:
            IP forwarding is required on systems configured to act as a router. If these parameters
            are disabled, the system will not be able to perform as a router.
            Many Cloud Service Provider (CSP) hosted systems require IP forwarding to be
            enabled. If the system is running on a CSP platform, this requirement should be
            reviewed before disabling IP forwarding.
            Audit:
            Verify net.ipv4.ip_forward is set to 0.

                 1. Run the following command to verify net.ipv4.ip_forward is set to 0 in the
                    running configuration:

            # sysctl net.ipv4.ip_forward
            Verify output is:
            net.ipv4.ip_forward = 0

                 2. Run the following script to verify net.ipv4.ip_forward = 0 is set in a file being
                    used by systemd sysctl to configure net.ipv4.ip_forward:

                                                                                             Page 354

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.ip_forward"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
                - "net.ipv4.ip_forward = 0" is set in: "/etc/sysctl.d/60-ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 355

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                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.ip_forward lines that are not net.ipv4.ip_forward=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.ip_forward" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 356

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.ip_forward = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.ip_forward = 0" >> /etc/sysctl.d/60-
            ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.ip_forward = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: SLES-15-040380 | RULE ID: SV-235024r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 357

Internal Only - General
            3.3.1.2 Ensure net.ipv4.conf.all.forwarding is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            ICMP Redirects are used to send routing information to other hosts. As a host itself
            does not act as a router (in a host only configuration), there is no need to send
            redirects.
            net.ipv4.conf.all.forwarding controls forwarding of IPv4 packet on all interfaces.
            Note:

                 •   If this system is a router this recommendation is not applicable.
                 •   If net.ipv4.ip_forward=0 is configured, this recommendation may be skipped.

            Rationale:
            Routing protocol daemons are typically used on routers to exchange network topology
            information with other routers. If this capability is used when not required, system
            network information may be unnecessarily transmitted across the network.
            Impact:
            IP forwarding is required on systems configured to act as a router. If these parameters
            are disabled, the system will not be able to perform as a router.
            Cloud Service Provider (CSP) hosted systems may require forwarding to be enabled. If
            the system is running on a CSP platform, this requirement should be reviewed before
            disabling IPv4 forwarding.




                                                                                            Page 358

Internal Only - General
            Audit:
            Verify net.ipv4.conf.all.forwarding is set to 0.

                  1. Run the following command to verify net.ipv4.conf.all.forwarding is set to
                     0 in the running configuration:

            # sysctl net.ipv4.conf.all.forwarding
            Verify output is:
            net.ipv4.conf.all.forwarding = 0

                  2. Run the following script to verify net.ipv4.conf.all.forwarding = 0 is set in
                     a file being used by systemd sysctl to configure
                     net.ipv4.conf.all.forwarding:

            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.all.forwarding"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.all.forwarding = 0" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"




                                                                                           Page 359

Internal Only - General
            Note:

                 •   This script looks at all files used by systemd sysctl.
                 •   More information about these files and their location is available in the section
                     overview.
                 •   If multiple lines are returned:
                         o The first line includes the value being used by systemd sysctl. If this is a
                             correct value, this is considered a passing state. If the file listed is not in
                             the /etc/sysctl.d/ directory, it is highly recommended to follow the
                             remediation procedure to create a .conf file in the /etc/sysctl.d/
                             directory with the correct setting to prevent a potential change due to an
                             update to the system.
                         o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                             should be modified to comment out or change the incorrect value to
                             minimize the potential of the incorrect value being used by systemd
                             sysctl due to system configuration changes.
                 •   SYSTEM FILE PRECEDENCE
                         o When using the --system option, sysctl will read files from directories in
                             the following list in given order from top to bottom. Once a file of a given
                             filename is loaded, any file of the same name in subsequent directories is
                             ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--




                                                                                                    Page 360

Internal Only - General
            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.all.forwarding lines that are not
                    net.ipv4.conf.all.forwarding=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.all.forwarding" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }

                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.all.forwarding = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.all.forwarding = 0" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system




                                                                                                Page 361

Internal Only - General
            Default Value:
            net.ipv4.conf.all.forwarding = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040259 | RULE ID: SV-250317r1017358 | CAT II
                 5. STIG ID: OL08-00-040259 | RULE ID: SV-252662r991589 | CAT II
                 6. STIG ID: RHEL-09-253075 | RULE ID: SV-257970r1045011 | CAT II
                 7. STIG ID: ALMA-09-019160 | RULE ID: SV-269249r1050131 | CAT II
                 8. STIG ID: OL09-00-006028 | RULE ID: SV-271872r1092328 | CAT II

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 362

Internal Only - General
            3.3.1.3 Ensure net.ipv4.conf.default.forwarding is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            ICMP Redirects are used to send routing information to other hosts. As a host itself
            does not act as a router (in a host only configuration), there is no need to send
            redirects.
            net.ipv4.conf.default.forwarding controls forwarding of IPv4 packet on newly
            added network interfaces.
            Note:

                 •   If this system is a router this recommendation is not applicable.
                 •   If net.ipv4.ip_forward=0 is configured, this recommendation may be skipped.

            Rationale:
            Routing protocol daemons are typically used on routers to exchange network topology
            information with other routers. If this capability is used when not required, system
            network information may be unnecessarily transmitted across the network.
            Impact:
            IP forwarding is required on systems configured to act as a router. If these parameters
            are disabled, the system will not be able to perform as a router.
            Cloud Service Provider (CSP) hosted systems may require forwarding to be enabled. If
            the system is running on a CSP platform, this requirement should be reviewed before
            disabling IPv4 forwarding.




                                                                                            Page 363

Internal Only - General
            Audit:
            Verify net.ipv4.conf.default.forwarding is set to 0.

                  1. Run the following command to verify net.ipv4.conf.default.forwarding is
                     set to 0 in the running configuration:

            # sysctl net.ipv4.conf.default.forwarding
            Verify output is:
            net.ipv4.conf.default.forwarding = 0

                  2. Run the following script to verify net.ipv4.conf.default.forwarding = 0 is
                     set in a file being used by systemd sysctl to configure
                     net.ipv4.conf.default.forwarding:

            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.default.forwarding"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.default.forwarding = 0" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"




                                                                                         Page 364

Internal Only - General
            Note:

                 •   This script looks at all files used by systemd sysctl.
                 •   More information about these files and their location is available in the section
                     overview.
                 •   If multiple lines are returned:
                         o The first line includes the value being used by systemd sysctl. If this is a
                             correct value, this is considered a passing state. If the file listed is not in
                             the /etc/sysctl.d/ directory, it is highly recommended to follow the
                             remediation procedure to create a .conf file in the /etc/sysctl.d/
                             directory with the correct setting to prevent a potential change due to an
                             update to the system.
                         o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                             should be modified to comment out or change the incorrect value to
                             minimize the potential of the incorrect value being used by systemd
                             sysctl due to system configuration changes.
                 •   SYSTEM FILE PRECEDENCE
                         o When using the --system option, sysctl will read files from directories in
                             the following list in given order from top to bottom. Once a file of a given
                             filename is loaded, any file of the same name in subsequent directories is
                             ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--




                                                                                                    Page 365

Internal Only - General
            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.default.forwarding lines that are not
                    net.ipv4.conf.default.forwarding=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.default.forwarding" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }

                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.default.forwarding = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.default.forwarding = 0" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system




                                                                                                Page 366

Internal Only - General
            Default Value:
            net.ipv4.conf.default.forwarding = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: ALMA-09-019160 | RULE ID: SV-269249r1050131 | CAT II

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 367

Internal Only - General
            3.3.1.4 Ensure net.ipv4.conf.all.send_redirects is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            ICMP Redirects are used to send routing information to other hosts. As a host itself
            does not act as a router (in a host only configuration), there is no need to send
            redirects.
            net.ipv4.conf.all.send_redirects controls sending of all IPv4 ICMP redirected
            packets on all interfaces.
            Note: If this system is a router this recommendation is not applicable.
            Rationale:
            An attacker could use a compromised host to send invalid ICMP redirects to other
            router devices in an attempt to corrupt routing and have users access a system set up
            by the attacker as opposed to a valid system.
            Impact:
            IP forwarding is required on systems configured to act as a router. If these parameters
            are disabled, the system will not be able to perform as a router.




                                                                                             Page 368

Internal Only - General
            Audit:
            Verify net.ipv4.conf.all.send_redirects is set to 0.

                  1. Run the following command to verify net.ipv4.conf.all.send_redirects is
                     set to 0 in the running configuration:

            # sysctl net.ipv4.conf.all.send_redirects
            Verify output is:
            net.ipv4.conf.all.send_redirects = 0

                  2. Run the following script to verify net.ipv4.ip_forward = 0 is set in a file being
                     used by systemd sysctl to configure net.ipv4.conf.all.send_redirects:

            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.all.send_redirects"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.all.send_redirects = 0" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"




                                                                                              Page 369

Internal Only - General
            Note:

                 •   This script looks at all files used by systemd sysctl.
                 •   More information about these files and their location is available in the section
                     overview.
                 •   If multiple lines are returned:
                         o The first line includes the value being used by systemd sysctl. If this is a
                             correct value, this is considered a passing state. If the file listed is not in
                             the /etc/sysctl.d/ directory, it is highly recommended to follow the
                             remediation procedure to create a .conf file in the /etc/sysctl.d/
                             directory with the correct setting to prevent a potential change due to an
                             update to the system.
                         o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                             should be modified to comment out or change the incorrect value to
                             minimize the potential of the incorrect value being used by systemd
                             sysctl due to system configuration changes.
                 •   SYSTEM FILE PRECEDENCE
                         o When using the --system option, sysctl will read files from directories in
                             the following list in given order from top to bottom. Once a file of a given
                             filename is loaded, any file of the same name in subsequent directories is
                             ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--




                                                                                                    Page 370

Internal Only - General
            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.all.send_redirects lines that are not
                    net.ipv4.conf.all.send_redirects=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.all.send_redirects" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }

                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.all.send_redirects = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.all.send_redirects = 0" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system




                                                                                                Page 371

Internal Only - General
            Default Value:
            net.ipv4.conf.all.send_redirects = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040220 | RULE ID: SV-230536r1017298 | CAT II
                 5. STIG ID: OL08-00-040220 | RULE ID: SV-248877r991589 | CAT II
                 6. STIG ID: RHEL-09-253065 | RULE ID: SV-257968r991589 | CAT II
                 7. STIG ID: ALMA-09-019930 | RULE ID: SV-269256r1050138 | CAT II
                 8. STIG ID: OL09-00-006032 | RULE ID: SV-271875r1092337 | CAT II
                 9. STIG ID: SLES-15-040370 | RULE ID: SV-235023r991589 | CAT II

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 372

Internal Only - General
            3.3.1.5 Ensure net.ipv4.conf.default.send_redirects is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            ICMP Redirects are used to send routing information to other hosts. As a host itself
            does not act as a router (in a host only configuration), there is no need to send
            redirects.
            net.ipv4.conf.default.send_redirects controls sending of all IPv4 ICMP
            redirected packets on a newly added network interface.
            Note: If this system is a router this recommendation is not applicable.
            Rationale:
            An attacker could use a compromised host to send invalid ICMP redirects to other
            router devices in an attempt to corrupt routing and have users access a system set up
            by the attacker as opposed to a valid system.
            Impact:
            IP forwarding is required on systems configured to act as a router. If these parameters
            are disabled, the system will not be able to perform as a router.




                                                                                             Page 373

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            Audit:
            Verify net.ipv4.conf.default.send_redirects is set to 0.

                  1. Run the following command to verify
                     net.ipv4.conf.default.send_redirects is set to 0 in the running
                     configuration:

            # sysctl net.ipv4.conf.default.send_redirects
            Verify output is:
            net.ipv4.conf.default.send_redirects = 0

                  2. Run the following script to verify net.ipv4.conf.default.send_redirects =
                     0 is set in a file being used by systemd sysctl to configure
                     net.ipv4.conf.default.send_redirects:

            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.default.send_redirects"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.default.send_redirects = 0" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"




                                                                                        Page 374

Internal Only - General
            Note:

                 •   This script looks at all files used by systemd sysctl.
                 •   More information about these files and their location is available in the section
                     overview.
                 •   If multiple lines are returned:
                         o The first line includes the value being used by systemd sysctl. If this is a
                             correct value, this is considered a passing state. If the file listed is not in
                             the /etc/sysctl.d/ directory, it is highly recommended to follow the
                             remediation procedure to create a .conf file in the /etc/sysctl.d/
                             directory with the correct setting to prevent a potential change due to an
                             update to the system.
                         o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                             should be modified to comment out or change the incorrect value to
                             minimize the potential of the incorrect value being used by systemd
                             sysctl due to system configuration changes.
                 •   SYSTEM FILE PRECEDENCE
                         o When using the --system option, sysctl will read files from directories in
                             the following list in given order from top to bottom. Once a file of a given
                             filename is loaded, any file of the same name in subsequent directories is
                             ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--




                                                                                                    Page 375

Internal Only - General
            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.default.send_redirects lines that are not
                    net.ipv4.conf.default.send_redirects=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.default.send_redirects" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }

                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.default.send_redirects = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.default.send_redirects = 0" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system




                                                                                                Page 376

Internal Only - General
            Default Value:
            net.ipv4.conf.default.send_redirects = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040270 | RULE ID: SV-230543r1017305 | CAT II
                 5. STIG ID: OL08-00-040270 | RULE ID: SV-248886r991589 | CAT II
                 6. STIG ID: RHEL-09-253070 | RULE ID: SV-257969r991589 | CAT II
                 7. STIG ID: ALMA-09-019930 | RULE ID: SV-269256r1050138 | CAT II
                 8. STIG ID: OL09-00-006033 | RULE ID: SV-271876r1092641 | CAT II
                 9. STIG ID: SLES-15-040360 | RULE ID: SV-235022r991589 | CAT II

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 377

Internal Only - General
            3.3.1.6 Ensure net.ipv4.icmp_ignore_bogus_error_responses is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            net.ipv4.icmp_ignore_bogus_error_responses controls if the kernel logs bogus
            responses (RFC-1122 non-compliant) from broadcast reframes.
            Rationale:
            Some routers (and some attackers) will send responses that violate RFC-1122 and
            attempt to fill up a log file system with many useless error messages.
            Audit:
            Verify net.ipv4.icmp_ignore_bogus_error_responses is set to 1.

                 1. Run the following command to verify
                    net.ipv4.icmp_ignore_bogus_error_responses is set to 1 in the running
                    configuration:

            # sysctl net.ipv4.icmp_ignore_bogus_error_responses
            Verify output is:
            net.ipv4.icmp_ignore_bogus_error_responses = 1

                 2. Run the following script to verify
                    net.ipv4.icmp_ignore_bogus_error_responses = 1 is set in a file being
                    used by systemd sysctl to configure
                    net.ipv4.icmp_ignore_bogus_error_responses:




                                                                                        Page 378

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.icmp_ignore_bogus_error_responses"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.icmp_ignore_bogus_error_responses = 1" is set in:
            "/etc/sysctl.d/60-ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 379

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.icmp_ignore_bogus_error_responses lines that are not
                    net.ipv4.icmp_ignore_bogus_error_responses=1.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.icmp_ignore_bogus_error_responses" l_value="1"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(0|[2-9]|1[0-9]+)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 380

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.icmp_ignore_bogus_error_responses = 1
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.icmp_ignore_bogus_error_responses = 1" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.icmp_ignore_bogus_error_responses = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-09-253060 | RULE ID: SV-257967r991589 | CAT II
                 5. STIG ID: ALMA-09-018940 | RULE ID: SV-269247r1050129 | CAT II
                 6. STIG ID: OL09-00-006031 | RULE ID: SV-271874r1092612 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 381

Internal Only - General
            3.3.1.7 Ensure net.ipv4.icmp_echo_ignore_broadcasts is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            net.ipv4.icmp_echo_ignore_broadcasts controls if all ICMP echo and timestamp
            requests to broadcast and multicast addresses are ignored.
            Rationale:
            Accepting ICMP echo and timestamp requests with broadcast or multicast destinations
            for your network could be used to trick your host into starting (or participating) in a
            Smurf attack. A Smurf attack relies on an attacker sending large amounts of ICMP
            broadcast messages with a spoofed source address. All hosts receiving this message
            and responding would send echo-reply messages back to the spoofed address, which is
            probably not routable. If many hosts respond to the packets, the amount of traffic on the
            network could be significantly multiplied.
            Audit:
            Verify net.ipv4.icmp_echo_ignore_broadcasts is set to 1.

                 1. Run the following command to verify
                    net.ipv4.icmp_echo_ignore_broadcasts is set to 1 in the running
                    configuration:

            # sysctl net.ipv4.icmp_echo_ignore_broadcasts
            Verify output is:
            net.ipv4.icmp_echo_ignore_broadcasts = 1

                 2. Run the following script to verify net.ipv4.icmp_echo_ignore_broadcasts =
                    1 is set in a file being used by systemd sysctl to configure
                    net.ipv4.icmp_echo_ignore_broadcasts:




                                                                                            Page 382

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.icmp_echo_ignore_broadcasts"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.icmp_echo_ignore_broadcasts = 1" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 383

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.icmp_echo_ignore_broadcasts lines that are not
                    net.ipv4.icmp_echo_ignore_broadcasts=1.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.icmp_echo_ignore_broadcasts" l_value="1"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(0|[2-9]|1[0-9]+)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 384

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.icmp_echo_ignore_broadcasts = 1
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.icmp_echo_ignore_broadcasts = 1" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.icmp_echo_ignore_broadcasts = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040230 | RULE ID: SV-230537r1017299 | CAT II
                 5. STIG ID: OL08-00-040230 | RULE ID: SV-248878r991589 | CAT II
                 6. STIG ID: RHEL-09-253055 | RULE ID: SV-257966r991589 | CAT II
                 7. STIG ID: ALMA-09-019050 | RULE ID: SV-269248r1050130 | CAT II
                 8. STIG ID: OL09-00-006030 | RULE ID: SV-271873r1092331 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 385

Internal Only - General
            3.3.1.8 Ensure net.ipv4.conf.all.accept_redirects is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            ICMP redirect messages are packets that convey routing information and tell your host
            (acting as a router) to send packets via an alternate path. It is a way of allowing an
            outside routing device to update your system routing tables.
            net.ipv4.conf.all.accept_redirects controls accepting of all IPv4 ICMP
            redirected packets on all interfaces.
            Rationale:
            ICMP redirect messages are packets that convey routing information and tell your host
            (acting as a router) to send packets via an alternate path. It is a way of allowing an
            outside routing device to update your system routing tables.
            By setting net.ipv4.conf.all.accept_redirects to 0, the system will not accept
            any IPv4 ICMP redirect messages, and therefore, won't allow outsiders to update the
            system's routing tables.
            Audit:
            Verify net.ipv4.conf.all.accept_redirects is set to 0.

                 1. Run the following command to verify net.ipv4.conf.all.accept_redirects
                    is set to 0 in the running configuration:

            # sysctl net.ipv4.conf.all.accept_redirects
            Verify output is:
            net.ipv4.conf.all.accept_redirects = 0

                 2. Run the following script to verify net.ipv4.conf.all.send_redirects = 0 is
                    set in a file being used by systemd sysctl to configure
                    net.ipv4.conf.all.send_redirects:




                                                                                           Page 386

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.all.accept_redirects"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.all.accept_redirects = 0" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 387

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.all.accept_redirects lines that are not
                    net.ipv4.conf.all.accept_redirects=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.all.accept_redirects" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 388

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.all.accept_redirects = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.all.accept_redirects = 0" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.conf.all.accept_redirects = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040279 | RULE ID: SV-244553r1017353 | CAT II
                 5. STIG ID: OL08-00-040279 | RULE ID: SV-248887r991589 | CAT II
                 6. STIG ID: RHEL-09-253015 | RULE ID: SV-257958r991589 | CAT II
                 7. STIG ID: ALMA-09-018610 | RULE ID: SV-269244r1050126 | CAT II
                 8. STIG ID: OL09-00-006020 | RULE ID: SV-271864r1092304 | CAT II
                 9. STIG ID: SLES-15-040330 | RULE ID: SV-235018r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 389

Internal Only - General
            3.3.1.9 Ensure net.ipv4.conf.default.accept_redirects is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            ICMP redirect messages are packets that convey routing information and tell your host
            (acting as a router) to send packets via an alternate path. It is a way of allowing an
            outside routing device to update your system routing tables.
            net.ipv4.conf.default.accept_redirects controls accepting of all IPv4 ICMP
            redirected packets on a newly added network interface.
            Note: If this system is a router this recommendation is not applicable.
            Rationale:
            ICMP redirect messages are packets that convey routing information and tell your host
            (acting as a router) to send packets via an alternate path. It is a way of allowing an
            outside routing device to update your system routing tables.
            By setting net.ipv4.conf.all.accept_redirects to 0, the system will not accept
            IPv4 ICMP redirect messages on a newly added network interface.
            Audit:
            Verify net.ipv4.conf.default.accept_redirects is set to 0.

                 1. Run the following command to verify
                    net.ipv4.conf.default.accept_redirects is set to 0 in the running
                    configuration:

            # sysctl net.ipv4.conf.default.accept_redirects
            Verify output is:
            net.ipv4.conf.default.accept_redirects = 0

                 2. Run the following script to verify net.ipv4.conf.default.accept_redirects
                    = 0 is set in a file being used by systemd sysctl to configure
                    net.ipv4.conf.default.accept_redirects:




                                                                                           Page 390

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.default.accept_redirects"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.default.accept_redirects = 0" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 391

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.default.accept_redirects lines that are not
                    net.ipv4.conf.default.accept_redirects=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.default.accept_redirects" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 392

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.default.accept_redirects = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.default.accept_redirects = 0" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.conf.default.accept_redirects = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040209 | RULE ID: SV-244550r1017350 | CAT II
                 5. STIG ID: OL08-00-040209 | RULE ID: SV-248875r991589 | CAT II
                 6. STIG ID: RHEL-09-253040 | RULE ID: SV-257963r991589 | CAT II
                 7. STIG ID: ALMA-09-018610 | RULE ID: SV-269244r1050126 | CAT II
                 8. STIG ID: OL09-00-006025 | RULE ID: SV-271869r1092319 | CAT II
                 9. STIG ID: SLES-15-040340 | RULE ID: SV-235019r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 393

Internal Only - General
            3.3.1.10 Ensure net.ipv4.conf.all.secure_redirects is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Secure ICMP redirects are the same as ICMP redirects, except they come from
            gateways listed on the default gateway list. It is assumed that these gateways are
            known to your system, and that they are likely to be secure.
            Rationale:
            It is still possible for even known gateways to be compromised.
            Setting net.ipv4.conf.all.secure_redirects to 0 the system will not accept any
            IPv4 routing table updates by possibly compromised known gateways.
            Audit:
            Verify net.ipv4.conf.all.secure_redirects is set to 0.

                 1. Run the following command to verify net.ipv4.conf.all.secure_redirects
                    is set to 0 in the running configuration:

            # sysctl net.ipv4.conf.all.secure_redirects
            Verify output is:
            net.ipv4.conf.all.secure_redirects = 0

                 2. Run the following script to verify net.ipv4.conf.all.secure_redirects = 0
                    is set in a file being used by systemd sysctl to configure
                    net.ipv4.conf.all.secure_redirects:




                                                                                            Page 394

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.all.secure_redirects"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.all.secure_redirects = 0" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 395

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.all.secure_redirects lines that are not
                    net.ipv4.conf.all.secure_redirects=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.all.secure_redirects" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 396

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.all.secure_redirects = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.all.secure_redirects = 0" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.conf.all.secure_redirects = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 397

Internal Only - General
            3.3.1.11 Ensure net.ipv4.conf.default.secure_redirects is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Secure ICMP redirects are the same as ICMP redirects, except they come from
            gateways listed on the default gateway list. It is assumed that these gateways are
            known to your system, and that they are likely to be secure.
            Rationale:
            It is still possible for even known gateways to be compromised.
            Setting net.ipv4.conf.default.secure_redirects to 0 the system the system will
            not accept IPv4 routing table updates by possibly compromised known gateways on a
            newly added network interface.
            Audit:
            Verify net.ipv4.conf.default.secure_redirects is set to 0.

                 1. Run the following command to verify
                    net.ipv4.conf.default.secure_redirects is set to 0 in the running
                    configuration:

            # sysctl      net.ipv4.conf.default.secure_redirects
            Verify output is:
            net.ipv4.conf.default.secure_redirects = 0

                 2. Run the following script to verify net.ipv4.conf.default.secure_redirects
                    = 0 is set in a file being used by systemd sysctl to configure
                    net.ipv4.conf.default.secure_redirects:




                                                                                            Page 398

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.default.secure_redirects"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.default.secure_redirects = 0" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 399

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.default.secure_redirects lines that are not
                    net.ipv4.conf.default.secure_redirects=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.default.secure_redirects" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 400

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.default.secure_redirects = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.default.secure_redirects = 0" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.conf.default.secure_redirects = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 401

Internal Only - General
            3.3.1.12 Ensure net.ipv4.conf.all.rp_filter is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            net.ipv4.conf.all.rp_filter controls reverse path filtering for IPv4 traffic on all
            network interfaces.
            Reverse path filtering is a security mechanism in Linux that helps prevent IP spoofing
            and other network attacks. When enabled, it checks if the source IP address of an
            incoming packet is reachable through the same network interface it was received on. If
            the packet's source address is not reachable through the interface it arrived on, the
            packet is dropped.
            Note: If this system is a router, and uses asymmetrical routing, this
            recommendation is not applicable.
            Rationale:
            Setting net.ipv4.conf.all.rp_filter to 1 is a good way to deter attackers from
            sending your system bogus packets that cannot be responded to. One instance where
            this feature breaks down is if asymmetrical routing is employed. This would occur when
            using dynamic routing protocols (bgp, ospf, etc) on your system. If you are using
            asymmetrical routing on your system, you will not be able to enable this feature without
            breaking the routing.
            Impact:
            If you are using asymmetrical routing on your system, you will not be able to enable this
            feature without breaking the routing.
            Audit:
            Verify net.ipv4.conf.all.rp_filter is set to 1.

                 1. Run the following command to verify net.ipv4.conf.all.rp_filter is set to 1
                    in the running configuration:

            # sysctl net.ipv4.conf.all.rp_filter
            Verify output is:
            net.ipv4.conf.all.rp_filter = 1

                 2. Run the following script to verify net.ipv4.conf.all.rp_filter = 1 is set in a
                    file being used by systemd sysctl to configure net.ipv4.conf.all.rp_filter:


                                                                                             Page 402

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.all.rp_filter"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.all.rp_filter = 1" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 403

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.all.rp_filter lines that are not
                    net.ipv4.conf.all.rp_filter=1.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.all.rp_filter" l_value="1"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(0|[2-9]|1[0-9]+)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 404

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.all.rp_filter = 1
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.all.rp_filter = 1" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.conf.all.rp_filter = 2
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040285 | RULE ID: SV-230549r1017311 | CAT II
                 5. STIG ID: OL08-00-040285 | RULE ID: SV-248893r991589 | CAT II
                 6. STIG ID: RHEL-09-253035 | RULE ID: SV-257962r991589 | CAT II
                 7. STIG ID: ALMA-09-019820 | RULE ID: SV-269255r1050137 | CAT II
                 8. STIG ID: OL09-00-006024 | RULE ID: SV-271868r1092316 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 405

Internal Only - General
            3.3.1.13 Ensure net.ipv4.conf.default.rp_filter is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            net.ipv4.conf.default.rp_filter controls reverse path filtering for IPv4 traffic on
            newly added network interfaces.
            Reverse path filtering is a security mechanism in Linux that helps prevent IP spoofing
            and other network attacks. When enabled, it checks if the source IP address of an
            incoming packet is reachable through the same network interface it was received on. If
            the packet's source address is not reachable through the interface it arrived on, the
            packet is dropped.
            Note: If this system is a router, and uses asymmetrical routing, this
            recommendation is not applicable.
            Rationale:
            Setting net.ipv4.conf.default.rp_filter to 1 is a good way to deter attackers
            from sending your system bogus packets that cannot be responded to. One instance
            where this feature breaks down is if asymmetrical routing is employed. This would occur
            when using dynamic routing protocols (bgp, ospf, etc) on your system. If you are using
            asymmetrical routing on your system, you will not be able to enable this feature without
            breaking the routing.
            Impact:
            If you are using asymmetrical routing on your system, you will not be able to enable this
            feature without breaking the routing.
            Audit:
            Verify net.ipv4.conf.default.rp_filter is set to 1.

                 1. Run the following command to verify net.ipv4.conf.default.rp_filter is
                    set to 1 in the running configuration:

            # sysctl net.ipv4.conf.default.rp_filter
            Verify output is:
            net.ipv4.conf.default.rp_filter = 1




                                                                                             Page 406

Internal Only - General
                  2. Run the following script to verify net.ipv4.conf.default.rp_filter = 1 is
                     set in a file being used by systemd sysctl to configure
                     net.ipv4.conf.default.rp_filter:

            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.default.rp_filter"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.default.rp_filter = 1" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.



                                                                                                    Page 407

Internal Only - General
            SYSTEM FILE PRECEDENCE

                          o   When using the --system option, sysctl will read files from directories in
                              the following list in given order from top to bottom. Once a file of a given
                              filename is loaded, any file of the same name in subsequent directories is
                              ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.default.rp_filter lines that are not
                    net.ipv4.conf.default.rp_filter=1.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.default.rp_filter" l_value="1"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(0|[2-9]|1[0-9]+)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 408

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.default.rp_filter = 1
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.default.rp_filter = 1" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.conf.default.rp_filter = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-09-253050 | RULE ID: SV-257965r991589 | CAT II
                 5. STIG ID: ALMA-09-019820 | RULE ID: SV-269255r1050137 | CAT II
                 6. STIG ID: OL09-00-006027 | RULE ID: SV-271871r1092325 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 409

Internal Only - General
            3.3.1.14 Ensure net.ipv4.conf.all.accept_source_route is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The accept_source_route option causes network interfaces to accept packets with
            the Strict Source Route (SSR) or Loose Source Routing (LSR) option set.
            net.ipv4.conf.all.accept_source_route controls accepting of all IPv4 packets
            with the SSR or LSR option set on all interfaces.
            In networking, source routing allows a sender to partially or fully specify the route
            packets take through a network. In contrast, non-source routed packets travel a path
            determined by routers in the network. In some cases, systems may not be routable or
            reachable from some locations (e.g. private addresses vs. Internet routable), and so
            source routed packets would need to be used.
            Rationale:
            Setting net.ipv4.conf.all.accept_source_route to 0 disables the system from
            accepting source routed packets. Assume this system was capable of routing packets to
            Internet routable addresses on one interface and private addresses on another
            interface. Assume that the private addresses were not routable to the Internet routable
            addresses and vice versa. Under normal routing circumstances, an attacker from the
            Internet routable addresses could not use the system as a way to reach the private
            address systems. If, however, source routed packets were allowed, they could be used
            to gain access to the private address systems as the route could be specified, rather
            than rely on routing protocols that did not allow this routing.
            Audit:
            Verify net.ipv4.conf.all.accept_source_route is set to 0.

                 1. Run the following command to verify
                    net.ipv4.conf.all.accept_source_route is set to 0 in the running
                    configuration:

            # sysctl net.ipv4.conf.all.accept_source_route
            Verify output is:
            net.ipv4.conf.all.accept_source_route = 0




                                                                                           Page 410

Internal Only - General
                  2. Run the following script to verify net.ipv4.conf.all.accept_source_route =
                     0 is set in a file being used by systemd sysctl to configure
                     net.ipv4.conf.all.accept_source_route:

            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.all.accept_source_route"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.all.accept_source_route = 0" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.
                  •


                                                                                                    Page 411

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.all.accept_source_route lines that are not
                    net.ipv4.conf.all.accept_source_route=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.all.accept_source_route" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 412

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.all.accept_source_route = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.all.accept_source_route = 0" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.conf.all.accept_source_route = 0
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040239 | RULE ID: SV-244551r1017351 | CAT II
                 5. STIG ID: OL08-00-040239 | RULE ID: SV-248879r991589 | CAT II
                 6. STIG ID: RHEL-09-253020 | RULE ID: SV-257959r991589 | CAT II
                 7. STIG ID: ALMA-09-020260 | RULE ID: SV-269259r1050141 | CAT II
                 8. STIG ID: OL09-00-006021 | RULE ID: SV-271865r1092307 | CAT II
                 9. STIG ID: SLES-15-040300 | RULE ID: SV-235014r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 413

Internal Only - General
            3.3.1.15 Ensure net.ipv4.conf.default.accept_source_route is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The accept_source_route option causes network interfaces to accept packets with
            the Strict Source Route (SSR) or Loose Source Routing (LSR) option set.
            net.ipv4.conf.default.accept_source_route controls accepting of all IPv4
            packets with the SSR or LSR option set on newly added network interfaces.
            In networking, source routing allows a sender to partially or fully specify the route
            packets take through a network. In contrast, non-source routed packets travel a path
            determined by routers in the network. In some cases, systems may not be routable or
            reachable from some locations (e.g. private addresses vs. Internet routable), and so
            source routed packets would need to be used.
            Rationale:
            Setting net.ipv4.conf.default.accept_source_route to 0 disables the system
            from accepting source routed packets. Assume this system was capable of routing
            packets to Internet routable addresses on one interface and private addresses on
            another interface. Assume that the private addresses were not routable to the Internet
            routable addresses and vice versa. Under normal routing circumstances, an attacker
            from the Internet routable addresses could not use the system as a way to reach the
            private address systems. If, however, source routed packets were allowed, they could
            be used to gain access to the private address systems as the route could be specified,
            rather than rely on routing protocols that did not allow this routing.
            Audit:
            Verify net.ipv4.conf.default.accept_source_route is set to 0.

                 1. Run the following command to verify
                    net.ipv4.conf.default.accept_source_route is set to 0 in the running
                    configuration:

            # sysctl net.ipv4.conf.default.accept_source_route
            Verify output is:
            net.ipv4.conf.default.accept_source_route = 0




                                                                                           Page 414

Internal Only - General
                  2. Run the following script to verify
                     net.ipv4.conf.default.accept_source_route = 0 is set in a file being used
                     by systemd sysctl to configure
                     net.ipv4.conf.default.accept_source_route:

            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.default.accept_source_route"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.default.accept_source_route = 0" is set in:
            "/etc/sysctl.d/60-ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.

                                                                                                    Page 415

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.default.accept_source_route lines that are not
                    net.ipv4.conf.default.accept_source_route=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.default.accept_source_route" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 416

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.default.accept_source_route = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.default.accept_source_route = 0" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.conf.default.accept_source_route = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040249 | RULE ID: SV-244552r1017352 | CAT II
                 5. STIG ID: OL08-00-040249 | RULE ID: SV-248881r991589 | CAT II
                 6. STIG ID: RHEL-09-253045 | RULE ID: SV-257964r991589 | CAT II
                 7. STIG ID: ALMA-09-020260 | RULE ID: SV-269259r1050141 | CAT II
                 8. STIG ID: OL09-00-006026 | RULE ID: SV-271870r1092322 | CAT II
                 9. STIG ID: SLES-15-040320 | RULE ID: SV-235016r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 417

Internal Only - General
            3.3.1.16 Ensure net.ipv4.conf.all.log_martians is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            When enabled, this feature logs packets with un-routable source addresses to the
            kernel log.
            net.ipv4.conf.all.log_martians controls if IPv4 packets with un-routable source
            addresses on any network interface is logged to the kernel log.
            Rationale:
            Setting net.ipv4.conf.all.log_martians to 1 enables this feature. Logging these
            packets allows an administrator to investigate the possibility that an attacker is sending
            spoofed packets to their system.
            Audit:
            Verify net.ipv4.conf.all.log_martians is set to 1.

                 1. Run the following command to verify net.ipv4.conf.all.log_martians is set
                    to 1 in the running configuration:

            # sysctl net.ipv4.conf.all.log_martians
            Verify output is:
            net.ipv4.conf.all.log_martians = 1

                 2. Run the following script to verify net.ipv4.conf.all.log_martians = 1 is set
                    in a file being used by systemd sysctl to configure
                    net.ipv4.conf.all.log_martians:




                                                                                               Page 418

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.all.log_martians"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.all.log_martians = 1" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 419

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.all.log_martians lines that are not
                    net.ipv4.conf.all.log_martians=1.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.all.log_martians" l_value="1"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(0|[2-9]|1[0-9]+)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 420

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.all.log_martians = 1
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.all.log_martians = 1" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.conf.all.log_martians = 0
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-09-253025 | RULE ID: SV-257960r991589 | CAT II
                 5. STIG ID: ALMA-09-019380 | RULE ID: SV-269251r1050133 | CAT II
                 6. STIG ID: OL09-00-006022 | RULE ID: SV-271866r1092310 | CAT II

            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          6.2 Activate audit logging
                   v7        Ensure that local logging has been enabled on all systems and networking             ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                   v7        Enable system logging to include detailed information such as an event source,
                          date, user, timestamp, source addresses, destination addresses, and other useful
                                                                                                                       ●    ●
                          elements.




                                                                                                                       Page 421

Internal Only - General
            3.3.1.17 Ensure net.ipv4.conf.default.log_martians is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            When enabled, this feature logs packets with un-routable source addresses to the
            kernel log.
            net.ipv4.conf.default.log_martians controls if IPv4 packets with un-routable
            source addresses on a newly added network interface is logged to the kernel log.
            Rationale:
            Setting net.ipv4.conf.default.log_martians to 1 enables this feature. Logging
            these packets allows an administrator to investigate the possibility that an attacker is
            sending spoofed packets to their system.
            Audit:
            Verify net.ipv4.conf.default.log_martians is set to 1.

                 1. Run the following command to verify net.ipv4.conf.default.log_martians
                    is set to 1 in the running configuration:

            # sysctl net.ipv4.conf.default.log_martians
            Verify output is:
            net.ipv4.conf.default.log_martians = 1

                 2. Run the following script to verify net.ipv4.conf.default.log_martians = 1
                    is set in a file being used by systemd sysctl to configure
                    net.ipv4.conf.default.log_martians:




                                                                                               Page 422

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.conf.default.log_martians"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.conf.default.log_martians = 1" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 423

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.conf.default.log_martians lines that are not
                    net.ipv4.conf.default.log_martians=1.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.conf.default.log_martians" l_value="1"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(0|[2-9]|1[0-9]+)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 424

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.conf.default.log_martians = 1
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.conf.default.log_martians = 1" \
            >> /etc/sysctl.d/60-ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.conf.default.log_martians = 0
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-09-253030 | RULE ID: SV-257961r991589 | CAT II
                 5. STIG ID: ALMA-09-019380 | RULE ID: SV-269251r1050133 | CAT II
                 6. STIG ID: OL09-00-006023 | RULE ID: SV-271867r1092313 | CAT II

            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          6.2 Activate audit logging
                   v7        Ensure that local logging has been enabled on all systems and networking             ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                   v7        Enable system logging to include detailed information such as an event source,
                          date, user, timestamp, source addresses, destination addresses, and other useful
                                                                                                                       ●    ●
                          elements.




                                                                                                                       Page 425

Internal Only - General
            3.3.1.18 Ensure net.ipv4.tcp_syncookies is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            When tcp_syncookies is set, the kernel will handle TCP SYN packets normally until
            the half-open connection queue is full, at which time, the SYN cookie functionality kicks
            in. SYN cookies work by not using the SYN queue at all. Instead, the kernel simply
            replies to the SYN with a SYN/ACK, but will include a specially crafted TCP sequence
            number that encodes the source and destination IP address and port number and the
            time the packet was sent. A legitimate connection would send the ACK packet of the
            three way handshake with the specially crafted sequence number. This allows the
            system to verify that it has received a valid response to a SYN cookie and allow the
            connection, even though there is no corresponding SYN in the queue.
            Rationale:
            Attackers use SYN flood attacks to perform a denial of service attacked on a system by
            sending many SYN packets without completing the three way handshake. This will
            quickly use up slots in the kernel's half-open connection queue and prevent legitimate
            connections from succeeding. Setting net.ipv4.tcp_syncookies to 1 enables SYN
            cookies, allowing the system to keep accepting valid connections, even if under a denial
            of service attack.
            Audit:
            Verify net.ipv4.tcp_syncookies is set to 1.

                 1. Run the following command to verify net.ipv4.tcp_syncookies is set to 1 in
                    the running configuration:

            # sysctl net.ipv4.tcp_syncookies
            Verify output is:
            net.ipv4.tcp_syncookies = 1

                 2. Run the following script to verify net.ipv4.tcp_syncookies = 1 is set in a file
                    being used by systemd sysctl to configure net.ipv4.tcp_syncookies:




                                                                                              Page 426

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv4.tcp_syncookies"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv4.tcp_syncookies = 1" is set in: "/etc/sysctl.d/60-
            ipv4_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 427

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv4.tcp_syncookies lines that are not net.ipv4.tcp_syncookies=1.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv4.tcp_syncookies" l_value="1"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(0|[2-9]|1[0-9]+)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 428

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv4.tcp_syncookies = 1
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv4.tcp_syncookies = 1" >> /etc/sysctl.d/60-
            ipv4_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv4.tcp_syncookies = 1
            References:

                 1. CCI-001095 | CCI-002385
                 2. NIST SP 800-53 :: SC-5 (2) | NIST SP 800-53 :: SC-5 a
                 3. NIST SP 800-53A :: SC-5 (2).1
                 4. STIG ID: RHEL-09-253010 | RULE ID: SV-257957r1045009 | CAT II
                 5. STIG ID: ALMA-09-042480 | RULE ID: SV-269435r1050318 | CAT II
                 6. STIG ID: OL09-00-006050 | RULE ID: SV-271884r1092364 | CAT II
                 7. STIG ID: UBTU-22-253010 | RULE ID: SV-260522r1069097 | CAT II
                 8. STIG ID: UBTU-24-600190 | RULE ID: SV-270753r1066748 | CAT II
                 9. STIG ID: SLES-15-010310 | RULE ID: SV-234829r958528 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 429

Internal Only - General
            3.3.2 Configure IPv6 parameters

            net.ipv6 kernel parameters control various aspects of the IPv6 network stack. These
            parameters effect functions to include routing, TCP, and security.
            Note: If IPv6 has been disabled on the system, the Recommendations in this
            subsection are not applicable and should be skipped.
            The following script creates and runs a function called f_ipv6_chk that may be used to
            determine if IPv6 has been disabled on the system:
            #!/usr/bin/env bash

            f_ipv6_chk()
            {
               a_output=()
               ! grep -Pqs -- '^\h*0\b' /sys/module/ipv6/parameters/disable && \
               a_output+=(" - IPv6 is disabled")
               if sysctl net.ipv6.conf.all.disable_ipv6 | \
               grep -Pqs -- "^\h*net\.ipv6\.conf\.all\.disable_ipv6\h*=\h*1\b" && \
               sysctl net.ipv6.conf.default.disable_ipv6 | \
               grep -Pqs -- "^\h*net\.ipv6\.conf\.default\.disable_ipv6\h*=\h*1\b"; then
                  [ "${#a_output[@]}" -le 0 ] && a_output+=(" - IPv6 is disabled")
               fi
               [ "${#a_output[@]}" -le 0 ] && a_output+=(" - IPv6 is not disabled")
               printf '%s\n' "" "${a_output[@]}" ""
            }
            f_ipv6_chk




                                                                                          Page 430

Internal Only - General
            3.3.2.1 Ensure net.ipv6.conf.all.forwarding is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The net.ipv6.conf.all.forwarding flag tells the system whether it can forward IPv6
            packets or not.
            Note: If IPv6 has been disabled, or this system is a router, this recommendation is
            not applicable.
            Rationale:
            Routing protocol daemons are typically used on routers to exchange network topology
            information with other routers. If this software is used when not required, system
            network information may be unnecessarily transmitted across the network.
            Setting net.ipv6.conf.all.forwarding to 0 ensures that a system with multiple
            interfaces (for example, a hard proxy), will not be able to forward IPv6 packets.
            Impact:
            IP forwarding is required on systems configured to act as a router. If these parameters
            are disabled, the system will not be able to perform as a router.
            Many Cloud Service Provider (CSP) hosted systems require IP forwarding to be
            enabled. If the system is running on a CSP platform, this requirement should be
            reviewed before disabling IP forwarding.
            Audit:
            - IF IPv6 is enabled on the system -
            Verify net.ipv6.conf.all.forwarding is set to 0.

                 1. Run the following command to verify net.ipv6.conf.all.forwarding is set to
                    0 in the running configuration:

            # sysctl net.ipv6.conf.all.forwarding
            Verify output is:
            net.ipv6.conf.all.forwarding = 0

                 2. Run the following script to verify net.ipv6.conf.all.forwarding = 0 is set in
                    a file being used by systemd sysctl to configure
                    net.ipv6.conf.all.forwarding:


                                                                                             Page 431

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv6.conf.all.forwarding"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv6.conf.all.forwarding = 0" is set in: "/etc/sysctl.d/60-
            ipv6_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 432

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv6.conf.all.forwarding lines that are not
                    net.ipv6.conf.all.forwarding=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv6.conf.all.forwarding" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 433

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv6.conf.all.forwarding = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv6.conf.all.forwarding = 0" >> /etc/sysctl.d/60-
            ipv6_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv6.conf.all.forwarding = 0
            References:

                 1. CI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040260 | RULE ID: SV-230540r1017302 | CAT II
                 5. STIG ID: OL08-00-040260 | RULE ID: SV-248883r991589 | CAT II
                 6. STIG ID: RHEL-09-254025 | RULE ID: SV-257974r991589 | CAT II
                 7. STIG ID: ALMA-09-019160 | RULE ID: SV-269249r1050131 | CAT II
                 8. STIG ID: OL09-00-006043 | RULE ID: SV-271880r1092352 | CAT II
                 9. STIG ID: SLES-15-040381 | RULE ID: SV-235025r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 434

Internal Only - General
            3.3.2.2 Ensure net.ipv6.conf.default.forwarding is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The net.ipv6.conf.all.forwarding flag tells the system whether it can forward IPv6
            on the default or newly added network interface.
            Note: If IPv6 has been disabled, or this system is a router, this recommendation is
            not applicable.
            Rationale:
            Routing protocol daemons are typically used on routers to exchange network topology
            information with other routers. If this software is used when not required, system
            network information may be unnecessarily transmitted across the network.
            Impact:
            IP forwarding is required on systems configured to act as a router. If these parameters
            are disabled, the system will not be able to perform as a router.
            Many Cloud Service Provider (CSP) hosted systems require IP forwarding to be
            enabled. If the system is running on a CSP platform, this requirement should be
            reviewed before disabling IP forwarding.
            Audit:
            - IF IPv6 is enabled on the system -
            Verify net.ipv6.conf.default.forwarding is set to 0.

                 1. Run the following command to verify net.ipv6.conf.default.forwarding is
                    set to 0 in the running configuration:

            # sysctl net.ipv6.conf.default.forwarding
            Verify output is:
            net.ipv6.conf.default.forwarding = 0

                 2. Run the following script to verify net.ipv6.conf.default.forwarding = 0 is
                    set in a file being used by systemd sysctl to configure
                    net.ipv6.conf.default.forwarding:




                                                                                             Page 435

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv6.conf.default.forwarding"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv6.conf.default.forwarding = 0" is set in: "/etc/sysctl.d/60-
            ipv6_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 436

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv6.conf.default.forwarding lines that are not
                    net.ipv6.conf.default.forwarding=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv6.conf.default.forwarding" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 437

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv6.conf.default.forwarding = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv6.conf.default.forwarding = 0" >>
            /etc/sysctl.d/60-ipv6_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv6.conf.default.forwarding = 0
            References:

                 1. CI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: ALMA-09-019160 | RULE ID: SV-269249r1050131 | CAT II
                 5. STIG ID: SLES-15-040382 | RULE ID: SV-235026r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 438

Internal Only - General
            3.3.2.3 Ensure net.ipv6.conf.all.accept_redirects is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            ICMP redirect messages are packets that convey routing information and tell your host
            (acting as a router) to send packets via an alternate path. It is a way of allowing an
            outside routing device to update your system routing tables.
            net.ipv6.conf.all.accept_redirects controls accepting of all IPv6 ICMP
            redirected packets on all interfaces.
            Note: If IPv6 has been disabled, or this system is a router, this recommendation is
            not applicable.
            Rationale:
            ICMP redirect messages are packets that convey routing information and tell your host
            (acting as a router) to send packets via an alternate path. It is a way of allowing an
            outside routing device to update your system routing tables.
            By setting net.ipv6.conf.all.accept_redirects to 0, the system will not accept
            any IPv6 ICMP redirect messages, and therefore, won't allow outsiders to update the
            system's routing tables.
            Audit:
            - IF IPv6 is enabled on the system -
            Verify net.ipv6.conf.all.accept_redirects is set to 0.

                 1. Run the following command to verify net.ipv6.conf.all.accept_redirects
                    is set to 0 in the running configuration:

            # sysctl net.ipv6.conf.all.accept_redirects
            Verify output is:
            net.ipv6.conf.all.accept_redirects = 0

                 2. Run the following script to verify net.ipv6.conf.all.accept_redirects = 0
                    is set in a file being used by systemd sysctl to configure
                    net.ipv6.conf.all.accept_redirects:




                                                                                           Page 439

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv6.conf.all.accept_redirects"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv6.conf.all.accept_redirects = 0" is set in: "/etc/sysctl.d/60-
            ipv6_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 440

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv6.conf.all.accept_redirects lines that are not
                    net.ipv6.conf.all.accept_redirects=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv6.conf.all.accept_redirects" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 441

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv6.conf.all.accept_redirects = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv6.conf.all.accept_redirects = 0" \
            >> /etc/sysctl.d/60-ipv6_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv6.conf.all.accept_redirects = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040280 | RULE ID: SV-230544r1017306 | CAT II
                 5. STIG ID: OL08-00-040280 | RULE ID: SV-248888r991589 | CAT II
                 6. STIG ID: RHEL-09-254015 | RULE ID: SV-257972r991589 | CAT II
                 7. STIG ID: ALMA-09-018610 | RULE ID: SV-269244r1050126 | CAT II
                 8. STIG ID: OL09-00-006041 | RULE ID: SV-271878r1092346 | CAT II
                 9. STIG ID: SLES-15-040341 | RULE ID: SV-235020r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 442

Internal Only - General
            3.3.2.4 Ensure net.ipv6.conf.default.accept_redirects is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            ICMP redirect messages are packets that convey routing information and tell your host
            (acting as a router) to send packets via an alternate path. It is a way of allowing an
            outside routing device to update your system routing tables.
            net.ipv6.conf.default.accept_redirects controls accepting of all IPv6 ICMP
            redirected packets on a newly added network interface.
            Note: If IPv6 has been disabled, or this system is a router, this recommendation is
            not applicable.
            Rationale:
            ICMP redirect messages are packets that convey routing information and tell your host
            (acting as a router) to send packets via an alternate path. It is a way of allowing an
            outside routing device to update your system routing tables.
            By setting net.ipv6.conf.default.accept_redirects to 0, the system will not
            accept IPv6 ICMP redirect messages on a newly added network interface.
            Audit:
            - IF IPv6 is enabled on the system -
            Verify net.ipv6.conf.default.accept_redirects is set to 0.

                 1. Run the following command to verify
                    net.ipv6.conf.default.accept_redirects is set to 0 in the running
                    configuration:

            # sysctl net.ipv6.conf.default.accept_redirects
            Verify output is:
            net.ipv6.conf.default.accept_redirects = 0

                 2. Run the following script to verify net.ipv6.conf.default.accept_redirects
                    = 0 is set in a file being used by systemd sysctl to configure
                    net.ipv6.conf.default.accept_redirects:




                                                                                           Page 443

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv6.conf.default.accept_redirects"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv6.conf.default.accept_redirects = 0" is set in: "/etc/sysctl.d/60-
            ipv6_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 444

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv6.conf.default.accept_redirects lines that are not
                    net.ipv6.conf.default.accept_redirects=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv6.conf.default.accept_redirects" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 445

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv6.conf.default.accept_redirects = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv6.conf.default.accept_redirects = 0" \
            >> /etc/sysctl.d/60-ipv6_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv6.conf.default.accept_redirects = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040210 | RULE ID: SV-230535r1017297 | CAT II
                 5. STIG ID: OL08-00-040210 | RULE ID: SV-248876r991589 | CAT II
                 6. STIG ID: RHEL-09-254035 | RULE ID: SV-257976r991589 | CAT II
                 7. STIG ID: ALMA-09-018610 | RULE ID: SV-269244r1050126 | CAT II
                 8. STIG ID: OL09-00-006045 | RULE ID: SV-271882r1092358 | CAT II
                 9. STIG ID: SLES-15-040350 | RULE ID: SV-235021r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 446

Internal Only - General
            3.3.2.5 Ensure net.ipv6.conf.all.accept_source_route is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The accept_source_route option causes network interfaces to accept packets with
            the Strict Source Route (SSR) or Loose Source Routing (LSR) option set.
            net.ipv6.conf.all.accept_source_route controls accepting of all IPv6 packets
            with the SSR or LSR option set on all interfaces.
            In networking, source routing allows a sender to partially or fully specify the route
            packets take through a network. In contrast, non-source routed packets travel a path
            determined by routers in the network. In some cases, systems may not be routable or
            reachable from some locations (e.g. private addresses vs. Internet routable), and so
            source routed packets would need to be used.
            Note: If IPv6 has been disabled this recommendation is not applicable.
            Rationale:
            Setting net.ipv6.conf.all.accept_source_route to 0 disables the system from
            accepting source routed packets. Assume this system was capable of routing packets to
            Internet routable addresses on one interface and private addresses on another
            interface. Assume that the private addresses were not routable to the Internet routable
            addresses and vice versa. Under normal routing circumstances, an attacker from the
            Internet routable addresses could not use the system as a way to reach the private
            address systems. If, however, source routed packets were allowed, they could be used
            to gain access to the private address systems as the route could be specified, rather
            than rely on routing protocols that did not allow this routing.
            Audit:
            - IF IPv6 is enabled on the system -
            Verify net.ipv6.conf.all.accept_source_route is set to 0.

                 1. Run the following command to verify
                    net.ipv6.conf.all.accept_source_route is set to 0 in the running
                    configuration:

            # sysctl net.ipv6.conf.all.accept_source_route
            Verify output is:
            net.ipv6.conf.all.accept_source_route = 0




                                                                                           Page 447

Internal Only - General
                  2. Run the following script to verify net.ipv6.conf.all.accept_source_route =
                     0 is set in a file being used by systemd sysctl to configure
                     net.ipv6.conf.all.accept_source_route:

            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv6.conf.all.accept_source_route"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv6.conf.all.accept_source_route = 0" is set in: "/etc/sysctl.d/60-
            ipv6_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.
                  •   SYSTEM FILE PRECEDENCE

                                                                                                    Page 448

Internal Only - General
                          o   When using the --system option, sysctl will read files from directories in
                              the following list in given order from top to bottom. Once a file of a given
                              filename is loaded, any file of the same name in subsequent directories is
                              ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv6.conf.all.accept_source_route lines that are not
                    net.ipv6.conf.all.accept_source_route=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv6.conf.all.accept_source_route" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 449

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv6.conf.all.accept_source_route = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv6.conf.all.accept_source_route = 0" \
            >> /etc/sysctl.d/60-ipv6_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv6.conf.all.accept_source_route = 0
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040240 | RULE ID: SV-230538r1017300 | CAT II
                 5. STIG ID: OL08-00-040240 | RULE ID: SV-248880r991589 | CAT II
                 6. STIG ID: RHEL-09-254020 | RULE ID: SV-257973r991589 | CAT II
                 7. STIG ID: ALMA-09-020260 | RULE ID: SV-269259r1050141 | CAT II
                 8. STIG ID: OL09-00-006042 | RULE ID: SV-271879r1092349 | CAT II
                 9. STIG ID: SLES-15-040310 | RULE ID: SV-235015r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 450

Internal Only - General
            3.3.2.6 Ensure net.ipv6.conf.default.accept_source_route is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The accept_source_route option causes network interfaces to accept packets with
            the Strict Source Route (SSR) or Loose Source Routing (LSR) option set.
            net.ipv6.conf.default.accept_source_route controls accepting of all IPv6
            packets with the SSR or LSR option set on newly added network interfaces.
            In networking, source routing allows a sender to partially or fully specify the route
            packets take through a network. In contrast, non-source routed packets travel a path
            determined by routers in the network. In some cases, systems may not be routable or
            reachable from some locations (e.g. private addresses vs. Internet routable), and so
            source routed packets would need to be used.
            Note: If IPv6 has been disabled this recommendation is not applicable.
            Rationale:
            Setting net.ipv6.conf.default.accept_source_route to 0 disables the system
            from accepting source routed packets. Assume this system was capable of routing
            packets to Internet routable addresses on one interface and private addresses on
            another interface. Assume that the private addresses were not routable to the Internet
            routable addresses and vice versa. Under normal routing circumstances, an attacker
            from the Internet routable addresses could not use the system as a way to reach the
            private address systems. If, however, source routed packets were allowed, they could
            be used to gain access to the private address systems as the route could be specified,
            rather than rely on routing protocols that did not allow this routing.
            Audit:
            - IF IPv6 is enabled on the system -
            Verify net.ipv6.conf.default.accept_source_route is set to 0.

                 1. Run the following command to verify
                    net.ipv6.conf.default.accept_source_route is set to 0 in the running
                    configuration:

            # sysctl net.ipv6.conf.default.accept_source_route
            Verify output is:
            net.ipv6.conf.default.accept_source_route = 0




                                                                                           Page 451

Internal Only - General
                  2. Run the following script to verify
                     net.ipv6.conf.default.accept_source_route = 0 is set in a file being used
                     by systemd sysctl to configure
                     net.ipv6.conf.default.accept_source_route:

            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv6.conf.default.accept_source_route"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv6.conf.default.accept_source_route = 0" is set in:
            "/etc/sysctl.d/60-ipv6_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.

                                                                                                    Page 452

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv6.conf.default.accept_source_route lines that are not
                    net.ipv6.conf.default.accept_source_route=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv6.conf.default.accept_source_route" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 453

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv6.conf.default.accept_source_route = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv6.conf.default.accept_source_route = 0" \
            >> /etc/sysctl.d/60-ipv6_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv6.conf.default.accept_source_route = 0
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040250 | RULE ID: SV-230539r1017301 | CAT II
                 5. STIG ID: OL08-00-040250 | RULE ID: SV-248882r991589 | CAT II
                 6. STIG ID: RHEL-09-254040 | RULE ID: SV-257977r991589 | CAT II
                 7. STIG ID: ALMA-09-020260 | RULE ID: SV-269259r1050141 | CAT II
                 8. STIG ID: OL09-00-006046 | RULE ID: SV-271883r1092361 | CAT II
                 9. STIG ID: SLES-15-040321 | RULE ID: SV-235017r991589 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 454

Internal Only - General
            3.3.2.7 Ensure net.ipv6.conf.all.accept_ra is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Routers periodically multicast Router Advertisement messages to announce their
            availability and convey information to neighboring nodes that enable them to be
            automatically configured on the network.
            net.ipv6.conf.all.accept_ra controls accepting any IPv6 RA messages on any
            network device.
            Note: If IPv6 has been disabled, this recommendation is not applicable.
            Rationale:
            It is recommended that systems do not accept router advertisements as they could be
            tricked into routing traffic to compromised machines. Setting hard routes within the
            system (usually a single default route to a trusted router) protects the system from bad
            routes.
            Audit:
            - IF IPv6 is enabled on the system -
            Verify net.ipv6.conf.all.accept_ra is set to 0.

                 1. Run the following command to verify net.ipv6.conf.all.accept_ra is set to 0
                    in the running configuration:

            # sysctl net.ipv6.conf.all.accept_ra
            Verify output is:
            net.ipv6.conf.all.accept_ra = 0

                 2. Run the following script to verify net.ipv6.conf.all.accept_ra = 0 is set in a
                    file being used by systemd sysctl to configure net.ipv6.conf.all.accept_ra:




                                                                                             Page 455

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv6.conf.all.accept_ra"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv6.conf.all.accept_ra = 0" is set in: "/etc/sysctl.d/60-
            ipv6_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 456

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv6.conf.all.accept_ra lines that are not
                    net.ipv6.conf.all.accept_ra=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv6.conf.all.accept_ra" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 457

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv6.conf.all.accept_ra = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv6.conf.all.accept_ra = 0" >> /etc/sysctl.d/60-
            ipv6_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv6.conf.all.accept_ra = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040261 | RULE ID: SV-230541r1017303 | CAT II
                 5. STIG ID: OL08-00-040261 | RULE ID: SV-248884r991589 | CAT II
                 6. STIG ID: RHEL-09-254010 | RULE ID: SV-257971r991589 | CAT II
                 7. STIG ID: ALMA-09-018500 | RULE ID: SV-269243r1050125 | CAT II
                 8. STIG ID: OL09-00-006040 | RULE ID: SV-271877r1092343 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 458

Internal Only - General
            3.3.2.8 Ensure net.ipv6.conf.default.accept_ra is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Routers periodically Multicast Router Advertisement (RA) messages to announce their
            availability and convey information to neighboring nodes that enable them to be
            automatically configured on the network.
            net.ipv6.conf.default.accept_ra controls accepting IPv6 RA messages on newly
            added network devices.
            Note: If IPv6 has been disabled, this recommendation is not applicable.
            Rationale:
            It is recommended that systems do not accept router advertisements as they could be
            tricked into routing traffic to compromised machines. Setting hard routes within the
            system (usually a single default route to a trusted router) protects the system from bad
            routes.
            Audit:
            - IF IPv6 is enabled on the system -
            Verify net.ipv6.conf.default.accept_ra is set to 0.

                 1. Run the following command to verify net.ipv6.conf.default.accept_ra is
                    set to 0 in the running configuration:

            # sysctl net.ipv6.conf.default.accept_ra
            Verify output is:
            net.ipv6.conf.default.accept_ra = 0

                 2. Run the following script to verify net.ipv6.conf.default.accept_ra = 0 is
                    set in a file being used by systemd sysctl to configure
                    net.ipv6.conf.default.accept_ra:




                                                                                             Page 459

Internal Only - General
            #!/usr/bin/env bash

            {
                  l_parameter_name="net.ipv6.conf.default.accept_ra"
                  l_grep="${l_parameter_name//./(\\.|\\/)}" a_output=() a_files=()
                  l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                  || readlink -e /usr/lib/systemd/systemd-sysctl)"
                  l_ufw_file="$([ -f /etc/default/ufw ] && \
                  awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                  [ -f "$(readlink -e "$l_ufw_file")" ] && \
                  a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                  while IFS= read -r l_fname; do
                     l_file="$(readlink -e "${l_fname//# /}")"
                     [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                     <<< "${a_files[*]}" && a_files+=("$l_file")
                  done < <("$l_systemdsysctl" --cat-config | tac | \
                  grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                  for l_file in "${a_files[@]}"; do
                     l_opt="$(grep -Poi '^\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" | tail -n
            1)"
                     l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                     [ -n "$l_option_value" ] && \
                     a_output+=(" - \"$l_parameter_name = $l_option_value\" is set in:" \
                     "    \"$l_file\"")
                  done
                  [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Example output:
             - "net.ipv6.conf.default.accept_ra = 0" is set in: "/etc/sysctl.d/60-
            ipv6_sysctl.conf"
            Note:

                  •   This script looks at all files used by systemd sysctl.
                  •   More information about these files and their location is available in the section
                      overview.
                  •   If multiple lines are returned:
                          o The first line includes the value being used by systemd sysctl. If this is a
                              correct value, this is considered a passing state. If the file listed is not in
                              the /etc/sysctl.d/ directory, it is highly recommended to follow the
                              remediation procedure to create a .conf file in the /etc/sysctl.d/
                              directory with the correct setting to prevent a potential change due to an
                              update to the system.
                          o Any files in the /etc/sysctl.d/ directory that include an incorrect value
                              should be modified to comment out or change the incorrect value to
                              minimize the potential of the incorrect value being used by systemd
                              sysctl due to system configuration changes.




                                                                                                    Page 460

Internal Only - General
                 •   SYSTEM FILE PRECEDENCE
                       o When using the --system option, sysctl will read files from directories in
                          the following list in given order from top to bottom. Once a file of a given
                          filename is loaded, any file of the same name in subsequent directories is
                          ignored.

                              /etc/sysctl.d/*.conf /run/sysctl.d/*.conf
                              /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf
                              /lib/sysctl.d/*.conf /etc/sysctl.conf

                          o   All configuration files are sorted in lexicographic order, regardless of the
                              directory they reside in. Configuration files can either be completely
                              replaced (by having a new configuration file with the same name in a
                              directory of higher priority) or partially replaced (by having a configuration
                              file that is ordered later)--

            Remediation:

                 1. Review all files being used by systemd sysctl and comment out or remove all
                    net.ipv6.conf.default.accept_ra lines that are not
                    net.ipv6.conf.default.accept_ra=0.

            Example script:
            #!/usr/bin/env bash

            {
                 l_option="net.ipv6.conf.default.accept_ra" l_value="0"
                 l_grep="${l_option//./(\\.|\\/)}" a_files=()
                 l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \
                 || readlink -e /usr/lib/systemd/systemd-sysctl)"
                 l_ufw_file="$([ -f /etc/default/ufw ] && \
                 awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
                 [ -f "$(readlink -e "$l_ufw_file")" ] && \
                 a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf")
                 while IFS= read -r l_fname; do
                    l_file="$(readlink -e "${l_fname//# /}")"
                    [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \
                    <<< "${a_files[*]}" && a_files+=("$l_file")
                 done < <("$l_systemdsysctl" --cat-config | tac | \
                 grep -Pio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 for l_file in "${a_files[@]}"; do
                    grep -Poi -- '\h*'"$l_grep"'\h*=\h*\H+\b' "$l_file" \
                    | grep -Pivq -- '^\h*'"$l_grep"'\h*=\h*'"$l_value"'\b' && \
                    sed -ri '/^\s*'"$l_grep"'\s*=\s*(1[0-9]*)/s/^/# /' "$l_file"
                 done
            }




                                                                                                    Page 461

Internal Only - General
                 2. Create or edit a file in the /etc/sysctl.d/ directory ending in .confand edit or
                    add the following line:

            net.ipv6.conf.default.accept_ra = 0
            Example:
            # [ ! -d "/etc/sysctl.d/" ] && mkdir -p /etc/sysctl.d/
            # printf '%s\n' "" "net.ipv6.conf.default.accept_ra = 0" >> /etc/sysctl.d/60-
            ipv6_sysctl.conf
            Note: If the UFW file was the first file listed in the audit, the entry will be commented out
            as part of the first step, however updating Uncomplicated Firewall (UFW) may update
            this change. In this case the updated entry will supersede the entry being created as
            part of this step.

                 3. Run the following command to load all sysctl configuration filles:

            # sysctl --system

            Default Value:
            net.ipv6.conf.default.accept_ra = 1
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-040262 | RULE ID: SV-230542r1017304 | CAT II
                 5. STIG ID: OL08-00-040262 | RULE ID: SV-248885r991589 | CAT II
                 6. STIG ID: RHEL-09-254030 | RULE ID: SV-257975r991589 | CAT II
                 7. STIG ID: ALMA-09-018500 | RULE ID: SV-269243r1050125 | CAT II
                 8. STIG ID: OL09-00-006044 | RULE ID: SV-271881r1092355 | CAT II

            CIS Controls:

               Controls
                                                              Control                                          IG 1 IG 2 IG 3
               Version
                            4.8 Uninstall or Disable Unnecessary Services on
                            Enterprise Assets and Software
                    v8         Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                            such as an unused file sharing service, web application module, or service
                            function.

                            9.2 Ensure Only Approved Ports, Protocols and Services
                    v7      Are Running                                                                              ●    ●
                               Ensure that only network ports, protocols, and services listening on a system
                            with validated business needs, are running on each system.




                                                                                                                     Page 462

Internal Only - General
            4 Host Based Firewall
            A firewall is a set of rules. When a data packet moves into or out of a protected network
            space, its contents (in particular, information about its origin, target, and the protocol it
            plans to use) are tested against the firewall rules to see if it should be allowed through.
            To provide a Host Based Firewall, the Linux kernel includes support for NFTables.
            NFTables is subsystem of the Linux kernel providing filtering and classification of
            network packets/datagrams/frames. NFTables replaces parts of Netfilter, while keeping
            and reusing most of it. NFTables utilizes the building blocks of the Netfilter
            infrastructure, such as the existing hooks into the networking stack, connection tracking
            system, userspace queueing component, and logging subsystem.
            In order to configure firewall rules for NFTables, a firewall utility needs to be installed.
            Guidance has been included for Uncomplicated Firewall (UFW) which provides firewall
            features by acting as a front-end for the Linux kernel's netfilter framework via the
            NFTables backend, acting as an alternative to the nft command line program. UFW
            supports both IPv4 and IPv6 networks.
            Important: This Benchmark includes guidance for configuring NFTables though the UFW
            front end utility. If your organization is using a different Host Based Firewall, or a
            different utility to configure the Host Based Firewall, we recommend verifying that
            your site's configuration meets the Recommendations in this section, otherwise this
            section may be skipped.
            Note:

                 •   Only one method should be used to configure a firewall on the system. Use of
                     more than one method could produce unexpected results.
                 •   NFTables is the default packet filtering framework. Though IPTables is still
                     supported, this support is done indirectly through UFW's ability to translate
                     IPTables commands to NFTables.
                 •   This section is intended only to ensure the resulting firewall rules are in place.




                                                                                                  Page 463

Internal Only - General
            4.1 Configure Uncomplicated Firewall

            In order to configure durable firewall rules a firewall utility needs to be installed.
            Uncomplicated Firewall (UFW) is the recommended utility and is used in guidance
            provided in the following recommendations.
            UFW is a user-friendly frontend firewall utility. It uses configurable default policies, and
            allows administrators to create specific rules to permit or deny connections based on
            applications, ports, or IP addresses. You can enable the firewall, view its status, and
            manage rules using simple command-line tools to secure your system.
            Warning: Configuration of a live systems firewall directly over a remote connection will
            often result in being locked out. It is advised to have a known good firewall configuration
            set to run on boot and to configure an entire firewall structure in a script that is then run
            and tested before saving to boot.




                                                                                                Page 464

Internal Only - General
            4.1.1 Ensure ufw is installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Uncomplicated Firewall (ufw) is a frontend for iptables and is particularly well-suited
            for host-based firewalls. ufw provides a framework for managing netfilter, as well as a
            command-line interface for manipulating the firewall
            Rationale:
            UFW acts as a frontend for both iptables and nftables and can use either as its
            backend, though the specific backend depends on the Linux distribution and system
            configuration.
            You can enable the firewall, view its status, and manage rules using simple command-
            line tools to secure your system.
            Impact:
            Changing firewall settings while connected over the network can result in being locked
            out of the system.
            Audit:
            Run the following command to verify that Uncomplicated Firewall (UFW) is installed:
            # dpkg-query -s ufw &>/dev/null && echo "ufw is installed"

            ufw is installed

            Remediation:
            Run the following command to install Uncomplicated Firewall (UFW):
            # apt install ufw

            References:

                 1. CCI-002314
                 2. NIST SP 800-53 :: AC-17 (1)
                 3. STIG ID: UBTU-22-251010 | Rule ID: SV-260514r958672 | CAT II
                 4. STIG ID: UBTU-24-100300 | Rule ID: SV-270654r1067143 | CAT II




                                                                                               Page 465

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            CIS Controls:

               Controls
                                                               Control                                         IG 1 IG 2 IG 3
               Version
                          4.4 Implement and Manage a Firewall on Servers
                   v8        Implement and manage a firewall on servers, where supported. Example
                          implementations include a virtual firewall, operating system firewall, or a third-
                                                                                                                ●    ●    ●
                          party firewall agent.

                          4.5 Implement and Manage a Firewall on End-User
                          Devices
                   v8        Implement and manage a host-based firewall or port-filtering tool on end-user      ●    ●    ●
                          devices, with a default-deny rule that drops all traffic except those services and
                          ports that are explicitly allowed.

                          9.4 Apply Host-based Firewalls or Port Filtering
                   v7        Apply host-based firewalls or port filtering tools on end systems, with a
                          default-deny rule that drops all traffic except those services and ports that are
                                                                                                                ●    ●    ●
                          explicitly allowed.




                                                                                                                     Page 466

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            4.1.2 Ensure ufw service is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The service, ufw.service, manages UFW. This service is responsible for applying and
            maintaining firewall rules, controlling which network traffic is allowed in and out of the
            system.
            Note:

                 •   When running ufw enable or starting ufw.service, ufw will flush its chains. This
                     is required so ufw can maintain a consistent state, but it may drop existing
                     connections, eg ssh. ufw does support adding rules before enabling the firewall.
                 •   Once ufw is 'enabled', ufw will not flush the chains when adding or removing
                     rules (but will when modifying a rule or changing the default policy)
                 •   By default ufw will prompt when enabling the firewall while running under ssh.
                     This can be disabled by using ufw --force enable

            Warning: If a rule for openSSH server does not exist, and openSSH is used to
            administer the host, the ability to administer and/or connect to the host may be lost.
            Example command to create a rule to allow ssh:
            # ufw allow proto tcp from any to any port 22
            This rule will allow connection to the ssh server from any location. It is highly
            recommended that this rule be modified to restrict ssh access to only required hosts and
            to follow local site policy.

                 •   The rules will still be flushed, but the ssh port will be open after enabling the
                     firewall. Please note that once ufw is 'enabled', ufw will not flush the chains when
                     adding or removing rules (but will when modifying a rule or changing the default
                     policy)
                 •   By default, ufw will prompt when enabling the firewall while running under ssh.
                     This can be disabled by using ufw --force enable

            Rationale:
            The ufw service must be enabled and running in order for ufw to protect the system
            Impact:
            Changing firewall settings while connected over network can result in being locked out
            of the system.




                                                                                                 Page 467

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            Audit:
            Run the following command to verify ufw.service is enabled:
            # systemctl is-enabled ufw.service

            enabled
            Run the following command to verify ufw.service is active:
            # systemctl is-active ufw.service

            active
            Run the following command to verify ufw is active
            # ufw status

            Status: active

            Remediation:
            Run the following command to unmask the ufw.service:
            # systemctl unmask ufw.service
            Run the following command to enable and start the ufw.service:
            # systemctl --now enable ufw.service

            active
            Run the following command to enable ufw:
            # ufw enable

            Default Value:
            Inactive
            References:

                 1. CCI-002314
                 2. NIST SP 800-53 :: AC-17 (1)
                 3. STIG ID: UBTU-20-010434 | Rule ID: SV-238355r958672 | CAT II
                 4. STIG ID: UBTU-22-251015 | Rule ID: SV-260515r958672 | CAT II
                 5. STIG ID: UBTU-24-100310 | Rule ID: SV-270655r1067145 | CAT II
                 6. http://manpages.ubuntu.com/manpages/precise/en/man8/ufw.8.html




                                                                                     Page 468

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            CIS Controls:

               Controls
                                                               Control                                         IG 1 IG 2 IG 3
               Version
                          4.4 Implement and Manage a Firewall on Servers
                   v8        Implement and manage a firewall on servers, where supported. Example
                          implementations include a virtual firewall, operating system firewall, or a third-
                                                                                                                ●    ●    ●
                          party firewall agent.

                          4.5 Implement and Manage a Firewall on End-User
                          Devices
                   v8        Implement and manage a host-based firewall or port-filtering tool on end-user      ●    ●    ●
                          devices, with a default-deny rule that drops all traffic except those services and
                          ports that are explicitly allowed.

                          9.4 Apply Host-based Firewalls or Port Filtering
                   v7        Apply host-based firewalls or port filtering tools on end systems, with a
                          default-deny rule that drops all traffic except those services and ports that are
                                                                                                                ●    ●    ●
                          explicitly allowed.




                                                                                                                     Page 469

Internal Only - General
            4.1.3 Ensure ufw incoming default is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The default policy for incoming traffic determines if connections attempting to reach your
            server from external sources will be allowed without requiring specific UFW rules.

            Rationale:
            With a default accept policy the firewall will accept any packet that is not configured to
            be denied. It is easier to allow list acceptable usage than to deny list unacceptable
            usage.
            Impact:
            Any port or protocol without a explicit allow before the default deny will be blocked. A
            deny policy silently drops packs causing an eventual time out with no response while a
            'reject' policy sends an immediate and explicit "connection refused" or "destination
            unreachable" message in response.
            The following is and example of a command to create a rule to allow connection to the
            ssh server on the host. This rule should be considered before applying the default deny.
            Example:
            # ufw allow ssh

            Audit:
            Run the following command to verify that the default policy for incoming is deny or
            reject:
            # ufw status verbose | awk -F',' '$1~/Default/ {print $1}'
            Example output:
            Default: deny (incoming)

            Remediation:
            Run the following command to set the default for incoming to deny:
            # ufw default deny incoming
            Warning: Any port or protocol without a explicit allow before the default deny will be
            blocked.
            References:

                 1. NIST SP 800-53 Rev. 5: SC-7


                                                                                                Page 470

Internal Only - General
            CIS Controls:

               Controls
                                                               Control                                         IG 1 IG 2 IG 3
               Version
                          4.4 Implement and Manage a Firewall on Servers
                   v8        Implement and manage a firewall on servers, where supported. Example
                          implementations include a virtual firewall, operating system firewall, or a third-
                                                                                                                ●    ●    ●
                          party firewall agent.

                          4.5 Implement and Manage a Firewall on End-User
                          Devices
                   v8        Implement and manage a host-based firewall or port-filtering tool on end-user      ●    ●    ●
                          devices, with a default-deny rule that drops all traffic except those services and
                          ports that are explicitly allowed.

                          9.4 Apply Host-based Firewalls or Port Filtering
                   v7        Apply host-based firewalls or port filtering tools on end systems, with a
                          default-deny rule that drops all traffic except those services and ports that are
                                                                                                                ●    ●    ●
                          explicitly allowed.




                                                                                                                     Page 471

Internal Only - General
            4.1.4 Ensure ufw outgoing default is configured (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The default policy for outgoing traffic determines if applications and services running on
            your server can initiate connections to external networks without requiring specific UFW
            rules.
            Rationale:
            With a default deny outgoing policy the firewall will deny ALL outgoing traffic and is a
            highly restrictive policy that requires the addition of specific allow rules.
            Impact:
            Any port and protocol not explicitly allowed will be blocked. The following rules are an
            example of some outgoing allow rules that should be considered before applying this
            default deny.
            ufw allow out http
            ufw allow out https
            ufw allow out ntp # Network Time Protocol
            ufw allow out to any port 53 # DNS
            ufw allow out to any port 853 # DNS over TLS
            ufw logging on

            Audit:
            Run the following command and verify that the default policy for outgoing is deny or
            reject:
            # ufw status verbose | awk -F',' '$1~/Default/ {print $2}'
            Example output:
              deny (outgoing)

            Remediation:
            Run the following command to set the default for outgoing to deny:
            # ufw default deny outgoing
            Warning: Any port or protocol without a explicit allow before the default deny will be
            blocked.
            Default Value:
            allow (outgoing)



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            References:

                 1. CCI-000382
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (iii)

            CIS Controls:

               Controls
                                                                Control                                         IG 1 IG 2 IG 3
               Version
                           4.4 Implement and Manage a Firewall on Servers
                   v8         Implement and manage a firewall on servers, where supported. Example
                           implementations include a virtual firewall, operating system firewall, or a third-
                                                                                                                 ●    ●    ●
                           party firewall agent.

                           4.5 Implement and Manage a Firewall on End-User
                           Devices
                   v8         Implement and manage a host-based firewall or port-filtering tool on end-user      ●    ●    ●
                           devices, with a default-deny rule that drops all traffic except those services and
                           ports that are explicitly allowed.

                           9.4 Apply Host-based Firewalls or Port Filtering
                   v7         Apply host-based firewalls or port filtering tools on end systems, with a
                           default-deny rule that drops all traffic except those services and ports that are
                                                                                                                 ●    ●    ●
                           explicitly allowed.




                                                                                                                      Page 473

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            4.1.5 Ensure ufw routed default is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The default policy for routed traffic determines if UFW forwards traffic between different
            network interfaces without requiring specific UFW rules.
            Rationale:
            A default deny policy ensures that UFW does not forward traffic between different
            network interfaces by default. This reduces the risk from unwanted or malicious routed
            traffic.
            Impact:
            Any port and protocol will be prevented for being routed.
            Audit:
            Run the following command and verify that the default policy for routed is disabled or
            deny:
            # ufw status verbose | awk -F',' '$1="Default"{print $3}'
            Example output:
            disabled (routed)
            Important: Any port and protocol will be prevented for being routed.
            Remediation:
            Run the following command to set the default policy for routed to deny:
            # ufw default deny routed

            Default Value:
            disabled
            References:

                 1. CCI-000382
                 2. NIST SP 800-53 :: CM-7
                 3. NIST SP 800-53A :: CM-7.1 (iii)




                                                                                                Page 474

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            CIS Controls:

               Controls
                                                               Control                                         IG 1 IG 2 IG 3
               Version
                          4.4 Implement and Manage a Firewall on Servers
                   v8        Implement and manage a firewall on servers, where supported. Example
                          implementations include a virtual firewall, operating system firewall, or a third-
                                                                                                                ●    ●    ●
                          party firewall agent.

                          4.5 Implement and Manage a Firewall on End-User
                          Devices
                   v8        Implement and manage a host-based firewall or port-filtering tool on end-user      ●    ●    ●
                          devices, with a default-deny rule that drops all traffic except those services and
                          ports that are explicitly allowed.

                          9.4 Apply Host-based Firewalls or Port Filtering
                   v7        Apply host-based firewalls or port filtering tools on end systems, with a
                          default-deny rule that drops all traffic except those services and ports that are
                                                                                                                ●    ●    ●
                          explicitly allowed.




            5 Access Control




                                                                                                                     Page 475

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            5.1 Configure SSH Server

            Secure Shell (SSH) is a secure, encrypted replacement for common login services such
            as telnet, ftp, rlogin, rsh, and rcp. It is strongly recommended that sites abandon
            older clear-text login protocols and use SSH to prevent session hijacking and sniffing of
            sensitive data off the network.
            The recommendations in this section only apply if the SSH daemon is installed on the
            system, if remote access is not required the SSH daemon can be removed and
            this section skipped.
            sshd_config:

                 •   The openSSH daemon configuration directives, Include and Match, may cause
                     the audits in this section's recommendations to report incorrectly. It is
                     recommended that these options only be used if they're needed and fully
                     understood. If these options are configured in accordance with local site policy,
                     they should be accounted for when following the recommendations in this
                     section.
                 •   The default Include location is the /etc/ssh/sshd_config.d directory. This
                     default has been accounted for in this section. If a file has an additional Include
                     that isn't this default location, the files should be reviewed to verify that the
                     recommended setting is not being over-ridden.
                 •   The audits of the running configuration in this section are run in the context of the
                     root user, the local host name, and the local host's IP address. If a Match block
                     exists that matches one of these criteria, the output of the audit will be from the
                     match block. The respective matched criteria should be replaced with a non-
                     matching substitution.
                 •   Include:
                        o Include the specified configuration file(s).
                        o Multiple pathnames may be specified and each pathname may contain
                             glob(7) wildcards that will be expanded and processed in lexical order.
                        o Files without absolute paths are assumed to be in /etc/ssh/.
                        o An Include directive may appear inside a Match block to perform
                             conditional inclusion.
                 •   Match:
                        o Introduces a conditional block. If all of the criteria on the Match line are
                             satisfied, the keywords on the following lines override those set in the
                             global section of the config file, until either another Match line or the end of
                             the file. If a keyword appears in multiple Match blocks that are satisfied,
                             only the first instance of the keyword is applied.
                        o The arguments to Match are one or more criteria-pattern pairs or the
                             single token All which matches all criteria. The available criteria are User,
                             Group, Host, LocalAddress, LocalPort, and Address.
                        o The match patterns may consist of single entries or comma-separated lists
                             and may use the wildcard and negation operators described in the
                             PATTERNS section of ssh_config(5).


                                                                                                    Page 476

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                          o The patterns in an Address criteria may additionally contain addresses to
                            match in CIDR address/masklen format, such as 192.0.2.0/24 or
                            2001:db8::/32. Note that the mask length provided must be consistent
                            with the address - it is an error to specify a mask length that is too long for
                            the address or one with bits set in this host portion of the address. For
                            example, 192.0.2.0/33 and 192.0.2.0/8, respectively.
                        o Only a subset of keywords may be used on the lines following a Match
                            keyword. Available keywords are available in the ssh_config man page.
                 •   Once all configuration changes have been made to /etc/ssh/sshd_config or
                     any included configuration files, the sshd configuration must be reloaded

            Command to re-load the SSH daemon configuration:
            # systemctl reload-or-restart sshd
            sshd command:

                 •   -T - Extended test mode. Check the validity of the configuration file, output the
                     effective configuration to stdout and then exit. Optionally, Match rules may be
                     applied by specifying the connection parameters using one or more -C options.
                 •   -C - connection_spec. Specify the connection parameters to use for the -T
                     extended test mode. If provided, any Match directives in the configuration file that
                     would apply are applied before the configuration is written to standard output.
                     The connection parameters are supplied as keyword=value pairs and may be
                     supplied in any order, either with multiple -C options or as a comma-separated
                     list. The keywords are addr, user, host, laddr, lport, and rdomain and
                     correspond to source address, user, resolved source host name, local address,
                     local port number and routing domain respectively.




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            5.1.1 Ensure access to /etc/ssh/sshd_config is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The file /etc/ssh/sshd_config, and files ending in .conf in the
            /etc/ssh/sshd_config.d directory, contain configuration specifications for sshd.

            Rationale:
            Configuration specifications for sshd need to be protected from unauthorized changes
            by non-privileged users.
            Audit:
            Run the following script and verify /etc/ssh/sshd_config and files ending in .conf in
            the /etc/ssh/sshd_config.d directory are:

                 •   Mode 0600 or more restrictive
                 •   Owned by the root user
                 •   Group owned by the group root.




                                                                                          Page 478

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output=(); a_output2=()
               perm_mask='0177' && maxperm="$( printf '%o' $(( 0777 & ~$perm_mask)) )"
               f_sshd_files_chk()
               {
                  while IFS=: read -r l_mode l_user l_group; do
                     a_out2=()
                     [ $(( $l_mode & $perm_mask )) -gt 0 ] && a_out2+=("      Is mode:
            \"$l_mode\"" \
                     "     should be mode: \"$maxperm\" or more restrictive")
                     [ "$l_user" != "root" ] && a_out2+=("     Is owned by \"$l_user\"
            should be owned by \"root\"")
                     [ "$l_group" != "root" ] && a_out2+=("     Is group owned by
            \"$l_user\" should be group owned by \"root\"")
                     if [ "${#a_out2[@]}" -gt "0" ]; then
                        a_output2+=(" - File: \"$l_file\":" "${a_out2[@]}")
                     else
                        a_output+=(" - File: \"$l_file\":" "      Correct: mode ($l_mode),
            owner ($l_user)" \
                        "     and group owner ($l_group) configured")
                     fi
                  done < <(stat -Lc '%#a:%U:%G' "$l_file")
               }
               [ -e "/etc/ssh/sshd_config" ] && l_file="/etc/ssh/sshd_config" &&
            f_sshd_files_chk
               while IFS= read -r -d $'\0' l_file; do
                  [ -e "$l_file" ] && f_sshd_files_chk
               done < <(find /etc/ssh/sshd_config.d -type f -name '*.conf' \( -perm /077
            -o ! -user root -o ! -group root \) -print0 2>/dev/null)
               if [ "${#a_output2[@]}" -le 0 ]; then
                  printf '%s\n' "" "- Audit Result:" " ** PASS **" "${a_output[@]}" ""
               else
                  printf '%s\n' "" "- Audit Result:" " ** FAIL **" " - Reason(s) for
            audit failure:" "${a_output2[@]}"
                  [ "${#a_output[@]}" -gt 0 ] && printf '%s\n' "" "- Correctly set:"
            "${a_output[@]}" ""
               fi
            }
            - IF - other locations are listed in an Include statement, *.conf files in these locations
            should also be checked.




                                                                                               Page 479

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            Remediation:
            Run the following script to set ownership and permissions on /etc/ssh/sshd_config
            and files ending in .conf in the /etc/ssh/sshd_config.d directory:
            #!/usr/bin/env bash

            {
                 chmod u-x,og-rwx /etc/ssh/sshd_config
                 chown root:root /etc/ssh/sshd_config
                 while IFS= read -r -d $'\0' l_file; do
                    if [ -e "$l_file" ]; then
                       chmod u-x,og-rwx "$l_file"
                       chown root:root "$l_file"
                    fi
                 done < <(find /etc/ssh/sshd_config.d -type f -print0 2>/dev/null)
            }
            - IF - other locations are listed in an Include statement, *.conf files in these locations
            access should also be modified.
            Default Value:
            Access: (0600/-rw-------) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2

            CIS Controls:

                Controls
                                                                Control                                          IG 1 IG 2 IG 3
                Version
                           3.3 Configure Data Access Control Lists
                   v8         Configure data access control lists based on a user’s need to know. Apply data
                           access control lists, also known as access permissions, to local and remote file
                                                                                                                  ●    ●    ●
                           systems, databases, and applications.

                           14.6 Protect Information through Access Control Lists
                               Protect all information stored on systems with file system, network share,
                   v7      claims, application, or database specific access control lists. These controls will
                           enforce the principle that only authorized individuals should have access to the
                                                                                                                  ●    ●    ●
                           information based on their need to access the information as a part of their
                           responsibilities.




                                                                                                                       Page 480

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            5.1.2 Ensure access to SSH private host key files is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            An SSH private key is one of two files used in SSH public key authentication. In this
            authentication method, the possession of the private key is proof of identity. Only a
            private key that corresponds to a public key will be able to authenticate successfully.
            The private keys need to be stored and handled carefully, and no copies of the private
            key should be distributed.
            Rationale:
            If an unauthorized user obtains the private SSH host key file, the host could be
            impersonated
            Audit:
            Run the following script to verify SSH private host key files are:

                 •   Mode 0600 or more restrictive.
                 •   Owned by the root user.
                 •   Group owned by the group root.




                                                                                               Page 481

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output=() a_output2=() l_pmask="0177"
               l_maxperm="$( printf '%o' $(( 0777 & ~$l_pmask )) )"
               f_file_chk()
               {
                  while IFS=: read -r l_fmode l_fowner l_fgroup; do
                     a_out2=()
                     if [ $(( $l_fmode & $l_pmask )) -gt 0 ]; then
                        a_out2+=("    - mode: \"$l_fmode\"" \
                        "      should be mode: \"$l_maxperm\" or more restrictive")
                     fi
                     if [ "$l_fowner" != "root" ]; then
                        a_out2+=("    - owned by: \"$l_fowner\"" \
                        "      should be owned by \"root\"")
                     fi
                     if [ "$l_fgroup" != "root" ]; then
                        a_out2+=("    - group owned by: \"$l_fgroup\"" \
                        "      should be group owned by group: \"root\"")
                     fi
                     if [ "${#a_out2[@]}" -gt "0" ]; then
                        a_output2+=(" - File: \"$l_file\"" "${a_out2[@]}")
                     else
                        a_output+=(" - File: \"$l_file\" Correct:" \
                        "    - mode: \"$l_fmode\"" \
                        "    - owner: \"$l_fowner\"" "     - group owner: \"$l_fgroup\"")
                     fi
                  done < <(stat -Lc '%#a:%U:%G' "$l_file")
               }
               while IFS= read -r -d $'\0' l_file; do
                  if ssh-keygen -lf &>/dev/null "$l_file"; then
                     file "$l_file" | \
                     grep -Piq -- '\bopenssh\h+([^#\n\r]+\h+)?private\h+key\b' &&
            f_file_chk
                  fi
               done < <(find -L /etc/ssh -xdev -type f -print0 2>/dev/null)
               if [ "${#a_output2[@]}" -le 0 ]; then
                  printf '%s\n' "" "- Audit Result:" " ** PASS **" "${a_output[@]}" ""
               else
                  printf '%s\n' "" "- Audit Result:" " ** FAIL **" \
                  " - Reason(s) for audit failure:" "${a_output2[@]}"
                  [ "${#a_output[@]}" -gt 0 ] && \
                  printf '%s\n' "" "- Correctly set:" "${a_output[@]}" ""
               fi
            }




                                                                                   Page 482

Internal Only - General
            Remediation:
            Run the following script to set mode, ownership, and group on the private SSH host key
            files:
            #!/usr/bin/env bash

            {
                 a_output2=() l_pmask="0177"
                 l_maxperm="$( printf '%o' $(( 0777 & ~$l_pmask )) )"
                 f_file_access_fix()
                 {
                    while IFS=: read -r l_file_mode l_file_owner l_file_group; do
                       a_out2=()
                       if [ $(( $l_file_mode & $l_pmask )) -gt 0 ]; then
                          a_out2+=("" "    Mode: \"$l_file_mode\"" \
                          "    should be mode: \"$l_maxperm\" or more restrictive" \
                          "    updating to mode: \"$l_maxperm\"")
                          chmod u-x,go-rwx "$l_file"
                       fi
                       if [ "$l_file_owner" != "root" ]; then
                          a_out2+=("" "    Owned by: \"$l_file_owner\"" \
                          "    should be owned by \"root\"" \
                          "    Changing ownership to \"root\"")
                          chown root "$l_file"
                       fi
                       if [ "$l_file_group" != "root" ]; then
                          a_out2+=("" "    Owned by group \"$l_file_group\"" \
                          "    should be group owned by: \"root\"" \
                          "    Changing group ownership to group: \"root\"")
                          chgrp root "$l_file"
                       fi
                       if [ "${#a_out2[@]}" -gt "0" ]; then
                          a_output2+=("" " - File: \"$l_file\"" "${a_out2[@]}")
                       fi
                    done < <(stat -Lc '%#a:%U:%G' "$l_file")
                 }
                 while IFS= read -r -d $'\0' l_file; do
                    if ssh-keygen -lf &>/dev/null "$l_file"; then
                       file "$l_file" | grep -Piq -- \
                       '\bopenssh\h+([^#\n\r]+\h+)?private\h+key\b' && f_file_access_fix
                    fi
                 done < <(find -L /etc/ssh -xdev -type f -print0 2>/dev/null)
                 if [ "${#a_output2[@]}" -le "0" ]; then
                    printf '%s\n' "" " - No access changes required" ""
                 else
                    printf '%s\n' "" " - Remediation results:" "${a_output2[@]}" ""
                 fi
            }




                                                                                          Page 483

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            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-010490 | RULE ID: SV-230287r1017098 | CAT II
                 5. STIG ID: RHEL-09-255120 | RULE ID: SV-258000r1045063 | CAT II
                 6. STIG ID: ALMA-09-020920 | RULE ID: SV-269265r1050147 | CAT II
                 7. STIG ID: SLES-15-040250 | RULE ID: SV-235009r991589 | CAT II

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 484

Internal Only - General
            5.1.3 Ensure access to SSH public host key files is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            An SSH public key is one of two files used in SSH public key authentication. In this
            authentication method, a public key is a key that can be used for verifying digital
            signatures generated using a corresponding private key. Only a public key that
            corresponds to a private key will be able to authenticate successfully.
            Rationale:
            If a public host key file is modified by an unauthorized user, the SSH service may be
            compromised.
            Audit:
            Run the following command and verify Access does not grant write or execute
            permissions to group or other for all returned files:
            Run the following script to verify SSH public host key files are mode 0644 or more
            restrictive, owned by the root user, and owned by the root group:




                                                                                             Page 485

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output=(); a_output2=()
               l_pmask="0133"; l_maxperm="$( printf '%o' $(( 0777 & ~$l_pmask )) )"
               f_file_chk()
               {
                  while IFS=: read -r l_file_mode l_file_owner l_file_group; do
                     a_out2=()
                     if [ $(( $l_file_mode & $l_pmask )) -gt 0 ]; then
                        a_out2+=("    Mode: \"$l_file_mode\" should be mode:
            \"$l_maxperm\" or more restrictive")
                     fi
                     if [ "$l_file_owner" != "root" ]; then
                        a_out2+=("    Owned by: \"$l_file_owner\" should be owned by:
            \"root\"")
                     fi
                     if [ "$l_file_group" != "root" ]; then
                        a_out2+=("    Owned by group \"$l_file_group\" should be group
            owned by group: \"root\"")
                     fi
                     if [ "${#a_out2[@]}" -gt "0" ]; then
                        a_output2+=(" - File: \"$l_file\"" "${a_out2[@]}")
                     else
                        a_output+=(" - File: \"$l_file\"" \
                        "    Correct: mode: \"$l_file_mode\", owner: \"$l_file_owner\"
            and group owner: \"$l_file_group\" configured")
                     fi
                  done < <(stat -Lc '%#a:%U:%G' "$l_file")
               }
               while IFS= read -r -d $'\0' l_file; do
                  if ssh-keygen -lf &>/dev/null "$l_file"; then
                     file "$l_file" | grep -Piq --
            '\bopenssh\h+([^#\n\r]+\h+)?public\h+key\b' && f_file_chk
                  fi
               done < <(find -L /etc/ssh -xdev -type f -print0 2>/dev/null)
               if [ "${#a_output2[@]}" -le 0 ]; then
                  [ "${#a_output[@]}" -le 0 ] && a_output+=(" - No openSSH public keys
            found")
                  printf '%s\n' "" "- Audit Result:" " ** PASS **" "${a_output[@]}" ""
               else
                  printf '%s\n' "" "- Audit Result:" " ** FAIL **" " - Reason(s) for
            audit failure:" "${a_output2[@]}"
                  [ "${#a_output[@]}" -gt 0 ] && printf '%s\n' "" "- Correctly set:"
            "${a_output[@]}" ""
               fi
            }




                                                                                 Page 486

Internal Only - General
            Remediation:
            Run the following script to set mode, ownership, and group on the public SSH host key
            files:
            #!/usr/bin/env bash

            {
               a_output=(); a_output2=()
               l_pmask="0133"; l_maxperm="$( printf '%o' $(( 0777 & ~$l_pmask )) )"
               f_file_access_fix()
               {
                  while IFS=: read -r l_file_mode l_file_owner l_file_group; do
                      a_out2=()
                      [ $(( $l_file_mode & $l_pmask )) -gt 0 ] && \
                         a_out2+=("    Mode: \"$l_file_mode\" should be mode:
            \"$l_maxperm\" or more restrictive" \
                         "    updating to mode: \"$l_maxperm\"") && chmod u-x,go-wx
            "$l_file"
                      [ "$l_file_owner" != "root" ] && \
                         a_out2+=("    Owned by: \"$l_file_owner\" should be owned by
            \"root\"" \
                         "    Changing ownership to \"root\"") && chown root "$l_file"
                      [ "$l_file_group" != "root" ] && \
                         a_out2+=("    Owned by group \"$l_file_group\" should be group
            owned by: \"root\"" \
                         "    Changing group ownership to \"root\"") && chgrp root
            "$l_file"
                      if [ "${#a_out2[@]}" -gt "0" ]; then
                         a_output2+=(" - File: \"$l_file\"" "${a_out2[@]}")
                      else
                         a_output+=(" - File: \"$l_file\"" \
                         "    Correct: mode: \"$l_file_mode\", owner: \"$l_file_owner\",
            and group owner: \"$l_file_group\" configured")
                      fi
                  done < <(stat -Lc '%#a:%U:%G' "$l_file")
               }
               while IFS= read -r -d $'\0' l_file; do
                  if ssh-keygen -lf &>/dev/null "$l_file"; then
                      file "$l_file" | grep -Piq --
            '\bopenssh\h+([^#\n\r]+\h+)?public\h+key\b' && f_file_access_fix
                  fi
               done < <(find -L /etc/ssh -xdev -type f -print0 2>/dev/null)
               if [ "${#a_output2[@]}" -le "0" ]; then
                  printf '%s\n' "" " - No access changes required" ""
               else
                  printf '%s\n' " - Remediation results:" "${a_output2[@]}" ""
               fi
            }

            Default Value:
            644 0/root 0/root




                                                                                          Page 487

Internal Only - General
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 488

Internal Only - General
            5.1.4 Ensure sshd access is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            There are several options available to limit which users and group can access the
            system via SSH. It is recommended that at least one of the following options be
            leveraged:

                 •   AllowUsers:
                        o The AllowUsers variable gives the system administrator the option of
                          allowing specific users to ssh into the system. The list consists of space
                          separated user names. Numeric user IDs are not recognized with this
                          variable. If a system administrator wants to restrict user access further by
                          only allowing the allowed users to log in from a particular host, the entry
                          can be specified in the form of user@host.
                 •   AllowGroups:
                        o The AllowGroups variable gives the system administrator the option of
                          allowing specific groups of users to ssh into the system. The list consists
                          of space separated group names. Numeric group IDs are not recognized
                          with this variable.
                 •   DenyUsers:
                        o The DenyUsers variable gives the system administrator the option of
                          denying specific users to ssh into the system. The list consists of space
                          separated user names. Numeric user IDs are not recognized with this
                          variable. If a system administrator wants to restrict user access further by
                          specifically denying a user's access from a particular host, the entry can
                          be specified in the form of user@host.
                 •   DenyGroups:
                        o The DenyGroups variable gives the system administrator the option of
                          denying specific groups of users to ssh into the system. The list consists
                          of space separated group names. Numeric group IDs are not recognized
                          with this variable.

            Rationale:
            Restricting which users can remotely access the system via SSH will help ensure that
            only authorized users access the system.




                                                                                               Page 489

Internal Only - General
            Audit:
            Run the following command and verify the output:
            # sshd -T | grep -Pi -- '^\h*(allow|deny)(users|groups)\h+\H+'
            Verify that the output matches at least one of the following lines:
            allowusers <userlist>
            -OR-
            allowgroups <grouplist>
            -OR-
            denyusers <userlist>
            -OR-
            denygroups <grouplist>
            Review the list(s) to ensure included users and/or groups follow local site policy
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep -Pi --
            '^\h*(allow|deny)(users|groups)\h+\H+'
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain).

            Remediation:
            Edit the /etc/ssh/sshd_config file to set one or more of the parameters above any
            Include and Match set statements as follows:
            AllowUsers <userlist>
             - AND/OR -
            AllowGroups <grouplist>
            Note:

                 •   First occurrence of a option takes precedence, Match set statements
                     withstanding. If Include locations are enabled, used, and order of precedence is
                     understood in your environment, the entry may be created in a .conf file in a
                     Include directory.
                 •   Be advised that these options are "ANDed" together. If both AllowUsers and
                     AllowGroups are set, connections will be limited to the list of users that are also
                     a member of an allowed group. It is recommended that only one be set for clarity
                     and ease of administration.
                 •   It is easier to manage an allow list than a deny list. In a deny list, you could
                     potentially add a user or group and forget to add it to the deny list.




                                                                                                Page 490

Internal Only - General
            Default Value:
            None
            References:

                 1. SSHD_CONFIG(5)
                 2. NIST SP 800-53 Rev. 5: AC-3. MP-2
                 3. SSHD(8)
                 4. https://documentation.suse.com/en-us/sles/15-SP6/html/SLES-all/cha-ssh.html

            CIS Controls:

              Controls
                                                               Control                                         IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                ●    ●    ●
                          systems, databases, and applications.

                          4.3 Ensure the Use of Dedicated Administrative Accounts
                   v7        Ensure that all users with administrative account access use a dedicated or
                          secondary account for elevated activities. This account should only be used for
                                                                                                                ●    ●    ●
                          administrative activities and not internet browsing, email, or similar activities.




                                                                                                                     Page 491

Internal Only - General
            5.1.5 Ensure sshd Banner is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The Banner parameter specifies a file whose contents must be sent to the remote user
            before authentication is permitted. By default, no banner is displayed.
            Rationale:
            Banners are used to warn connecting users of the particular site's policy regarding
            connection. Presenting a warning message prior to the normal user login may assist the
            prosecution of trespassers on the computer system.
            Audit:
            Run the following command to verify Banner is set:
            # sshd -T | grep -Pi -- '^banner\h+\/\H+'
            Example:
            banner /etc/issue.net
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep -Pi -- '^banner\h+\/\H+'
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain).
            Run the following command and verify that the contents or the file being called by the
            Banner argument match site policy:
            # [ -e "$(sshd -T | awk '$1 == "banner" {print $2}')" ] && cat "$(sshd -T |
            awk '$1 == "banner" {print $2}')"
            Run the following command and verify no results are returned:
            # grep -Psi -- "(\\\v|\\\r|\\\m|\\\s|\b$(grep '^ID=' /etc/os-release | cut -
            d= -f2 | sed -e 's/"//g')\b)" "$(sshd -T | awk '$1 == "banner" {print $2}')"




                                                                                             Page 492

Internal Only - General
            Remediation:
            Edit the /etc/ssh/sshd_config file to set the Banner parameter above any Include
            and Match entries as follows:
            Banner /etc/issue.net
            Note: First occurrence of a option takes precedence, Match set statements
            withstanding. If Include locations are enabled, used, and order of precedence is
            understood in your environment, the entry may be created in a file in Include location.
            Edit the file being called by the Banner argument with the appropriate contents
            according to your site policy, remove any instances of \m , \r , \s , \v or references to
            the OS platform
            Example:
            # printf '%s\n' "Authorized users only. All activity may be monitored and
            reported." > "$(sshd -T | awk '$1 == "banner" {print $2}')"

            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            CIS Controls:

                 Controls Version                       Control             IG 1 IG 2 IG 3

                          v8          0.0 Explicitly Not Mapped
                                         Explicitly Not Mapped

                          v7          0.0 Explicitly Not Mapped
                                         Explicitly Not Mapped




                                                                                              Page 493

Internal Only - General
            5.1.6 Ensure sshd Ciphers are configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            This variable limits the ciphers that SSH can use during communication.
            Notes:

                 •   Some organizations may have stricter requirements for approved ciphers.
                 •   Ensure that ciphers used are in compliance with site policy.
                 •   The only "strong" ciphers currently FIPS 140 compliant are:
                        o aes256-gcm@openssh.com
                        o aes128-gcm@openssh.com
                        o aes256-ctr
                        o aes192-ctr
                        o aes128-ctr

            Rationale:
            Weak ciphers that are used for authentication to the cryptographic module cannot be
            relied upon to provide confidentiality or integrity, and system data may be compromised.

                 •   The Triple DES ciphers, as used in SSH, have a birthday bound of approximately
                     four billion blocks, which makes it easier for remote attackers to obtain clear text
                     data via a birthday attack against a long-duration encrypted session, aka a
                     "Sweet32" attack.
                 •   Error handling in the SSH protocol; Client and Server, when using a block cipher
                     algorithm in Cipher Block Chaining (CBC) mode, makes it easier for remote
                     attackers to recover certain plain text data from an arbitrary block of cipher text in
                     an SSH session via unknown vectors.




                                                                                                  Page 494

Internal Only - General
            Audit:
            Run the following command to verify none of the "weak" ciphers are being used:
            # sshd -T | grep -Pi --
            '^ciphers\h+\"?([^#\n\r]+,)?((3des|blowfish|cast128|aes(128|192|256))-
            cbc|arcfour(128|256)?|rijndael-cbc@lysator\.liu\.se|chacha20-
            poly1305@openssh\.com)\b'
            - IF - a line is returned, review the list of ciphers. If the line includes chacha20-
            poly1305@openssh.com, review CVE-2023-48795 and verify the system has been
            patched. No ciphers in the list below should be returned as they're considered "weak":
            3des-cbc
            aes128-cbc
            aes192-cbc
            aes256-cbc

            Remediation:
            Edit the /etc/ssh/sshd_config file and add/modify the Ciphers line to contain a comma
            separated list of the site unapproved (weak) Ciphers preceded with a - above any
            Include entries:
            Example:
            Ciphers -3des-cbc,aes128-cbc,aes192-cbc,aes256-cbc,chacha20-
            poly1305@openssh.com
            - IF - CVE-2023-48795 has been addressed, and it meets local site policy, chacha20-
            poly1305@openssh.com may be removed from the list of excluded ciphers.
            Note: First occurrence of an option takes precedence. If Include locations are enabled,
            used, and order of precedence is understood in your environment, the entry may be
            created in a file in Include location.
            Default Value:
            Ciphers chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-
            gcm@openssh.com,aes256-gcm@openssh.com
            References:

                 1. https://nvd.nist.gov/vuln/detail/CVE-2023-48795
                 2. https://nvd.nist.gov/vuln/detail/CVE-2019-1543
                 3. https://nvd.nist.gov/vuln/detail/CVE-2016-2183
                 4. https://nvd.nist.gov/vuln/detail/CVE-2008-5161
                 5. https://www.openssh.com/txt/cbc.adv
                 6. https://www.openssh.com/txt/cbc.adv
                 7. SSHD_CONFIG(5)
                 8. NIST SP 800-53 Rev. 5: SC-8




                                                                                             Page 495

Internal Only - General
            CIS Controls:

                Controls
                                                                Control                                  IG 1 IG 2 IG 3
                Version
                            3.10 Encrypt Sensitive Data in Transit
                    v8         Encrypt sensitive data in transit. Example implementations can include:         ●    ●
                            Transport Layer Security (TLS) and Open Secure Shell (OpenSSH).

                    v7      14.4 Encrypt All Sensitive Information in Transit                                  ●    ●
                               Encrypt all sensitive information in transit.




                                                                                                               Page 496

Internal Only - General
            5.1.7 Ensure sshd ClientAliveInterval and ClientAliveCountMax
            are configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Note: To clarify, the two settings described below are only meant for idle connections
            from a protocol perspective and are not meant to check if the user is active or not. An
            idle user does not mean an idle connection. SSH does not and never had, intentionally,
            the capability to drop idle users. In SSH versions before 8.2p1 there was a bug that
            caused these values to behave in such a manner that they were abused to disconnect
            idle users. This bug has been resolved in 8.2p1 and thus it can no longer be abused
            disconnect idle users.
            The two options ClientAliveInterval and ClientAliveCountMax control the timeout
            of SSH sessions. Taken directly from man 5 sshd_config:

                 •   ClientAliveInterval Sets a timeout interval in seconds after which if no data
                     has been received from the client, sshd(8) will send a message through the
                     encrypted channel to request a response from the client. The default is 0,
                     indicating that these messages will not be sent to the client.
                 •   ClientAliveCountMax Sets the number of client alive messages which may be
                     sent without sshd(8) receiving any messages back from the client. If this
                     threshold is reached while client alive messages are being sent, sshd will
                     disconnect the client, terminating the session. It is important to note that the use
                     of client alive messages is very different from TCPKeepAlive. The client alive
                     messages are sent through the encrypted channel and therefore will not be
                     spoofable. The TCP keepalive option en‐abled by TCPKeepAlive is spoofable.
                     The client alive mechanism is valuable when the client or server depend on
                     knowing when a connection has become unresponsive.

                     The default value is 3. If ClientAliveInterval is set to 15, and ClientAliveCountMax
                     is left at the default, unresponsive SSH clients will be disconnected after
                     approximately 45 seconds. Setting a zero ClientAliveCountMax disables
                     connection termination.




                                                                                                  Page 497

Internal Only - General
            Rationale:
            In order to prevent resource exhaustion, appropriate values should be set for both
            ClientAliveInterval and ClientAliveCountMax. Specifically, looking at the source
            code, ClientAliveCountMax must be greater than zero in order to utilize the ability of
            SSH to drop idle connections. If connections are allowed to stay open indefinitely, this
            can potentially be used as a DDOS attack or simple resource exhaustion could occur
            over unreliable networks.
            The example set here is a 45 second timeout. Consult your site policy for network
            timeouts and apply as appropriate.
            Audit:
            Run the following command and verify ClientAliveInterval and
            ClientAliveCountMax are greater than zero:
            # sshd -T | grep -Pi -- '(clientaliveinterval|clientalivecountmax)'
            Example Output:
            clientaliveinterval 15
            clientalivecountmax 3
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep -Pi --
            '(clientaliveinterval|clientalivecountmax)'
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain).

            Remediation:
            Edit the /etc/ssh/sshd_config file to set the ClientAliveInterval and
            ClientAliveCountMax parameters above any Include and Match entries according to
            site policy.
            Example:
            ClientAliveInterval 15
            ClientAliveCountMax 3
            Note: First occurrence of a option takes precedence, Match set statements
            withstanding. If Include locations are enabled, used, and order of precedence is
            understood in your environment, the entry may be created in a file in Include location.




                                                                                             Page 498

Internal Only - General
            Default Value:
            ClientAliveInterval 0
            ClientAliveCountMax 3
            References:

                 1. SSHD_CONFIG(5)
                 2. SSHD(8)
                 3. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            Additional Information:
            https://bugzilla.redhat.com/show_bug.cgi?id=1873547
            https://github.com/openssh/openssh-portable/blob/V_8_9/serverloop.c#L137
            CIS Controls:

                 Controls Version                      Control        IG 1 IG 2 IG 3

                          v8          0.0 Explicitly Not Mapped
                                        Explicitly Not Mapped

                          v7          0.0 Explicitly Not Mapped
                                        Explicitly Not Mapped




                                                                                       Page 499

Internal Only - General
            5.1.8 Ensure sshd DisableForwarding is enabled (Automated)
            Profile Applicability:

            • Level 1 - Workstation
            • Level 2 - Server
            Description:
            The DisableForwarding parameter disables all forwarding features, including X11,
            ssh-agent(1), TCP and StreamLocal. This option overrides all other forwarding-related
            options and may simplify restricted configurations.

                 •   X11Forwarding provides the ability to tunnel X11 traffic through the connection to
                     enable remote graphic connections.
                 •   ssh-agent is a program to hold private keys used for public key authentication.
                     Through use of environment variables the agent can be located and
                     automatically used for authentication when logging in to other machines using
                     ssh.
                 •   SSH port forwarding is a mechanism in SSH for tunneling application ports from
                     the client to the server, or servers to clients. It can be used for adding encryption
                     to legacy applications, going through firewalls, and some system administrators
                     and IT professionals use it for opening backdoors into the internal network from
                     their home machines.

            Rationale:
            Disable X11 forwarding unless there is an operational requirement to use X11
            applications directly. There is a small risk that the remote X11 servers of users who are
            logged in via SSH with X11 forwarding could be compromised by other users on the
            X11 server. Note that even if X11 forwarding is disabled, users can always install their
            own forwarders.
            anyone with root privilege on the the intermediate server can make free use of ssh-
            agent to authenticate them to other servers
            Leaving port forwarding enabled can expose the organization to security risks and
            backdoors. SSH connections are protected with strong encryption. This makes their
            contents invisible to most deployed network monitoring and traffic filtering solutions.
            This invisibility carries considerable risk potential if it is used for malicious purposes
            such as data exfiltration. Cybercriminals or malware could exploit SSH to hide their
            unauthorized communications, or to exfiltrate stolen data from the target network.
            Impact:
            SSH tunnels are widely used in many corporate environments. In some environments
            the applications themselves may have very limited native support for security. By
            utilizing tunneling, compliance with SOX, HIPAA, PCI-DSS, and other standards can be
            achieved without having to modify the applications.


                                                                                                  Page 500

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            Audit:
            Run the following command to verify DisableForwarding is set to yes:
            # sshd -T | grep disableforwarding

            disableforwarding yes
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep disableforwarding
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain)

            Remediation:
            Edit the /etc/ssh/sshd_config file to set the DisableForwarding parameter to yes
            above any Include and Match entries as follows:
            DisableForwarding yes
            Note: First occurrence of an option takes precedence, Match set statements
            withstanding. If Include locations are enabled, used, and order of precedence is
            understood in your environment, the entry may be created in a file in Include location.

            Default Value:
            disableforwarding no
            References:

                 1. sshd_config(5)
                 2. SSHD(8)
                 3. NIST SP 800-53 Rev. 5: CM-7




                                                                                             Page 501

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            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 502

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            5.1.9 Ensure sshd GSSAPIAuthentication is disabled (Automated)
            Profile Applicability:

            • Level 1 - Workstation
            • Level 2 - Server
            Description:
            The GSSAPIAuthentication parameter specifies whether user authentication based on
            GSSAPI is allowed
            Rationale:
            Allowing GSSAPI authentication through SSH exposes the system's GSSAPI to remote
            hosts, and should be disabled to reduce the attack surface of the system
            Audit:
            Run the following command to verify GSSAPIAuthentication is set to no:
            # sshd -T | grep gssapiauthentication

            gssapiauthentication no
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep gssapiauthentication
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain)

            Remediation:
            Edit the /etc/ssh/sshd_config file to set the GSSAPIAuthentication parameter to
            no above any Include and Match entries as follows:
            GSSAPIAuthentication no
            Note: First occurrence of an option takes precedence, Match set statements
            withstanding. If Include locations are enabled, used, and order of precedence is
            understood in your environment, the entry may be created in a file in Include location.

            Default Value:
            GSSAPIAuthentication no



                                                                                             Page 503

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            References:

                 1. SSHD_CONFIG(5)
                 2. SSHD(8)
                 3. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




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            5.1.10 Ensure sshd HostbasedAuthentication is disabled
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The HostbasedAuthentication parameter specifies if authentication is allowed
            through trusted hosts via the user of .rhosts, or /etc/hosts.equiv, along with
            successful public key client host authentication.
            Rationale:
            Even though the .rhosts files are ineffective if support is disabled in /etc/pam.conf,
            disabling the ability to use .rhosts files in SSH provides an additional layer of
            protection.
            Audit:
            Run the following command to verify HostbasedAuthentication is set to no:
            # sshd -T | grep hostbasedauthentication

            hostbasedauthentication no
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep hostbasedauthentication
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain)

            Remediation:
            Edit the /etc/ssh/sshd_config file to set the HostbasedAuthentication parameter
            to no above any Include and Match entries as follows:
            HostbasedAuthentication no
            Note: First occurrence of a option takes precedence, Match set statements
            withstanding. If Include locations are enabled, used, and order of precedence is
            understood in your environment, the entry may be created in a file in Include location.



                                                                                             Page 505

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            Default Value:
            HostbasedAuthentication no
            References:

                 1. SSHD_CONFIG(5)
                 2. SSHD(8)
                 3. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 506

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            5.1.11 Ensure sshd IgnoreRhosts is enabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The IgnoreRhosts parameter specifies that .rhosts and .shosts files will not be used
            in RhostsRSAAuthentication or HostbasedAuthentication.

            Rationale:
            Setting this parameter forces users to enter a password when authenticating with SSH.
            Audit:
            Run the following command to verify IgnoreRhosts is set to yes:
            # sshd -T | grep ignorerhosts

            ignorerhosts yes

            Remediation:
            Edit the /etc/ssh/sshd_config file to set the IgnoreRhosts parameter to yes above
            any Include entry as follows:
            IgnoreRhosts yes
            Note: First occurrence of a option takes precedence. If Include locations are enabled,
            used, and order of precedence is understood in your environment, the entry may be
            created in a file in Include location.

            Default Value:
            IgnoreRhosts yes
            References:

                 1. SSHD_CONFIG(5)
                 2. SSHD(8)
                 3. NIST SP 800-53 Rev. 5: CM-1,CM-2, CM-6, CM-7, IA-5




                                                                                           Page 507

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            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 508

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            5.1.12 Ensure sshd KexAlgorithms is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Key exchange is any method in cryptography by which cryptographic keys are
            exchanged between two parties, allowing use of a cryptographic algorithm. If the sender
            and receiver wish to exchange encrypted messages, each must be equipped to encrypt
            messages to be sent and decrypt messages received
            Notes:

                 •   Kex algorithms have a higher preference the earlier they appear in the list
                 •   Some organizations may have stricter requirements for approved Key exchange
                     algorithms
                 •   Ensure that Key exchange algorithms used are in compliance with site policy
                 •   The only Key Exchange Algorithms currently FIPS 140 approved are:
                        o ecdh-sha2-nistp256
                        o ecdh-sha2-nistp384
                        o ecdh-sha2-nistp521
                        o diffie-hellman-group-exchange-sha256
                        o diffie-hellman-group16-sha512
                        o diffie-hellman-group18-sha512
                        o diffie-hellman-group14-sha256

            Rationale:
            Key exchange methods that are considered weak should be removed. A key exchange
            method may be weak because too few bits are used, or the hashing algorithm is
            considered too weak. Using weak algorithms could expose connections to man-in-the-
            middle attacks




                                                                                           Page 509

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            Audit:
            Run the following command to verify none of the "weak" Key Exchange algorithms are
            being used:
            # sshd -T | grep -Pi -- 'kexalgorithms\h+([^#\n\r]+,)?(diffie-hellman-group1-
            sha1|diffie-hellman-group14-sha1|diffie-hellman-group-exchange-sha1)\b'
            Nothing should be returned.
            - IF - A line is returned, review the list of Key Exchange Algorithms. The following are
            considered "weak" Key Exchange Algorithms, and should not be used:
            diffie-hellman-group1-sha1
            diffie-hellman-group14-sha1
            diffie-hellman-group-exchange-sha1

            Remediation:
            Edit the /etc/ssh/sshd_config file and add/modify the KexAlgorithms line to contain
            a comma separated list of the site unapproved (weak) KexAlgorithms preceded with a -
            above any Include entries:
            Example:
            KexAlgorithms -diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-
            hellman-group-exchange-sha1
            Note: First occurrence of an option takes precedence. If Include locations are enabled,
            used, and order of precedence is understood in your environment, the entry may be
            created in a file in Include location.
            Default Value:
            KexAlgorithms sntrup761x25519-sha512@openssh.com,curve25519-
            sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-
            sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-
            sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256
            References:

                 1. https://ubuntu.com/server/docs/openssh-crypto-configuration
                 2. NIST SP 800-53 Rev. 5: SC-8
                 3. SSHD(8)
                 4. SSHD_CONFIG(5)




                                                                                               Page 510

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            Additional Information:
            The supported algorithms are:
            curve25519-sha256
            curve25519-sha256@libssh.org
            diffie-hellman-group1-sha1
            diffie-hellman-group14-sha1
            diffie-hellman-group14-sha256
            diffie-hellman-group16-sha512
            diffie-hellman-group18-sha512
            diffie-hellman-group-exchange-sha1
            diffie-hellman-group-exchange-sha256
            ecdh-sha2-nistp256
            ecdh-sha2-nistp384
            ecdh-sha2-nistp521
            sntrup4591761x25519-sha512@tinyssh.org

            CIS Controls:

                Controls
                                                                Control                                  IG 1 IG 2 IG 3
                Version
                            3.10 Encrypt Sensitive Data in Transit
                    v8         Encrypt sensitive data in transit. Example implementations can include:         ●    ●
                            Transport Layer Security (TLS) and Open Secure Shell (OpenSSH).

                    v7      14.4 Encrypt All Sensitive Information in Transit                                  ●    ●
                               Encrypt all sensitive information in transit.




                                                                                                               Page 511

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            5.1.13 Ensure sshd LoginGraceTime is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The LoginGraceTime parameter specifies the time allowed for successful
            authentication to the SSH server. The longer the Grace period is the more open
            unauthenticated connections can exist. Like other session controls in this session the
            Grace Period should be limited to appropriate organizational limits to ensure the service
            is available for needed access.
            Rationale:
            Setting the LoginGraceTime parameter to a low number will minimize the risk of
            successful brute force attacks to the SSH server. It will also limit the number of
            concurrent unauthenticated connections While the recommended setting is 60 seconds
            (1 Minute), set the number based on site policy.
            Audit:
            Run the following command and verify that output LoginGraceTime is between 1 and
            60 seconds:
            # sshd -T | grep logingracetime

            logingracetime 60

            Remediation:
            Edit the /etc/ssh/sshd_config file to set the LoginGraceTime parameter to 60
            seconds or less above any Include entry as follows:
            LoginGraceTime 60
            Note: First occurrence of a option takes precedence. If Include locations are enabled,
            used, and order of precedence is understood in your environment, the entry may be
            created in a file in Include location.
            Default Value:
            LoginGraceTime 120
            References:

                 1. SSHD_CONFIG(5)
                 2. NIST SP 800-53 Rev. 5: CM-6
                 3. SSHD(8)



                                                                                             Page 512

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            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 513

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            5.1.14 Ensure sshd LogLevel is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            SSH provides several logging levels with varying amounts of verbosity. The DEBUG
            options are specifically not recommended other than strictly for debugging SSH
            communications. These levels provide so much data that it is difficult to identify
            important security information, and may violate the privacy of users.
            Rationale:
            The INFO level is the basic level that only records login activity of SSH users. In many
            situations, such as Incident Response, it is important to determine when a particular
            user was active on a system. The logout record can eliminate those users who
            disconnected, which helps narrow the field.
            The VERBOSE level specifies that login and logout activity as well as the key fingerprint
            for any SSH key used for login will be logged. This information is important for SSH key
            management, especially in legacy environments.
            Audit:
            Run the following command and verify that output matches loglevel VERBOSE or
            loglevel INFO:
            # sshd -T | grep loglevel

            loglevel VERBOSE
               - OR -
            loglevel INFO
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep loglevel
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain)




                                                                                             Page 514

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            Remediation:
            Edit the /etc/ssh/sshd_config file to set the LogLevel parameter to VERBOSE or
            INFO above any Include and Match entries as follows:
            LogLevel VERBOSE
               - OR -
            LogLevel INFO
            Note: First occurrence of an option takes precedence, Match set statements
            withstanding. If Include locations are enabled, used, and order of precedence is
            understood in your environment, the entry may be created in a file in Include location.

            Default Value:
            LogLevel INFO
            References:

                 1. https://www.ssh.com/ssh/sshd_config/
                 2. NIST SP 800-53 Rev. 5: AU-3, AU-12, SI-5

            CIS Controls:

               Controls
                                                             Control                                    IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                              ●    ●
                          other useful elements.




                                                                                                              Page 515

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            5.1.15 Ensure sshd MACs are configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            This variable limits the types of MAC algorithms that SSH can use during
            communication.
            Notes:

                 •   Some organizations may have stricter requirements for approved MACs.
                 •   Ensure that MACs used are in compliance with site policy.
                 •   The only "strong" MACs currently FIPS 140 approved are:
                        o HMAC-SHA1
                        o HMAC-SHA2-256
                        o HMAC-SHA2-384
                        o HMAC-SHA2-512

            Rationale:
            MD5 and 96-bit MAC algorithms are considered weak and have been shown to increase
            exploitability in SSH downgrade attacks. Weak algorithms continue to have a great deal
            of attention as a weak spot that can be exploited with expanded computing power. An
            attacker that breaks the algorithm could take advantage of a MiTM position to decrypt
            the SSH tunnel and capture credentials and information.




                                                                                            Page 516

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            Audit:
            Run the following command to verify none of the "weak" MACs are being used:
            # sshd -T | grep -Pi -- 'macs\h+([^#\n\r]+,)?(hmac-md5|hmac-md5-96|hmac-
            ripemd160|hmac-sha1-96|umac-64@openssh\.com|hmac-md5-etm@openssh\.com|hmac-
            md5-96-etm@openssh\.com|hmac-ripemd160-etm@openssh\.com|hmac-sha1-96-
            etm@openssh\.com|umac-64-etm@openssh\.com|umac-128-etm@openssh\.com)\b'
            Nothing should be returned
            Note: Review CVE-2023-48795 and verify the system has been patched. If the system
            has not been patched, review the use of the Encrypt Then Mac (etm) MACs.
            The following are considered "weak" MACs, and should not be used:
            hmac-md5
            hmac-md5-96
            hmac-ripemd160
            hmac-sha1-96
            umac-64@openssh.com
            hmac-md5-etm@openssh.com
            hmac-md5-96-etm@openssh.com
            hmac-ripemd160-etm@openssh.com
            hmac-sha1-96-etm@openssh.com
            umac-64-etm@openssh.com
            umac-128-etm@openssh.com

            Remediation:
            Edit the /etc/ssh/sshd_config file and add/modify the MACs line to contain a comma
            separated list of the site unapproved (weak) MACs preceded with a - above any
            Include entries:
            Example:
            MACs -hmac-md5,hmac-md5-96,hmac-ripemd160,hmac-sha1-96,umac-
            64@openssh.com,hmac-md5-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-
            ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,umac-64-
            etm@openssh.com,umac-128-etm@openssh.com
            - IF - CVE-2023-48795 has not been reviewed and addressed, the following etm MACs
            should be added to the exclude list: hmac-sha1-etm@openssh.com,hmac-sha2-256-
            etm@openssh.com,hmac-sha2-512-etm@openssh.com
            Note: First occurrence of an option takes precedence. If Include locations are enabled,
            used, and order of precedence is understood in your environment, the entry may be
            created in a file in Include location.
            Default Value:
            MACs umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-
            etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-
            etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-
            256,hmac-sha2-512,hmac-sha1




                                                                                            Page 517

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            References:

                 1. https://nvd.nist.gov/vuln/detail/CVE-2023-48795
                 2. More information on SSH downgrade attacks can be found here:
                    http://www.mitls.org/pages/attacks/SLOTH
                 3. SSHD_CONFIG(5)
                 4. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            CIS Controls:

                Controls
                                                                Control                                  IG 1 IG 2 IG 3
                Version
                            3.10 Encrypt Sensitive Data in Transit
                    v8         Encrypt sensitive data in transit. Example implementations can include:         ●    ●
                            Transport Layer Security (TLS) and Open Secure Shell (OpenSSH).

                    v7      14.4 Encrypt All Sensitive Information in Transit                                  ●    ●
                               Encrypt all sensitive information in transit.

                            16.5 Encrypt Transmittal of Username and
                    v7      Authentication Credentials                                                         ●    ●
                               Ensure that all account usernames and authentication credentials are
                            transmitted across networks using encrypted channels.




                                                                                                               Page 518

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            5.1.16 Ensure sshd MaxAuthTries is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The MaxAuthTries parameter specifies the maximum number of authentication
            attempts permitted per connection. When the login failure count reaches half the
            number, error messages will be written to the syslog file detailing the login failure.

            Rationale:
            Setting the MaxAuthTries parameter to a low number will minimize the risk of
            successful brute force attacks to the SSH server. While the recommended setting is 4,
            set the number based on site policy.
            Audit:
            Run the following command and verify that MaxAuthTries is 4 or less:
            # sshd -T | grep maxauthtries

            maxauthtries 4
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep maxauthtries
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain)

            Remediation:
            Edit the /etc/ssh/sshd_config file to set the MaxAuthTries parameter to 4 or less
            above any Include and Match entries as follows:
            MaxAuthTries 4
            Note: First occurrence of an option takes precedence, Match set statements
            withstanding. If Include locations are enabled, used, and order of precedence is
            understood in your environment, the entry may be created in a file in Include location.




                                                                                               Page 519

Internal Only - General
            Default Value:
            MaxAuthTries 6
            References:

                 1. SSHD_CONFIG(5)
                 2. NIST SP 800-53 Rev. 5: AU-3

            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          16.13 Alert on Account Login Behavior Deviation
                   v7       Alert when users deviate from normal login behavior, such as time-of-day,                       ●
                          workstation location and duration.




                                                                                                                       Page 520

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            5.1.17 Ensure sshd MaxSessions is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The MaxSessions parameter specifies the maximum number of open sessions
            permitted from a given connection.
            Rationale:
            To protect a system from denial of service due to a large number of concurrent
            sessions, use the rate limiting function of MaxSessions to protect availability of sshd
            logins and prevent overwhelming the daemon.
            Audit:
            Run the following command and verify that MaxSessions is 10 or less:
            # sshd -T | grep maxsessions

            maxsessions 10
            Run the following command and verify the output:
            grep -Psi -- '^\h*MaxSessions\h+\"?(1[1-9]|[2-9][0-9]|[1-9][0-9][0-9]+)\b'
            /etc/ssh/sshd_config /etc/ssh/sshd_config.d/*.conf

            Nothing should be returned
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep maxsessions
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain)




                                                                                               Page 521

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            Remediation:
            Edit the /etc/ssh/sshd_config file to set the MaxSessions parameter to 10 or less
            above any Include and Match entries as follows:
            MaxSessions 10
            Note: First occurrence of an option takes precedence, Match set statements
            withstanding. If Include locations are enabled, used, and order of precedence is
            understood in your environment, the entry may be created in a file in Include location.

            Default Value:
            MaxSessions 10
            References:

                 1. SSHD_CONFIG(5)
                 2. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            CIS Controls:

                 Controls Version                      Control            IG 1 IG 2 IG 3

                          v8          0.0 Explicitly Not Mapped
                                        Explicitly Not Mapped

                          v7          0.0 Explicitly Not Mapped
                                        Explicitly Not Mapped




                                                                                            Page 522

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            5.1.18 Ensure sshd MaxStartups is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The MaxStartups parameter specifies the maximum number of concurrent
            unauthenticated connections to the SSH daemon.
            Rationale:
            To protect a system from denial of service due to a large number of pending
            authentication connection attempts, use the rate limiting function of MaxStartups to
            protect availability of sshd logins and prevent overwhelming the daemon.
            Audit:
            Run the following command to verify MaxStartups is 10:30:60 or more restrictive:
            # sshd -T | awk '$1 ~ /^\s*maxstartups/{split($2, a, ":");{if(a[1] > 10 ||
            a[2] > 30 || a[3] > 60) print $0}}'
            Nothing should be returned
            Remediation:
            Edit the /etc/ssh/sshd_config file to set the MaxStartups parameter to 10:30:60 or
            more restrictive above any Include entries as follows:
            MaxStartups 10:30:60
            Note: First occurrence of a option takes precedence. If Include locations are enabled,
            used, and order of precedence is understood in your environment, the entry may be
            created in a file in Include location.
            Default Value:
            MaxStartups 10:30:100
            References:

                 1. SSHD_CONFIG(5)
                 2. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5




                                                                                             Page 523

Internal Only - General
            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 524

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            5.1.19 Ensure sshd PermitEmptyPasswords is disabled
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The PermitEmptyPasswords parameter specifies if the SSH server allows login to
            accounts with empty password strings.
            Rationale:
            Disallowing remote shell access to accounts that have an empty password reduces the
            probability of unauthorized access to the system.
            Audit:
            Run the following command to verify PermitEmptyPasswords is set to no:
            # sshd -T | grep permitemptypasswords

            permitemptypasswords no
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep permitemptypasswords
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain)

            Remediation:
            Edit /etc/ssh/sshd_config and set the PermitEmptyPasswords parameter to no
            above any Include and Match entries as follows:
            PermitEmptyPasswords no
            Note: First occurrence of an option takes precedence, Match set statements
            withstanding. If Include locations are enabled, used, and order of precedence is
            understood in your environment, the entry may be created in a file in Include location.




                                                                                             Page 525

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            Default Value:
            PermitEmptyPasswords no
            References:

                 1. SSHD_CONFIG(5)
                 2. NIST SP 800-53 Rev. 5: CM-1,CM-2, CM-6, CM-7, IA-5

            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 526

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            5.1.20 Ensure sshd PermitRootLogin is disabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The PermitRootLogin parameter specifies if the root user can log in using SSH. The
            default is prohibit-password.

            Rationale:
            Disallowing root logins over SSH requires system admins to authenticate using their
            own individual account, then escalating to root. This limits opportunity for non-
            repudiation and provides a clear audit trail in the event of a security incident.
            Audit:
            Run the following command to verify PermitRootLogin is set to no:
            # sshd -T | grep permitrootlogin

            permitrootlogin no
            - IF - Match set statements are used in your environment, specify the connection
            parameters to use for the -T extended test mode and run the audit to verify the setting
            is not incorrectly configured in a match block
            Example additional audit needed for a match block for the user sshuser:
            # sshd -T -C user=sshuser | grep permitrootlogin
            Note: If provided, any Match directives in the configuration file that would apply are
            applied before the configuration is written to standard output. The connection
            parameters are supplied as keyword=value pairs and may be supplied in any order,
            either with multiple -C options or as a comma-separated list. The keywords are addr
            (source address), user (user), host (resolved source host name), laddr (local
            address), lport (local port number), and rdomain (routing domain)

            Remediation:
            Edit the /etc/ssh/sshd_config file to set the PermitRootLogin parameter to no
            above any Include and Match entries as follows:
            PermitRootLogin no
            Note: First occurrence of an option takes precedence, Match set statements
            withstanding. If Include locations are enabled, used, and order of precedence is
            understood in your environment, the entry may be created in a file in Include location.

            Default Value:
            PermitRootLogin without-password

                                                                                             Page 527

Internal Only - General
            References:

                 1. SSHD_CONFIG(5)
                 2. NIST SP 800-53 Rev. 5:AC-6

            CIS Controls:

              Controls
                                                               Control                                           IG 1 IG 2 IG 3
              Version
                          5.4 Restrict Administrator Privileges to Dedicated
                          Administrator Accounts
                   v8        Restrict administrator privileges to dedicated administrator accounts on
                          enterprise assets. Conduct general computing activities, such as internet
                                                                                                                  ●    ●    ●
                          browsing, email, and productivity suite use, from the user’s primary, non-privileged
                          account.

                          4.3 Ensure the Use of Dedicated Administrative Accounts
                   v7        Ensure that all users with administrative account access use a dedicated or
                          secondary account for elevated activities. This account should only be used for
                                                                                                                  ●    ●    ●
                          administrative activities and not internet browsing, email, or similar activities.




                                                                                                                       Page 528

Internal Only - General
            5.1.21 Ensure sshd PermitUserEnvironment is disabled
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The PermitUserEnvironment option allows users to present environment options to
            the SSH daemon.
            Rationale:
            Permitting users the ability to set environment variables through the SSH daemon could
            potentially allow users to bypass security controls (e.g. setting an execution path that
            has SSH executing trojan'd programs)
            Audit:
            Run the following command to verify PermitUserEnvironment is set to no:
            # sshd -T | grep permituserenvironment

            permituserenvironment no

            Remediation:
            Edit the /etc/ssh/sshd_config file to set the PermitUserEnvironment parameter to
            no above any Include entries as follows:
            PermitUserEnvironment no
            Note: First occurrence of an option takes precedence. If Include locations are enabled,
            used, and order of precedence is understood in your environment, the entry may be
            created in a file in Include location.
            Default Value:
            PermitUserEnvironment no
            References:

                 1. SSHD_CONFIG(5)
                 2. NIST SP 800-53 Rev. 5: CM-1,CM-2, CM-6, CM-7, IA-5
                 3. SSHD(8)




                                                                                            Page 529

Internal Only - General
            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 530

Internal Only - General
            5.1.22 Ensure sshd UsePAM is enabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The UsePAM directive enables the Pluggable Authentication Module (PAM) interface. If
            set to yes this will enable PAM authentication using
            ChallengeResponseAuthentication and PasswordAuthentication directives in
            addition to PAM account and session module processing for all authentication types.
            Rationale:
            When usePAM is set to yes, PAM runs through account and session types properly. This
            is important if you want to restrict access to services based off of IP, time or other
            factors of the account. Additionally, you can make sure users inherit certain
            environment variables on login or disallow access to the server
            Audit:
            Run the following command to verify UsePAM is set to yes:
            # sshd -T | grep usepam

            usepam yes

            Remediation:
            Edit the /etc/ssh/sshd_config file to set the UsePAM parameter to yes above any
            Include entries as follows:
            UsePAM yes
            Note: First occurrence of an option takes precedence. If Include locations are enabled,
            used, and order of precedence is understood in your environment, the entry may be
            created in a file in Include location.
            Default Value:
            UsePAM yes
            References:

                 1. SSHD_CONFIG(5)
                 2. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5
                 3. SSHD(8)




                                                                                            Page 531

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 532

Internal Only - General
            5.2 Configure privilege escalation

            There are various tools which allows a permitted user to execute a command as the
            superuser or another user, as specified by the security policy.
            sudo
            sudo documentation
            The invoking user's real (not effective) user ID is used to determine the user name with
            which to query the security policy.
            sudo supports a plug-in architecture for security policies and input/output logging. Third
            parties can develop and distribute their own policy and I/O logging plug-ins to work
            seamlessly with the sudo front end. The default security policy is sudoers, which is
            configured via the file /etc/sudoers and any entries in /etc/sudoers.d.
            pkexec
            pkexec documentation
            pkexec allows an authorized user to execute PROGRAM as another user. If username
            is not specified, then the program will be executed as the administrative super user,
            root.




                                                                                              Page 533

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            5.2.1 Ensure sudo is installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            sudo allows a permitted user to execute a command as the superuser or another user,
            as specified by the security policy. The invoking user's real (not effective) user ID is
            used to determine the user name with which to query the security policy.
            Rationale:
            sudo supports a plug-in architecture for security policies and input/output logging. Third
            parties can develop and distribute their own policy and I/O logging plug-ins to work
            seamlessly with the sudo front end. The default security policy is sudoers, which is
            configured via the file /etc/sudoers and any entries in /etc/sudoers.d.
            The security policy determines what privileges, if any, a user has to run sudo. The policy
            may require that users authenticate themselves with a password or another
            authentication mechanism. If authentication is required, sudo will exit if the user's
            password is not entered within a configurable time limit. This limit is policy-specific.
            Audit:
            Run the following command to verify that either sudo is installed:
            # dpkg-query -s sudo &>/dev/null && echo "sudo is installed"

            sudo is installed
            - OR -
            Run the following command to verify that either sudo-ldap is installed:
            # dpkg-query -s sudo-ldap &>/dev/null && echo "sudo-ldap is installed"

            sudo-ldap is installed

            Remediation:
            First determine is LDAP functionality is required. If so, then install sudo-ldap, else
            install sudo.
            Example:
            # apt install sudo

            References:

                 1. SUDO(8)
                 2. NIST SP 800-53 Rev. 5: AC-6


                                                                                               Page 534

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                           IG 1 IG 2 IG 3
              Version
                          5.4 Restrict Administrator Privileges to Dedicated
                          Administrator Accounts
                   v8        Restrict administrator privileges to dedicated administrator accounts on
                          enterprise assets. Conduct general computing activities, such as internet
                                                                                                                  ●    ●    ●
                          browsing, email, and productivity suite use, from the user’s primary, non-privileged
                          account.

                          4.3 Ensure the Use of Dedicated Administrative Accounts
                   v7        Ensure that all users with administrative account access use a dedicated or
                          secondary account for elevated activities. This account should only be used for
                                                                                                                  ●    ●    ●
                          administrative activities and not internet browsing, email, or similar activities.




                                                                                                                       Page 535

Internal Only - General
            5.2.2 Ensure sudo commands use pty (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            sudo can be configured to run only from a pseudo terminal (pseudo-pty).

            Rationale:
            Attackers can run a malicious program using sudo which would fork a background
            process that remains even when the main program has finished executing.
            Impact:
            WARNING: Editing the sudo configuration incorrectly can cause sudo to stop
            functioning. Always use visudo to modify sudo configuration files.

            Audit:
            Verify that sudo can only run other commands from a pseudo terminal.
            Run the following command to verify Defaults use_pty is set:
            # grep -rPi -- '^\h*Defaults\h+([^#\n\r]+,\h*)?use_pty\b' /etc/sudoers*
            Verify the output matches:
            /etc/sudoers:Defaults use_pty
            Run the follow command to to verify Defaults !use_pty is not set:
            # grep -rPi -- '^\h*Defaults\h+([^#\n\r]+,\h*)?!use_pty\b' /etc/sudoers*
            Nothing should be returned




                                                                                         Page 536

Internal Only - General
            Remediation:
            Edit the file /etc/sudoers with visudo or a file in /etc/sudoers.d/ with visudo -f
            <PATH TO FILE> and add the following line:
            Defaults use_pty
            Edit the file /etc/sudoers with visudo and any files in /etc/sudoers.d/ with visudo
            -f <PATH TO FILE> and remove any occurrence of !use_pty
            Note:

                 •    sudo will read each file in /etc/sudoers.d, skipping file names that end in ~ or
                      contain a . character to avoid causing problems with package manager or editor
                      temporary/backup files.
                 •    Files are parsed in sorted lexical order. That is, /etc/sudoers.d/01_first will
                      be parsed before /etc/sudoers.d/10_second.
                 •    Be aware that because the sorting is lexical, not numeric,
                      /etc/sudoers.d/1_whoops would be loaded after
                      /etc/sudoers.d/10_second.
                 •    Using a consistent number of leading zeroes in the file names can be used to
                      avoid such problems.

            References:

                 1. SUDO(8)
                 2. VISUDO(8)
                 3. sudoers(5)
                 4. NIST SP 800-53 Rev. 5: AC-6

            CIS Controls:

              Controls
                                                                 Control                                           IG 1 IG 2 IG 3
              Version
                            5.4 Restrict Administrator Privileges to Dedicated
                            Administrator Accounts
                     v8        Restrict administrator privileges to dedicated administrator accounts on
                            enterprise assets. Conduct general computing activities, such as internet
                                                                                                                    ●    ●    ●
                            browsing, email, and productivity suite use, from the user’s primary, non-privileged
                            account.

                            4.3 Ensure the Use of Dedicated Administrative Accounts
                     v7        Ensure that all users with administrative account access use a dedicated or
                            secondary account for elevated activities. This account should only be used for
                                                                                                                    ●    ●    ●
                            administrative activities and not internet browsing, email, or similar activities.




                                                                                                                         Page 537

Internal Only - General
            5.2.3 Ensure sudo log file exists (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            sudo can use a custom log file
            Rationale:
            A sudo log file simplifies auditing of sudo commands
            Impact:
            WARNING: Editing the sudo configuration incorrectly can cause sudo to stop
            functioning. Always use visudo to modify sudo configuration files.

            Audit:
            Run the following command to verify that sudo has a custom log file configured:
            # grep -rPsi
            "^\h*Defaults\h+([^#]+,\h*)?logfile\h*=\h*(\"|\')?\H+(\"|\')?(,\h*\H+\h*)*\h*
            (#.*)?$" /etc/sudoers*
            Verify the output matches:
            Defaults logfile="/var/log/sudo.log"

            Remediation:
            Edit the file /etc/sudoers or a file in /etc/sudoers.d/ with visudo -f <PATH TO
            FILE> and add the following line:
            Defaults      logfile="<PATH TO CUSTOM LOG FILE>"
            Example:
            Defaults logfile="/var/log/sudo.log"
            Notes:

                 •   sudo will read each file in /etc/sudoers.d, skipping file names that end in ~ or
                     contain a . character to avoid causing problems with package manager or editor
                     temporary/backup files.
                 •   Files are parsed in sorted lexical order. That is, /etc/sudoers.d/01_first will
                     be parsed before /etc/sudoers.d/10_second.
                 •   Be aware that because the sorting is lexical, not numeric,
                     /etc/sudoers.d/1_whoops would be loaded after
                     /etc/sudoers.d/10_second.
                 •   Using a consistent number of leading zeroes in the file names can be used to
                     avoid such problems.

                                                                                              Page 538

Internal Only - General
            References:

                 1. SUDO(8)
                 2. VISUDO(8)
                 3. sudoers(5)
                 4. NIST SP 800-53 Rev. 5: AU-3, AU-12

            Additional Information:
            visudo edits the sudoers file in a safe fashion, analogous to vipw(8). visudo locks the
            sudoers file against multiple simultaneous edits, provides basic sanity checks, and
            checks for parse errors. If the sudoers file is currently being edited you will receive a
            message to try again later.
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          6.3 Enable Detailed Logging
                   v7        Enable system logging to include detailed information such as an event source,
                          date, user, timestamp, source addresses, destination addresses, and other useful
                                                                                                                       ●    ●
                          elements.




                                                                                                                       Page 539

Internal Only - General
            5.2.4 Ensure users must provide password for escalation
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The operating system must be configured so that users must provide a password for
            privilege escalation.
            Rationale:
            Without (re-)authentication, users may access resources or perform tasks for which they
            do not have authorization.
            When operating systems provide the capability to escalate a functional capability, it is
            critical the user (re-)authenticate.
            Impact:
            This will prevent automated processes from being able to elevate privileges.
            Audit:
            Note: If passwords are not being used for authentication, this is not applicable.
            Verify the operating system requires users to supply a password for privilege escalation.
            Check the configuration of the /etc/sudoers and /etc/sudoers.d/* files with the
            following command:
            # grep -r "^[^#].*NOPASSWD" /etc/sudoers*
            If any line is found refer to the remediation procedure below.
            Remediation:
            Based on the outcome of the audit procedure, use visudo -f <PATH TO FILE> to edit
            the relevant sudoers file.
            Remove any line with occurrences of NOPASSWD tags in the file.

            References:

                 1. NIST SP 800-53 Rev. 5: AC-6




                                                                                             Page 540

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                           IG 1 IG 2 IG 3
              Version
                          5.4 Restrict Administrator Privileges to Dedicated
                          Administrator Accounts
                   v8        Restrict administrator privileges to dedicated administrator accounts on
                          enterprise assets. Conduct general computing activities, such as internet
                                                                                                                  ●    ●    ●
                          browsing, email, and productivity suite use, from the user’s primary, non-privileged
                          account.

                          4.3 Ensure the Use of Dedicated Administrative Accounts
                   v7        Ensure that all users with administrative account access use a dedicated or
                          secondary account for elevated activities. This account should only be used for
                                                                                                                  ●    ●    ●
                          administrative activities and not internet browsing, email, or similar activities.




                                                                                                                       Page 541

Internal Only - General
            5.2.5 Ensure re-authentication for privilege escalation is not
            disabled globally (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The operating system must be configured so that users must re-authenticate for
            privilege escalation.
            Rationale:
            Without re-authentication, users may access resources or perform tasks for which they
            do not have authorization.
            When operating systems provide the capability to escalate a functional capability, it is
            critical the user re-authenticate.
            Audit:
            Verify the operating system requires users to re-authenticate for privilege escalation.
            Check the configuration of the /etc/sudoers and /etc/sudoers.d/* files with the
            following command:
            # grep -r "^[^#].*\!authenticate" /etc/sudoers*
            If any line is found with a !authenticate tag, refer to the remediation procedure below.

            Remediation:
            Configure the operating system to require users to reauthenticate for privilege
            escalation.
            Based on the outcome of the audit procedure, use visudo -f <PATH TO FILE> to edit
            the relevant sudoers file.
            Remove any occurrences of !authenticate tags in the file(s).

            References:

                 1. NIST SP 800-53 Rev. 5: AC-6




                                                                                              Page 542

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                           IG 1 IG 2 IG 3
              Version
                          5.4 Restrict Administrator Privileges to Dedicated
                          Administrator Accounts
                   v8        Restrict administrator privileges to dedicated administrator accounts on
                          enterprise assets. Conduct general computing activities, such as internet
                                                                                                                  ●    ●    ●
                          browsing, email, and productivity suite use, from the user’s primary, non-privileged
                          account.

                          4.3 Ensure the Use of Dedicated Administrative Accounts
                   v7        Ensure that all users with administrative account access use a dedicated or
                          secondary account for elevated activities. This account should only be used for
                                                                                                                  ●    ●    ●
                          administrative activities and not internet browsing, email, or similar activities.




                                                                                                                       Page 543

Internal Only - General
            5.2.6 Ensure sudo timestamp_timeout is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            sudo timestamp_timeout controls how long a user's sudo privileges remain active
            after the initial password entry.
            Rationale:
            A timeout value reduces the window of opportunity for unauthorized privileged sudo
            access.
            Audit:
            Ensure that the caching timeout is not disabled and greater than 15 minutes.
            Run the following command:
            # grep -roP "timestamp_timeout=\K[0-9]*" /etc/sudoers*
            If there is no timestamp_timeout configured in /etc/sudoers* then the default of 5
            minutes is being used.
            If the default value is being used, run the following command to verify the default is not
            disabled or greater than 15 minutes:
            # sudo -V | grep "Authentication timestamp timeout:"
            Example output:
            Authentication timestamp timeout: 15.0 minutes
            Verify Authentication timestamp timeout:

                 •   Is not a negative number (disabled).
                 •   Is not greater than 15 minutes, and follows local site policy.
                 •   Follows local site policy




                                                                                               Page 544

Internal Only - General
            Remediation:
            Edit the file listed in the audit section with visudo -f <PATH TO FILE> and modify the
            entry timestamp_timeout= to 15 minutes or less as per your site policy. The value is in
            minutes. This particular entry may appear on its own, or on the same line as
            env_reset. See the following two examples:
            Example 1:
            Defaults      env_reset, timestamp_timeout=15
            Example 2:
            Defaults      timestamp_timeout=15
            Defaults      env_reset

            Default Value:
            timestamp_timeout=15
            References:

                 1. https://www.sudo.ws/man/1.9.0/sudoers.man.html
                 2. NIST SP 800-53 Rev. 5: AC-6

            CIS Controls:

              Controls
                                                               Control                                           IG 1 IG 2 IG 3
              Version
                          5.4 Restrict Administrator Privileges to Dedicated
                          Administrator Accounts
                   v8        Restrict administrator privileges to dedicated administrator accounts on
                          enterprise assets. Conduct general computing activities, such as internet
                                                                                                                  ●    ●    ●
                          browsing, email, and productivity suite use, from the user’s primary, non-privileged
                          account.

                          4.3 Ensure the Use of Dedicated Administrative Accounts
                   v7        Ensure that all users with administrative account access use a dedicated or
                          secondary account for elevated activities. This account should only be used for
                                                                                                                  ●    ●    ●
                          administrative activities and not internet browsing, email, or similar activities.




                                                                                                                       Page 545

Internal Only - General
            5.2.7 Ensure access to the su command is restricted (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The su command allows a user to run a command or shell as another user. The
            program has been superseded by sudo, which allows for more granular control over
            privileged access. Normally, the su command can be executed by any user. By
            uncommenting the pam_wheel.so statement in /etc/pam.d/su, the su command will
            only allow users in a specific groups to execute su. This group should be empty to
            reinforce the use of sudo for privileged access.

            Rationale:
            Restricting the use of su , and using sudo in its place, provides system administrators
            better control of the escalation of user privileges to execute privileged commands. The
            sudo utility also provides a better logging and audit mechanism, as it can log each
            command executed via sudo , whereas su can only record that a user executed the su
            program.
            Audit:
            Run the following command:
            # grep -Pi
            '^\h*auth\h+(?:required|requisite)\h+pam_wheel\.so\h+(?:[^#\n\r]+\h+)?((?!\2)
            (use_uid\b|group=\H+\b))\h+(?:[^#\n\r]+\h+)?((?!\1)(use_uid\b|group=\H+\b))(\
            h+.*)?$' /etc/pam.d/su
            Verify the output matches:
            auth required pam_wheel.so use_uid group=<group_name>
            Run the following command and verify that the group specified in <group_name>
            contains no users:
            # grep <group_name> /etc/group
            Verify the output does not contain any users in the relevant group:
            <group_name>:x:<GID>:




                                                                                            Page 546

Internal Only - General
            Remediation:
            Create an empty group that will be specified for use of the su command. The group
            should be named according to site policy.
            Example:
            # groupadd sugroup
            Add the following line to the /etc/pam.d/su file, specifying the empty group:
            auth required pam_wheel.so use_uid group=sugroup

            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 547

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            5.3 Pluggable Authentication Modules

            Pluggable Authentication Modules (PAM) is a service that implements modular
            authentication modules on Linux systems. PAM is implemented as a set of shared
            objects that are loaded and executed when a program needs to authenticate a user.
            Files for PAM are typically located in the /etc/pam.d directory. PAM must be carefully
            configured to secure system authentication. While this section covers some of PAM,
            please consult other PAM resources to fully understand the configuration capabilities.
            Note: This section includes guidance that requires the additional modules and the latest
            version of software packages as covered in the "Configure required security packages"
            subsection of the "Package Management" section




                                                                                            Page 548

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            5.3.1 Configure PAM software packages

            Updated versions of PAM include additional functionality




                                                                       Page 549

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            5.3.1.1 Ensure latest version of pam is installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Linux Pluggable Authentication Modules (PAM) is a suite of libraries that allow a Linux
            system administrator to configure methods to authenticate users. It provides a flexible
            and centralized way to switch authentication methods for secured applications by using
            configuration files instead of changing application code
            The libpam-runtime provides the runtime support for the PAM library

            Rationale:
            Older versions of the libpam-runtime package may not include the latest security and
            feature patches and updates.
            Note: This Benchmark was tested against libpam-runtime Version: 1.4.0-
            11ubuntu2.6

            Audit:
            Run the following command to verify libpam-runtime is installed:
            # dpkg-query -s libpam-runtime &>/dev/null && echo "libpam-runtime is
            installed"

            libpam-runtime is installed
            Run the following command to verify libpam-runtime is the latest version:
            # apt list --upgradable 2>&1 | grep -P '^libpam-runtime\b'
            Nothing should be returned
            Remediation:
            Run the following command to install the latest version of libpam-runtime:
            # apt install libpam-runtime

            References:

                 1. PAM(7)




                                                                                            Page 550

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            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 551

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            5.3.1.2 Ensure latest version of libpam-modules is installed
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            libpam-modules is a package containing a set of Pluggable Authentication Modules
            (PAM) which allows system administrators to configure different authentication methods
            for user logins, providing flexibility in how users can access applications by using
            various authentication modules to include password checks and other security
            mechanisms.
            Rationale:
            Older versions of the libpam-modules package may not include the latest security and
            feature patches and updates.
            Note: This Benchmark was tested and written against libpam-modules Version:
            1.4.0-11ubuntu2.6

            Audit:
            Run the following command to verify libpam-modules is installed:
            # dpkg-query -s libpam-modules &>/dev/null && echo "libpam-modules is
            installed"

            libpam-modules is installed
            Run the following command to verify libpam-modules is the latest version:
            # apt list --upgradable 2>&1 | grep -P '^libpam-modules\b'
            Nothing should be returned
            Remediation:
            Run the following command to install the latest version of libpam-modules:
            # apt install libpam-modules

            CIS Controls:

                 Controls Version                       Control          IG 1 IG 2 IG 3

                          v8          0.0 Explicitly Not Mapped
                                         Explicitly Not Mapped

                          v7          0.0 Explicitly Not Mapped
                                         Explicitly Not Mapped




                                                                                          Page 552

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            5.3.1.3 Ensure latest version of libpam-pwquality is installed
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            libpwquality provides common functions for password quality checking and scoring
            them based on their apparent randomness. The library also provides a function for
            generating random passwords with good pronounceability.
            This module can be plugged into the password stack of a given service to provide some
            plug-in strength-checking for passwords. The code was originally based on
            pam_cracklib module and the module is backwards compatible with its options.

            Rationale:
            Strong passwords reduce the risk of systems being hacked through brute force
            methods.
            Older versions of the libpam-pwquality package may not include the latest security
            and feature patches and updates.
            Note: This Benchmark was tested and written against libpam-pwquality Version:
            1.4.4-1build2

            Audit:
            Run the following command to verify libpam-pwquality is installed:
            # dpkg-query -s libpam-pwquality &>/dev/null && echo "libpam-pwquality is
            installed"

            libpam-pwquality is installed
            Run the following command to verify libpam-pwquality is the latest version:
            # apt list --upgradable 2>&1 | grep -P '^libpam-pwquality\b'
            Nothing should be returned
            Remediation:
            Run the following command to install the latest version of libpam-pwquality:
            # apt install libpam-pwquality

            References:

                 1. https://packages.debian.org/buster/libpam-pwquality




                                                                                           Page 553

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            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 554

Internal Only - General
            5.3.2 Configure pam-auth-update profiles

            pam-auth-update is a utility that permits configuring the central authentication policy
            for the system using pre-defined profiles as supplied by PAM module packages.
            Profiles - Shipped in the /usr/share/pam-configs/ directory specify the modules,
            with options, to enable; the preferred ordering with respect to other profiles; and
            whether a profile should be enabled by default. Packages providing PAM modules
            register their profiles at install time by calling pam-auth-update --package.
            Selection of profiles is done using the standard debconf interface. The profile selection
            question will be asked at medium priority when packages are added or removed, so no
            user interaction is required by default. Users may invoke pam-auth-update directly to
            change their authentication configuration.
            The pam-auth-update script makes every effort to respect local changes to
            /etc/pam.d/common-*. Local modifications to the list of module options will be
            preserved, and additions of modules within the managed portion of the stack will cause
            pam-auth-update to treat the config files as locally modified and not make further
            changes to the config files unless given the --force option.
            If the user specifies that pam-auth-update should override local configuration changes,
            the locally-modified files will be saved in /etc/pam.d/ with a suffix of .pam-old.




                                                                                             Page 555

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            5.3.2.1 Ensure pam_unix module is enabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            pam_unix is the standard Unix authentication module. It uses standard calls from the
            system's libraries to retrieve and set account information as well as authentication.
            Usually this is obtained from the /etc/passwd and if shadow is enabled, the
            /etc/shadow file as well.
            The account component performs the task of establishing the status of the user's
            account and password based on the following shadow elements: expire,
            last_change, max_change, min_change, warn_change. In the case of the latter, it may
            offer advice to the user on changing their password or, through the
            PAM_AUTHTOKEN_REQD return, delay giving service to the user until they have
            established a new password. The entries listed above are documented in the shadow(5)
            manual page. Should the user's record not contain one or more of these entries, the
            corresponding shadow check is not performed.
            The authentication component performs the task of checking the users credentials
            (password). The default action of this module is to not permit the user access to a
            service if their official password is blank.
            Rationale:
            The system should only provide access after performing authentication of a user.
            Audit:
            Run the following command to verify that pam_unix is enabled:
            # grep -PH -- '\bpam_unix\.so\b' /etc/pam.d/common-
            {account,auth,password,session,session-noninteractive}
            Output should be simular to:
            /etc/pam.d/common-account:account   [success=1 new_authtok_reqd=done
            default=ignore]   pam_unix.so
            /etc/pam.d/common-auth:auth   [success=2 default=ignore]   pam_unix.so
            try_first_pass
            /etc/pam.d/common-password:password   [success=1 default=ignore]
            pam_unix.so obscure use_authtok try_first_pass yescrypt
            /etc/pam.d/common-session:session   required   pam_unix.so
            /etc/pam.d/common-session-noninteractive:session   required   pam_unix.so




                                                                                            Page 556

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            Remediation:
            Run the following command to enable the pam_unix module:
            # pam-auth-update --enable unix
            Note: If a site specific custom profile is being used in your environment to configure
            PAM that includes the configuration for the pam_unix module, enable that module
            instead
            References:

                 1. NIST SP 800-53 Rev. 5: IA-5(1)

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 557

Internal Only - General
            5.3.2.2 Ensure pam_faillock module is enabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The pam_faillock.so module maintains a list of failed authentication attempts per
            user during a specified interval and locks the account in case there were more than the
            configured number of consecutive failed authentications (this is defined by the deny
            parameter in the faillock configuration). It stores the failure records into per-user files in
            the tally directory.
            Rationale:
            Locking out user IDs after n unsuccessful consecutive login attempts mitigates brute
            force password attacks against your systems.
            Audit:
            Run the following commands to verify that pam_faillock is enabled:
            # grep -P -- '\bpam_faillock\.so\b' /etc/pam.d/common-{auth,account}
            Output should be similar to:
            /etc/pam.d/common-auth:auth     requisite
            pam_faillock.so preauth
            /etc/pam.d/common-auth:auth     [default=die]
            pam_faillock.so authfail
            /etc/pam.d/common-account:account       required
            pam_faillock.so




                                                                                                  Page 558

Internal Only - General
            Remediation:
            Create two pam-auth-update profiles in /usr/share/pam-configs/:
               1. Create the faillock profile in /usr/share/pam-configs/ with the following
                  lines:
            Name: Enable pam_faillock to deny access
            Default: yes
            Priority: 0
            Auth-Type: Primary
            Auth:
                    [default=die]                    pam_faillock.so authfail
            Example Script:
            #!/usr/bin/env bash

            {
               arr=('Name: Enable pam_faillock to deny access' 'Default: yes' 'Priority:
            0' 'Auth-Type: Primary' 'Auth:' '        [default=die]
            pam_faillock.so authfail')
               printf '%s\n' "${arr[@]}" > /usr/share/pam-configs/faillock
            }

                 2. Create the faillock_notify profile in /usr/share/pam-configs/ with the
                    following lines:

            Name: Notify of failed login attempts and reset count upon success
            Default: yes
            Priority: 1024
            Auth-Type: Primary
            Auth:
                     requisite                      pam_faillock.so preauth
            Account-Type: Primary
            Account:
                     required                       pam_faillock.so
            Example Script:
            #!/usr/bin/env bash

            {
               arr=('Name: Notify of failed login attempts and reset count upon success'
            'Default: yes' 'Priority: 1024' 'Auth-Type: Primary' 'Auth:' '
            requisite                       pam_faillock.so preauth' 'Account-Type:
            Primary' 'Account:' '        required
            pam_faillock.so')
               printf '%s\n' "${arr[@]}" > /usr/share/pam-configs/faillock_notify
            }
            Run the following command to update the common-auth and common-account PAM
            files with the new profiles:
            # pam-auth-update --enable <profile_filename>
            Example:
            # pam-auth-update --enable faillock
            # pam-auth-update --enable faillock_notify



                                                                                       Page 559

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            Note:

                 •    The name used for the file must be used in the pam-auth-update --enable
                      command
                 •    The Name: line should be easily recognizable and understood
                 •    The Priority: Line is important as it effects the order of the lines in the
                      /etc/pam.d/ files
                 •    If a site specific custom profile is being used in your environment to configure
                      PAM that includes the configuration for the pam_faillock module, enable that
                      module instead

            CIS Controls:

              Controls
                                                               Control                                           IG 1 IG 2 IG 3
              Version
                           6.2 Establish an Access Revoking Process
                              Establish and follow a process, preferably automated, for revoking access to
                     v8    enterprise assets, through disabling accounts immediately upon termination, rights     ●    ●    ●
                           revocation, or role change of a user. Disabling accounts, instead of deleting
                           accounts, may be necessary to preserve audit trails.

                           16.7 Establish Process for Revoking Access
                               Establish and follow an automated process for revoking system access by
                     v7    disabling accounts immediately upon termination or change of responsibilities of an         ●    ●
                           employee or contractor . Disabling these accounts, instead of deleting accounts,
                           allows preservation of audit trails.




                                                                                                                       Page 560

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            5.3.2.3 Ensure pam_pwquality module is enabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The pam_pwquality.so module performs password quality checking. This module can
            be plugged into the password stack of a given service to provide strength-checking for
            passwords. The code was originally based on pam_cracklib module and the module is
            backwards compatible with its options.
            The action of this module is to prompt the user for a password and check its strength
            against a system dictionary and a set of rules for identifying poor choices.
            The first action is to prompt for a single password, check its strength and then, if it is
            considered strong, prompt for the password a second time (to verify that it was typed
            correctly on the first occasion). All being well, the password is passed on to subsequent
            modules to be installed as the new authentication token.
            Rationale:
            Use of a unique, complex passwords helps to increase the time and resources required
            to compromise the password.
            Audit:
            Run the following command to verify that pam_pwquality.so is enabled:
            # grep -P -- '\bpam_pwquality\.so\b' /etc/pam.d/common-password
            Output should be similar to:
            password      requisite   pam_pwquality.so retry=3




                                                                                              Page 561

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            Remediation:
            Run the following script to verify the pam_pwquality.so line exists in a pam-auth-
            update profile:
            # grep -P -- '\bpam_pwquality\.so\b' /usr/share/pam-configs/*
            Output should be similar to:
            /usr/share/pam-configs/pwquality:           requisite
            pam_pwquality.so retry=3
            /usr/share/pam-configs/pwquality:           requisite
            pam_pwquality.so retry=3
            - IF - similar output is returned:
            Run the following command to update /etc/pam.d/common-password with the
            returned profile:
            # pam-auth-update --enable {PROFILE_NAME}
            Example:
            # pam-auth-update pwquality
            - IF - similar output is NOT returned:
            Create a pam-auth-update profile in /usr/share/pam-configs/ with the following
            lines:
            Name: Pwquality password strength checking
            Default: yes
            Priority: 1024
            Conflicts: cracklib
            Password-Type: Primary
            Password:
                    requisite                       pam_pwquality.so retry=3
            Example:
            #!/usr/bin/env bash

            {
               arr=('Name: Pwquality password strength checking' 'Default: yes'
            'Priority: 1024' 'Conflicts: cracklib' 'Password-Type: Primary' 'Password:' '
            requisite                       pam_pwquality.so retry=3')
               printf '%s\n' "${arr[@]}" > /usr/share/pam-configs/pwquality
            }
            Run the following command to update /etc/pam.d/common-password with the
            pwquality profile:
            # pam-auth-update --enable pwquality




                                                                                           Page 562

Internal Only - General
            Note:
                 •    The name used for the file must be used in the pam-auth-update --enable
                      command
                 •    The Name: line should be easily recognizable and understood
                 •    The Priority: Line is important as it effects the order of the lines in the
                      /etc/pam.d/ files
                 •    If a site specific custom profile is being used in your environment to configure
                      PAM that includes the configuration for the pam_pwquality module, enable that
                      module instead
            CIS Controls:

               Controls
                                                               Control                                            IG 1 IG 2 IG 3
               Version
                            5.2 Use Unique Passwords
                     v8         Use unique passwords for all enterprise assets. Best practice implementation
                            includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                   ●    ●    ●
                            14-character password for accounts not using MFA.

                            4.4 Use Unique Passwords
                     v7        Where multi-factor authentication is not supported (such as local administrator,
                            root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                        ●    ●
                            system.




                                                                                                                        Page 563

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            5.3.2.4 Ensure pam_pwhistory module is enabled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The pam_pwhistory.so module saves the last passwords for each user in order to
            force password change history and keep the user from alternating between the same
            password too frequently.
            This module does not work together with kerberos. In general, it does not make much
            sense to use this module in conjunction with NIS or LDAP, since the old passwords are
            stored on the local machine and are not available on another machine for password
            history checking.
            Rationale:
            Use of a unique, complex passwords helps to increase the time and resources required
            to compromise the password.
            Audit:
            Run the following command to verify that pam_pwhistory.so is enabled:
            # grep -P -- '\bpam_pwhistory\.so\b' /etc/pam.d/common-password
            Output should be similar to:
            password    requisite     pam_pwhistory.so remember=24 enforce_for_root
            use_authtok




                                                                                           Page 564

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            Remediation:
            Run the following script to verify the pam_pwhistory.so line exists in a pam-auth-
            update profile:
            # grep -P -- '\bpam_pwhistory\.so\b' /usr/share/pam-configs/*
            Output should be similar to:
            /usr/share/pam-configs/pwhistory:         requisite     pam_pwhistory.so remember=24
            enforce_for_root use_authtok
            - IF - similar output is returned:
            Run the following command to update /etc/pam.d/common-password with the
            returned profile:
            # pam-auth-update --enable {PROFILE_NAME}
            Example:
            # pam-auth-update pwhistory
            - IF - similar output is NOT returned:
            Create a pwhistory profile in /usr/share/pam-configs/ with the following lines:
            Name: pwhistory password history checking
            Default: yes
            Priority: 1024
            Password-Type: Primary
            Password: requisite pam_pwhistory.so remember=24 enforce_for_root use_authtok
            Example Script:
            #!/usr/bin/env bash

            {
               arr=('Name: pwhistory password history checking' 'Default: yes' 'Priority:
            1024' 'Password-Type: Primary' 'Password:' '        requisite
            pam_pwhistory.so remember=24 enforce_for_root use_authtok')
               printf '%s\n' "${arr[@]}" > /usr/share/pam-configs/pwhistory
            }
            Run the following command to update /etc/pam.d/common-password with the
            pwhistory profile:
            # pam-auth-update --enable pwhistory
            Note:

                 •   The name used for the file must be used in the pam-auth-update --enable
                     command
                 •   The Name: line should be easily recognizable and understood
                 •   The Priority: Line is important as it effects the order of the lines in the
                     /etc/pam.d/ files
                 •   If a site specific custom profile is being used in your environment to configure
                     PAM that includes the configuration for the pam_pwhistory module, enable that
                     module instead




                                                                                              Page 565

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 566

Internal Only - General
            5.3.3 Configure PAM Arguments

            Pluggable Authentication Modules (PAM) uses arguments to pass information to a
            pluggable module during authentication for a particular module type. These arguments
            allow the PAM configuration files for particular programs to use a common PAM module
            but in different ways.
            Invalid arguments are ignored and do not otherwise affect the success or failure of the
            PAM module. When an invalid argument is passed, an error is usually written to
            /var/log/messages file. However, since the reporting method is controlled by the PAM
            module, the module must be written correctly to log the error to this file.
            Note: If custom PAM files are being used, for this section's remediation, the
            corresponding files in /etc/pam.d/ would need to be edited directly, and the pam-
            auth-update --enable <EDITED_PROFILE_NAME> command skipped




                                                                                           Page 567

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            5.3.3.1 Configure pam_faillock module
            pam_faillock.so provides a way to configure the default settings for locking the user
            after multiple failed authentication attempts.
            Options:

                 •   <dir=/path/to/tally-directory> - The directory where the user files with the
                     failure records are kept. The default is /var/run/faillock. Note: These files will
                     disappear after reboot on systems configured with directory /var/run/faillock
                     mounted on virtual memory.
                 •   audit - Will log the user name into the system log if the user is not found.
                 •   silent - Don't print informative messages to the user. Please note that when
                     this option is not used there will be difference in the authentication behavior for
                     users which exist on the system and non-existing users.
                 •   no_log_info - Don't log informative messages via syslog(3).
                 •   local_users_only - Only track failed user authentications attempts for local
                     users in /etc/passwd and ignore centralized (AD, IdM, LDAP, etc.) users. The
                     faillock(8) command will also no longer track user failed authentication attempts.
                     Enabling this option will prevent a double-lockout scenario where a user is locked
                     out locally and in the centralized mechanism.
                 •   nodelay - Don't enforce a delay after authentication failures.
                 •   deny=<n> - Deny access if the number of consecutive authentication failures for
                     this user during the recent interval exceeds . The default is 3.
                 •   fail_interval=n - The length of the interval during which the consecutive
                     authentication failures must happen for the user account lock out is n seconds.
                     The default is 900 (15 minutes).
                 •   unlock_time=n - The access will be re-enabled after n seconds after the lock
                     out. The value 0 has the same meaning as value never - the access will not be
                     re-enabled without resetting the faillock entries by the faillock(8) command. The
                     default is 600 (10 minutes). Note that the default directory that pam_faillock uses
                     is usually cleared on system boot so the access will be also re-enabled after
                     system reboot. If that is undesirable a different tally directory must be set with the
                     dir option. Also note that it is usually undesirable to permanently lock out users
                     as they can become easily a target of denial of service attack unless the
                     usernames are random and kept secret to potential attackers.
                 •   even_deny_root - Root account can become locked as well as regular accounts.
                 •   root_unlock_time=n - This option implies even_deny_root option. Allow access
                     after n seconds to root account after the account is locked. In case the option is
                     not specified the value is the same as of the unlock_time option.
                 •   admin_group=name - If a group name is specified with this option, members of
                     the group will be handled by this module the same as the root account (the
                     options even_deny_root and root_unlock_time will apply to them. By default the
                     option is not set.




                                                                                                  Page 568

Internal Only - General
            5.3.3.1.1 Ensure password failed attempts lockout is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The deny=<n> option will deny access if the number of consecutive authentication
            failures for this user during the recent interval exceeds .
            Rationale:
            Locking out user IDs after n unsuccessful consecutive login attempts mitigates brute
            force password attacks against your systems.
            Audit:
            Run the following command to verify that Number of failed logon attempts before the
            account is locked is no greater than 5 and meets local site policy:
            # grep -Pi -- '^\h*deny\h*=\h*[1-5]\b' /etc/security/faillock.conf

            deny = 5
            Run the following command to verify that the deny argument has not been set, or 5 or
            less and meets local site policy:
            # grep -Pi --
            '^\h*auth\h+(requisite|required|sufficient)\h+pam_faillock\.so\h+([^#\n\r]+\h
            +)?deny\h*=\h*(0|[6-9]|[1-9][0-9]+)\b' /etc/pam.d/common-auth
            Nothing should be returned
            Remediation:
            Create or edit the following line in /etc/security/faillock.conf setting the deny
            option to 5 or less:
            deny = 5
            Run the following command:
            # grep -Pl -- '\bpam_faillock\.so\h+([^#\n\r]+\h+)?deny\b' /usr/share/pam-
            configs/*
            Edit any returned files and remove the deny=<N> arguments from the
            pam_faillock.so line(s):

            Default Value:
            deny = 3




                                                                                            Page 569

Internal Only - General
            Additional Information:
            If a user has been locked out because they have reached the maximum consecutive
            failure count defined by deny= in the pam_faillock.so module, the user can be
            unlocked by issuing the command faillock --user <USERNAME> --reset. This
            command sets the failed count to 0, effectively unlocking the user.
            CIS Controls:

              Controls
                                                              Control                                           IG 1 IG 2 IG 3
              Version
                          6.2 Establish an Access Revoking Process
                             Establish and follow a process, preferably automated, for revoking access to
                   v8     enterprise assets, through disabling accounts immediately upon termination, rights     ●    ●    ●
                          revocation, or role change of a user. Disabling accounts, instead of deleting
                          accounts, may be necessary to preserve audit trails.

                          16.7 Establish Process for Revoking Access
                              Establish and follow an automated process for revoking system access by
                   v7     disabling accounts immediately upon termination or change of responsibilities of an         ●    ●
                          employee or contractor . Disabling these accounts, instead of deleting accounts,
                          allows preservation of audit trails.




                                                                                                                      Page 570

Internal Only - General
            5.3.3.1.2 Ensure password unlock time is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            unlock_time=<n> - The access will be re-enabled after seconds after the lock out. The
            value 0 has the same meaning as value never - the access will not be re-enabled
            without resetting the faillock entries by the faillock(8) command.
            Note:

                 •   The default directory that pam_faillock uses is usually cleared on system boot so
                     the access will be also re-enabled after system reboot. If that is undesirable a
                     different tally directory must be set with the dir option.
                 •   It is usually undesirable to permanently lock out users as they can become easily
                     a target of denial of service attack unless the usernames are random and kept
                     secret to potential attackers.
                 •   The maximum configurable value for unlock_time is 604800

            Rationale:
            Locking out user IDs after n unsuccessful consecutive login attempts mitigates brute
            force password attacks against your systems.
            Impact:
            Use of unlock_time=0 may allow an attacker to cause denial of service to legitimate
            users. This will also require a systems administrator with elevated privileges to unlock
            the account.
            Audit:
            Run the following command to verify that the time in seconds before the account is
            unlocked is either 0 (never) or 900 (15 minutes) or more and meets local site policy:
            # grep -Pi -- '^\h*unlock_time\h*=\h*(0|9[0-9][0-9]|[1-9][0-9]{3,})\b'
            /etc/security/faillock.conf

            unlock_time = 900
            Run the following command to verify that the unlock_time argument has not been set,
            or is either 0 (never) or 900 (15 minutes) or more and meets local site policy:
            # grep -Pi --
            '^\h*auth\h+(requisite|required|sufficient)\h+pam_faillock\.so\h+([^#\n\r]+\h
            +)?unlock_time\h*=\h*([1-9]|[1-9][0-9]|[1-8][0-9][0-9])\b' /etc/pam.d/common-
            auth
            Nothing should be returned


                                                                                              Page 571

Internal Only - General
            Remediation:
            Set password unlock time to conform to site policy. unlock_time should be 0 (never),
            or 900 seconds or greater.
            Edit /etc/security/faillock.conf and update or add the following line:
            unlock_time = 900
            Run the following command: remove the unlock_time argument from the
            pam_faillock.so module in the PAM files:
            # grep -Pl -- '\bpam_faillock\.so\h+([^#\n\r]+\h+)?unlock_time\b'
            /usr/share/pam-configs/*
            Edit any returned files and remove the unlock_time=<N> argument from the
            pam_faillock.so line(s):

            Default Value:
            unlock_time = 600
            Additional Information:
            If a user has been locked out because they have reached the maximum consecutive
            failure count defined by deny= in the pam_faillock.so module, the user can be
            unlocked by issuing the command faillock --user <USERNAME> --reset. This
            command sets the failed count to 0, effectively unlocking the user.
            CIS Controls:

              Controls
                                                              Control                                           IG 1 IG 2 IG 3
              Version
                          6.2 Establish an Access Revoking Process
                             Establish and follow a process, preferably automated, for revoking access to
                   v8     enterprise assets, through disabling accounts immediately upon termination, rights     ●    ●    ●
                          revocation, or role change of a user. Disabling accounts, instead of deleting
                          accounts, may be necessary to preserve audit trails.

                          16.7 Establish Process for Revoking Access
                              Establish and follow an automated process for revoking system access by
                   v7     disabling accounts immediately upon termination or change of responsibilities of an         ●    ●
                          employee or contractor . Disabling these accounts, instead of deleting accounts,
                          allows preservation of audit trails.




                                                                                                                      Page 572

Internal Only - General
            5.3.3.1.3 Ensure password failed attempts lockout includes root
            account (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            even_deny_root - Root account can become locked as well as regular accounts
            root_unlock_time=n - This option implies even_deny_root option. Allow access after n
            seconds to root account after the account is locked. In case the option is not specified
            the value is the same as of the unlock_time option.
            Rationale:
            Locking out user IDs after n unsuccessful consecutive login attempts mitigates brute
            force password attacks against your systems.
            Impact:
            Use of unlock_time=0 or root_unlock_time=0 may allow an attacker to cause denial
            of service to legitimate users.




                                                                                            Page 573

Internal Only - General
            Audit:
            Run the following command to verify that even_deny_root and/or root_unlock_time
            is enabled:
            # grep -Pi -- '^\h*(even_deny_root|root_unlock_time\h*=\h*\d+)\b'
            /etc/security/faillock.conf
            Example output:
            even_deny_root

            --AND/OR--

            root_unlock_time = 60
            Run the following command to verify that - IF - root_unlock_time is set, it is set to 60
            (One minute) or more:
            # grep -Pi -- '^\h*root_unlock_time\h*=\h*([1-9]|[1-5][0-9])\b'
            /etc/security/faillock.conf
            Nothing should be returned
            Run the following command to check the pam_faillock.so module for the
            root_unlock_time argument. Verify -IF- root_unlock_time is set, it is set to 60 (One
            minute) or more:
            # grep -Pi --
            '^\h*auth\h+([^#\n\r]+\h+)pam_faillock\.so\h+([^#\n\r]+\h+)?root_unlock_time\
            h*=\h*([1-9]|[1-5][0-9])\b' /etc/pam.d/common-auth
            Nothing should be returned
            Remediation:
            Edit /etc/security/faillock.conf:

                 •   Remove or update any line containing root_unlock_time, - OR - set it to a
                     value of 60 or more
                 •   Update or add the following line:

            even_deny_root
            Run the following command:
            # grep -Pl --
            '\bpam_faillock\.so\h+([^#\n\r]+\h+)?(even_deny_root|root_unlock_time)'
            /usr/share/pam-configs/*
            Edit any returned files and remove the even_deny_root and root_unlock_time
            arguments from the pam_faillock.so line(s):

            Default Value:
            disabled




                                                                                             Page 574

Internal Only - General
            Additional Information:
            If a user has been locked out because they have reached the maximum consecutive
            failure count defined by deny= in the pam_faillock.so module, the user can be
            unlocked by issuing the command faillock --user <USERNAME> --reset. This
            command sets the failed count to 0, effectively unlocking the user.
            CIS Controls:

              Controls
                                                              Control                                           IG 1 IG 2 IG 3
              Version
                          6.2 Establish an Access Revoking Process
                             Establish and follow a process, preferably automated, for revoking access to
                   v8     enterprise assets, through disabling accounts immediately upon termination, rights     ●    ●    ●
                          revocation, or role change of a user. Disabling accounts, instead of deleting
                          accounts, may be necessary to preserve audit trails.

                          16.7 Establish Process for Revoking Access
                              Establish and follow an automated process for revoking system access by
                   v7     disabling accounts immediately upon termination or change of responsibilities of an         ●    ●
                          employee or contractor . Disabling these accounts, instead of deleting accounts,
                          allows preservation of audit trails.




                                                                                                                      Page 575

Internal Only - General
            5.3.3.2 Configure pam_pwquality module
            The pam_pwquality.so module checks the strength of passwords. It performs checks
            such as making sure a password is not a dictionary word, it is a certain length, contains
            a mix of characters (e.g. alphabet, numeric, other) and more.
            These checks are configurable by either:

                 •   use of the module arguments
                 •   modifying the /etc/security/pwquality.conf configuration file
                 •   creating a .conf file in the /etc/security/pwquality.conf.d/ directory.

            Note: The module arguments override the settings in the
            /etc/security/pwquality.conf configuration file. Settings in the
            /etc/security/pwquality.conf configuration file override settings in a .conf file in
            the /etc/security/pwquality.conf.d/ directory.
            The possible options in the file are:

                 •   difok - Number of characters in the new password that must not be present in
                     the old password. (default 1). The special value of 0 disables all checks of
                     similarity of the new password with the old password except the new password
                     being exactly the same as the old one.
                 •   minlen - Minimum acceptable size for the new password (plus one if credits are
                     not disabled which is the default). (See pam_pwquality(8).) Cannot be set to
                     lower value than 6. (default 8)
                 •   dcredit - The maximum credit for having digits in the new password. If less than
                     0 it is the minimum number of digits in the new password. (default 0)
                 •   ucredit - The maximum credit for having uppercase characters in the new
                     password. If less than 0 it is the minimum number of uppercase characters in the
                     new password. (default 0)
                 •   lcredit - The maximum credit for having lowercase characters in the new
                     password. If less than 0 it is the minimum number of lowercase characters in the
                     new password. (default 0)
                 •   ocredit - The maximum credit for having other characters in the new password.
                     If less than 0 it is the minimum number of other characters in the new password.
                     (default 0)
                 •   minclass - The minimum number of required classes of characters for the new
                     password (digits, uppercase, lowercase, others). (default 0)
                 •   maxrepeat - The maximum number of allowed same consecutive characters in
                     the new password. The check is disabled if the value is 0. (default 0)
                 •   maxsequence - The maximum length of monotonic character sequences in the
                     new password. Examples of such sequence are '12345' or 'fedcb'. Note that most
                     such passwords will not pass the simplicity check unless the sequence is only a
                     minor part of the password. The check is disabled if the value is 0. (default 0)




                                                                                             Page 576

Internal Only - General
                 •   maxclassrepeat - The maximum number of allowed consecutive characters of
                     the same class in the new password. The check is disabled if the value is 0.
                     (default 0)
                 •   gecoscheck - If nonzero, check whether the words longer than 3 characters from
                     the GECOS field of the user's passwd(5) entry are contained in the new
                     password. The check is disabled if the value is 0. (default 0)
                 •   dictcheck - If nonzero, check whether the password (with possible
                     modifications) matches a word in a dictionary. Currently the dictionary check is
                     performed

                     using the cracklib library. (default 1)

                 •   usercheck=<N> - If nonzero, check whether the password (with possible
                     modifications) contains the user name in some form. It is not performed for user
                     names

                     shorter than 3 characters. (default 1)

                 •   usersubstr=<N> - If greater than 3 (due to the minimum length in usercheck),
                     check whether the password contains a substring of at least N length in some
                     form.

                     (default 0)

                 •   enforcing=<N> - If nonzero, reject the password if it fails the checks, otherwise
                     only print the warning. This setting applies only to the pam_pwquality module

                     and possibly other applications that explicitly change their behavior based on it. It
                     does not affect pwmake(1) and pwscore(1). (default 1)

                 •   badwords - Space separated list of words that must not be contained in the
                     password. These are additional words to the cracklib dictionary check. This
                     setting can be also used by applications to emulate the gecos check for user
                     accounts that are not created yet.
                 •   dictpath - Path to the cracklib dictionaries. Default is to use the cracklib default.
                 •   retry=<N> - Prompt user at most N times before returning with error. The default
                     is 1.
                 •   enforce_for_root - The module will return error on failed check even if the user
                     changing the password is root. This option is off by default which means that just
                     the message about the failed check is printed but root can change the password
                     anyway. Note that root is not asked for an old password so the checks that
                     compare the old and new password are not performed.
                 •   local_users_only - The module will not test the password quality for users that
                     are not present in the /etc/passwd file. The module still asks for the password so
                     the following modules in the stack can use the use_authtok option. This option is
                     off by default.


                                                                                                 Page 577

Internal Only - General
            5.3.3.2.1 Ensure password number of changed characters is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The pwquality difok option sets the number of characters in a password that must not
            be present in the old password.
            Rationale:
            Use of a complex password helps to increase the time and resources required to
            compromise the password. Password complexity, or strength, is a measure of the
            effectiveness of a password in resisting attempts at guessing and brute-force attacks.
            Password complexity is one factor of several that determines how long it takes to crack
            a password. The more complex the password, the greater the number of possible
            combinations that need to be tested before the password is compromised.
            Audit:
            Run the following command to verify that the difok option is set to 2 or more and
            follows local site policy:
            # grep -Psi -- '^\h*difok\h*=\h*([2-9]|[1-9][0-9]+)\b'
            /etc/security/pwquality.conf /etc/security/pwquality.conf.d/*.conf
            Example output:
            /etc/security/pwquality.conf.d/50-pwdifok.conf:difok = 2
            Verify returned value(s) are 2 or more and meet local site policy
            Run the following command to verify that difok is not set, is 2 or more, and conforms to
            local site policy:
            grep -Psi --
            '^\h*password\h+(requisite|required|sufficient)\h+pam_pwquality\.so\h+([^#\n\
            r]+\h+)?difok\h*=\h*([0-1])\b' /etc/pam.d/common-password
            Nothing should be returned




                                                                                            Page 578

Internal Only - General
            Note:

                 •   settings should be configured in only one location for clarity
                 •   Settings observe an order of precedence:
                          o module arguments override the settings in the
                              /etc/security/pwquality.conf configuration file
                          o settings in the /etc/security/pwquality.conf configuration file
                              override settings in a .conf file in the
                              /etc/security/pwquality.conf.d/ directory
                          o settings in a .conf file in the /etc/security/pwquality.conf.d/
                              directory are read in canonical order, with last read file containing the
                              setting taking precedence
                 •   It is recommended that settings be configured in a .conf file in the
                     /etc/security/pwquality.conf.d/ directory for clarity, convenience, and
                     durability.

            Remediation:
            Create or modify a file ending in .conf in the /etc/security/pwquality.conf.d/
            directory or the file /etc/security/pwquality.conf and add or modify the following
            line to set difok to 2 or more. Ensure setting conforms to local site policy:
            Example:
            #!/usr/bin/env bash

            {
               sed -ri 's/^\s*difok\s*=/# &/' /etc/security/pwquality.conf
               [ ! -d /etc/security/pwquality.conf.d/ ] && mkdir
            /etc/security/pwquality.conf.d/
               printf '\n%s' "difok = 2" > /etc/security/pwquality.conf.d/50-pwdifok.conf
            }
            Run the following command:
            # grep -Pl -- '\bpam_pwquality\.so\h+([^#\n\r]+\h+)?difok\b' /usr/share/pam-
            configs/*
            Edit any returned files and remove the difok argument from the pam_pwquality.so
            line(s):
            Default Value:
            difok = 1
            References:

                 1. NIST SP 800-53 Rev. 5: IA-5




                                                                                                   Page 579

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 580

Internal Only - General
            5.3.3.2.2 Ensure minimum password length is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The minimum password length setting determines the lowers number of characters that
            make up a password for a user account. There are many different theories about how to
            determine the best password length for an organization, but perhaps "passphrase" is a
            better term than "password".
            The minlen option sets the minimum acceptable size for the new password (plus one if
            credits are not disabled which is the default). Cannot be set to lower value than 6.
            Rationale:
            Strong passwords help protect systems from password attacks. Types of password
            attacks include dictionary attacks, which attempt to use common words and phrases,
            and brute force attacks, which try every possible combination of characters. Also
            attackers may try to obtain the account database so they can use tools to discover the
            accounts and passwords.
            Impact:
            In general, it is true that longer passwords are better (harder to crack), but it is also true
            that forced password length requirements can cause user behavior that is predictable
            and undesirable. For example, requiring users to have a minimum 16-character
            password may cause them to choose repeating patterns like fourfourfourfour or
            passwordpassword that meet the requirement but aren’t hard to guess. Additionally,
            length requirements increase the chances that users will adopt other insecure practices,
            like writing them down, re-using them or storing them unencrypted in their documents.
            Having a reasonable minimum length with no maximum character limit increases the
            resulting average password length used (and therefore the strength).6




                                                                                                 Page 581

Internal Only - General
            Audit:
            Run the following command to verify that password length is 14 or more characters, and
            conforms to local site policy:
            # grep -Psi -- '^\h*minlen\h*=\h*(1[4-9]|[2-9][0-9]|[1-9][0-9]{2,})\b'
            /etc/security/pwquality.conf /etc/security/pwquality.conf.d/*.conf
            Example output:
            /etc/security/pwquality.conf.d/50-pwlength.conf:minlen = 14
            Verify returned value(s) are no less than 14 characters and meet local site policy
            Run the following command to verify that minlen is not set, or is 14 or more characters,
            and conforms to local site policy:
            # grep -Psi --
            '^\h*password\h+(requisite|required|sufficient)\h+pam_pwquality\.so\h+([^#\n\
            r]+\h+)?minlen\h*=\h*([0-9]|1[0-3])\b' /etc/pam.d/system-auth
            /etc/pam.d/common-password
            Nothing should be returned
            Note:

                 •   settings should be configured in only one location for clarity
                 •   Settings observe an order of precedence:
                          o module arguments override the settings in the
                              /etc/security/pwquality.conf configuration file
                          o settings in the /etc/security/pwquality.conf configuration file
                              override settings in a .conf file in the
                              /etc/security/pwquality.conf.d/ directory
                          o settings in a .conf file in the /etc/security/pwquality.conf.d/
                              directory are read in canonical order, with last read file containing the
                              setting taking precedence
                 •   It is recommended that settings be configured in a .conf file in the
                     /etc/security/pwquality.conf.d/ directory for clarity, convenience, and
                     durability.




                                                                                                   Page 582

Internal Only - General
            Remediation:
            Create or modify a file ending in .conf in the /etc/security/pwquality.conf.d/
            directory or the file /etc/security/pwquality.conf and add or modify the following
            line to set password length of 14 or more characters. Ensure that password length
            conforms to local site policy:
            Example:
            #!/usr/bin/env bash

            {
               sed -ri 's/^\s*minlen\s*=/# &/' /etc/security/pwquality.conf
               [ ! -d /etc/security/pwquality.conf.d/ ] && mkdir
            /etc/security/pwquality.conf.d/
               printf '\n%s' "minlen = 14" > /etc/security/pwquality.conf.d/50-
            pwlength.conf
            }
            Run the following command:
            # grep -Pl -- '\bpam_pwquality\.so\h+([^#\n\r]+\h+)?minlen\b' /usr/share/pam-
            configs/*
            Edit any returned files and remove the minlen argument from the pam_pwquality.so
            line(s):
            Default Value:
            minlen = 8
            References:

                 1. pam_pwquality(8)
                 2. CIS Password Policy Guide
                 3. NIST SP 800-53 Rev. 5: IA-5(1)

            CIS Controls:

                Controls
                                                              Control                                            IG 1 IG 2 IG 3
                Version
                           5.2 Use Unique Passwords
                   v8          Use unique passwords for all enterprise assets. Best practice implementation
                           includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                  ●    ●    ●
                           14-character password for accounts not using MFA.

                           4.4 Use Unique Passwords
                   v7         Where multi-factor authentication is not supported (such as local administrator,
                           root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                       ●    ●
                           system.




                                                                                                                       Page 583

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            5.3.3.2.3 Ensure password complexity is configured (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Password complexity can be set through:

                 •   minclass - The minimum number of classes of characters required in a new
                     password. (digits, uppercase, lowercase, others). e.g. minclass = 4 requires
                     digits, uppercase, lower case, and special characters.
                 •   dcredit - The maximum credit for having digits in the new password. If less than
                     0 it is the minimum number of digits in the new password. e.g. dcredit = -1
                     requires at least one digit
                 •   ucredit - The maximum credit for having uppercase characters in the new
                     password. If less than 0 it is the minimum number of uppercase characters in the
                     new password. e.g. ucredit = -1 requires at least one uppercase character
                 •   ocredit - The maximum credit for having other characters in the new password.
                     If less than 0 it is the minimum number of other characters in the new password.
                     e.g. ocredit = -1 requires at least one special character
                 •   lcredit - The maximum credit for having lowercase characters in the new
                     password. If less than 0 it is the minimum number of lowercase characters in the
                     new password. e.g. lcredit = -1 requires at least one lowercase character

            Rationale:
            Strong passwords protect systems from being hacked through brute force methods.
            Requiring at least one non-alphabetic character increases the search space beyond
            pure dictionary words, which makes the resulting password harder to crack.
            Forcing users to choose an excessively complex password, e.g. some combination of
            upper-case, lower-case, numbers, and special characters, has a negative impact. It
            places an extra burden on users and many will use predictable patterns (for example, a
            capital letter in the first position, followed by lowercase letters, then one or two numbers,
            and a “special character” at the end). Attackers know this, so dictionary attacks will
            often contain these common patterns and use the most common substitutions like, $ for
            s, @ for a, 1 for l, 0 for o.
            Impact:
            Passwords that are too complex in nature make it harder for users to remember, leading
            to bad practices. In addition, composition requirements provide no defense against
            common attack types such as social engineering or insecure storage of passwords




                                                                                                Page 584

Internal Only - General
            Audit:
            Run the following command to verify:

                 •   dcredit, ucredit, lcredit, and ocredit are not set to a value greater than 0
                 •   Complexity conforms to local site policy:

            # grep -Psi -- '^\h*(minclass|[dulo]credit)\b' /etc/security/pwquality.conf
            /etc/security/pwquality.conf.d/*.conf
            Example output:
            /etc/security/pwquality.conf.d/50-pwcomplexity.conf:minclass = 3
            /etc/security/pwquality.conf.d/50-pwcomplexity.conf:ucredit = -2
            /etc/security/pwquality.conf.d/50-pwcomplexity.conf:lcredit = -2
            /etc/security/pwquality.conf.d/50-pwcomplexity.conf:dcredit = -1
            /etc/security/pwquality.conf.d/50-pwcomplexity.conf:ocredit = 0
            The example represents a requirement of three character classes, with passwords
            requiring two upper case, two lower case, and one numeric character.
            Run the following command to verify that module arguments in the configuration file(s)
            are not being overridden by arguments in /etc/pam.d/common-password:
            # grep -Psi --
            '^\h*password\h+(requisite|required|sufficient)\h+pam_pwquality\.so\h+([^#\n\
            r]+\h+)?(minclass=\d*|[dulo]credit=-?\d*)\b' /etc/pam.d/common-password
            Nothing should be returned
            Note:

                 •   settings should be configured in only one location for clarity
                 •   Settings observe an order of precedence:
                          o module arguments override the settings in the
                              /etc/security/pwquality.conf configuration file
                          o settings in the /etc/security/pwquality.conf configuration file
                              override settings in a .conf file in the
                              /etc/security/pwquality.conf.d/ directory
                          o settings in a .conf file in the /etc/security/pwquality.conf.d/
                              directory are read in canonical order, with last read file containing the
                              setting taking precedence
                 •   It is recommended that settings be configured in a .conf file in the
                     /etc/security/pwquality.conf.d/ directory for clarity, convenience, and
                     durability.




                                                                                                   Page 585

Internal Only - General
            Remediation:
            Run the following command:
            # grep -Pl --
            '\bpam_pwquality\.so\h+([^#\n\r]+\h+)?(minclass|[dulo]credit)\b'
            /usr/share/pam-configs/*
            Edit any returned files and remove the minclass, dcredit, ucredit, lcredit, and
            ocredit arguments from the pam_pwquality.so line(s)
            Create or modify a file ending in .conf in the /etc/security/pwquality.conf.d/
            directory or the file /etc/security/pwquality.conf and add or modify the following
            line(s) to set complexity according to local site policy:

                 •   minclass = _N_
                 •   dcredit = _N_ # Value should be either 0 or a number proceeded by a minus (-
                     ) symbol
                 •   ucredit = -1 # Value should be either 0 or a number proceeded by a minus (-)
                     symbol
                 •   ocredit = -1 # Value should be either 0 or a number proceeded by a minus (-)
                     symbol
                 •   lcredit = -1 # Value should be either 0 or a number proceeded by a minus (-)
                     symbol

            Example 1 - Set minclass = 3:
            #!/usr/bin/env bash

            {
               sed -ri 's/^\s*minclass\s*=/# &/' /etc/security/pwquality.conf
               sed -ri 's/^\s*[dulo]credit\s*=/# &/' /etc/security/pwquality.conf
               [ ! -d /etc/security/pwquality.conf.d/ ] && mkdir
            /etc/security/pwquality.conf.d/
               printf '\n%s' "minclass = 3" > /etc/security/pwquality.conf.d/50-
            pwcomplexity.conf
            }
            Example 2 - set dcredit = -1, ucredit = -1, and lcredit = -1:
            #!/usr/bin/env bash

            {
               sed -ri 's/^\s*minclass\s*=/# &/' /etc/security/pwquality.conf
               sed -ri 's/^\s*[dulo]credit\s*=/# &/' /etc/security/pwquality.conf
               [ ! -d /etc/security/pwquality.conf.d/ ] && mkdir
            /etc/security/pwquality.conf.d/
               printf '%s\n' "dcredit = -1" "ucredit = -1" "lcredit = -1" >
            /etc/security/pwquality.conf.d/50-pwcomplexity.conf
            }




                                                                                         Page 586

Internal Only - General
            Default Value:
            minclass = 0
            dcredit = 0
            ucredit = 0
            ocredit = 0
            lcredit = 0
            References:

                 1. pam_pwquality(8)
                 2. PWQUALITY.CONF(5)
                 3. https://www.cisecurity.org/insights/white-papers/cis-password-policy-guide
                 4. NIST SP 800-53 Rev. 5: IA-5

            CIS Controls:

               Controls
                                                              Control                                            IG 1 IG 2 IG 3
               Version
                           5.2 Use Unique Passwords
                   v8          Use unique passwords for all enterprise assets. Best practice implementation
                           includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                  ●    ●    ●
                           14-character password for accounts not using MFA.

                           4.4 Use Unique Passwords
                   v7         Where multi-factor authentication is not supported (such as local administrator,
                           root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                       ●    ●
                           system.




                                                                                                                       Page 587

Internal Only - General
            5.3.3.2.4 Ensure password same consecutive characters is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The pwquality maxrepeat option sets the maximum number of allowed same
            consecutive characters in a new password.
            Rationale:
            Use of a complex password helps to increase the time and resources required to
            compromise the password. Password complexity, or strength, is a measure of the
            effectiveness of a password in resisting attempts at guessing and brute-force attacks.
            Password complexity is one factor of several that determines how long it takes to crack
            a password. The more complex the password, the greater the number of possible
            combinations that need to be tested before the password is compromised.
            Audit:
            Run the following command to verify that the maxrepeat option is set to 3 or less, not 0,
            and follows local site policy:
            # grep -Psi -- '^\h*maxrepeat\h*=\h*[1-3]\b' /etc/security/pwquality.conf
            /etc/security/pwquality.conf.d/*.conf
            Example output:
            /etc/security/pwquality.conf.d/50-pwrepeat.conf:maxrepeat = 3
            Verify returned value(s) are 3 or less, not 0, and meet local site policy
            Run the following command to verify that maxrepeat is not set, is 3 or less, not 0, and
            conforms to local site policy:
            # grep -Psi --
            '^\h*password\h+(requisite|required|sufficient)\h+pam_pwquality\.so\h+([^#\n\
            r]+\h+)?maxrepeat\h*=\h*(0|[4-9]|[1-9][0-9]+)\b' /etc/pam.d/common-password
            Nothing should be returned




                                                                                             Page 588

Internal Only - General
            Note:

                 •   settings should be configured in only one location for clarity
                 •   Settings observe an order of precedence:
                          o module arguments override the settings in the
                              /etc/security/pwquality.conf configuration file
                          o settings in the /etc/security/pwquality.conf configuration file
                              override settings in a .conf file in the
                              /etc/security/pwquality.conf.d/ directory
                          o settings in a .conf file in the /etc/security/pwquality.conf.d/
                              directory are read in canonical order, with last read file containing the
                              setting taking precedence
                 •   It is recommended that settings be configured in a .conf file in the
                     /etc/security/pwquality.conf.d/ directory for clarity, convenience, and
                     durability.

            Remediation:
            Create or modify a file ending in .conf in the /etc/security/pwquality.conf.d/
            directory or the file /etc/security/pwquality.conf and add or modify the following
            line to set maxrepeat to 3 or less and not 0. Ensure setting conforms to local site policy:
            Example:
            #!/usr/bin/env bash

            {
               sed -ri 's/^\s*maxrepeat\s*=/# &/' /etc/security/pwquality.conf
               [ ! -d /etc/security/pwquality.conf.d/ ] && mkdir
            /etc/security/pwquality.conf.d/
               printf '\n%s' "maxrepeat = 3" > /etc/security/pwquality.conf.d/50-
            pwrepeat.conf
            }
            Run the following command:
            # grep -Pl -- '\bpam_pwquality\.so\h+([^#\n\r]+\h+)?maxrepeat\b'
            /usr/share/pam-configs/*
            Edit any returned files and remove the maxrepeat argument from the
            pam_pwquality.so line(s):

            Default Value:
            maxrepeat = 0
            References:

                 1. NIST SP 800-53 Rev. 5: IA-5




                                                                                                   Page 589

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 590

Internal Only - General
            5.3.3.2.5 Ensure password maximum sequential characters is
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The pwquality maxsequence option sets the maximum length of monotonic character
            sequences in the new password. Examples of such sequence are 12345 or fedcb. The
            check is disabled if the value is 0.
            Note: Most such passwords will not pass the simplicity check unless the sequence is
            only a minor part of the password.
            Rationale:
            Use of a complex password helps to increase the time and resources required to
            compromise the password. Password complexity, or strength, is a measure of the
            effectiveness of a password in resisting attempts at guessing and brute-force attacks.
            Password complexity is one factor of several that determines how long it takes to crack
            a password. The more complex the password, the greater the number of possible
            combinations that need to be tested before the password is compromised.




                                                                                            Page 591

Internal Only - General
            Audit:
            Run the following command to verify that the maxsequence option is set to 3 or less, not
            0, and follows local site policy:
            # grep -Psi -- '^\h*maxsequence\h*=\h*[1-3]\b' /etc/security/pwquality.conf
            /etc/security/pwquality.conf.d/*.conf
            Example output:
            /etc/security/pwquality.conf.d/50-pwmaxsequence.conf:maxsequence = 3
            Verify returned value(s) are 3 or less, not 0, and meet local site policy
            Run the following command to verify that maxsequence is not set, is 3 or less, not 0, and
            conforms to local site policy:
            # grep -Psi --
            '^\h*password\h+(requisite|required|sufficient)\h+pam_pwquality\.so\h+([^#\n\
            r]+\h+)?maxsequence\h*=\h*(0|[4-9]|[1-9][0-9]+)\b' /etc/pam.d/common-password
            Nothing should be returned
            Note:

                 •   settings should be configured in only one location for clarity
                 •   Settings observe an order of precedence:
                          o module arguments override the settings in the
                              /etc/security/pwquality.conf configuration file
                          o settings in the /etc/security/pwquality.conf configuration file
                              override settings in a .conf file in the
                              /etc/security/pwquality.conf.d/ directory
                          o settings in a .conf file in the /etc/security/pwquality.conf.d/
                              directory are read in canonical order, with last read file containing the
                              setting taking precedence
                 •   It is recommended that settings be configured in a .conf file in the
                     /etc/security/pwquality.conf.d/ directory for clarity, convenience, and
                     durability.




                                                                                                   Page 592

Internal Only - General
            Remediation:
            Create or modify a file ending in .conf in the /etc/security/pwquality.conf.d/
            directory or the file /etc/security/pwquality.conf and add or modify the following
            line to set maxsequence to 3 or less and not 0. Ensure setting conforms to local site
            policy:
            Example:
            #!/usr/bin/env bash

            {
               sed -ri 's/^\s*maxsequence\s*=/# &/' /etc/security/pwquality.conf
               [ ! -d /etc/security/pwquality.conf.d/ ] && mkdir
            /etc/security/pwquality.conf.d/
               printf '\n%s' "maxsequence = 3" > /etc/security/pwquality.conf.d/50-
            pwmaxsequence.conf
            }
            Run the following command:
            # grep -Pl -- '\bpam_pwquality\.so\h+([^#\n\r]+\h+)?maxsequence\b'
            /usr/share/pam-configs/*
            Edit any returned files and remove the maxsequence argument from the
            pam_pwquality.so line(s):

            Default Value:
            maxsequence = 0
            References:

                 1. NIST SP 800-53 Rev. 5: IA-5

            CIS Controls:

                Controls
                                                              Control                                            IG 1 IG 2 IG 3
                Version
                           5.2 Use Unique Passwords
                   v8          Use unique passwords for all enterprise assets. Best practice implementation
                           includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                  ●    ●    ●
                           14-character password for accounts not using MFA.

                           4.4 Use Unique Passwords
                   v7         Where multi-factor authentication is not supported (such as local administrator,
                           root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                       ●    ●
                           system.




                                                                                                                       Page 593

Internal Only - General
            5.3.3.2.6 Ensure password dictionary check is enabled
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The pwquality dictcheck option sets whether to check for the words from the
            cracklib dictionary.

            Rationale:
            If the operating system allows the user to select passwords based on dictionary words,
            this increases the chances of password compromise by increasing the opportunity for
            successful guesses, and brute-force attacks.




                                                                                           Page 594

Internal Only - General
            Audit:
            Run the following command to verify that the dictcheck option is not set to 0 (disabled)
            in a pwquality configuration file:
            # grep -Psi -- '^\h*dictcheck\h*=\h*0\b' /etc/security/pwquality.conf
            /etc/security/pwquality.conf.d/*.conf
            Nothing should be returned
            Run the following command to verify that the dictcheck option is not set to 0 (disabled)
            as a module argument in a PAM file:
            # grep -Psi --
            '^\h*password\h+(requisite|required|sufficient)\h+pam_pwquality\.so\h+([^#\n\
            r]+\h+)?dictcheck\h*=\h*0\b' /etc/pam.d/common-password
            Nothing should be returned
            Note:

                 •   Settings observe an order of precedence:
                          o module arguments override the settings in the
                              /etc/security/pwquality.conf configuration file
                          o settings in the /etc/security/pwquality.conf configuration file
                              override settings in a .conf file in the
                              /etc/security/pwquality.conf.d/ directory
                          o settings in a .conf file in the /etc/security/pwquality.conf.d/
                              directory are read in canonical order, with last read file containing the
                              setting taking precedence
                 •   It is recommended that settings be configured in a .conf file in the
                     /etc/security/pwquality.conf.d/ directory for clarity, convenience, and
                     durability.

            Remediation:
            Edit any file ending in .conf in the /etc/security/pwquality.conf.d/ directory
            and/or the file /etc/security/pwquality.conf and comment out or remove any
            instance of dictcheck = 0:
            Example:
            # sed -ri 's/^\s*dictcheck\s*=/# &/' /etc/security/pwquality.conf
            /etc/security/pwquality.conf.d/*.conf
            Run the following command:
            # grep -Pl -- '\bpam_pwquality\.so\h+([^#\n\r]+\h+)?dictcheck\b'
            /usr/share/pam-configs/*
            Edit any returned files and remove the dictcheck argument from the
            pam_pwquality.so line(s)

            Default Value:
            dictcheck = 1



                                                                                                   Page 595

Internal Only - General
            References:

                 1. NIST SP 800-53 Rev. 5: IA-5

            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 596

Internal Only - General
            5.3.3.2.7 Ensure password quality checking is enforced
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The pam_pwquality module can be configured to either reject a password if it fails the
            checks, or only print a warning.
            This is configured by setting the enforcing=<N> argument. If nonzero, a password will
            be rejected if it fails the checks, otherwise only a warning message will be provided.
            This setting applies only to the pam_pwquality module and possibly other applications
            that explicitly change their behavior based on it. It does not affect pwmake(1) and
            pwscore(1).
            Rationale:
            Strong passwords help protect systems from password attacks. Types of password
            attacks include dictionary attacks, which attempt to use common words and phrases,
            and brute force attacks, which try every possible combination of characters. Also
            attackers may try to obtain the account database so they can use tools to discover the
            accounts and passwords.
            Audit:
            Run the following command to verify that enforcing=0 has not been set in a
            pwquality configuration file:
            # grep -PHsi -- '^\h*enforcing\h*=\h*0\b' /etc/security/pwquality.conf
            /etc/security/pwquality.conf.d/*.conf
            Nothing should be returned
            Run the following command to verify that the enforcing=0 argument has not been set
            on the pam_pwquality module:
            # grep -PHsi --
            '^\h*password\h+[^#\n\r]+\h+pam_pwquality\.so\h+([^#\n\r]+\h+)?enforcing=0\b'
            /etc/pam.d/common-password
            Nothing should be returned




                                                                                            Page 597

Internal Only - General
            Remediation:
            Run the following command:
            # grep -Pl -- '\bpam_pwquality\.so\h+([^#\n\r]+\h+)?enforcing=0\b'
            /usr/share/pam-configs/*
            Edit any returned files and remove the enforcing=0 argument from the
            pam_pwquality.so line(s)
            Edit /etc/security/pwquality.conf and all files ending in .conf in the
            /etc/security/pwquality.conf.d/ directory and remove or comment out any line
            containing the enforcing = 0 argument:
            Example:
            # sed -ri 's/^\s*enforcing\s*=\s*0/# &/' /etc/security/pwquality.conf
            /etc/security/pwquality.conf.d/*.conf

            Default Value:
            enforcing=1
            References:

                 1. pam_pwquality(8)
                 2. PWQUALITY.CONF(5)
                 3. NIST SP 800-53 Rev. 5: IA-5

            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 598

Internal Only - General
            5.3.3.2.8 Ensure password quality is enforced for the root user
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            If the pwquality enforce_for_root option is enabled, the module will return error on
            failed check even if the user changing the password is root.
            This option is off by default which means that just the message about the failed check is
            printed but root can change the password anyway.
            Note: The root is not asked for an old password so the checks that compare the old and
            new password are not performed.
            Rationale:
            Use of a complex password helps to increase the time and resources required to
            compromise the password. Password complexity, or strength, is a measure of the
            effectiveness of a password in resisting attempts at guessing and brute-force attacks.
            Password complexity is one factor of several that determines how long it takes to crack
            a password. The more complex the password, the greater the number of possible
            combinations that need to be tested before the password is compromised.




                                                                                             Page 599

Internal Only - General
            Audit:
            Run the following command to verify that the enforce_for_root option is enabled in a
            pwquality configuration file:
            # grep -Psi -- '^\h*enforce_for_root\b' /etc/security/pwquality.conf
            /etc/security/pwquality.conf.d/*.conf
            Example output:
            /etc/security/pwquality.conf.d/50-pwroot.conf:enforce_for_root
            Note:
                 •   Settings observe an order of precedence:
                          o module arguments override the settings in the
                              /etc/security/pwquality.conf configuration file
                          o settings in the /etc/security/pwquality.conf configuration file
                              override settings in a .conf file in the
                              /etc/security/pwquality.conf.d/ directory
                          o settings in a .conf file in the /etc/security/pwquality.conf.d/
                              directory are read in canonical order, with last read file containing the
                              setting taking precedence
                 •   It is recommended that settings be configured in a .conf file in the
                     /etc/security/pwquality.conf.d/ directory for clarity, convenience, and
                     durability.
            Remediation:
            Edit or add the following line in a *.conf file in /etc/security/pwquality.conf.d or
            in /etc/security/pwquality.conf:
            Example:
            #!/usr/bin/env bash

            {
               [ ! -d /etc/security/pwquality.conf.d/ ] && mkdir
            /etc/security/pwquality.conf.d/
               printf '\n%s\n' "enforce_for_root" > /etc/security/pwquality.conf.d/50-
            pwroot.conf
            }

            Default Value:
            disabled
            References:

                 1. NIST SP 800-53 Rev. 5: IA-5




                                                                                                   Page 600

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 601

Internal Only - General
            5.3.3.3 Configure pam_pwhistory module
            pam_pwhistory - PAM module to remember last passwords
            pam_history.so module - This module saves the last passwords for each user in order
            to force password change history and keep the user from alternating between the same
            password too frequently.
            This module does not work together with kerberos. In general, it does not make much
            sense to use this module in conjunction with NIS or LDAP, since the old passwords are
            stored on the local machine and are not available on another machine for password
            history checking.
            Options:

                 •     debug - Turns on debugging via syslog(3).
                 •     use_authtok - When password changing enforce the module to use the new
                       password provided by a previously stacked password module (this is used in the
                       example of the stacking of the pam_passwdqc module documented below).
                 •     enforce_for_root - If this option is set, the check is enforced for root, too.
                 •     remember=<N> - The last <N> passwords for each user are saved. The default is
                       10. Value of 0 makes the module to keep the existing contents of the opasswd
                       file unchanged.
                 •     retry=<N> - Prompt user at most <N> times before returning with error. The
                       default is 1.
                 •     authtok_type=<STRING> - See pam_get_authtok(3) for more details.

            Examples:
            An example password section would be:

                     #%PAM-1.0
                     password      required        pam_pwhistory.so
                     password      required        pam_unix.so          use_authtok

            In combination with pam_passwdqc:

                     #%PAM-1.0
                     password      required        pam_passwdqc.so      config=/etc/passwdqc.conf
                     password      required        pam_pwhistory.so     use_authtok
                     password      required        pam_unix.so          use_authtok




                                                                                              Page 602

Internal Only - General
            5.3.3.3.1 Ensure password history remember is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/security/opasswd file stores the users' old passwords and can be checked
            to ensure that users are not recycling recent passwords. The number of passwords
            remembered is set via the remember argument value in set for the pam_pwhistory
            module.

                 •   remember=<N> - <N> is the number of old passwords to remember

            Rationale:
            Requiring users not to reuse their passwords make it less likely that an attacker will be
            able to guess the password or use a compromised password.
            Note: These change only apply to accounts configured on the local system.
            Audit:
            Run the following command and verify:

                 •   The pwhistory line in /etc/pam.d/common-password includes remember=<N>
                 •   The value of <N> is 24 or more
                 •   The value meets local site policy

            # grep -Psi --
            '^\h*password\h+[^#\n\r]+\h+pam_pwhistory\.so\h+([^#\n\r]+\h+)?remember=\d+\b
            ' /etc/pam.d/common-password
            Output should be similar to:
            password    requisite     pam_pwhistory.so remember=24 enforce_for_root
            use_authtok




                                                                                              Page 603

Internal Only - General
            Remediation:
            Run the following command:
            # awk '/Password-Type:/{ f = 1;next } /-Type:/{ f = 0 } f {if
            (/pam_pwhistory\.so/) print FILENAME}' /usr/share/pam-configs/*
            Edit any returned files and edit or add the remember= argument, with a value of 24 or
            more, that meets local site policy to the pam_pwhistory line in the Password section:
            Example File:
            Name: pwhistory password history checking
            Default: yes
            Priority: 1024
            Password-Type: Primary
            Password:
               requisite   pam_pwhistory.so remember=24 enforce_for_root use_authtok # <-
            **ensure line includes remember=<N>**
            Run the following command to update the files in the /etc/pam.d/ directory:
            # pam-auth-update --enable <MODIFIED_PROFILE_NAME>
            Example:
            # pam-auth-update --enable pwhistory

            References:

                 1. NIST SP 800-53 Rev. 5: IA-5(1)

            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 604

Internal Only - General
            5.3.3.3.2 Ensure password history is enforced for the root user
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            If the pwhistory enforce_for_root option is enabled, the module will enforce
            password history for the root user as well
            Rationale:
            Requiring users not to reuse their passwords make it less likely that an attacker will be
            able to guess the password or use a compromised password
            Note: These change only apply to accounts configured on the local system.
            Audit:
            Run the following command to verify that the enforce_for_root argument is exists on
            the pwhistory line in /etc/pam.d/common-password:
            # grep -Psi --
            '^\h*password\h+[^#\n\r]+\h+pam_pwhistory\.so\h+([^#\n\r]+\h+)?enforce_for_ro
            ot\b' /etc/pam.d/common-password
            Output should be similar to:
            password    requisite     pam_pwhistory.so remember=24 enforce_for_root
            use_authtok




                                                                                              Page 605

Internal Only - General
            Remediation:
            Run the following command:
            # awk '/Password-Type:/{ f = 1;next } /-Type:/{ f = 0 } f {if
            (/pam_pwhistory\.so/) print FILENAME}' /usr/share/pam-configs/*
            Edit any returned files and add the enforce_for_root argument to the
            pam_pwhistory line in the Password section:
            Example File:
            Name: pwhistory password history checking
            Default: yes
            Priority: 1024
            Password-Type: Primary
            Password:
               requisite   pam_pwhistory.so remember=24 enforce_for_root use_authtok # <-
            **ensure line includes enforce_for_root**
            Run the following command to update the files in the /etc/pam.d/ directory:
            # pam-auth-update --enable <MODIFIED_PROFILE_NAME>
            Example:
            # pam-auth-update --enable pwhistory

            Default Value:
            disabled
            References:

                 1. NIST SP 800-53 Rev. 5: IA-5

            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 606

Internal Only - General
            5.3.3.3.3 Ensure pam_pwhistory includes use_authtok
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            use_authtok - When password changing enforce the module to set the new password
            to the one provided by a previously stacked password module
            Rationale:
            use_authtok allows multiple pam modules to confirm a new password before it is
            accepted.
            Audit:
            Run the following command to verify that the use_authtok argument exists on the
            pwhistory line in /etc/pam.d/common-password:
            # grep -Psi --
            '^\h*password\h+[^#\n\r]+\h+pam_pwhistory\.so\h+([^#\n\r]+\h+)?use_authtok\b'
            /etc/pam.d/common-password
            Output should be similar to:
            password    requisite     pam_pwhistory.so remember=24 enforce_for_root
            use_authtok




                                                                                        Page 607

Internal Only - General
            Remediation:
            Run the following command:
            # awk '/Password-Type:/{ f = 1;next } /-Type:/{ f = 0 } f {if
            (/pam_pwhistory\.so/) print FILENAME}' /usr/share/pam-configs/*
            Edit any returned files and add the use_authtok argument to the pam_pwhistory line
            in the Password section:
            Example File:
            Name: pwhistory password history checking
            Default: yes
            Priority: 1024
            Password-Type: Primary
            Password:
               requisite   pam_pwhistory.so remember=24 enforce_for_root use_authtok # <-
            **ensure line includes use_authtok**
            Run the following command to update the files in the /etc/pam.d/ directory:
            # pam-auth-update --enable <MODIFIED_PROFILE_NAME>
            Example:
            # pam-auth-update --enable pwhistory

            References:

                 1. NIST SP 800-53 Rev. 5: IA-5

            CIS Controls:

              Controls
                                                               Control                                           IG 1 IG 2 IG 3
              Version
                          3.11 Encrypt Sensitive Data at Rest
                             Encrypt sensitive data at rest on servers, applications, and databases containing
                          sensitive data. Storage-layer encryption, also known as server-side encryption,
                  v8      meets the minimum requirement of this Safeguard. Additional encryption methods               ●    ●
                          may include application-layer encryption, also known as client-side encryption,
                          where access to the data storage device(s) does not permit access to the plain-text
                          data.

                  v7      16.4 Encrypt or Hash all Authentication Credentials                                          ●    ●
                             Encrypt or hash with a salt all authentication credentials when stored.




                                                                                                                       Page 608

Internal Only - General
            5.3.3.4 Configure pam_unix module
            The pam_unix.so module is the standard Unix authentication module. It uses standard
            calls from the system's libraries to retrieve and set account information as well as
            authentication. Usually this is obtained from the /etc/passwd and the /etc/shadow file
            as well if shadow is enabled.




                                                                                          Page 609

Internal Only - General
            5.3.3.4.1 Ensure pam_unix does not include nullok (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The nullok argument overrides the default action of pam_unix.so to not permit the
            user access to a service if their official password is blank.
            Rationale:
            Using a strong password is essential to helping protect personal and sensitive
            information from unauthorized access
            Audit:
            Run the following command to verify that the nullok argument is not set on the
            pam_unix.so module:
            # grep -PHs -- '^\h*[^#\n\r]+\h+pam_unix\.so\h+([^#\n\r]+\h+)?nullok\b'
            /etc/pam.d/common-{password,auth,account,session,session-noninteractive}
            Nothing should be returned




                                                                                             Page 610

Internal Only - General
            Remediation:
            Run the following command:
            # grep -PH -- '^\h*([^#\n\r]+\h+)?pam_unix\.so\h+([^#\n\r]+\h+)?nullok\b'
            /usr/share/pam-configs/*
            Edit any files returned and remove the nullok argument for the pam_unix lines
            Example File:
            Name: Unix authentication
            Default: yes
            Priority: 256
            Auth-Type: Primary
            Auth:
                     [success=end default=ignore]    pam_unix.so try_first_pass # <-
            **ensure line does not include nullok nullok**
            Auth-Initial:
                     [success=end default=ignore]    pam_unix.so # <- **ensure line does
            not include nullok nullok**
            Account-Type: Primary
            Account:
                     [success=end new_authtok_reqd=done default=ignore]      pam_unix.so
            Account-Initial:
                     [success=end new_authtok_reqd=done default=ignore]      pam_unix.so
            Session-Type: Additional
            Session:
                     required        pam_unix.so
            Session-Initial:
                     required        pam_unix.so
            Password-Type: Primary
            Password:
                     [success=end default=ignore]    pam_unix.so obscure use_authtok
            try_first_pass yescrypt
            Password-Initial:
                     [success=end default=ignore]    pam_unix.so obscure yescrypt
            Run the following command to update the files in the /etc/pam.d/ directory:
            # pam-auth-update --enable <EDITED_PROFILE_NAME>
            Example:
            # pam-auth-update --enable unix
            Note: If custom files are being used, the corresponding files in /etc/pam.d/ would
            need to be edited directly, and the pam-auth-update --enable
            <EDITED_PROFILE_NAME> command skipped




                                                                                            Page 611

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 612

Internal Only - General
            5.3.3.4.2 Ensure pam_unix does not include remember
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The remember=n argument saves the last n passwords for each user in
            /etc/security/opasswd in order to force password change history and keep the user
            from alternating between the same password too frequently. The MD5 password hash
            algorithm is used for storing the old passwords. Instead of this option the
            pam_pwhistory module should be used. The pam_pwhistory module saves the last n
            passwords for each user in /etc/security/opasswd using the password hash
            algorithm set on the pam_unix module. This allows for the yescrypt or sha512 hash
            algorithm to be used.
            Rationale:
            The remember=n argument should be removed to ensure a strong password hashing
            algorithm is being used. A stronger hash provides additional protection to the system by
            increasing the level of effort needed for an attacker to successfully determine local
            user's old passwords stored in /etc/security/opasswd.

            Audit:
            Run the following command to verify that the remember argument is not set on the
            pam_unix.so module:
            # grep -PHs --
            '^\h*^\h*[^#\n\r]+\h+pam_unix\.so\h+([^#\n\r]+\h+)?remember=\d+\b'
            /etc/pam.d/common-{password,auth,account,session,session-noninteractive}
            Nothing should be returned




                                                                                            Page 613

Internal Only - General
            Remediation:
            Run the following command:
            # grep -PH -- '^\h*([^#\n\r]+\h+)?pam_unix\.so\h+([^#\n\r]+\h+)?remember\b'
            /usr/share/pam-configs/*
            Edit any files returned and remove the remember=_<N>_ argument for the pam_unix
            lines
            Example output:
            [success=end default=ignore]   pam_unix.so obscure use_authtok try_first_pass
            yescrypt remember=5 # **<- remove remember=<N>**
            [success=end default=ignore]   pam_unix.so obscure yescrypt remember=5 # **<-
            remove remember=<N>**

            Run the following command to update the files in the /etc/pam.d/ directory:
            # pam-auth-update --enable <EDITED_PROFILE_NAME>
            Example:
            # pam-auth-update --enable unix
            Note: If custom files are being used, the corresponding files in /etc/pam.d/ would
            need to be edited directly, and the pam-auth-update --enable
            <EDITED_PROFILE_NAME> command skipped

            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 614

Internal Only - General
            5.3.3.4.3 Ensure pam_unix includes a strong password hashing
            algorithm (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            A cryptographic hash function converts an arbitrary-length input into a fixed length
            output. Password hashing performs a one-way transformation of a password, turning
            the password into another string, called the hashed password.
            The pam_unix module can be configured to use one of the following hashing algorithms
            for user's passwords:

                 •   md5 - When a user changes their password next, encrypt it with the MD5
                     algorithm.
                 •   bigcrypt - When a user changes their password next, encrypt it with the DEC C2
                     algorithm.
                 •   sha256 - When a user changes their password next, encrypt it with the SHA256
                     algorithm. The SHA256 algorithm must be supported by the crypt(3) function.
                 •   sha512 - When a user changes their password next, encrypt it with the SHA512
                     algorithm. The SHA512 algorithm must be supported by the crypt(3) function.
                 •   blowfish - When a user changes their password next, encrypt it with the
                     blowfish algorithm. The blowfish algorithm must be supported by the crypt(3)
                     function.
                 •   gost_yescrypt - When a user changes their password next, encrypt it with the
                     gost-yescrypt algorithm. The gost-yescrypt algorithm must be supported by
                     the crypt(3) function.
                 •   yescrypt - When a user changes their password next, encrypt it with the
                     yescrypt algorithm. The yescrypt algorithm must be supported by the crypt(3)
                     function.

            Rationale:
            The SHA-512 and yescrypt algorithms provide a stronger hash than other algorithms
            used by Linux for password hash generation. A stronger hash provides additional
            protection to the system by increasing the level of effort needed for an attacker to
            successfully determine local user passwords.
            Note: These changes only apply to the local system.




                                                                                           Page 615

Internal Only - General
            Audit:
            Run the following command to verify that a strong password hashing algorithm is set on
            the pam_unix.so module:
            # grep -PH --
            '^\h*password\h+([^#\n\r]+)\h+pam_unix\.so\h+([^#\n\r]+\h+)?(sha512|yescrypt)
            \b' /etc/pam.d/common-password
            Output should be similar to:
            /etc/pam.d/common-password:password   [success=1 default=ignore]
            pam_unix.so obscure use_authtok try_first_pass yescrypt
            Verify that the line(s) include either sha512 - OR - yescrypt




                                                                                          Page 616

Internal Only - General
            Remediation:
            Run the following command:
            # awk '/Password-Type:/{ f = 1;next } /-Type:/{ f = 0 } f {if
            (/pam_unix\.so/) print FILENAME}' /usr/share/pam-configs/*
            Edit any returned files and edit or add a strong hashing algorithm, either sha512 or
            yescrypt, that meets local site policy to the pam_unix lines in the Password section:
            Example File:
            Name: Unix authentication
            Default: yes
            Priority: 256
            Auth-Type: Primary # <- Start of "Auth" section
            Auth:
                     [success=end default=ignore]    pam_unix.so try_first_pass
            Auth-Initial:
                     [success=end default=ignore]    pam_unix.so
            Account-Type: Primary # <- Start of "Account" section
            Account:
                     [success=end new_authtok_reqd=done default=ignore]      pam_unix.so
            Account-Initial:
                     [success=end new_authtok_reqd=done default=ignore]      pam_unix.so
            Session-Type: Additional # <- Start of "Session" section
            Session:
                     required        pam_unix.so
            Session-Initial:
                     required        pam_unix.so
            Password-Type: Primary # <- Start of "Password" section
            Password:
                     [success=end default=ignore]    pam_unix.so obscure use_authtok
            try_first_pass yescrypt # <- **ensure hashing algorithm is either sha512 or
            yescrypt**
            Password-Initial:
                     [success=end default=ignore]    pam_unix.so obscure yescrypt # <-
            **ensure hashing algorithm is either sha512 or yescrypt**
            Run the following command to update the files in the /etc/pam.d/ directory:
            # pam-auth-update --enable <MODIFIED_PROFILE_NAME>
            Example:
            # pam-auth-update --enable unix

            References:

                 1. NIST SP 800-53 Rev. 5: IA-5




                                                                                            Page 617

Internal Only - General
            Additional Information:
            The following command may be used to expire all non-system user ID's immediately
            and force them to change their passwords on next login. Any system accounts that
            need to be expired should be carefully done separately by the system administrator to
            prevent any potential problems.
            # awk -F: '( $3<'"$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)"' && $1 !=
            "nfsnobody" ) { print $1 }' /etc/passwd | xargs -n 1 chage -d 0

            CIS Controls:

              Controls
                                                               Control                                           IG 1 IG 2 IG 3
              Version
                          3.11 Encrypt Sensitive Data at Rest
                             Encrypt sensitive data at rest on servers, applications, and databases containing
                          sensitive data. Storage-layer encryption, also known as server-side encryption,
                  v8      meets the minimum requirement of this Safeguard. Additional encryption methods               ●    ●
                          may include application-layer encryption, also known as client-side encryption,
                          where access to the data storage device(s) does not permit access to the plain-text
                          data.

                  v7      16.4 Encrypt or Hash all Authentication Credentials                                          ●    ●
                             Encrypt or hash with a salt all authentication credentials when stored.




                                                                                                                       Page 618

Internal Only - General
            5.3.3.4.4 Ensure pam_unix includes use_authtok (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            use_authtok - When password changing enforce the module to set the new password
            to the one provided by a previously stacked password module
            Rationale:
            use_authtok allows multiple pam modules to confirm a new password before it is
            accepted.
            Audit:
            Run the following command to verify that use_authtok is set on the pam_unix.so
            module lines in the password stack:
            # grep -PH --
            '^\h*password\h+([^#\n\r]+)\h+pam_unix\.so\h+([^#\n\r]+\h+)?use_authtok\b'
            /etc/pam.d/common-password
            Output should be similar to:
            /etc/pam.d/common-password:password   [success=1 default=ignore]
            pam_unix.so obscure use_authtok try_first_pass yescrypt
            Verify that the line(s) include use_authtok




                                                                                        Page 619

Internal Only - General
            Remediation:
            Run the following command:
            # awk '/Password-Type:/{ f = 1;next } /-Type:/{ f = 0 } f {if
            (/pam_unix\.so/) print FILENAME}' /usr/share/pam-configs/*
            Edit any returned files add use_authtok to the pam_unix line in the Password section
            under Password: subsection:
            Note: The if the file's Password section includes a Password-Initial: subsection,
            use_authtok should not be added to the pam_unix line in the Password-Initial:
            subsection
            Example File:
            Name: Unix authentication
            Default: yes
            Priority: 256
            Auth-Type: Primary # <- Start of "Auth" section
            Auth:
                     [success=end default=ignore]    pam_unix.so try_first_pass
            Auth-Initial:
                     [success=end default=ignore]    pam_unix.so
            Account-Type: Primary # <- Start of "Account" section
            Account:
                     [success=end new_authtok_reqd=done default=ignore]      pam_unix.so
            Account-Initial:
                     [success=end new_authtok_reqd=done default=ignore]      pam_unix.so
            Session-Type: Additional # <- Start of "Session" section
            Session:
                     required        pam_unix.so
            Session-Initial:
                     required        pam_unix.so
            Password-Type: Primary # <- Start of "Password" section
            Password:
                     [success=end default=ignore]    pam_unix.so obscure use_authtok
            try_first_pass yescrypt # <- **ensure line includes use_authtok**
            Password-Initial:
                     [success=end default=ignore]    pam_unix.so obscure yescrypt # <-
            **Password-Initial: subsection does not include use_authtok
            Run the following command to update the files in the /etc/pam.d/ directory:
            # pam-auth-update --enable <MODIFIED_PROFILE_NAME>
            Example:
            # pam-auth-update --enable unix

            References:

                 1. NIST SP 800-53 Rev. 5: IA-5




                                                                                          Page 620

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                           IG 1 IG 2 IG 3
              Version
                          3.11 Encrypt Sensitive Data at Rest
                             Encrypt sensitive data at rest on servers, applications, and databases containing
                          sensitive data. Storage-layer encryption, also known as server-side encryption,
                  v8      meets the minimum requirement of this Safeguard. Additional encryption methods               ●    ●
                          may include application-layer encryption, also known as client-side encryption,
                          where access to the data storage device(s) does not permit access to the plain-text
                          data.

                  v7      16.4 Encrypt or Hash all Authentication Credentials                                          ●    ●
                             Encrypt or hash with a salt all authentication credentials when stored.




            5.4 User Accounts and Environment

            This section provides guidance on setting up secure defaults for system and user
            accounts and their environment.




                                                                                                                       Page 621

Internal Only - General
            5.4.1 Configure shadow password suite parameters

            While a majority of the password control parameters have been moved to PAM, some
            parameters are still available through the shadow password suite. Any changes made to
            /etc/login.defs will only be applied if the usermod command is used. If user IDs are
            added a different way, use the chage command to effect changes to individual user IDs.




                                                                                          Page 622

Internal Only - General
            5.4.1.1 Ensure password expiration is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The PASS_MAX_DAYS parameter in /etc/login.defs allows an administrator to force
            passwords to expire once they reach a defined age.
            PASS_MAX_DAYS <N> - The maximum number of days a password may be used. If the
            password is older than this, a password change will be forced. If not specified, -1 will be
            assumed (which disables the restriction).
            Rationale:
            The window of opportunity for an attacker to leverage compromised credentials or
            successfully compromise credentials via an online brute force attack is limited by the
            age of the password. Therefore, reducing the maximum age of a password also reduces
            an attacker's window of opportunity.
            We recommend a yearly password change. This is primarily because for all their good
            intentions users will share credentials across accounts. Therefore, even if a breach is
            publicly identified, the user may not see this notification, or forget they have an account
            on that site. This could leave a shared credential vulnerable indefinitely. Having an
            organizational policy of a 1-year (annual) password expiration is a reasonable
            compromise to mitigate this with minimal user burden.
            Impact:
            The password expiration must be greater than the minimum days between password
            changes or users will be unable to change their password.
            Excessive password expiration requirements do more harm than good, because these
            requirements make users select predictable passwords, composed of sequential words
            and numbers that are closely related to each other. In these cases, the next password
            can be predicted based on the previous one (incrementing a number used in the
            password for example). Also, password expiration requirements offer no containment
            benefits because attackers will often use credentials as soon as they compromise them.
            Instead, immediate password changes should be based on key events including, but not
            limited to:

                 •   Indication of compromise
                 •   Change of user roles
                 •   When a user leaves the organization.




                                                                                               Page 623

Internal Only - General
            Not only does changing passwords every few weeks or months frustrate the user, but
            it’s also been suggested that it does more harm than good, because it could lead to bad
            practices by the user such as adding a character to the end of their existing password.
            Audit:
            Run the following command and verify PASS_MAX_DAYS is set to 365 days or less and
            conforms to local site policy:
            # grep -Pi -- '^\h*PASS_MAX_DAYS\h+\d+\b' /etc/login.defs
            Example output:
            PASS_MAX_DAYS 365
            Run the following command to verify all /etc/shadow passwords PASS_MAX_DAYS:

                 •   is greater than 0 days
                 •   is less than or equal to 365 days
                 •   conforms to local site policy

            # awk -F: '($2~/^\$.+\$/) {if($5 > 365 || $5 < 1)print "User: " $1 "
            PASS_MAX_DAYS: " $5}' /etc/shadow
            Nothing should be returned
            Remediation:
            Set the PASS_MAX_DAYS parameter to conform to site policy in /etc/login.defs :
            PASS_MAX_DAYS 365
            Modify user parameters for all users with a password set to match:
            # chage --maxdays 365 <user>
            Edit /etc/login.defs and set PASS_MAX_DAYS to a value greater than 0 that follows
            local site policy:
            Example:
            PASS_MAX_DAYS 365
            Run the following command to modify user parameters for all users with a password set
            to a maximum age no greater than 365 or less than 1 that follows local site policy:
            # chage --maxdays <N> <user>
            Example:
            # awk -F: '($2~/^\$.+\$/) {if($5 > 365 || $5 < 1)system ("chage --maxdays 365
            " $1)}' /etc/shadow
            Warning: If a password has been set at system install or kickstart, the last change
            date field is not set, In this case, setting PASS_MAX_DAYS will immediately expire the
            password. One possible solution is to populate the last change date field through a
            command like: chage -d "$(date +%Y-%m-%d)" root

            Default Value:
            PASS_MAX_DAYS 99999


                                                                                            Page 624

Internal Only - General
            References:

                 1. CIS Password Policy Guide
                 2. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            Additional Information:
            A value of -1 will disable password expiration.
            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 625

Internal Only - General
            5.4.1.2 Ensure minimum password days is configured (Manual)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            PASS_MIN_DAYS <N> - The minimum number of days allowed between password
            changes. Any password changes attempted sooner than this will be rejected. If not
            specified, 0 will be assumed (which disables the restriction).
            Rationale:
            Users may have favorite passwords that they like to use because they are easy to
            remember and they believe that their password choice is secure from compromise.
            Unfortunately, passwords are compromised and if an attacker is targeting a specific
            individual user account, with foreknowledge of data about that user, reuse of old,
            potentially compromised passwords, may cause a security breach.
            By restricting the frequency of password changes, an administrator can prevent users
            from repeatedly changing their password in an attempt to circumvent password reuse
            controls
            Impact:
            If a users password is set by other personnel as a procedure in dealing with a lost or
            expired password, the user should be forced to update this "set" password with their
            own password. e.g. force "change at next logon".
            If it is not possible to have a user set their own password immediately, and this
            recommendation or local site procedure may cause a user to continue using a third
            party generated password, PASS_MIN_DAYS for the effected user should be temporally
            changed to 0via chage --mindays <user>, to allow a user to change their password
            immediately.
            For applications where the user is not using the password at console, the ability to
            "change at next logon" may be limited. This may cause a user to continue to use a
            password created by other personnel.




                                                                                            Page 626

Internal Only - General
            Audit:
            Run the following command to verify that PASS_MIN_DAYS is set to a value greater than
            0 and follows local site policy:
            # grep -Pi -- '^\h*PASS_MIN_DAYS\h+\d+\b' /etc/login.defs
            Example output:
            PASS_MIN_DAYS     1
            Run the following command to verify all passwords have a PASS_MIN_DAYS greater than
            0:
            # awk -F: '($2~/^\$.+\$/) {if($4 < 1)print "User: " $1 " PASS_MIN_DAYS: "
            $4}' /etc/shadow
            Nothing should be returned
            Remediation:
            Edit /etc/login.defs and set PASS_MIN_DAYS to a value greater than 0 that follows
            local site policy:
            Example:
            PASS_MIN_DAYS 1
            Run the following command to modify user parameters for all users with a password set
            to a minimum days greater than zero that follows local site policy:
            # chage --mindays <N> <user>
            Example:
            # awk -F: '($2~/^\$.+\$/) {if($4 < 1)system ("chage --mindays 1 " $1)}'
            /etc/shadow

            Default Value:
            PASS_MIN_DAYS 0
            References:

                 1. CIS Password Policy Guide
                 2. NIST SP 800-53 :: IA-5 (1) (d)
                 3. NIST SP 800-53A :: IA-5 (1).1 (v)
                 4. STIG ID: RHEL-08-020180 | Rule ID: SV-230364r627750 | CAT II
                 5. STIG ID: RHEL-08-020190 | Rule ID: SV-230365r858727 | CAT II
                 6. STIG ID: UBTU-20-010007 | Rule ID: SV-238202r1015140 | CAT III
                 7. STIG ID: UBTU-22-411025 | Rule ID: SV-260545r1015007 | CAT III




                                                                                          Page 627

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 628

Internal Only - General
            5.4.1.3 Ensure password expiration warning days is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The PASS_WARN_AGE parameter in /etc/login.defs allows an administrator to notify
            users that their password will expire in a defined number of days.
            PASS_WARN_AGE <N> - The number of days warning given before a password expires. A
            zero means warning is given only upon the day of expiration, a negative value means
            no warning is given. If not specified, no warning will be provided.
            Rationale:
            Providing an advance warning that a password will be expiring gives users time to think
            of a secure password. Users caught unaware may choose a simple password or write it
            down where it may be discovered.
            Audit:
            Run the following command and verify PASS_WARN_AGE is 7 or more and follows local
            site policy:
            # grep -Pi -- '^\h*PASS_WARN_AGE\h+\d+\b' /etc/login.defs
            Example output:
            PASS_WARN_AGE 7
            Run the following command to verify all passwords have a PASS_WARN_AGE of 7 or
            more:
            # awk -F: '($2~/^\$.+\$/) {if($6 < 7)print "User: " $1 " PASS_WARN_AGE: "
            $6}' /etc/shadow
            Nothing should be returned




                                                                                           Page 629

Internal Only - General
            Remediation:
            Edit /etc/login.defs and set PASS_WARN_AGE to a value of 7 or more that follows
            local site policy:
            Example:
            PASS_WARN_AGE 7
            Run the following command to modify user parameters for all users with a password set
            to a minimum warning to 7 or more days that follows local site policy:
            # chage --warndays <N> <user>
            Example:
            # awk -F: '($2~/^\$.+\$/) {if($6 < 7)system ("chage --warndays 7 " $1)}'
            /etc/shadow

            Default Value:
            PASS_WARN_AGE 7
            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 630

Internal Only - General
            5.4.1.4 Ensure strong password hashing algorithm is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            A cryptographic hash function converts an arbitrary-length input into a fixed length
            output. Password hashing performs a one-way transformation of a password, turning
            the password into another string, called the hashed password.
            ENCRYPT_METHOD (string) - This defines the system default encryption algorithm for
            encrypting passwords (if no algorithm are specified on the command line). It can take
            one of these values:

                 •   MD5 - MD5-based algorithm will be used for encrypting password
                 •   SHA256 - SHA256-based algorithm will be used for encrypting password
                 •   SHA512 - SHA512-based algorithm will be used for encrypting password
                 •   BCRYPT - BCRYPT-based algorithm will be used for encrypting password
                 •   YESCRYPT - YESCRYPT-based algorithm will be used for encrypting password
                 •   DES - DES-based algorithm will be used for encrypting password (default)

            Note:

                 •   This parameter overrides the deprecated MD5_CRYPT_ENAB variable.
                 •   This parameter will only affect the generation of group passwords.
                 •   The generation of user passwords is done by PAM and subject to the PAM
                     configuration.
                 •   It is recommended to set this variable consistently with the PAM configuration.

            Rationale:
            The SHA-512 and yescrypt algorithms provide a stronger hash than other algorithms
            used by Linux for password hash generation. A stronger hash provides additional
            protection to the system by increasing the level of effort needed for an attacker to
            successfully determine local group passwords.




                                                                                               Page 631

Internal Only - General
            Audit:
            Run the following command to verify the hashing algorithm is sha512 or yescrypt in
            /etc/login.defs:
            # grep -Pi -- '^\h*ENCRYPT_METHOD\h+(SHA512|YESCRYPT)\b' /etc/login.defs
            Example output:
            ENCRYPT_METHOD SHA512
             - OR -
            ENCRYPT_METHOD YESCRYPT

            Remediation:
            Edit /etc/login.defs and set the ENCRYPT_METHOD to SHA512 or YESCRYPT:
            ENCRYPT_METHOD <HASHING_ALGORITHM>
            Example:
            ENCRYPT_METHOD YESCRYPT
            Note:

                 •        This only effects local groups' passwords created after updating the file to use
                          sha512 or yescrypt.
                 •        If it is determined that the password algorithm being used is not sha512 or
                          yescrypt, once it is changed, it is recommended that all group passwords be
                          updated to use the stronger hashing algorithm.
                 •        It is recommended that the chosen hashing algorithm is consistent across
                          /etc/login.defs and the PAM configuration

            Default Value:
            ENCRYPT_METHOD SHA512
            References:

                 1. NIST SP 800-53 Rev. 5: IA-5

            CIS Controls:

              Controls
                                                                    Control                                           IG 1 IG 2 IG 3
              Version
                               3.11 Encrypt Sensitive Data at Rest
                                  Encrypt sensitive data at rest on servers, applications, and databases containing
                               sensitive data. Storage-layer encryption, also known as server-side encryption,
                     v8        meets the minimum requirement of this Safeguard. Additional encryption methods               ●    ●
                               may include application-layer encryption, also known as client-side encryption,
                               where access to the data storage device(s) does not permit access to the plain-text
                               data.

                     v7        16.4 Encrypt or Hash all Authentication Credentials                                          ●    ●
                                  Encrypt or hash with a salt all authentication credentials when stored.




                                                                                                                            Page 632

Internal Only - General
            5.4.1.5 Ensure inactive password lock is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            User accounts that have been inactive for over a given period of time can be
            automatically disabled.
            INACTIVE - Defines the number of days after the password exceeded its maximum age
            where the user is expected to replace this password.
            The value is stored in the shadow password file. An input of 0 will disable an expired
            password with no delay. An input of -1 will blank the respective field in the shadow
            password file.
            Rationale:
            Inactive accounts pose a threat to system security since the users are not logging in to
            notice failed login attempts or other anomalies.
            Audit:
            Run the following command and verify INACTIVE conforms to site policy (no more than
            45 days):
            # useradd -D | grep INACTIVE

            INACTIVE=45
            Verify all users with a password have Password inactive no more than 45 days after
            password expires
            Verify all users with a password have Password inactive no more than 45 days after
            password expires: Run the following command and Review list of users and INACTIVE
            to verify that all users INACTIVE conforms to site policy (no more than 45 days):
            # awk -F: '($2~/^\$.+\$/) {if($7 > 45 || $7 < 0)print "User: " $1 " INACTIVE:
            " $7 "Days"}' /etc/shadow
            Nothing should be returned




                                                                                             Page 633

Internal Only - General
            Remediation:
            Run the following command to set the default password inactivity period to 45 days or
            less that meets local site policy:
            # useradd -D -f <N>
            Example:
            # useradd -D -f 45
            Run the following command to modify user parameters for all users with a password set
            to a inactive age of 45 days or less that follows local site policy:
            # chage --inactive <N> <user>
            Example:
            # awk -F: '($2~/^\$.+\$/) {if($7 > 45 || $7 < 0)system ("chage --inactive 45
            " $1)}' /etc/shadow

            Default Value:
            INACTIVE=-1
            References:

                 1. CIS Password Policy Guide

            Additional Information:
            A value of -1 would disable this setting.
            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 634

Internal Only - General
            5.4.1.6 Ensure all users last password change date is in the past
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            All users should have a password change date in the past.
            Rationale:
            If a user's recorded password change date is in the future, then they could bypass any
            set password expiration.
            Audit:
            Run the following script and verify nothing is returned:
            #!/usr/bin/env bash

            {
               while IFS= read -r l_user; do
                  l_change=$(date -d "$(chage --list $l_user | grep '^Last password
            change' | cut -d: -f2 | grep -v 'never$')" +%s)
                  if [[ "$l_change" -gt "$(date +%s)" ]]; then
                     echo "User: \"$l_user\" last password change was \"$(chage --list
            $l_user | grep '^Last password change' | cut -d: -f2)\""
                  fi
               done < <(awk -F: '$2~/^\$.+\$/{print $1}' /etc/shadow)
            }

            Remediation:
            Investigate any users with a password change date in the future and correct them.
            Locking the account, expiring the password, or resetting the password manually may be
            appropriate.
            CIS Controls:

                Controls
                                                              Control                                            IG 1 IG 2 IG 3
                Version
                           5.2 Use Unique Passwords
                   v8          Use unique passwords for all enterprise assets. Best practice implementation
                           includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                  ●    ●    ●
                           14-character password for accounts not using MFA.

                           4.4 Use Unique Passwords
                   v7         Where multi-factor authentication is not supported (such as local administrator,
                           root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                       ●    ●
                           system.



                                                                                                                       Page 635

Internal Only - General
            5.4.2 Configure root and system accounts and environment




                                                                       Page 636

Internal Only - General
            5.4.2.1 Ensure root is the only UID 0 account (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Any account with UID 0 has superuser privileges on the system.
            Rationale:
            This access must be limited to only the default root account and only from the system
            console. Administrative access must be through an unprivileged account using an
            approved mechanism as noted in the Recommendation "Ensure access to the su
            command is restricted".
            Audit:
            Run the following command and verify that only "root" is returned:
            # awk -F: '($3 == 0) { print $1 }' /etc/passwd

            root

            Remediation:
            Run the following command to change the root account UID to 0:
            # usermod -u 0 root
            Modify any users other than root with UID 0 and assign them a new UID.

            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 637

Internal Only - General
            5.4.2.2 Ensure root is the only GID 0 account (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The usermod command can be used to specify which group the root account belongs
            to. This affects permissions of files that are created by the root account.

            Rationale:
            Using GID 0 for the root account helps prevent root -owned files from accidentally
            becoming accessible to non-privileged users.
            Audit:
            Run the following command to verify the root user's primary GID is 0, and no other
            user's have GID 0 as their primary GID:
            # awk -F: '($1 !~ /^(sync|shutdown|halt|operator)/ && $4=="0") {print
            $1":"$4}' /etc/passwd

            root:0
            Note: User's: sync, shutdown, halt, and operator are excluded from the check for other
            user's with GID 0

            Remediation:
            Run the following command to set the root user's GID to 0:
            # usermod -g 0 root
            Run the following command to set the root group's GID to 0:
            # groupmod -g 0 root
            Remove any users other than the root user with GID 0 or assign them a new GID if
            appropriate.
            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5




                                                                                           Page 638

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 639

Internal Only - General
            5.4.2.3 Ensure group root is the only GID 0 group (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The groupmod command can be used to specify which group the root group belongs
            to. This affects permissions of files that are group owned by the root group.

            Rationale:
            Using GID 0 for the root group helps prevent root group owned files from accidentally
            becoming accessible to non-privileged users.
            Audit:
            Run the following command to verify no group other than root is assigned GID 0:
            # awk -F: '$3=="0"{print $1":"$3}' /etc/group

            root:0

            Remediation:
            Run the following command to set the root group's GID to 0:
            # groupmod -g 0 root
            Remove any groups other than the root group with GID 0 or assign them a new GID if
            appropriate.
            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 640

Internal Only - General
            5.4.2.4 Ensure root account access is controlled (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            There are a number of methods to access the root account directly. Without a password
            set any user would be able to gain access and thus control over the entire system.
            Rationale:
            Access to root should be secured at all times.

            Impact:
            If there are any automated processes that relies on access to the root account without
            authentication, they will fail after remediation.
            Audit:
            Run the following command to verify that either the root user's password is set or the
            root user's account is locked:
            # passwd -S root | awk '$2 ~ /^(P|L)/ {print "User: \"" $1 "\" Password is
            status: " $2}'
            Verify the output is either:
            User: "root" Password is status: P
            - OR -
            User: "root" Password is status: L
            Note:

                 •   P - Password is set
                 •   L - Password is locked

            Remediation:
            Run the following command to set a password for the root user:
            # passwd root
            - OR -
            Run the following command to lock the root user account:
            # usermod -L root




                                                                                             Page 641

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 642

Internal Only - General
            5.4.2.5 Ensure root path integrity (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The root user can execute any command on the system and could be fooled into
            executing programs unintentionally if the PATH is not set correctly.

            Rationale:
            Including the current working directory (.) or other writable directory in root's
            executable path makes it likely that an attacker can gain superuser access by forcing an
            administrator operating as root to execute a Trojan horse program.




                                                                                            Page 643

Internal Only - General
            Audit:
            Run the following script to verify root's path does not include:
              • Locations that are not directories
              • An empty directory (::)
              • A trailing (:)
              • Current working directory (.)
              • Non root owned directories
              • Directories that less restrictive than mode 0755
            #!/usr/bin/env bash

            {
                 a_output2=() l_pmask="0022"
                 l_maxperm="$( printf '%o' $(( 0777 & ~$l_pmask )) )"
                 l_root_path="$(sudo su - root -c env | awk -F= '$1=="PATH"{print $2}')"
                 IFS=":" read -ra a_path_loc <<< "$l_root_path"
                 grep -q -- "::" <<< "$l_root_path" && \
                 a_output2+=(" - root's path contains a empty directory (::)")
                 grep -Pq -- ":\h*$" <<< "$l_root_path" && \
                 a_output2+=(" - root's path contains a trailing (:)")
                 grep -Pq -- '(^\h*|:)\.(:|\h*$)' <<< "$l_root_path" && \
                 a_output2+=(" - root's path contains current working directory (.)")
                 for l_path in "${a_path_loc[@]}"; do
                    if [ -d "$l_path" ]; then
                       while IFS=: read -r l_fmode l_fown; do
                          [ "$l_fown" != "root" ] && \
                          a_output2+=(" - Directory: \"$l_path\" is owned by: \"$l_fown\""
            \
                          "    should be owned by \"root\"")
                          [ $(( $l_fmode & $l_pmask )) -gt 0 ] && \
                          a_output2+=(" - Directory: \"$l_path\" is mode: \"$l_fmode\"" \
                          "    and should be mode: \"$l_maxperm\" or more restrictive")
                       done <<< "$(stat -Lc '%#a:%U' "$l_path")"
                    else
                       a_output2+=(" - \"$l_path\" is not a directory")
                    fi
                 done
                 if [ "${#a_output2[@]}" -le 0 ]; then
                    printf '%s\n' "" "- Audit Result:" " ** PASS **" \
                    " - Root's path is correctly configured"
                 else
                    printf '%s\n' "" "- Audit Result:" " ** FAIL **" \
                    "- * Reasons for audit failure * :" "${a_output2[@]}"
                 fi
            }




                                                                                    Page 644

Internal Only - General
            Remediation:
            Correct or justify any:

                 •   Locations that are not directories
                 •   Empty directories (::)
                 •   Trailing (:)
                 •   Current working directory (.)
                 •   Non root owned directories
                 •   Directories that less restrictive than mode 0755

            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            CIS Controls:

                 Controls Version                         Control       IG 1 IG 2 IG 3

                          v8            0.0 Explicitly Not Mapped
                                           Explicitly Not Mapped

                          v7            0.0 Explicitly Not Mapped
                                           Explicitly Not Mapped




                                                                                         Page 645

Internal Only - General
            5.4.2.6 Ensure root user umask is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The user file-creation mode mask (umask) is used to determine the file permission for
            newly created directories and files. In Linux, the default permissions for any newly
            created directory is 0777 (rwxrwxrwx), and for any newly created file it is 0666 (rw-rw-
            rw-). The umask modifies the default Linux permissions by restricting (masking) these
            permissions. The umask is not simply subtracted, but is processed bitwise. Bits set in
            the umask are cleared in the resulting file mode.
            umask can be set with either Octal or Symbolic values:

                 •   Octal (Numeric) Value - Represented by either three or four digits. ie umask
                     0027 or umask 027. If a four digit umask is used, the first digit is ignored. The
                     remaining three digits effect the resulting permissions for user, group, and
                     world/other respectively.
                 •   Symbolic Value - Represented by a comma separated list for User u, group g,
                     and world/other o. The permissions listed are not masked by umask. ie a umask
                     set by umask u=rwx,g=rx,o= is the Symbolic equivalent of the Octal umask
                     027. This umask would set a newly created directory with file mode drwxr-x---
                     and a newly created file with file mode rw-r-----.

            root user Shell Configuration Files:

                 •   /root/.profile - Is executed to configure the root users' shell before the initial
                     command prompt. Is only read by login shells.
                 •   /root/.bashrc - Is executed for interactive shells. only read by a shell that's
                     both interactive and non-login

            umask is set by order of precedence. If umask is set in multiple locations, this order of
            precedence will determine the system's default umask.
            Order of precedence:

                 1. /root/.profile
                 2. /root/.bashrc
                 3. The system default umask




                                                                                                Page 646

Internal Only - General
            Rationale:
            Setting a secure value for umask ensures that users make a conscious choice about
            their file permissions. A permissive umask value could result in directories or files with
            excessive permissions that can be read and/or written to by unauthorized users.
            Audit:
            Run the following command to verify that the root user files, /root/.profile and
            /root/.bashrc, do not include a umask that is less restrictive than 0027:
            # grep -Psi -- '^\h*umask\h+((\d{1,2}(\d[^7]|[^2-
            7]\d)\b)|(u=[rwx]{1,3},)?(((g=[rx]?[rx]?w[rx]?[rx]?\b)(,o=[rwx]{1,3})?)|((g=[
            wrx]{1,3},)?o=[wrx]{1,3}\b)))' /root/.profile /root/.bashrc
            Nothing should be returned.
            Remediation:
            Edit /root/.profile and /root/.bashrc and either:

                 •   remove, comment out, or update any line with umask.

            - OR -

                 •   update any line that includes umask to a value of 0027 or more restrictive.

            Example:
            umask 027
            Note: the Recommendation "Ensure default user umask is configured" includes
            guidance to set the default umask
            Default Value:
            System default umask

            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2




                                                                                                Page 647

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 648

Internal Only - General
            5.4.2.7 Ensure system accounts do not have a valid login shell
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            There are a number of accounts provided with most distributions that are used to
            manage applications and are not intended to provide an interactive shell. Furthermore,
            a user may add special accounts that are not intended to provide an interactive shell.
            Rationale:
            It is important to make sure that accounts that are not being used by regular users are
            prevented from being used to provide an interactive shell. By default, most distributions
            set the password field for these accounts to an invalid string, but it is also recommended
            that the shell field in the password file be set to the nologin shell. This prevents the
            account from potentially being used to run any commands.
            Audit:
            Run the following command to verify system accounts, except for root, halt, sync,
            shutdown or nfsnobody, do not have a valid login shell:
            #!/usr/bin/env bash

            {
               l_valid_shells="^($(awk -F\/ '$NF != "nologin" {print}' /etc/shells | sed
            -rn '/^\//{s,/,\\\\/,g;p}' | paste -s -d '|' - ))$"
               awk -v pat="$l_valid_shells" -F:
            '($1!~/^(root|halt|sync|shutdown|nfsnobody)$/ && ($3<'"$(awk
            '/^\s*UID_MIN/{print $2}' /etc/login.defs)"' || $3 == 65534) && $(NF) ~ pat)
            {print "Service account: \"" $1 "\" has a valid shell: " $7}' /etc/passwd
            }
            Nothing should be returned




                                                                                             Page 649

Internal Only - General
            Remediation:
            Run the following command to set the shell for any service accounts returned by the
            audit to nologin:
            # usermod -s $(command -v nologin) <user>
            Example script:
            #!/usr/bin/env bash

            {
               l_valid_shells="^($( awk -F\/ '$NF != "nologin" {print}' /etc/shells | sed
            -rn '/^\//{s,/,\\\\/,g;p}' | paste -s -d '|' - ))$"
               awk -v pat="$l_valid_shells" -F:
            '($1!~/^(root|halt|sync|shutdown|nfsnobody)$/ && ($3<'"$(awk
            '/^\s*UID_MIN/{print $2}' /etc/login.defs)"' || $3 == 65534) && $(NF) ~ pat)
            {system ("usermod -s '"$(command -v nologin)"' " $1)}' /etc/passwd
            }

            References:

                 1. NIST SP 800-53 Rev. 5: AC-2(5), AC-3, AC-11, MP-2

            Additional Information:
            The root, sync, shutdown, and halt users are exempted from requiring a non-login
            shell.
            CIS Controls:

                Controls
                                                                Control                                          IG 1 IG 2 IG 3
                Version
                           3.3 Configure Data Access Control Lists
                   v8         Configure data access control lists based on a user’s need to know. Apply data
                           access control lists, also known as access permissions, to local and remote file
                                                                                                                  ●    ●    ●
                           systems, databases, and applications.

                           14.6 Protect Information through Access Control Lists
                               Protect all information stored on systems with file system, network share,
                   v7      claims, application, or database specific access control lists. These controls will
                           enforce the principle that only authorized individuals should have access to the
                                                                                                                  ●    ●    ●
                           information based on their need to access the information as a part of their
                           responsibilities.




                                                                                                                       Page 650

Internal Only - General
            5.4.2.8 Ensure accounts without a valid login shell are locked
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            There are a number of accounts provided with most distributions that are used to
            manage applications and are not intended to provide an interactive shell. Furthermore,
            a user may add special accounts that are not intended to provide an interactive shell.
            Rationale:
            It is important to make sure that accounts that are not being used by regular users are
            prevented from being used to provide an interactive shell. By default, most distributions
            set the password field for these accounts to an invalid string, but it is also recommended
            that the shell field in the password file be set to the nologin shell. This prevents the
            account from potentially being used to run any commands.
            Audit:
            Run the following script to verify all non-root accounts without a valid login shell are
            locked.
            #!/usr/bin/env bash

            {
               l_valid_shells="^($(awk -F\/ '$NF != "nologin" {print}' /etc/shells | sed
            -rn '/^\//{s,/,\\\\/,g;p}' | paste -s -d '|' - ))$"
               while IFS= read -r l_user; do
                  passwd -S "$l_user" | awk '$2 !~ /^L/ {print "Account: \"" $1 "\" does
            not have a valid login shell and is not locked"}'
               done < <(awk -v pat="$l_valid_shells" -F: '($1 != "root" && $(NF) !~ pat)
            {print $1}' /etc/passwd)
            }
            Nothing should be returned




                                                                                                Page 651

Internal Only - General
            Remediation:
            Run the following command to lock any non-root accounts without a valid login shell
            returned by the audit:
            # usermod -L <user>
            Example script:
            #!/usr/bin/env bash

            {
               l_valid_shells="^($(awk -F\/ '$NF != "nologin" {print}' /etc/shells | sed
            -rn '/^\//{s,/,\\\\/,g;p}' | paste -s -d '|' - ))$"
               while IFS= read -r l_user; do
                  passwd -S "$l_user" | awk '$2 !~ /^L/ {system ("usermod -L " $1)}'
               done < <(awk -v pat="$l_valid_shells" -F: '($1 != "root" && $(NF) !~ pat)
            {print $1}' /etc/passwd)
            }

            References:

                 1. NIST SP 800-53 Rev. 5: AC-2(5), AC-3, AC-11, MP-2

            CIS Controls:

                Controls
                                                                Control                                          IG 1 IG 2 IG 3
                Version
                           3.3 Configure Data Access Control Lists
                   v8         Configure data access control lists based on a user’s need to know. Apply data
                           access control lists, also known as access permissions, to local and remote file
                                                                                                                  ●    ●    ●
                           systems, databases, and applications.

                           14.6 Protect Information through Access Control Lists
                               Protect all information stored on systems with file system, network share,
                   v7      claims, application, or database specific access control lists. These controls will
                           enforce the principle that only authorized individuals should have access to the
                                                                                                                  ●    ●    ●
                           information based on their need to access the information as a part of their
                           responsibilities.




                                                                                                                       Page 652

Internal Only - General
            5.4.3 Configure user default environment




                                                       Page 653

Internal Only - General
            5.4.3.1 Ensure nologin is not listed in /etc/shells (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            /etc/shells is a text file which contains the full pathnames of valid login shells. This
            file is consulted by chsh and available to be queried by other programs.
            Be aware that there are programs which consult this file to find out if a user is a normal
            user; for example, FTP daemons traditionally disallow access to users with shells not
            included in this file.
            Rationale:
            A user can use chsh to change their configured shell.
            If a user has a shell configured that isn't in in /etc/shells, then the system assumes
            that they're somehow restricted. In the case of chsh it means that the user cannot
            change that value.
            Other programs might query that list and apply similar restrictions.
            By putting nologin in /etc/shells, any user that has nologin as its shell is
            considered a full, unrestricted user. This is not the expected behavior for nologin.

            Audit:
            Run the following command to verify that nologin is not listed in the /etc/shells file:
            # grep -Ps '^\h*([^#\n\r]+)?\/nologin\b' /etc/shells
            Nothing should be returned
            Remediation:
            Edit /etc/shells and remove any lines that include nologin

            References:

                 1. shells(5)
                 2. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5




                                                                                               Page 654

Internal Only - General
            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 655

Internal Only - General
            5.4.3.2 Ensure default user shell timeout is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            TMOUT is an environmental setting that determines the timeout of a shell in seconds.

                 •   TMOUT=n - Sets the shell timeout to n seconds. A setting of TMOUT=0 disables
                     timeout.
                 •   readonly TMOUT- Sets the TMOUT environmental variable as readonly,
                     preventing unwanted modification during run-time.
                 •   export TMOUT - exports the TMOUT variable

            System Wide Shell Configuration Files:

                 •   /etc/profile - used to set system wide environmental variables on users
                     shells. The variables are sometimes the same ones that are in the
                     .bash_profile, however this file is used to set an initial PATH or PS1 for all
                     shell users of the system. is only executed for interactive login shells, or
                     shells executed with the --login parameter.
                 •   /etc/profile.d - /etc/profile will execute the scripts within
                     /etc/profile.d/*.sh. It is recommended to place your configuration in a shell
                     script within /etc/profile.d to set your own system wide environmental
                     variables.
                 •   /etc/bash.bashrc - System wide version of .bashrc. In Fedora derived
                     distributions, /etc/bashrc also invokes /etc/profile.d/*.sh if non-login shell, but
                     redirects output to /dev/null if non-interactive. Is only executed for
                     interactive shells or if BASH_ENV is set to /etc/bash.bashrc.

            Rationale:
            Setting a timeout value reduces the window of opportunity for unauthorized user access
            to another user's shell session that has been left unattended. It also ends the inactive
            session and releases the resources associated with that session.
            Audit:
            Run the following script to verify that TMOUT is configured to: include a timeout of no
            more than 900 seconds, to be readonly, to be exported, and is not being changed to
            a longer timeout.




                                                                                                Page 656

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output=(); a_output2=(); l_tmout_set="900"
               f_tmout_read_chk()
               {
                  a_out=(); a_out2=()
                  l_tmout_readonly="$(grep -P -- '^\h*(typeset\h\-
            xr\hTMOUT=\d+|([^#\n\r]+)?\breadonly\h+TMOUT\b)' "$l_file")"
                  l_tmout_export="$(grep -P -- '^\h*(typeset\h\-
            xr\hTMOUT=\d+|([^#\n\r]+)?\bexport\b([^#\n\r]+\b)?TMOUT\b)' "$l_file")"
                  if [ -n "$l_tmout_readonly" ]; then
                     a_out+=(" - Readonly is set as: \"$l_tmout_readonly\" in: \"$l_file\"")
                  else
                     a_out2+=(" - Readonly is not set in: \"$l_file\"")
                  fi
                  if [ -n "$l_tmout_export" ]; then
                     a_out+=(" - Export is set as: \"$l_tmout_export\" in: \"$l_file\"")
                  else
                     a_out2+=(" - Export is not set in: \"$l_file\"")
                  fi
               }
               while IFS= read -r l_file; do
                  l_tmout_value="$(grep -Po -- '^([^#\n\r]+)?\bTMOUT=\d+\b' "$l_file" | awk -F=
            '{print $2}')"
                  f_tmout_read_chk
                  if [ -n "$l_tmout_value" ]; then
                     if [[ "$l_tmout_value" -le "$l_tmout_set" && "$l_tmout_value" -gt "0" ]];
            then
                        a_output+=(" - TMOUT is set to: \"$l_tmout_value\" in: \"$l_file\"")
                        [ "${#a_out[@]}" -gt 0 ] && a_output+=("${a_out[@]}")
                        [ "${#a_out2[@]}" -gt 0 ] && a_output2+=("${a_out[@]}")
                     fi
                     if [[ "$l_tmout_value" -gt "$l_tmout_set" || "$l_tmout_value" -le "0" ]];
            then
                        a_output2+=(" - TMOUT is incorrectly set to: \"$l_tmout_value\" in:
            \"$l_file\"")
                        [ "${#a_out[@]}" -gt 0 ] && a_output2+=(" ** Incorrect TMOUT value **"
            "${a_out[@]}")
                        [ "${#a_out2[@]}" -gt 0 ] && a_output2+=("${a_out2[@]}")
                     fi
                  else
                     [ "${#a_out[@]}" -gt 0 ] && a_output2+=(" - TMOUT is not set" "${a_out[@]}")
                     [ "${#a_out2[@]}" -gt 0 ] && a_output2+=(" - TMOUT is not set"
            "${a_out2[@]}")
                  fi
               done < <(grep -Pls -- '^([^#\n\r]+)?\bTMOUT\b' /etc/*bashrc /etc/profile
            /etc/profile.d/*.sh)
               [[ "${#a_output[@]}" -le 0 && "${#a_output2[@]}" -le 0 ]] && a_output2+=(" - TMOUT
            is not configured")
               if [ "${#a_output2[@]}" -le 0 ]; then
                  printf '%s\n' "" "- Audit Result:" " ** PASS **" "${a_output[@]}"
               else
                  printf '%s\n' "" "- Audit Result:" " ** FAIL **" " * Reasons for audit failure
            *" "${a_output2[@]}" ""
                  [ "${#a_output[@]}" -gt 0 ] && printf '%s\n' "- Correctly set:" "${a_output[@]}"
               fi
            }




                                                                                          Page 657

Internal Only - General
            Note: If TMOUT is set as readonly through readonly TMOUT and/or typeset -xr in
            more than once, you will receive an error message when logging into a terminal session
            or connecting with openSSH. It is recommended that TMOUT be set only once in only
            one file.
            Remediation:
            Review /etc/bashrc, /etc/profile, and all files ending in *.sh in the
            /etc/profile.d/ directory and remove or edit all TMOUT=_n_ entries to follow local site
            policy. TMOUT should not exceed 900 or be equal to 0.
            Configure TMOUT in one of the following files:

                 •   A file in the /etc/profile.d/ directory ending in .sh
                 •   /etc/profile
                 •   /etc/bashrc

            Example command to set TMOUT to 900 seconds in a file in /etc/profile.d/:
            # printf '%s\n' "# Set TMOUT to 900 seconds" "typeset -xr TMOUT=900" >
            /etc/profile.d/50-tmout.sh
            TMOUT configuration examples:
            typeset -xr TMOUT=900
            Deprecated methods:

                 •   As multiple lines:

            TMOUT=900
            readonly TMOUT
            export TMOUT

                 •   As a single line:

            readonly TMOUT=900 ; export TMOUT

            Additional Information:
            The audit and remediation in this recommendation apply to bash and shell. If other
            shells are supported on the system, it is recommended that their configuration files also
            are checked. Other methods of setting a timeout exist for other shells not covered here.
            Ensure that the timeout conforms to your local policy.




                                                                                             Page 658

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                           IG 1 IG 2 IG 3
              Version
                          4.3 Configure Automatic Session Locking on Enterprise
                          Assets
                   v8         Configure automatic session locking on enterprise assets after a defined period    ●    ●    ●
                          of inactivity. For general purpose operating systems, the period must not exceed
                          15 minutes. For mobile end-user devices, the period must not exceed 2 minutes.

                   v7     16.11 Lock Workstation Sessions After Inactivity                                       ●    ●    ●
                             Automatically lock workstation sessions after a standard period of inactivity.




                                                                                                                      Page 659

Internal Only - General
            5.4.3.3 Ensure default user umask is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The user file-creation mode mask (umask) is used to determine the file permission for
            newly created directories and files. In Linux, the default permissions for any newly
            created directory is 0777 (rwxrwxrwx), and for any newly created file it is 0666 (rw-rw-
            rw-). The umask modifies the default Linux permissions by restricting (masking) these
            permissions. The umask is not simply subtracted, but is processed bitwise. Bits set in
            the umask are cleared in the resulting file mode.
            umask can be set with either Octal or Symbolic values:

                 •   Octal (Numeric) Value - Represented by either three or four digits. ie umask
                     0027 or umask 027. If a four digit umask is used, the first digit is ignored. The
                     remaining three digits effect the resulting permissions for user, group, and
                     world/other respectively.
                 •   Symbolic Value - Represented by a comma separated list for User u, group g,
                     and world/other o. The permissions listed are not masked by umask. ie a umask
                     set by umask u=rwx,g=rx,o= is the Symbolic equivalent of the Octal umask
                     027. This umask would set a newly created directory with file mode drwxr-x---
                     and a newly created file with file mode rw-r-----.

            The default umask can be set to use the pam_umask module or in a System Wide
            Shell Configuration File. The user creating the directories or files has the
            discretion of changing the permissions via the chmod command, or choosing a different
            default umask by adding the umask command into a User Shell Configuration
            File, ( .bash_profile or .bashrc), in their home directory.
            Setting the default umask:

                 •   pam_umask module:
                       o will set the umask according to the system default in /etc/login.defs
                          and user settings, solving the problem of different umask settings with
                          different shells, display managers, remote sessions etc.
                       o umask=<mask> value in the /etc/login.defs file is interpreted as Octal
                       o Setting USERGROUPS_ENAB to yes in /etc/login.defs (default):
                              ▪ will enable setting of the umask group bits to be the same as owner
                                 bits. (examples: 022 -> 002, 077 -> 007) for non-root users, if the
                                 uid is the same as gid, and username is the same as the
                                 <primary group name>



                                                                                               Page 660

Internal Only - General
                               ▪  userdel will remove the user's group if it contains no more
                                  members, and useradd will create by default a group with the name
                                  of the user
                 •   System Wide Shell Configuration File:
                        o /etc/profile - used to set system wide environmental variables on
                          users shells. The variables are sometimes the same ones that are in the
                          .bash_profile, however this file is used to set an initial PATH or PS1 for
                          all shell users of the system. is only executed for interactive login
                          shells, or shells executed with the --login parameter.
                        o /etc/profile.d - /etc/profile will execute the scripts within
                          /etc/profile.d/*.sh. It is recommended to place your configuration in
                          a shell script within /etc/profile.d to set your own system wide
                          environmental variables.
                        o /etc/bashrc - System wide version of .bashrc. In Fedora derived
                          distributions, etc/bashrc also invokes /etc/profile.d/*.sh if non-login shell,
                          but redirects output to /dev/null if non-interactive. Is only executed for
                          interactive shells or if BASH_ENV is set to /etc/bashrc.

            User Shell Configuration Files:

                 •   ~/.bash_profile - Is executed to configure your shell before the initial
                     command prompt. Is only read by login shells.
                 •   ~/.bashrc - Is executed for interactive shells. only read by a shell that's both
                     interactive and non-login

            umask is set by order of precedence. If umask is set in multiple locations, this order of
            precedence will determine the system's default umask.
            Order of precedence:

                 1. A file in /etc/profile.d/ ending in .sh - This will override any other system-
                    wide umask setting
                 2. In the file /etc/profile
                 3. On the pam_umask.so module in /etc/pam.d/postlogin
                 4. In the file /etc/login.defs
                 5. In the file /etc/default/login

            Rationale:
            Setting a secure default value for umask ensures that users make a conscious choice
            about their file permissions. A permissive umask value could result in directories or files
            with excessive permissions that can be read and/or written to by unauthorized users.
            Satisfies: SRG-OS-000480-GPOS-00228, SRG-OS-000480-GPOS-00227




                                                                                                Page 661

Internal Only - General
            Audit:
            Run the following commands to verify the systemwide umask is 0027
            (u=rwx,g=rx,o=) or more restrictive:

                 1. Run the following command to verify umask is set to 027 or more restrictive in a
                    file ending in .sh in /etc/profile.d/

            # grep -Psi -- '^\h*umask\b' /etc/profile.d/*.sh
            Example output:
            umask 027

                 2. Run the following command to verify UMASK is 027 or more restrictive in
                    /etc/login.defs:

            # grep -Psi -- '^\h*UMASK\b' /etc/login.defs
            Example output:
            UMASK              027

            Remediation:

                 1. Run the following script to comment out all occurrences of umask that are less
                    restrictive than 027 in files ending in *.sh in the /etc/profile.d/ directory:

            #!/usr/bin/env bash

            {
               while IFS= read -r -d $'\0' l_file; do
                  sed -ri '/^\s*umask\s+0?(0[01][0-7]|0[0-7][^7]|[^0][0-7][0-
            7])(\s*|\s+.*)$/s/^/# /' "$l_file"
               done < <(find /etc/profile.d/ -type f -name '*.sh' -print0)
            }
                 2. Create or edit a file in /etc/profile.d/ ending in *.sh and add or modify the
                    following line:
            umask 0027
            Example:
            # printf '%s\n' "" "umask 027" >> /etc/profile.d/60-default_umask.sh

                 3. Edit /etc/login.defs and add or update the following line:

            UMASK 027
            Notes:
               • This method only applies to bash and shell. If other shells are supported on the
                  system, it is recommended that their configuration files also are checked
               • If the pam_umask.so module is going to be used to set umask, ensure that it's not
                  being overridden by another setting. Refer to the PAM_UMASK(8) man page for
                  more information

                                                                                              Page 662

Internal Only - General
            Default Value:
            UMASK 022
            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-020351 | RULE ID: SV-230383r1017192 | CAT II
                 5. STIG ID: RHEL-08-020353 | RULE ID: SV-230385r1017194 | CAT II
                 6. STIG ID: RHEL-09-412055 | RULE ID: SV-258072r1045155 | CAT II
                 7. STIG ID: RHEL-09-412065 | RULE ID: SV-258074r991590 | CAT II
                 8. STIG ID: RHEL-09-412070 | RULE ID: SV-258075r991590 | CAT II
                 9. STIG ID: ALMA-09-017620 | RULE ID: SV-269235r1050117 | CAT II
                 10. STIG ID: ALMA-09-017840 | RULE ID: SV-269237r1050119 | CAT II
                 11. STIG ID: UBTU-22-412035 | RULE ID: SV-260555r991590 | CAT II
                 12. STIG ID: UBTU-24-300030 | RULE ID: SV-270716r1066637 | CAT II
                 13. STIG ID: SLES-15-040420 | RULE ID: SV-235030r991590 | CAT II

            Additional Information:

                 •    Other methods of setting a default user umask exist
                 •    If other methods are in use in your environment they should be audited
                 •    The default user umask can be overridden with a user specific umask
                 •    The user creating the directories or files has the discretion of changing the
                      permissions:
                          o Using the chmod command
                          o Setting a different default umask by adding the umask command into a
                              User Shell Configuration File, (.bashrc), in their home directory
                          o Manually changing the umask for the duration of a login session by
                              running the umask command

            CIS Controls:

              Controls
                                                                Control                                          IG 1 IG 2 IG 3
              Version
                           3.3 Configure Data Access Control Lists
                     v8       Configure data access control lists based on a user’s need to know. Apply data
                           access control lists, also known as access permissions, to local and remote file
                                                                                                                  ●    ●    ●
                           systems, databases, and applications.

                           14.6 Protect Information through Access Control Lists
                               Protect all information stored on systems with file system, network share,
                     v7    claims, application, or database specific access control lists. These controls will
                           enforce the principle that only authorized individuals should have access to the
                                                                                                                  ●    ●    ●
                           information based on their need to access the information as a part of their
                           responsibilities.




                                                                                                                       Page 663

Internal Only - General
            6 Logging and Auditing
            The items in this section describe how to configure logging, log monitoring, and
            auditing, using tools included in most distributions.
            It is recommended that rsyslog be used for logging (with logwatch providing
            summarization) and auditd be used for auditing (with aureport providing
            summarization) to automatically monitor logs for intrusion attempts and other suspicious
            system behavior.
            In addition to the local log files created by the steps in this section, it is also
            recommended that sites collect copies of their system logs on a secure, centralized log
            server via an encrypted connection. Not only does centralized logging help sites
            correlate events that may be occurring on multiple systems, but having a second copy
            of the system log information may be critical after a system compromise where the
            attacker has modified the local log files on the affected system(s). If a log correlation
            system is deployed, configure it to process the logs described in this section.
            Because it is often necessary to correlate log information from many different systems
            (particularly after a security incident) it is recommended that the time be synchronized
            among systems and devices connected to the local network. The standard Internet
            protocol for time synchronization is the Network Time Protocol (NTP), which is
            supported by most network-ready devices. Reference <http://chrony.tuxfamily.org/>
            manual page for more information on configuring chrony.
            It is important that all logs described in this section be monitored on a regular basis and
            correlated to determine trends. A seemingly innocuous entry in one log could be more
            significant when compared to an entry in another log.
            Note on log file permissions: There really isn't a "one size fits all" solution to the
            permissions on log files. Many sites utilize group permissions so that administrators who
            are in a defined security group, such as "wheel" do not have to elevate privileges to root
            in order to read log files. Also, if a third party log aggregation tool is used, it may need to
            have group permissions to read the log files, which is preferable to having it run setuid
            to root. Therefore, there are two remediation and audit steps for log file permissions.
            One is for systems that do not have a secured group method implemented that only
            permits root to read the log files (root:root 600). The other is for sites that do have
            such a setup and are designated as root:securegrp 640 where securegrp is the
            defined security group (in some cases wheel).




                                                                                                  Page 664

Internal Only - General
            6.1 System Logging

            Logging services should be configured to prevent information leaks and to aggregate
            logs on a remote server so that they can be reviewed in the event of a system
            compromise. A centralized log server provides a single point of entry for further
            analysis, monitoring and filtering.
            Security principals for logging

                 •   Ensure transport layer security is implemented between the client and the log
                     server.
                 •   Ensure that logs are rotated as per the environment requirements.
                 •   Ensure all locally generated logs have the appropriate permissions.
                 •   Ensure all security logs are sent to a remote log server.
                 •   Ensure the required events are logged.

            What is covered
            This section will cover the minimum best practices for the usage of either rsyslog or
            journald. The recommendations are written such that each is wholly independent of
            each other and only one is implemented.

                 •   If your organization makes use of an enterprise wide logging system completely
                     outside of rsyslog or journald, then the following recommendations do not
                     directly apply. However, the principals of the recommendations should be
                     followed regardless of what solution is implemented. If the enterprise solution
                     incorporates either of these tools, careful consideration should be given to the
                     following recommendations to determine exactly what applies.
                 •   Should your organization make use of both rsyslog and journald, take care
                     how the recommendations may or may not apply to you.

            What is not covered

                 •   Enterprise logging systems not utilizing rsyslog or journald.

                     As logging is very situational and dependent on the local environment, not
                     everything can be covered here.

                 •   Transport layer security should be applied to all remote logging functionality.
                     Both rsyslog and journald supports secure transport and should be configured
                     as such.
                 •   The log server. There are a multitude of reasons for a centralized log server (and
                     keeping a short period of logging on the local system), but the log server is out of
                     scope for these recommendations.




                                                                                                Page 665

Internal Only - General
            6.1.1 Configure journald

            Included in the systemd suite is a journaling service called systemd-
            journald.service for the collection and storage of logging data. It creates and
            maintains structured, indexed journals based on logging information that is received
            from a variety of sources such as:

                 •   Classic RFC3164 BSD syslog via the /dev/log socket
                 •   STDOUT/STDERR of programs via StandardOutput=journal +
                     StandardError=journal in service files (both of which are default settings)
                 •   Kernel log messages via the /dev/kmsg device node
                 •   Audit records via the kernel’s audit subsystem
                 •   Structured log messages via journald’s native protocol

            Any changes made to the systemd-journald configuration will require a re-start of
            systemd-journald




                                                                                                   Page 666

Internal Only - General
            6.1.1.1 Configure systemd-journald service
            systemd-journald is a system service that collects and stores logging data. It creates
            and maintains structured, indexed journals based on logging information that is received
            from a variety of sources:

                 •   Kernel log messages, via kmsg
                 •   Simple system log messages, via the libc syslog call
                 •   Structured system log messages via the native Journal API
                 •   Standard output and standard error of service units
                 •   Audit records, originating from the kernel audit subsystem

            The daemon will implicitly collect numerous metadata fields for each log messages in a
            secure and unfakeable way. See systemd.journal-fields man page for more information
            about the collected metadata.
            The journal service stores log data either persistently below /var/log/journal or in a
            volatile way below /run/log/journal/. By default, log data is stored persistently if
            /var/log/journal/ exists during boot, with an implicit fallback to volatile storage. Use
            Storage= in journald.conf to configure where log data is placed, independently of
            the existence of /var/log/journal/.
            On systems where /var/log/journal/ does not exist but where persistent logging is
            desired, and the default journald.conf is used, it is sufficient to create the directory
            and ensure it has the correct access modes and ownership.




                                                                                             Page 667

Internal Only - General
            6.1.1.1.1 Ensure journald service is active (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Ensure that the systemd-journald service is enabled to allow capturing of logging
            events.
            Rationale:
            If the systemd-journald service is not enabled to start on boot, the system will not
            capture logging events.
            Audit:
            Run the following command to verify systemd-journald is active:
            # systemctl is-active systemd-journald.service

            active

            Remediation:
            Run the following commands to unmask, enable, and start systemd-
            journald.service
            # systemctl unmask systemd-journald.service
            # systemctl --now enable systemd-journald.service

            References:

                 1. CCI-001665
                 2. NIST SP 800-53 :: SC-24
                 3. NIST SP 800-53A :: SC-24.1 (v)
                 4. STIG ID: RHEL-09-211040 | RULE ID: SV-257783r991562 | CAT II
                 5. STIG ID: ALMA-09-041490 | RULE ID: SV-269428r1050311 | CAT II
                 6. STIG ID: OL09-00-002400 | RULE ID: SV-271739r1091929 | CAT II




                                                                                            Page 668

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                    IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                              ●    ●
                          other useful elements.




                                                                                                              Page 669

Internal Only - General
            6.1.1.1.2 Ensure journald log file access is configured (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Journald will create logfiles that do not already exist on the system. This setting controls
            what permissions will be applied to these newly created files.
            Rationale:
            It is important to ensure that log files have the correct permissions to ensure that
            sensitive data is archived and protected.




                                                                                                Page 670

Internal Only - General
            Audit:
            First determine if there is an override file /etc/tmpfiles.d/systemd.conf. If so, this
            file will override all default settings as defined in /usr/lib/tmpfiles.d/systemd.conf
            and should be inspected.
            If no override file exists, inspect the default /usr/lib/tmpfiles.d/systemd.conf
            against the site specific requirements.
            Ensure that file permissions are mode 0640 or more restrictive.
            Run the following script to verify if an override file exists or not and if the files
            permissions are mode 0640 or more restrictive:
            #!/usr/bin/env bash

            {
            config_files=(/etc/tmpfiles.d/systemd.conf /usr/lib/tmpfiles.d/systemd.conf)
            warn=()
            for file in "${config_files[@]}"; do
               [ -f "$file" ] || continue
               while read -r type path perm _; do
                 if [[ "$type" == "f" && "$perm" =~ ^0?[0-7]{3,4}$ ]]; then
                    perm="${perm#0}"
                    if [ -f "$path" ]; then
                       actual=$(stat -c "%a" "$path" 2>/dev/null)
                       if [[ -n "$actual" && "$actual" -gt 640 ]]; then
                          warn+=("File: $path | Perm: $actual (expected max: 640) | Defined
            in: $file")
                       fi
                    fi
                 fi
               done < "$file"
            done
            if [ "${#warn[@]}" -eq 0 ]; then
               echo "No files with permissions more permissive than 0640."
            else
               echo -e " *** REVIEW ***"
               printf "%s\n" "${warn[@]}"
            fi
            }

            Remediation:
            If the default configuration is not appropriate for the site specific requirements, copy
            /usr/lib/tmpfiles.d/systemd.conf to /etc/tmpfiles.d/systemd.conf and
            modify as required. Requirements is either 0640 or site policy if that is less restrictive.

            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, AU-2, AU-12, MP-2, SI-5




                                                                                                    Page 671

Internal Only - General
            Additional Information:
            See man 5 tmpfiles.d for detailed information on the permission sets for the relevant
            log files. Further information with examples can be found at
            https://www.freedesktop.org/software/systemd/man/tmpfiles.d.html
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 672

Internal Only - General
            6.1.1.1.3 Ensure journald log file rotation is configured (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Journald includes the capability of rotating log files regularly to avoid filling up the
            system with logs or making the logs unmanageably large. The file
            /etc/systemd/journald.conf is the configuration file used to specify how logs
            generated by Journald should be rotated.
            Rationale:
            By keeping the log files smaller and more manageable, a system administrator can
            easily archive these files to another system and spend less time looking through
            inordinately large log files.
            Audit:
            Review /etc/systemd/journald.conf and files in the
            /etc/systemd/journald.conf.d/ directory ending in .conf. Verify logs are rotated
            according to site policy.
            Run the following command and ensure logs are rotated according to site policy:
            # systemd-analyze cat-config systemd/journald.conf | tac | \
            grep -Psi --
            '\b(SystemMaxUse|SystemKeepFree|RuntimeMaxUse|RuntimeKeepFree|MaxFileSec)='
            SystemMaxUse=
            SystemKeepFree=
            RuntimeMaxUse=
            RuntimeKeepFree=
            MaxFileSec=




                                                                                                   Page 673

Internal Only - General
            Remediation:
            Edit /etc/systemd/journald.conf or a file ending in .conf the
            /etc/systemd/journald.conf.d/ directory. Set the following parameters in the
            [Journal] section to ensure logs are rotated according to site policy. The settings
            should be carefully understood as there are specific edge cases and prioritization of
            parameters.
            Example Configuration
            [Journal]
            SystemMaxUse=1G
            SystemKeepFree=500M
            RuntimeMaxUse=200M
            RuntimeKeepFree=50M
            MaxFileSec=1month
            Note: If these settings appear in a canonically later file, or later in the same file, the
            setting will be overwritten
            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-7, AU-12
                 2. https://man7.org/linux/man-pages/man5/journald.conf.5.html

            Additional Information:
            See man 5 journald.conf for detailed information regarding the parameters in use.

            CIS Controls:

               Controls
                                                              Control                                    IG 1 IG 2 IG 3
               Version
                           8.2 Collect Audit Logs
                    v8       Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                           management process, has been enabled across enterprise assets.

                           6.2 Activate audit logging
                    v7        Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                           devices.

                           6.3 Enable Detailed Logging
                    v7        Enable system logging to include detailed information such as an event
                           source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                               ●    ●
                           other useful elements.




                                                                                                               Page 674

Internal Only - General
            6.1.1.1.4 Ensure journald ForwardToSyslog is disabled
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Data from journald should be kept in the confines of the service and not forwarded to
            other services.
            Rationale:
            - IF - journald is the method for capturing logs, all logs of the system should be
            handled by journald and not forwarded to other logging mechanisms.
            Note: This recommendation only applies if journald is the chosen method for
            client side logging. Do not apply this recommendation if rsyslog is used.




                                                                                             Page 675

Internal Only - General
            Audit:
            - IF - journald is the method for capturing logs
            Run the following script to verify ForwardToSyslog in not set to yes:
            #!/usr/bin/env bash

            {
                 l_analyze_cmd="$(readlink -e /bin/systemd-analyze || \
                 readlink -e /usr/bin/systemd-analyze)"
                 l_conf_file="systemd/journald.conf" l_block="Journal"
                 l_option="ForwardToSyslog" l_option_value="no" a_output=()
                 while IFS= read -r l_file; do
                    l_file="${l_file//# /}"
                    l_opt="$(awk '/\['"$l_block"'\]/{a=1;next}/\[/{a=0}a' "$l_file" \
                    2>/dev/null | grep -Poi '^\h*'"$l_option"'\h*=\h*\H+\b' | tail -n 1)"
                       l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                    [ -n "$l_option_value" ] && \
                    a_output+=(" - \"$l_option\" is set to: \"$l_option_value\"" \
                    "    in: \"$l_file\"")
                 done < <("$l_analyze_cmd" cat-config "$l_conf_file" | tac | \
                 grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 if [ "${#a_output[@]}" -le "0" ]; then
                    l_file="$(readlink -e /etc/"$l_conf_file" || \
                    readlink -e /usr/lib/"$l_conf_file")"
                    l_opt="$(awk '/\['"$l_block"'\]/{a=1;next}/\[/{a=0}a' "$l_file" \
                    2>/dev/null | grep -Poim 1 '^(\h*#)?\h*'"$l_option"'\h*=\h*\H+\b')"
                    l_option_value="$(cut -d= -f2 <<< "${l_opt//# /}" | xargs)"
                    [ -n "$l_option_value" ] && \
                    a_output+=(" - The default value: \"${l_opt//#/}\"" \
                    "    is being used in the configuration")
                 fi
                 [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }




                                                                                    Page 676

Internal Only - General
            Remediation:
            - IF - rsyslog is the preferred method for capturing logs, this section and
            Recommendation should be skipped and the "Configure rsyslog" section followed.
            - IF - journald is the preferred method for capturing logs:
            Set the following parameter in the [Journal] section in
            /etc/systemd/journald.conf or a file in /etc/systemd/journald.conf.d/ ending
            in .conf:
            ForwardToSyslog=no
            Example:
            #!/usr/bin/env bash

            {
               [ ! -d /etc/systemd/journald.conf.d/ ] && mkdir -p
            /etc/systemd/journald.conf.d/
               if grep -Psq -- '^\h*\[Journal\]' /etc/systemd/journald.conf.d/60-
            journald.conf; then
                  printf '%s\n' "" "ForwardToSyslog=no" >>
            /etc/systemd/journald.conf.d/60-journald.conf
               else
                  printf '%s\n' "" "[Journal]" "ForwardToSyslog=no" >>
            /etc/systemd/journald.conf.d/60-journald.conf
               fi
            }
            Note: Drop-in configuration files have higher precedence and override the main
            configuration file. Files in the *.conf.d/ configuration subdirectories are sorted by their
            filename in lexicographic order, regardless of in which of the subdirectories they reside.
            When multiple files specify the same option, for options which accept just a single value,
            the entry in the file sorted last takes precedence, and for options which accept a list of
            values, entries are collected as they occur in the sorted files.
            Run to following command to update the parameters in the service:
            # systemctl reload-or-restart systemd-journald

            Default Value:
            ForwardToSyslog=no
            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-6, AU-7, AU-12
                 2. journald.conf(5) - Linux manual page: https://man7.org/linux/man-
                    pages/man5/journald.conf.5.html




                                                                                              Page 677

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                    IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                              ●    ●
                          other useful elements.




                                                                                                              Page 678

Internal Only - General
            6.1.1.1.5 Ensure journald Storage is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Data from journald may be stored in volatile memory or persisted locally on the server.
            Logs in memory will be lost upon a system reboot. By persisting logs to local disk on the
            server they are protected from loss due to a reboot.
            Rationale:
            Writing log data to disk will provide the ability to forensically reconstruct events which
            may have impacted the operations or security of a system even after a system crash or
            reboot.




                                                                                              Page 679

Internal Only - General
            Audit:
            Run the following script to verify Storage is set to persistent:
            #!/usr/bin/env bash

            {
                 l_analyze_cmd="$(readlink -e /bin/systemd-analyze || \
                 readlink -e /usr/bin/systemd-analyze)"
                 l_conf_file="systemd/journald.conf" l_block="Journal"
                 l_option="Storage" l_option_value="persistent" a_output=()
                 while IFS= read -r l_file; do
                    l_file="${l_file//# /}"
                    l_opt="$(awk '/\['"$l_block"'\]/{a=1;next}/\[/{a=0}a' "$l_file" \
                    2>/dev/null | grep -Poi '^\h*'"$l_option"'\h*=\h*\H+\b' | tail -n 1)"
                       l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                    [ -n "$l_option_value" ] && \
                    a_output+=(" - \"$l_option\" is set to: \"$l_option_value\"" \
                    "    in: \"$l_file\"")
                 done < <("$l_analyze_cmd" cat-config "$l_conf_file" | tac | \
                 grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 if [ "${#a_output[@]}" -le "0" ]; then
                    l_file="$(readlink -e /etc/"$l_conf_file" || \
                    readlink -e /usr/lib/"$l_conf_file")"
                    l_opt="$(awk '/\['"$l_block"'\]/{a=1;next}/\[/{a=0}a' "$l_file" \
                    2>/dev/null | grep -Poim 1 '^(\h*#)?\h*'"$l_option"'\h*=\h*\H+\b')"
                    l_option_value="$(cut -d= -f2 <<< "${l_opt//# /}" | xargs)"
                    [ -n "$l_option_value" ] && \
                    a_output+=(" - The default value: \"${l_opt//#/}\"" \
                    "    is being used in the configuration")
                 fi
                 [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }




                                                                                    Page 680

Internal Only - General
            Remediation:
            Set the following parameter in the [Journal] section in
            /etc/systemd/journald.conf or a file in /etc/systemd/journald.conf.d/ ending
            in .conf:
            Storage=persistent
            Example:
            #!/usr/bin/env bash

            {
               [ ! -d /etc/systemd/journald.conf.d/ ] && mkdir -p
            /etc/systemd/journald.conf.d/
               if grep -Psq -- '^\h*\[Journal\]' /etc/systemd/journald.conf.d/60-
            journald.conf; then
                  printf '%s\n' "Storage=persistent" >> /etc/systemd/journald.conf.d/60-
            journald.conf
               else
                  printf '%s\n' "" "[Journal]" "Storage=persistent" >>
            /etc/systemd/journald.conf.d/60-journald.conf
               fi
            }
            Note: Drop-in configuration files have higher precedence and override the main
            configuration file. Files in the *.conf.d/ configuration subdirectories are sorted by their
            filename in lexicographic order, regardless of in which of the subdirectories they reside.
            When multiple files specify the same option, for options which accept just a single value,
            the entry in the file sorted last takes precedence, and for options which accept a list of
            values, entries are collected as they occur in the sorted files.
            Run to following command to update the parameters in the service:
            # systemctl reload-or-restart systemd-journald

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3, AU-12
                 2. journald.conf(5) - Linux manual page: https://man7.org/linux/man-
                    pages/man5/journald.conf.5.html




                                                                                              Page 681

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                    IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                              ●    ●
                          other useful elements.




                                                                                                              Page 682

Internal Only - General
            6.1.1.1.6 Ensure journald Compress is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The journald system includes the capability of compressing overly large files to avoid
            filling up the system with logs or making the logs unmanageably large.
            Rationale:
            Uncompressed large files may unexpectedly fill a filesystem leading to resource
            unavailability. Compressing logs prior to write can prevent sudden, unexpected
            filesystem impacts.




                                                                                              Page 683

Internal Only - General
            Audit:
            Run the following script to verify Compress is set to yes:
            #!/usr/bin/env bash

            {
                 l_analyze_cmd="$(readlink -e /bin/systemd-analyze || \
                 readlink -e /usr/bin/systemd-analyze)"
                 l_conf_file="systemd/journald.conf" l_block="Journal"
                 l_option="Compress" l_option_value="yes" a_output=()
                 while IFS= read -r l_file; do
                    l_file="${l_file//# /}"
                    l_opt="$(awk '/\['"$l_block"'\]/{a=1;next}/\[/{a=0}a' "$l_file" \
                    2>/dev/null | grep -Poi '^\h*'"$l_option"'\h*=\h*\H+\b' | tail -n 1)"
                       l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                    [ -n "$l_option_value" ] && \
                    a_output+=(" - \"$l_option\" is set to: \"$l_option_value\"" \
                    "    in: \"$l_file\"")
                 done < <("$l_analyze_cmd" cat-config "$l_conf_file" | tac | \
                 grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 if [ "${#a_output[@]}" -le "0" ]; then
                    l_file="$(readlink -e /etc/"$l_conf_file" || \
                    readlink -e /usr/lib/"$l_conf_file")"
                    l_opt="$(awk '/\['"$l_block"'\]/{a=1;next}/\[/{a=0}a' "$l_file" \
                    2>/dev/null | grep -Poim 1 '^(\h*#)?\h*'"$l_option"'\h*=\h*\H+\b')"
                    l_option_value="$(cut -d= -f2 <<< "${l_opt//# /}" | xargs)"
                    [ -n "$l_option_value" ] && \
                    a_output+=(" - The default value: \"${l_opt//#/}\"" \
                    "    is being used in the configuration")
                 fi
                 [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }




                                                                                    Page 684

Internal Only - General
            Remediation:
            Set the following parameter in the [Journal] section in
            /etc/systemd/journald.conf or a file in /etc/systemd/journald.conf.d/ ending
            in .conf:
            Compress=yes
            Example:
            #!/usr/bin/env bash

            {
               [ ! -d /etc/systemd/journald.conf.d/ ] && mkdir -p
            /etc/systemd/journald.conf.d/
               if grep -Psq -- '^\h*\[Journal\]' /etc/systemd/journald.conf.d/60-
            journald.conf; then
                  printf '%s\n' "" "Compress=yes" >> /etc/systemd/journald.conf.d/60-
            journald.conf
               else
                  printf '%s\n' "" "[Journal]" "Compress=yes" >>
            /etc/systemd/journald.conf.d/60-journald.conf
               fi
            }
            Note: Drop-in configuration files have higher precedence and override the main
            configuration file. Files in the *.conf.d/ configuration subdirectories are sorted by their
            filename in lexicographic order, regardless of in which of the subdirectories they reside.
            When multiple files specify the same option, for options which accept just a single value,
            the entry in the file sorted last takes precedence, and for options which accept a list of
            values, entries are collected as they occur in the sorted files.
            Run to following command to update the parameters in the service:
            # systemctl reload-or-restart systemd-journald

            References:

                 1. NIST SP 800-53 Rev. 5: AU-4
                 2. journald.conf(5) - Linux manual page: https://man7.org/linux/man-
                    pages/man5/journald.conf.5.html




                                                                                              Page 685

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                       IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log         ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          8.3 Ensure Adequate Audit Log Storage
                    v8       Ensure that logging destinations maintain adequate storage to comply with      ●    ●    ●
                          the enterprise’s audit log management process.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking       ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                                 ●    ●
                          other useful elements.

                          6.4 Ensure adequate storage for logs
                    v7       Ensure that all systems that store logs have adequate storage space for the         ●    ●
                          logs generated.




                                                                                                                 Page 686

Internal Only - General
            6.1.1.2 Configure systemd-journal-remote
            The systemd-journal-remote package includes systemd-journal-upload.
            systemd-journal-upload will upload journal entries to the URL specified with --url=.
            This program reads journal entries from one or more journal files, similarly to journalctl.
            systemd-journal-upload transfers the raw content of journal file and uses HTTP as a
            transport protocol.
            systemd-journal-upload.service is a system service that uses systemd-journal-
            upload to upload journal entries to a server. It uses the configuration in journal-
            upload.conf.




                                                                                               Page 687

Internal Only - General
            6.1.1.2.1 Ensure systemd-journal-remote is installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Journald systemd-journal-remote supports the ability to send log events it gathers to
            a remote log host or to receive messages from remote hosts, thus enabling centralized
            log management.
            Rationale:
            Storing log data on a remote host protects log integrity from local attacks. If an attacker
            gains root access on the local system, they could tamper with or remove log data that is
            stored on the local system.
            Note: This recommendation only applies if journald is the chosen method for
            client side logging. Do not apply this recommendation if rsyslog is used.

            Audit:
            - IF - journald will be used for logging on the system:
            Run the following command to verify systemd-journal-remote is installed.
            # dpkg-query -s systemd-journal-remote &>/dev/null && echo "systemd-journal-
            remote is installed"
            Verify the output matches:
            systemd-journal-remote is installed

            Remediation:
            Run the following command to install systemd-journal-remote:
            # apt install systemd-journal-remote

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-7 AU-12




                                                                                               Page 688

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                    IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                              ●    ●
                          other useful elements.




                                                                                                              Page 689

Internal Only - General
            6.1.1.2.2 Ensure systemd-journal-upload authentication is
            configured (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Journald systemd-journal-upload supports the ability to send log events it gathers to
            a remote log host.
            Rationale:
            Storing log data on a remote host protects log integrity from local attacks. If an attacker
            gains root access on the local system, they could tamper with or remove log data that is
            stored on the local system.
            Note: This recommendation only applies if journald is the chosen method for
            client side logging. Do not apply this recommendation if rsyslog is used.




                                                                                               Page 690

Internal Only - General
            Audit:
            Run the following script to verify systemd-journal-upload authentication is
            configured:
            #!/usr/bin/env bash

            {
                 l_analyze_cmd="$(readlink -e /bin/systemd-analyze || \
                 readlink -e /usr/bin/systemd-analyze)"
                 l_conf_file="systemd/journal-upload.conf" l_block="Upload"
                 while IFS= read -r l_file; do
                    l_file="${l_file//# /}"
                    gawk '/\['"$l_block"'\]/{a=1;next}/\[/{a=0}a' "$l_file" \
                    2>/dev/null | grep -Poi -- \

            '^\h*(URL|ServerKeyFile|ServerCertificateFile|TrustedCertificateFile)\h*=\h*\
            H+\b'
               done < <("$l_analyze_cmd" cat-config "$l_conf_file" | tac | \
               grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
            }
            Verify the output matches per your environments certificate locations and the URL of
            the log server:
            Example output:
            URL=192.168.50.42
            ServerKeyFile=/etc/ssl/private/journal-upload.pem
            ServerCertificateFile=/etc/ssl/certs/journal-upload.pem
            TrustedCertificateFile=/etc/ssl/ca/trusted.pem




                                                                                           Page 691

Internal Only - General
            Remediation:
            Edit the /etc/systemd/journal-upload.conf file or a file in
            /etc/systemd/journal-upload.conf.d ending in .conf and ensure the following
            lines are set in the [Upload] section per your environment:
            [Upload]
            URL=192.168.50.42
            ServerKeyFile=/etc/ssl/private/journal-upload.pem
            ServerCertificateFile=/etc/ssl/certs/journal-upload.pem
            TrustedCertificateFile=/etc/ssl/ca/trusted.pem
            Example script:
            #!/usr/bin/env bash

            {
                 [ ! -d "/etc/systemd/journal-upload.conf.d" ] && \
                 mkdir -p /etc/systemd/journal-upload.conf.d
                 printf '%s\n' "" "[Upload]" "URL=192.168.50.42" \
                 "ServerKeyFile=/etc/ssl/private/journal-upload.pem" \
                 "ServerCertificateFile=/etc/ssl/certs/journal-upload.pem" \
                 "TrustedCertificateFile=/etc/ssl/ca/trusted.pem" \
                 >> /etc/systemd/journal-upload.conf.d/60-journal-upload.conf
            }
            Restart the service:
            # systemctl reload-or-restart systemd-journal-upload

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-12

            CIS Controls:

                Controls
                                                              Control                                    IG 1 IG 2 IG 3
                Version
                           8.2 Collect Audit Logs
                    v8       Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                           management process, has been enabled across enterprise assets.

                           6.2 Activate audit logging
                    v7        Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                           devices.

                           6.3 Enable Detailed Logging
                    v7        Enable system logging to include detailed information such as an event
                           source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                               ●    ●
                           other useful elements.




                                                                                                               Page 692

Internal Only - General
            6.1.1.2.3 Ensure systemd-journal-upload is enabled and active
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Journald systemd-journal-upload supports the ability to send log events it gathers to
            a remote log host.
            Rationale:
            Storing log data on a remote host protects log integrity from local attacks. If an attacker
            gains root access on the local system, they could tamper with or remove log data that is
            stored on the local system.
            Audit:
            Run the following command to verify systemd-journal-upload is enabled.
            # systemctl is-enabled systemd-journal-upload.service

            enabled
            Run the following command to verify systemd-journal-upload is active:
            # systemctl is-active systemd-journal-upload.service

            active

            Remediation:
            Run the following commands to unmask, enable and start systemd-journal-upload:
            # systemctl unmask systemd-journal-upload.service
            # systemctl --now enable systemd-journal-upload.service

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-12




                                                                                               Page 693

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                    IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                              ●    ●
                          other useful elements.




                                                                                                              Page 694

Internal Only - General
            6.1.1.2.4 Ensure systemd-journal-remote service is not in use
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Journald systemd-journal-remote supports the ability to receive messages from
            remote hosts, thus acting as a log server. Clients should not receive data from other
            hosts.
            Note:

                 •   The same package, systemd-journal-remote, is used for both sending logs to
                     remote hosts and receiving incoming logs.
                 •   With regards to receiving logs, there are two services; systemd-journal-
                     remote.socket and systemd-journal-remote.service.

            Rationale:
            If a client is configured to also receive data, thus turning it into a server, the client
            system is acting outside it's operational boundary.
            Note: This recommendation only applies if journald is the chosen method for
            client side logging. Do not apply this recommendation if rsyslog is used.

            Audit:
            Run the following command to verify systemd-journal-remote.socket and systemd-
            journal-remote.service are not enabled:
            # systemctl is-enabled systemd-journal-remote.socket systemd-journal-
            remote.service | grep -P -- '^enabled'
            Nothing should be returned
            Run the following command to verify systemd-journal-remote.socket and systemd-
            journal-remote.service are not active:
            # systemctl is-active systemd-journal-remote.socket systemd-journal-
            remote.service | grep -P -- '^active'
            Nothing should be returned




                                                                                                   Page 695

Internal Only - General
            Remediation:
            Run the following commands to stop and mask systemd-journal-remote.socket and
            systemd-journal-remote.service:
            # systemctl stop systemd-journal-remote.socket systemd-journal-remote.service
            # systemctl mask systemd-journal-remote.socket systemd-journal-remote.service

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-7 AU-12

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 696

Internal Only - General
            6.1.2 Configure rsyslog

            The rsyslog software package may be used instead of the default journald logging
            mechanism.
            Rsyslog has evolved over several decades. For this reason it supports three different
            configuration formats (“languages”):

                 •   basic - previously known as the sysklogd format, this is the format best used to
                     express basic things, such as where the statement fits on a single line.
                          o It stems back to the original syslog.conf format, in use now for several
                              decades.
                          o The most common use case is matching on facility/severity and writing
                              matching messages to a log file.
                 •   advanced - previously known as the RainerScript format, this format was first
                     available in rsyslog v6 and is the current, best and most precise format for non-
                     trivial use cases where more than one line is needed.
                          o Prior to v7, there was a performance impact when using this format that
                              encouraged use of the basic format for best results. Current versions of
                              rsyslog do not suffer from this (historical) performance impact.
                          o This new style format is specifically targeted towards more advanced use
                              cases like forwarding to remote hosts that might be partially offline.
                 •   obsolete legacy - previously known simply as the legacy format, this format is
                     exactly what its name implies: it is obsolete and should not be used when writing
                     new configurations. It was created in the early days (up to rsyslog version 5)
                     where we expected that rsyslog would extend sysklogd just mildly. Consequently,
                     it was primarily aimed at small additions to the original sysklogd format.
                          o Practice has shown that it was notoriously hard to use for more advanced
                              use cases, and thus we replaced it with the advanced format.
                          o In essence, everything that needs to be written on a single line that starts
                              with a dollar sign is legacy format. Users of this format are encouraged to
                              migrate to the basic or advanced formats.

            Note: This section only applies if rsyslog is the chosen method for client side logging.
            Do not apply this section if journald is used.




                                                                                                Page 697

Internal Only - General
            6.1.2.1 Ensure rsyslog is installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The rsyslog software is recommended in environments where journald does not
            meet operation requirements.
            Rationale:
            The security enhancements of rsyslog such as connection-oriented (i.e. TCP)
            transmission of logs, the option to log to database formats, and the encryption of log
            data en route to a central logging server) justify installing and configuring the package.
            Audit:
            - IF - rsyslog is being used for logging on the system:
            Run the following command to verify rsyslog is installed:
            # dpkg-query -s rsyslog &>/dev/null && echo "rsyslog is installed"
            Verify the output matches:
            rsyslog is installed

            Remediation:
            Run the following command to install rsyslog:
            # apt install rsyslog

            Default Value:
            Installed
            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-3, AU-12




                                                                                               Page 698

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                    IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                              ●    ●
                          other useful elements.




                                                                                                              Page 699

Internal Only - General
            6.1.2.2 Ensure rsyslog service is enabled and active (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Once the rsyslog package is installed, ensure that the service is enabled.

            Rationale:
            If the rsyslog service is not enabled to start on boot, the system will not capture
            logging events.
            Audit:
            - IF - rsyslog is being used for logging on the system:
            Run the following command to verify rsyslog.service is enabled:
            # systemctl is-enabled rsyslog

            enabled
            Run the following command to verify rsyslog.service is active:
            # systemctl is-active rsyslog.service

            active

            Remediation:
            - IF - rsyslog is being used for logging on the system:
            Run the following commands to unmask, enable, and start rsyslog.service:
            # systemctl unmask rsyslog.service
            # systemctl enable rsyslog.service
            # systemctl start rsyslog.service

            References:

                 1. CCI-000366
                 2. NIST SP 800-53 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)
                 4. STIG ID: RHEL-08-010561 | RULE ID: SV-230298r1017108 | CAT II
                 5. STIG ID: OL08-00-010561 | RULE ID: SV-248615r991589 | CAT II
                 6. STIG ID: ALMA-09-053150 | RULE ID: SV-269518r1050401 | CAT II
                 7. STIG ID: UBTU-22-652010 | RULE ID: SV-260588r991562 | CAT II




                                                                                              Page 700

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                    IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                              ●    ●
                          other useful elements.




                                                                                                              Page 701

Internal Only - General
            6.1.2.3 Ensure journald is configured to send logs to rsyslog
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Data from systemd-journald may be stored in volatile memory or persisted locally on
            the server. Utilities exist to accept remote export of systemd-journald logs, however,
            use of the rsyslog service provides a consistent means of log collection and export.

            Rationale:
            - IF - rsyslog is the preferred method for capturing logs, all logs of the system should
            be sent to it for further processing.
            Note: This recommendation only applies if rsyslog is the chosen method for client
            side logging. Do not apply this recommendation if systemd-journald is used.




                                                                                            Page 702

Internal Only - General
            Audit:
            - IF - rsyslog is the preferred method for capturing logs
            Run the following script to verify that logs are forwarded to rsyslog by setting
            ForwardToSyslog to yes in the systemd-journald configuration:
            #!/usr/bin/env bash

            {
                 l_analyze_cmd="$(readlink -e /bin/systemd-analyze || \
                 readlink -e /usr/bin/systemd-analyze)"
                 l_conf_file="systemd/journald.conf" l_block="Journal"
                 l_option="ForwardToSyslog" l_option_value="yes" a_output=()
                 while IFS= read -r l_file; do
                    l_file="${l_file//# /}"
                    l_opt="$(awk '/\['"$l_block"'\]/{a=1;next}/\[/{a=0}a' "$l_file" \
                    2>/dev/null | grep -Poi '^\h*'"$l_option"'\h*=\h*\H+\b' | tail -n 1)"
                       l_option_value="$(cut -d= -f2 <<< "$l_opt" | xargs)"
                    [ -n "$l_option_value" ] && \
                    a_output+=(" - \"$l_option\" is set to: \"$l_option_value\"" \
                    "    in: \"$l_file\"")
                 done < <("$l_analyze_cmd" cat-config "$l_conf_file" | tac | \
                 grep -Pio '^\h*#\h*\/[^#\n\r\h]+\.conf\b')
                 if [ "${#a_output[@]}" -le "0" ]; then
                    l_file="/etc/$l_conf_file"
                    l_opt="$(awk '/\['"$l_block"'\]/{a=1;next}/\[/{a=0}a' "$l_file" \
                    2>/dev/null | grep -Poim 1 '^(\h*#)?\h*'"$l_option"'\h*=\h*\H+\b')"
                    l_option_value="$(cut -d= -f2 <<< "${l_opt//# /}" | xargs)"
                    [ -n "$l_option_value" ] && \
                    a_output+=(" - The default value: \"${l_opt//#/}\"" \
                    "    is being used in the configuration")
                 fi
                 [ "${#a_output[@]}" -gt "0" ] && printf '%s\n' "" "${a_output[@]}" ""
            }
            Run the following command to verify systemd-journald.service and
            rsyslog.service are loaded and active:
            # systemctl list-units --type service | grep -P -- '(journald|rsyslog)'
            Output should be similar to:
            rsyslog.service                                               loaded active running
            System Logging Service
            systemd-journald.service                                      loaded active running
            Journal Service




                                                                                               Page 703

Internal Only - General
            Remediation:
            - IF - Journald is the preferred method for capturing logs, this section and
            Recommendation should be skipped and the "Configure Journald" section followed.
            - IF - rsyslog is the preferred method for capturing logs:
            Set the following parameter in the [Journal] section in
            /etc/systemd/journald.conf or a file in /etc/systemd/journald.conf.d/ ending
            in .conf:
            ForwardToSyslog=yes
            Example:
            #!/usr/bin/env bash

            {
               [ ! -d /etc/systemd/journald.conf.d/ ] && mkdir
            /etc/systemd/journald.conf.d/
               if grep -Psq -- '^\h*\[Journal\] /etc/systemd/journald.conf.d/60-
            journald.conf; then
                  printf '%s\n' "ForwardToSyslog=yes" >> /etc/systemd/journald.conf.d/60-
            journald.conf
               else
                  printf '%s\n' "[Journal]" "ForwardToSyslog=yes" >>
            /etc/systemd/journald.conf.d/60-journald.conf
               fi
            }
            Note: Drop-in configuration files have higher precedence and override the main
            configuration file. Files in the *.conf.d/ configuration subdirectories are sorted by their
            filename in lexicographic order, regardless of in which of the subdirectories they reside.
            When multiple files specify the same option, for options which accept just a single value,
            the entry in the file sorted last takes precedence, and for options which accept a list of
            values, entries are collected as they occur in the sorted files.
            Run to following command to update the parameters in the service:
            Restart systemd-journald.service:
            # systemctl reload-or-restart systemd-journald.service

            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, AU-2, AU-4, AU-12, MP-2
                 2. SYSTEMD-JOURNALD.SERVICE(8)
                 3. JOURNALD.CONF(5)




                                                                                              Page 704

Internal Only - General
            Additional Information:
            As noted in the systemd-journald man pages, systemd-journald logs may be
            exported to rsyslog either through the process mentioned here, or through a facility
            like systemd-journald.service. There are trade-offs involved in each
            implementation, where ForwardToSyslog will immediately capture all events (and
            forward to an external log server, if properly configured), but may not capture all boot-up
            activities. Mechanisms such as systemd-journald.service, on the other hand, will
            record bootup events, but may delay sending the information to rsyslog, leading to the
            potential for log manipulation prior to export. Be aware of the limitations of all tools
            employed to secure a system.
            CIS Controls:

               Controls
                                                              Control                                        IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log           ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          8.9 Centralize Audit Logs
                    v8       Centralize, to the extent possible, audit log collection and retention across         ●    ●
                          enterprise assets.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking         ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                                   ●    ●
                          other useful elements.

                          6.5 Central Log Management
                    v7      Ensure that appropriate logs are being aggregated to a central log                     ●    ●
                          management system for analysis and review.




                                                                                                                   Page 705

Internal Only - General
            6.1.2.4 Ensure rsyslog log file creation mode is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            rsyslog will create logfiles that do not already exist on the system.
            The global() configuration object umask, available in rsyslog 8.26.0+, sets the
            rsyslogd process’ umask. If not specified, the system-provided default is used. The
            value given must always be a 4-digit octal number, with the initial digit being zero.
            The legacy $umask parameter sets the rsyslogd process' umask. If not specified, the
            system-provided default is used. The value given must always be a 4-digit octal
            number, with the initial digit being zero.
            The legacy $FileCreateMode parameter allows the setting of the mode with which
            rsyslogd creates new files. If not specified, the value 0644 is used. The value given
            must always be a 4-digit octal number, with the initial digit being zero. Please note that
            the actual permission depend on rsyslogd process umask. If in doubt, use $umask
            0000 right at the beginning of the configuration file to remove any restrictions.
            The legacy $FileCreateMode may be specified multiple times. If so, it specifies the
            creation mode for all selector lines that follow until the next $FileCreateMode
            parameter. Order of lines is vitally important.
            Rationale:
            It is important to ensure that log files have the correct permissions to ensure that
            sensitive data is archived and protected.
            Audit:
            Run the following command
            Run the following command to verify $FileCreateMode:
            # grep -Ps '^\h*\$FileCreateMode\h+0[0,2,4,6][0,2,4]0\b' /etc/rsyslog.conf
            /etc/rsyslog.d/*.conf
            Verify the output is includes 0640 or more restrictive:
            $FileCreateMode 0640
            Should a site policy dictate less restrictive permissions, ensure to follow said policy.
            NOTE: More restrictive permissions such as 0600 is implicitly sufficient.




                                                                                                Page 706

Internal Only - General
            Remediation:
            Edit either /etc/rsyslog.conf or a dedicated .conf file in /etc/rsyslog.d/ and set
            $FileCreateMode to 0640 or more restrictive:
            $FileCreateMode 0640
            Restart the service:
            # systemctl restart rsyslog

            References:

                 1. RSYSLOG.CONF(5)
                 2. NIST SP 800-53 Rev. 5: AC-3, AC-6, MP-2
                 3. https://www.rsyslog.com/doc/

            CIS Controls:

               Controls
                                                              Control                                        IG 1 IG 2 IG 3
               Version
                          3.3 Configure Data Access Control Lists
                   v8         Configure data access control lists based on a user’s need to know. Apply
                          data access control lists, also known as access permissions, to local and remote
                                                                                                              ●    ●    ●
                          file systems, databases, and applications.

                          8.2 Collect Audit Logs
                   v8       Collect audit logs. Ensure that logging, per the enterprise’s audit log           ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          5.1 Establish Secure Configurations
                   v7        Maintain documented, standard security configuration standards for all           ●    ●    ●
                          authorized operating systems and software.

                          6.2 Activate audit logging
                   v7        Ensure that local logging has been enabled on all systems and networking         ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                   v7        Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                                   ●    ●
                          other useful elements.




                                                                                                                   Page 707

Internal Only - General
            6.1.2.5 Ensure rsyslog logging is configured (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/rsyslog.conf and /etc/rsyslog.d/*.conf files specifies rules for logging
            and which files are to be used to log certain classes of messages.
            Rationale:
            A great deal of important security-related information is sent via rsyslog (e.g.,
            successful and failed su attempts, failed login attempts, root login attempts, etc.).
            Audit:
            Review the contents of /etc/rsyslog.conf and /etc/rsyslog.d/*.conf files to
            ensure appropriate logging is set. In addition, run the following command and verify that
            the log files are logging information as expected:
            # ls -l /var/log/

            Remediation:
            Edit the following lines in the /etc/rsyslog.conf and /etc/rsyslog.d/*.conf files
            as appropriate for your environment.
            Note: The below configuration is shown for example purposes only. Due care should be
            given to how the organization wishes to store log data.
            *.emerg                                         :omusrmsg:*
            auth,authpriv.*                                 /var/log/secure
            mail.*                                         -/var/log/mail
            mail.info                                      -/var/log/mail.info
            mail.warning                                   -/var/log/mail.warn
            mail.err                                        /var/log/mail.err
            cron.*                                          /var/log/cron
            *.=warning;*.=err                              -/var/log/warn
            *.crit                                          /var/log/warn
            *.*;mail.none;news.none                        -/var/log/messages
            local0,local1.*                                -/var/log/localmessages
            local2,local3.*                                -/var/log/localmessages
            local4,local5.*                                -/var/log/localmessages
            local6,local7.*                                -/var/log/localmessages
            Run the following command to reload the rsyslogd configuration:
            # systemctl restart rsyslog




                                                                                                Page 708

Internal Only - General
            References:

                 1. See the rsyslog.conf(5) man page for more information.
                 2. NIST SP 800-53 Rev. 5: AU-2, AU-7, AU-12

            CIS Controls:

               Controls
                                                              Control                                    IG 1 IG 2 IG 3
               Version
                           8.2 Collect Audit Logs
                    v8       Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                           management process, has been enabled across enterprise assets.

                           6.2 Activate audit logging
                    v7        Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                           devices.

                           6.3 Enable Detailed Logging
                    v7        Enable system logging to include detailed information such as an event
                           source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                               ●    ●
                           other useful elements.




                                                                                                               Page 709

Internal Only - General
            6.1.2.6 Ensure rsyslog is configured to send logs to a remote log
            host (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            rsyslog supports the ability to send log events it gathers to a remote log host or to
            receive messages from remote hosts, thus enabling centralized log management.
            Rationale:
            Storing log data on a remote host protects log integrity from local attacks. If an attacker
            gains root access on the local system, they could tamper with or remove log data that is
            stored on the local system.
            Audit:
            Review the /etc/rsyslog.conf and /etc/rsyslog.d/*.conf files and verify that
            logs are sent to a central host:
            basic format
            # grep "^*.*[^I][^I]*@" /etc/rsyslog.conf /etc/rsyslog.d/*.conf
            Output should include @@<FQDN or IP of remote loghost>:
            Example:
            *.* @@loghost.example.com
            advanced format
            # grep -Psi -- '^\s*([^#]+\s+)?action\(([^#]+\s+)?\btarget=\"?[^#"]+\"?\b'
            /etc/rsyslog.conf /etc/rsyslog.d/*.conf
            Output should include target=<FQDN or IP of remote loghost>:
            Example:
            *.* action(type="omfwd" target="loghost.example.com" port="514"
            protocol="tcp"




                                                                                               Page 710

Internal Only - General
            Remediation:
            Edit the /etc/rsyslog.conf and /etc/rsyslog.d/*.conf files and add the following
            line (where loghost.example.com is the name of your central log host). The target
            directive may either be a fully qualified domain name or an IP address.
            Example:
            *.* action(type="omfwd" target="loghost.example.com" port="514"
            protocol="tcp"
                       action.resumeRetryCount="100"
                       queue.type="LinkedList" queue.size="1000")
            Run the following command to reload rsyslog.service:
            # systemctl reload-or-restart rsyslog.service

            References:

                 1. See the rsyslog.conf(5) man page for more information.
                 2. NIST SP 800-53 Rev. 5: AU-6
                 3. https://www.rsyslog.com/doc/

            Additional Information:
            In addition, see the rsyslog documentation for implementation details of TLS.
            CIS Controls:

               Controls
                                                              Control                                    IG 1 IG 2 IG 3
               Version
                           8.2 Collect Audit Logs
                    v8       Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                           management process, has been enabled across enterprise assets.

                           6.2 Activate audit logging
                    v7        Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                           devices.

                           6.3 Enable Detailed Logging
                    v7        Enable system logging to include detailed information such as an event
                           source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                               ●    ●
                           other useful elements.




                                                                                                               Page 711

Internal Only - General
            6.1.2.7 Ensure rsyslog is not configured to receive logs from a
            remote client (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            rsyslog supports the ability to receive messages from remote hosts, thus acting as a
            log server. Clients should not receive data from other hosts.
            Rationale:
            If a client is configured to also receive data, thus turning it into a server, the client
            system is acting outside its operational boundary.
            Audit:
            Review the /etc/rsyslog.conf and /etc/rsyslog.d/*.conf files and verify that the
            system is not configured to accept incoming logs.
            advanced format
            # grep -Psi -- '^\h*module\(load=\"?imtcp\"?\)' /etc/rsyslog.conf
            /etc/rsyslog.d/*.conf
            # grep -Psi -- '^\h*input\(type=\"?imtcp\"?\b' /etc/rsyslog.conf
            /etc/rsyslog.d/*.conf
            Nothing should be returned
            obsolete legacy format
            # grep -Psi -- '^\h*\$ModLoad\h+imtcp\b' /etc/rsyslog.conf
            /etc/rsyslog.d/*.conf
            # grep -Psi -- '^\h*\$InputTCPServerRun\b' /etc/rsyslog.conf
            /etc/rsyslog.d/*.conf
            Nothing should be returned




                                                                                                    Page 712

Internal Only - General
            Remediation:
            Should there be any active log server configuration found in the auditing section, modify
            those files and remove the specific lines highlighted by the audit. Verify none of the
            following entries are present in any of /etc/rsyslog.conf or
            /etc/rsyslog.d/*.conf.
            advanced format
            module(load="imtcp")
            input(type="imtcp" port="514")
            deprecated legacy format
            $ModLoad imtcp
            $InputTCPServerRun
            Restart the service:
            # systemctl restart rsyslog

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-7, AU-12, CM-6
                 2. https://www.rsyslog.com/doc/index.html

            CIS Controls:

               Controls
                                                            Control                                          IG 1 IG 2 IG 3
               Version
                          4.8 Uninstall or Disable Unnecessary Services on
                          Enterprise Assets and Software
                    v8       Uninstall or disable unnecessary services on enterprise assets and software,          ●    ●
                          such as an unused file sharing service, web application module, or service
                          function.

                          9.2 Ensure Only Approved Ports, Protocols and Services
                    v7    Are Running                                                                              ●    ●
                             Ensure that only network ports, protocols, and services listening on a system
                          with validated business needs, are running on each system.




                                                                                                                   Page 713

Internal Only - General
            6.1.2.8 Ensure logrotate is configured (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The system includes the capability of rotating log files regularly to avoid filling up the
            system with logs or making the logs unmanageably large. The file
            /etc/logrotate.d/syslog is the configuration file used to rotate log files created by
            syslog or rsyslog.

            Rationale:
            By keeping the log files smaller and more manageable, a system administrator can
            easily archive these files to another system and spend less time looking through
            inordinately large log files.
            Audit:
            Review /etc/logrotate.conf and /etc/logrotate.d/* and verify logs are rotated
            according to site policy.
            Remediation:
            Edit /etc/logrotate.conf and /etc/logrotate.d/* to ensure logs are rotated
            according to site policy.
            References:

                 1. NIST SP 800-53 Rev. 5: AU-8

            Additional Information:
            If no maxage setting is set for logrotate a situation can occur where logrotate is
            interrupted and fails to delete rotated log files. It is recommended to set this to a value
            greater than the longest any log file should exist on your system to ensure that any such
            log file is removed but standard rotation settings are not overridden.




                                                                                                Page 714

Internal Only - General
            CIS Controls:

                Controls
                                                             Control                                         IG 1 IG 2 IG 3
                Version
                            8.3 Ensure Adequate Audit Log Storage
                     v8        Ensure that logging destinations maintain adequate storage to comply with      ●    ●    ●
                            the enterprise’s audit log management process.

                            6.4 Ensure adequate storage for logs
                     v7        Ensure that all systems that store logs have adequate storage space for the         ●    ●
                            logs generated.




                                                                                                                   Page 715

Internal Only - General
            6.1.3 Configure Logfiles




                                       Page 716

Internal Only - General
            6.1.3.1 Ensure access to all logfiles has been configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Log files contain information from many services on the the local system, or in the event
            of a centralized log server, others systems logs as well.
            In general log files are found in /var/log/, although application can be configured to
            store logs elsewhere. Should your application store logs in another, ensure to run the
            same test on that location.
            Rationale:
            It is important that log files have the correct permissions to ensure that sensitive data is
            protected and that only the appropriate users / groups have access to them.
            Audit:
            Run the following script to verify that files in /var/log/ have appropriate permissions
            and ownership:




                                                                                                Page 717

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output=(); a_output2=()
               f_file_test_chk()
               {
                  a_out2=()
                  maxperm="$( printf '%o' $(( 0777 & ~$perm_mask)) )"
                  [ $(( $l_mode & $perm_mask )) -gt 0 ] && \
                     a_out2+=("   o Mode: \"$l_mode\" should be \"$maxperm\" or more restrictive")
                  [[ ! "$l_user" =~ $l_auser ]] && \
                     a_out2+=("   o Owned by: \"$l_user\" and should be owned by \"${l_auser//|/ or }\"")
                  [[ ! "$l_group" =~ $l_agroup ]] && \
                     a_out2+=("   o Group owned by: \"$l_group\" and should be group owned by
            \"${l_agroup//|/ or }\"")
                  [ "${#a_out2[@]}" -gt 0 ] && a_output2+=(" - File: \"$l_fname\" is:" "${a_out2[@]}")
               }
               while IFS= read -r -d $'\0' l_file; do
                  while IFS=: read -r l_fname l_mode l_user l_group; do
                     if grep -Pq -- '\/(apt)\h*$' <<< "$(dirname "$l_fname")"; then
                        perm_mask='0133' l_auser="root" l_agroup="(root|adm)"; f_file_test_chk
                     else
                        case "$(basename "$l_fname")" in
                           lastlog | lastlog.* | wtmp | wtmp.* | wtmp-* | btmp | btmp.* | btmp-* | README)
                              perm_mask='0113' l_auser="root" l_agroup="(root|utmp)"
                              f_file_test_chk ;;
                           cloud-init.log* | localmessages* | waagent.log*)
                              perm_mask='0133' l_auser="(root|syslog)" l_agroup="(root|adm)"
                              file_test_chk ;;
                           secure{,*.*,.*,-*} | auth.log | syslog | messages)
                              perm_mask='0137' l_auser="(root|syslog)" l_agroup="(root|adm)"
                              f_file_test_chk ;;
                           SSSD | sssd)
                              perm_mask='0117' l_auser="(root|SSSD)" l_agroup="(root|SSSD)"
                              f_file_test_chk ;;
                           gdm | gdm3)
                              perm_mask='0117' l_auser="root" l_agroup="(root|gdm|gdm3)"
                              f_file_test_chk ;;
                           *.journal | *.journal~)
                              perm_mask='0137' l_auser="root" l_agroup="(root|systemd-journal)"
                              f_file_test_chk ;;
                           *)
                              perm_mask='0137' l_auser="(root|syslog)" l_agroup="(root|adm)"
                              if [ "$l_user" = "root" ] || ! grep -Pq -- "^\h*$(awk -F: '$1=="'"$l_user"'"
            {print $7}' /etc/passwd)\b" /etc/shells; then
                                 ! grep -Pq -- "$l_auser" <<< "$l_user" && l_auser="(root|syslog|$l_user)"
                                 ! grep -Pq -- "$l_agroup" <<< "$l_group" && l_agroup="(root|adm|$l_group)"
                              fi
                              f_file_test_chk ;;
                        esac
                     fi
                  done < <(stat -Lc '%n:%#a:%U:%G' "$l_file")
               done < <(find -L /var/log -type f \( -perm /0137 -o ! -user root -o ! -group root \) -print0)
               if [ "${#a_output2[@]}" -le 0 ]; then
                  a_output+=(" - All files in \"/var/log/\" have appropriate permissions and ownership")
                  printf '\n%s' "- Audit Result:" " ** PASS **" "${a_output[@]}" ""
               else
                  printf '\n%s' "- Audit Result:" " ** FAIL **" " - Reason(s) for audit failure:"
            "${a_output2[@]}" ""
               fi
            }




                                                                                                    Page 718

Internal Only - General
            Remediation:
            Run the following script to update permissions and ownership on files in /var/log.
            Although the script is not destructive, ensure that the output is captured in the event that
            the remediation causes issues.




                                                                                               Page 719

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output2=()
               f_file_test_fix()
               {
                   a_out2=()
                   maxperm="$( printf '%o' $(( 0777 & ~$perm_mask)) )"
                   if [ $(( $l_mode & $perm_mask )) -gt 0 ]; then
                      a_out2+=("   o Mode: \"$l_mode\" should be \"$maxperm\" or more restrictive" "     x Removing
            excess permissions")
                      chmod "$l_rperms" "$l_fname"
                   fi
                   if [[ ! "$l_user" =~ $l_auser ]]; then
                      a_out2+=("   o Owned by: \"$l_user\" and should be owned by \"${l_auser//|/ or }\"" "     x
            Changing ownership to: \"$l_fix_account\"")
                      chown "$l_fix_account" "$l_fname"
                   fi
                   if [[ ! "$l_group" =~ $l_agroup ]]; then
                      a_out2+=("   o Group owned by: \"$l_group\" and should be group owned by \"${l_agroup//|/ or
            }\"" "      x Changing group ownership to: \"$l_fix_account\"")
                      chgrp "$l_fix_account" "$l_fname"
                   fi
                   [ "${#a_out2[@]}" -gt 0 ] && a_output2+=(" - File: \"$l_fname\" is:" "${a_out2[@]}")
               }
               l_fix_account='root'
               while IFS= read -r -d $'\0' l_file; do
                   while IFS=: read -r l_fname l_mode l_user l_group; do
                      if grep -Pq -- '\/(apt)\h*$' <<< "$(dirname "$l_fname")"; then
                         perm_mask='0133' l_rperms="u-x,go-wx" l_auser="root" l_agroup="(root|adm)"; f_file_test_fix
                      else
                         case "$(basename "$l_fname")" in
                            lastlog | lastlog.* | wtmp | wtmp.* | wtmp-* | btmp | btmp.* | btmp-* | README)
                               perm_mask='0113' l_rperms="ug-x,o-wx" l_auser="root" l_agroup="(root|utmp)"
                               f_file_test_fix ;;
                            cloud-init.log* | localmessages* | waagent.log*)
                               perm_mask='0133' l_rperms="u-x,go-wx" l_auser="(root|syslog)" l_agroup="(root|adm)"
                               file_test_fix ;;
                            secure | auth.log | syslog | messages)
                               perm_mask='0137' l_rperms="u-x,g-wx,o-rwx" l_auser="(root|syslog)"
            l_agroup="(root|adm)"
                               f_file_test_fix ;;
                            SSSD | sssd)
                               perm_mask='0117' l_rperms="ug-x,o-rwx" l_auser="(root|SSSD)" l_agroup="(root|SSSD)"
                               f_file_test_fix ;;
                            gdm | gdm3)
                               perm_mask='0117' l_rperms="ug-x,o-rwx" l_auser="root" l_agroup="(root|gdm|gdm3)"
                               f_file_test_fix ;;
                            *.journal | *.journal~)
                               perm_mask='0137' l_rperms="u-x,g-wx,o-rwx" l_auser="root" l_agroup="(root|systemd-
            journal)"
                               f_file_test_fix ;;
                            *)
                               perm_mask='0137' l_rperms="u-x,g-wx,o-rwx" l_auser="(root|syslog)"
            l_agroup="(root|adm)"
                               if [ "$l_user" = "root" ] || ! grep -Pq -- "^\h*$(awk -F: '$1=="'"$l_user"'" {print
            $7}' /etc/passwd)\b" /etc/shells; then
                                  ! grep -Pq -- "$l_auser" <<< "$l_user" && l_auser="(root|syslog|$l_user)"
                                  ! grep -Pq -- "$l_agroup" <<< "$l_group" && l_agroup="(root|adm|$l_group)"
                               fi
                               f_file_test_fix ;;
                         esac
                      fi
                   done < <(stat -Lc '%n:%#a:%U:%G' "$l_file")
               done < <(find -L /var/log -type f \( -perm /0137 -o ! -user root -o ! -group root \) -print0)
               if [ "${#a_output2[@]}" -le 0 ]; then # If all files passed, then we report no changes
                   a_output+=(" - All files in \"/var/log/\" have appropriate permissions and ownership")
                   printf '\n%s' "- All files in \"/var/log/\" have appropriate permissions and ownership" " o No
            changes required" ""
               else
                   printf '\n%s' "${a_output2[@]}" ""
               fi
            }




                                                                                                           Page 720

Internal Only - General
            Note: You may also need to change the configuration for your logging software or
            services for any logs that had incorrect permissions.
            If there are services that log to other locations, ensure that those log files have the
            appropriate access configured.
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 721

Internal Only - General
            6.2 System Auditing

            The Linux Auditing System operates on a set of rules that collects certain types of
            system activity to facilitate incident investigation, detect unauthorized access or
            modification of data. By default events will be logged to /var/log/audit/audit.log,
            which can be configured in /etc/audit/auditd.conf.
            The following types of audit rules can be specified:

                 •   Control rules: Configuration of the auditing system.
                 •   File system rules: Allow the auditing of access to a particular file or a directory.
                     Also known as file watches.
                 •   System call rules: Allow logging of system calls that any specified program
                     makes.

            Audit rules can be set:

                 •   On the command line using the auditctl utility. These rules are not persistent
                     across reboots.
                 •   In /etc/audit/audit.rules. These rules have to be merged and loaded before
                     they are active.

            Notes:

                 •   For 64 bit systems that have arch as a rule parameter, you will need two rules:
                     one for 64 bit and one for 32 bit systems calls.
                 •   If the auditing system is configured to be locked (-e 2), a system reboot will be
                     required in order to load any changes.
                 •   Key names are optional on the rules and will not be used as a compliance
                     auditing. The usage of key names is highly recommended as it facilitates
                     organization and searching, as such, all remediation steps will have key names
                     supplied.
                 •   It is best practice to store the rules, in number prepended files, in
                     /etc/audit/rules.d/. Rules must end in a .rules suffix. This then requires
                     the use of augenrules to merge all the rules into /etc/audit/audit.rules
                     based on their their alphabetical (lexical) sort order. All benchmark
                     recommendations follow this best practice for remediation, specifically using the
                     prefix of 50 which is centre weighed if all rule sets make use of the number
                     prepending naming convention.
                 •   Your system may have been customized to change the default UID_MIN. All
                     samples output uses 1000, but this value will not be used in compliance auditing.
                     To confirm the UID_MIN for your system, run the following command: awk
                     '/^\s*UID_MIN/{print $2}' /etc/login.defs

            Normalization



                                                                                                   Page 722

Internal Only - General
            The Audit system normalizes some entries, so when you look at the sample output keep
            in mind that:

                 •   With regards to users whose login UID is not set, the values -1 / unset /
                     4294967295 are equivalent and normalized to -1.
                 •   When comparing field types and both sides of the comparison is valid fields
                     types, such aseuid!=uid, then the auditing system may normalize such that the
                     output is uid!=euid.
                 •   Some parts of the rule may be rearranged whilst others are dependant on
                     previous syntax. For example, the following two statements are the same:

            -a always,exit -F arch=b64 -S execve -C uid!=euid -F auid!=-1 -F
            key=user_emulation
            and
            -a always,exit -F arch=b64 -C euid!=uid -F auid!=unset -S execve -k
            user_emulation
            Capacity planning
            The recommendations in this section implement auditing policies that not only produces
            large quantities of logged data, but may also negatively impact system performance.
            Capacity planning is critical in order not to adversely impact production environments.

                 •   Disk space. If a significantly large set of events are captured, additional on
                     system or off system storage may need to be allocated. If the logs are not sent to
                     a remote log server, ensure that log rotation is implemented else the disk will fill
                     up and the system will halt. Even when logs are sent to a log server, ensure
                     sufficient disk space to allow caching of logs in the case of temporary network
                     outages.
                 •   Disk IO. It is not just the amount of data collected that should be considered, but
                     the rate at which logs are generated.
                 •   CPU overhead. System call rules might incur considerable CPU overhead. Test
                     the systems open/close syscalls per second with and without the rules to gauge
                     the impact of the rules.




                                                                                                 Page 723

Internal Only - General
            6.2.1 Configure auditd Service

            The capturing of system events provides system administrators with information to allow
            them to determine if unauthorized access to their system is occurring.




                                                                                           Page 724

Internal Only - General
            6.2.1.1 Ensure auditd packages are installed (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            auditd is the userspace component to the Linux Auditing System. It's responsible for
            writing audit records to the disk
            Rationale:
            The capturing of system events provides system administrators with information to allow
            them to determine if unauthorized access to their system is occurring.
            Audit:
            Run the following command and verify auditd is installed:
            # dpkg-query -s auditd &>/dev/null && echo auditd is installed

            auditd is installed
            Run the following command to verify audispd-plugins is installed:
            # dpkg-query -s audispd-plugins &>/dev/null && echo audispd-plugins is
            installed

            audispd-plugins is installed

            Remediation:
            Run the following command to Install auditd and audispd-plugins
            # apt install auditd audispd-plugins

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-3, AU-12, SI-5
                 2. STIG ID: UBTU-20-010182 | RULE ID: SV-238298r958506 | CAT II
                 3. STIG ID: UBTU-22-653015 | RULE ID: SV-260591r1015023 | CAT II




                                                                                            Page 725

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          6.2 Activate audit logging
                   v7        Ensure that local logging has been enabled on all systems and networking             ●    ●    ●
                          devices.




                                                                                                                       Page 726

Internal Only - General
            6.2.1.2 Ensure auditd service is enabled and active (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Turn on the auditd daemon to record system events.

            Rationale:
            The capturing of system events provides system administrators with information to allow
            them to determine if unauthorized access to their system is occurring.
            Audit:
            Run the following command to verify auditd is enabled:
            # systemctl is-enabled auditd | grep '^enabled'

            enabled
            Verify result is "enabled".
            Run the following command to verify auditd is active:
            # systemctl is-active auditd | grep '^active'

            active
            Verify result is active
            Remediation:
            Run the following commands to unmask, enable and start auditd:
            # systemctl unmask auditd
            # systemctl enable auditd
            # systemctl start auditd

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-12, SI-5
                 2. STIG ID: UBTU-20-010182 | RULE ID: SV-238298r958506 | CAT II
                 3. STIG ID: UBTU-22-653015 | RULE ID: SV-260591r1015023 | CAT II




                                                                                           Page 727

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                    IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                              ●    ●
                          other useful elements.




                                                                                                              Page 728

Internal Only - General
            6.2.1.3 Ensure auditing for processes that start prior to auditd is
            enabled (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Configure grub2 so that processes that are capable of being audited can be audited
            even if they start up prior to auditd startup.

            Rationale:
            Audit events need to be captured on processes that start up prior to auditd , so that
            potential malicious activity cannot go undetected.
            Audit:
            Run the following command:
            # find /boot -type f -name 'grub.cfg' -exec grep -Ph -- '^\h*linux' {} + |
            grep -v 'audit=1'
            Nothing should be returned.
            Remediation:
            Edit /etc/default/grub and add audit=1 to GRUB_CMDLINE_LINUX:
            Example:
            GRUB_CMDLINE_LINUX="audit=1"
            Run the following command to update the grub2 configuration:
            # update-grub

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-3, AU-12
                 2. STIG ID: UBTU-20-010198 | RULE ID: SV-238299r991555 | CAT II
                 3. STIG ID: UBTU-22-212015 | RULE ID: SV-260471r991555 | CAT II

            Additional Information:
            This recommendation is designed around the grub2 bootloader, if another bootloader is
            in use in your environment enact equivalent settings.




                                                                                            Page 729

Internal Only - General
            CIS Controls:

                Controls
                                                               Control                                    IG 1 IG 2 IG 3
                Version
                            8.2 Collect Audit Logs
                    v8        Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                            management process, has been enabled across enterprise assets.

                            6.2 Activate audit logging
                    v7         Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                            devices.




                                                                                                                Page 730

Internal Only - General
            6.2.1.4 Ensure audit_backlog_limit is configured (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            In the kernel-level audit subsystem, a socket buffer queue is used to hold audit events.
            Whenever a new audit event is received, it is logged and prepared to be added to this
            queue.
            The kernel boot parameter audit_backlog_limit=N, with N representing the amount of
            messages, will ensure that a queue cannot grow beyond a certain size. If an audit event
            is logged which would grow the queue beyond this limit, then a failure occurs and is
            handled according to the system configuration
            Rationale:
            If an audit event is logged which would grow the queue beyond the
            audit_backlog_limit, then a failure occurs, auditd records will be lost, and potential
            malicious activity could go undetected.
            Audit:
            Run the following command and verify the audit_backlog_limit= parameter is set:
            # find /boot -type f -name 'grub.cfg' -exec grep -Ph -- '^\h*linux' {} + |
            grep -Pv 'audit_backlog_limit=\d+\b'
            Nothing should be returned.
            Remediation:
            Edit /etc/default/grub and add audit_backlog_limit=N to
            GRUB_CMDLINE_LINUX. The recommended size for N is 8192 or larger.
            Example:
            GRUB_CMDLINE_LINUX="audit_backlog_limit=8192"
            Run the following command to update the grub2 configuration:
            # update-grub

            Default Value:
            if audit_backlog_limit is not set, the system defaults to audit_backlog_limit=64

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-3, AU-12




                                                                                            Page 731

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                    IG 1 IG 2 IG 3
               Version
                          8.2 Collect Audit Logs
                    v8      Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                          management process, has been enabled across enterprise assets.

                          6.2 Activate audit logging
                    v7       Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                    v7       Enable system logging to include detailed information such as an event
                          source, date, user, timestamp, source addresses, destination addresses, and
                                                                                                              ●    ●
                          other useful elements.




                                                                                                              Page 732

Internal Only - General
            6.2.2 Configure Data Retention

            When auditing, it is important to carefully configure the storage requirements for audit
            logs. By default, auditd will max out the log files at 5MB and retain only 4 copies of
            them. Older versions will be deleted. It is possible on a system that the 20 MBs of audit
            logs may fill up the system causing loss of audit data. While the recommendations here
            provide guidance, check your site policy for audit storage requirements.




                                                                                             Page 733

Internal Only - General
            6.2.2.1 Ensure audit log storage size is configured (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Configure the maximum size of the audit log file. Once the log reaches the maximum
            size, it will be rotated and a new log file will be started.
            Rationale:
            It is important that an appropriate size is determined for log files so that they do not
            impact the system and audit data is not lost.
            Audit:
            Run the following command and ensure output is in compliance with site policy:
            # grep -Po -- '^\h*max_log_file\h*=\h*\d+\b' /etc/audit/auditd.conf

            max_log_file = <MB>

            Remediation:
            Set the following parameter in /etc/audit/auditd.conf in accordance with site
            policy:
            max_log_file = <MB>

            Default Value:
            max_log_file = 8

            References:

                 1. NIST SP 800-53 Rev. 5: AU-8

            Additional Information:
            The max_log_file parameter is measured in megabytes.
            Other methods of log rotation may be appropriate based on site policy. One example is
            time-based rotation strategies which don't have native support in auditd configurations.
            Manual audit of custom configurations should be evaluated for effectiveness and
            completeness.




                                                                                                 Page 734

Internal Only - General
            CIS Controls:

                Controls
                                                             Control                                         IG 1 IG 2 IG 3
                Version
                            8.3 Ensure Adequate Audit Log Storage
                     v8        Ensure that logging destinations maintain adequate storage to comply with      ●    ●    ●
                            the enterprise’s audit log management process.

                            6.4 Ensure adequate storage for logs
                     v7        Ensure that all systems that store logs have adequate storage space for the         ●    ●
                            logs generated.




                                                                                                                   Page 735

Internal Only - General
            6.2.2.2 Ensure audit logs are not automatically deleted
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The max_log_file_action setting determines how to handle the audit log file reaching
            the max file size. A value of keep_logs will rotate the logs but never delete old logs.

            Rationale:
            In high security contexts, the benefits of maintaining a long audit history exceed the cost
            of storing the audit history.
            Audit:
            Run the following command and verify output matches:
            # grep max_log_file_action /etc/audit/auditd.conf

            max_log_file_action = keep_logs

            Remediation:
            Set the following parameter in /etc/audit/auditd.conf:
            max_log_file_action = keep_logs

            References:

                 1. NIST SP 800-53 Rev. 5: AU-8

            CIS Controls:

                Controls
                                                             Control                                         IG 1 IG 2 IG 3
                Version
                            8.3 Ensure Adequate Audit Log Storage
                     v8        Ensure that logging destinations maintain adequate storage to comply with      ●    ●    ●
                            the enterprise’s audit log management process.

                            6.4 Ensure adequate storage for logs
                     v7        Ensure that all systems that store logs have adequate storage space for the         ●    ●
                            logs generated.




                                                                                                                   Page 736

Internal Only - General
            6.2.2.3 Ensure system is disabled when audit logs are full
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The auditd daemon can be configured to halt the system or put the system in single
            user mode, if no free space is available or an error is detected on the partition that holds
            the audit log files.
            The disk_full_action parameter tells the system what action to take when no free
            space is available on the partition that holds the audit log files. Valid values are ignore,
            syslog, rotate, exec, suspend, single, and halt.

                 •   ignore, the audit daemon will issue a syslog message but no other action is
                     taken
                 •   syslog, the audit daemon will issue a warning to syslog
                 •   rotate, the audit daemon will rotate logs, losing the oldest to free up space
                 •   exec, /path-to-script will execute the script. You cannot pass parameters to the
                     script. The script is also responsible for telling the auditd daemon to resume
                     logging once its completed its action
                 •   suspend, the audit daemon will stop writing records to the disk
                 •   single, the audit daemon will put the computer system in single user mode
                 •   halt, the audit daemon will shut down the system

            The disk_error_action parameter tells the system what action to take when an error
            is detected on the partition that holds the audit log files. Valid values are ignore,
            syslog, exec, suspend, single, and halt.

                 •   ignore, the audit daemon will not take any action
                 •   syslog, the audit daemon will issue no more than 5 consecutive warnings to
                     syslog
                 •   exec, /path-to-script will execute the script. You cannot pass parameters to the
                     script
                 •   suspend, the audit daemon will stop writing records to the disk
                 •   single, the audit daemon will put the computer system in single user mode
                 •   halt, the audit daemon will shut down the system

            Rationale:
            In high security contexts, the risk of detecting unauthorized access or nonrepudiation
            exceeds the benefit of the system's availability.



                                                                                               Page 737

Internal Only - General
            Impact:
            disk_full_action parameter:

                 •   Set to halt - the auditd daemon will shutdown the system when the disk
                     partition containing the audit logs becomes full.
                 •   Set to single - the auditd daemon will put the computer system in single user
                     mode when the disk partition containing the audit logs becomes full.

            disk_error_action parameter:

                 •   Set to halt - the auditd daemon will shutdown the system when an error is
                     detected on the partition that holds the audit log files.
                 •   Set to single - the auditd daemon will put the computer system in single user
                     mode when an error is detected on the partition that holds the audit log files.
                 •   Set to syslog - the auditd daemon will issue no more than 5 consecutive
                     warnings to syslog when an error is detected on the partition that holds the audit
                     log files.

            Audit:
            Run the following command and verify the disk_full_action is set to either halt or
            single:
            # grep -Pi -- '^\h*disk_full_action\h*=\h*(halt|single)\b'
            /etc/audit/auditd.conf

            disk_full_action = <halt|single>
            Run the following command and verify the disk_error_action is set to syslog,
            single, or halt:
            # grep -Pi -- '^\h*disk_error_action\h*=\h*(syslog|single|halt)\b'
            /etc/audit/auditd.conf

            disk_error_action = <syslog|single|halt>

            Remediation:
            Set one of the following parameters in /etc/audit/auditd.conf depending on your
            local security policies.
            disk_full_action = <halt|single>
            disk_error_action = <syslog|single|halt>
            Example:
            disk_full_action = halt
            disk_error_action = halt




                                                                                                Page 738

Internal Only - General
            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-8, AU-12, SI-5
                 2. AUDITD.CONF(5)

            CIS Controls:

                Controls
                                                               Control                                     IG 1 IG 2 IG 3
                Version
                            8.2 Collect Audit Logs
                    v8        Collect audit logs. Ensure that logging, per the enterprise’s audit log       ●    ●    ●
                            management process, has been enabled across enterprise assets.

                            8.3 Ensure Adequate Audit Log Storage
                    v8         Ensure that logging destinations maintain adequate storage to comply with    ●    ●    ●
                            the enterprise’s audit log management process.




                                                                                                                 Page 739

Internal Only - General
            6.2.2.4 Ensure system warns when audit logs are low on space
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The auditd daemon can be configured to halt the system, put the system in single user
            mode or send a warning message, if the partition that holds the audit log files is low on
            space.
            The space_left_action parameter tells the system what action to take when the
            system has detected that it is starting to get low on disk space. Valid values are ignore,
            syslog, rotate, email, exec, suspend, single, and halt.

                 •   ignore, the audit daemon does nothing
                 •   syslog, the audit daemon will issue a warning to syslog
                 •   rotate, the audit daemon will rotate logs, losing the oldest to free up space
                 •   email, the audit daemon will send a warning to the email account specified in
                     action_mail_acct as well as sending the message to syslog
                 •   exec, /path-to-script will execute the script. You cannot pass parameters to the
                     script. The script is also responsible for telling the auditd daemon to resume
                     logging once its completed its action
                 •   suspend, the audit daemon will stop writing records to the disk
                 •   single, the audit daemon will put the computer system in single user mode
                 •   halt, the audit daemon will shut down the system

            The admin_space_left_action parameter tells the system what action to take when
            the system has detected that it is low on disk space. Valid values are ignore, syslog,
            rotate, email, exec, suspend, single, and halt.

                 •   ignore, the audit daemon does nothing
                 •   syslog, the audit daemon will issue a warning to syslog
                 •   rotate, the audit daemon will rotate logs, losing the oldest to free up space
                 •   email, the audit daemon will send a warning to the email account specified in
                     action_mail_acct as well as sending the message to syslog
                 •   exec, /path-to-script will execute the script. You cannot pass parameters to the
                     script. The script is also responsible for telling the auditd daemon to resume
                     logging once its completed its action
                 •   suspend, the audit daemon will stop writing records to the disk
                 •   single, the audit daemon will put the computer system in single user mode
                 •   halt, the audit daemon will shut down the system



                                                                                               Page 740

Internal Only - General
            Rationale:
            In high security contexts, the risk of detecting unauthorized access or nonrepudiation
            exceeds the benefit of the system's availability.
            Impact:
            If the admin_space_left_action is set to single the audit daemon will put the
            computer system in single user mode.
            Audit:
            Run the following command and verify the space_left_action is set to email, exec,
            single, or halt:
            grep -Pi -- '^\h*space_left_action\h*=\h*(email|exec|single|halt)\b'
            /etc/audit/auditd.conf
            Verify the output is email, exec, single, or halt
            Example output
            space_left_action = email
            Run the following command and verify the admin_space_left_action is set to single
            - OR - halt:
            grep -Pi -- '^\h*admin_space_left_action\h*=\h*(single|halt)\b'
            /etc/audit/auditd.conf
            Verify the output is single or halt
            Example output:
            admin_space_left_action = single
            Note: A Mail Transfer Agent (MTA) must be installed and configured properly to set
            space_left_action = email

            Remediation:
            Set the space_left_action parameter in /etc/audit/auditd.conf to email, exec,
            single, or halt:
            Example:
            space_left_action = email
            Set the admin_space_left_action parameter in /etc/audit/auditd.conf to
            single or halt:
            Example:
            admin_space_left_action = single
            Note: A Mail Transfer Agent (MTA) must be installed and configured properly to set
            space_left_action = email




                                                                                             Page 741

Internal Only - General
            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-8, AU-12, SI-5
                 2. AUDITD.CONF(5)

            CIS Controls:

                Controls
                                                               Control                                     IG 1 IG 2 IG 3
                Version
                            8.2 Collect Audit Logs
                    v8        Collect audit logs. Ensure that logging, per the enterprise’s audit log       ●    ●    ●
                            management process, has been enabled across enterprise assets.

                            8.3 Ensure Adequate Audit Log Storage
                    v8         Ensure that logging destinations maintain adequate storage to comply with    ●    ●    ●
                            the enterprise’s audit log management process.

                            6.2 Activate audit logging
                    v7         Ensure that local logging has been enabled on all systems and networking     ●    ●    ●
                            devices.




                                                                                                                 Page 742

Internal Only - General
            6.2.3 Configure auditd Rules

            The Audit system operates on a set of rules that define what is to be captured in the log
            files.
            The following types of Audit rules can be specified:

                 •   Control rules: Allow the Audit system's behavior and some of its configuration to
                     be modified.
                 •   File system rules: Allow the auditing of access to a particular file or a directory.
                     (Also known as file watches)
                 •   System call rules: Allow logging of system calls that any specified program
                     makes.

            Audit rules can be set:

                 •   on the command line using the auditctl utility. Note that these rules are not
                     persistent across reboots.
                 •   in a file ending in .rules in the /etc/audit/rules.d/ directory.

            Note: The Linux Benchmarks are written and tested against x86_64 processor
            architecture. If you are running a different processor type, please review and update the
            audit rules for the processor architecture of the system




                                                                                                  Page 743

Internal Only - General
            6.2.3.1 Ensure changes to system administration scope (sudoers)
            is collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor scope changes for system administrators. If the system has been properly
            configured to force system administrators to log in as themselves first and then use the
            sudo command to execute privileged commands, it is possible to monitor changes in
            scope. The file /etc/sudoers, or files in /etc/sudoers.d, will be written to when the
            file(s) or related attributes have changed. The audit records will be tagged with the
            identifier "scope".
            Rationale:
            Changes in the /etc/sudoers and /etc/sudoers.d files can indicate that an
            unauthorized change has been made to the scope of system administrator activity.
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # awk '/^ *-w/ \
            &&/\/etc\/sudoers/ \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules
            Verify the output matches:
            -w /etc/sudoers -p wa -k scope
            -w /etc/sudoers.d -p wa -k scope
            Running configuration
            Run the following command to check loaded rules:
            # auditctl -l | awk '/^ *-w/ \
            &&/\/etc\/sudoers/ \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'
            Verify the output matches:
            -w /etc/sudoers -p wa -k scope
            -w /etc/sudoers.d -p wa -k scope




                                                                                             Page 744

Internal Only - General
            Remediation:
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor scope changes for system administrators.
            Example:
            # printf "
            -w /etc/sudoers -p wa -k scope
            -w /etc/sudoers.d -p wa -k scope
            " >> /etc/audit/rules.d/50-scope.rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          4.8 Log and Alert on Changes to Administrative Group
                   v7     Membership                                                                                   ●    ●
                              Configure systems to issue a log entry and alert when an account is added to
                          or removed from any group assigned administrative privileges.




                                                                                                                       Page 745

Internal Only - General
            6.2.3.2 Ensure actions as another user are always logged
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            sudo provides users with temporary elevated privileges to perform operations, either as
            the superuser or another user.
            Rationale:
            Creating an audit log of users with temporary elevated privileges and the operation(s)
            they performed is essential to reporting. Administrators will want to correlate the events
            written to the audit trail with the records written to sudo's logfile to verify if unauthorized
            commands have been executed.




                                                                                                   Page 746

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # awk '/^ *-a *always,exit/ \
            &&/ -F *arch=b(32|64)/ \
            &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
            &&(/ -C *euid!=uid/||/ -C *uid!=euid/) \
            &&/ -S *execve/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules
            Verify the output matches:
            -a always,exit -F arch=b64 -C euid!=uid -F auid!=unset -S execve -k
            user_emulation
            -a always,exit -F arch=b32 -C euid!=uid -F auid!=unset -S execve -k
            user_emulation
            Running configuration
            Run the following command to check loaded rules:
            # auditctl -l | awk '/^ *-a *always,exit/ \
            &&/ -F *arch=b(32|64)/ \
            &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
            &&(/ -C *euid!=uid/||/ -C *uid!=euid/) \
            &&/ -S *execve/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'
            Verify the output matches:
            -a always,exit -F arch=b64 -S execve -C uid!=euid -F auid!=-1 -F
            key=user_emulation
            -a always,exit -F arch=b32 -S execve -C uid!=euid -F auid!=-1 -F
            key=user_emulation




                                                                                   Page 747

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor elevated privileges.
            Example:
            # printf "
            -a always,exit -F arch=b64 -C euid!=uid -F auid!=unset -S execve -k
            user_emulation
            -a always,exit -F arch=b32 -C euid!=uid -F auid!=unset -S execve -k
            user_emulation
            " >> /etc/audit/rules.d/50-user_emulation.rules
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 748

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          4.9 Log and Alert on Unsuccessful Administrative Account
                   v7     Login                                                                                        ●    ●
                            Configure systems to issue a log entry and alert on unsuccessful logins to an
                          administrative account.




                                                                                                                       Page 749

Internal Only - General
            6.2.3.3 Ensure events that modify the sudo log file are collected
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor the sudo log file. If the system has been properly configured to disable the use
            of the su command and force all administrators to have to log in first and then use sudo
            to execute privileged commands, then all administrator commands will be logged to
            /var/log/sudo.log . Any time a command is executed, an audit event will be
            triggered as the /var/log/sudo.log file will be opened for write and the executed
            administration command will be written to the log.
            Rationale:
            Changes in /var/log/sudo.log indicate that an administrator has executed a
            command or the log file itself has been tampered with. Administrators will want to
            correlate the events written to the audit trail with the records written to
            /var/log/sudo.log to verify if unauthorized commands have been executed.




                                                                                             Page 750

Internal Only - General
            Audit:
            Note: This recommendation requires that the sudo logfile is configured. See guidance
            provided in the recommendation "Ensure sudo log file exists"
            On disk configuration
            Run the following command to check the on disk rules:
            # {
              SUDO_LOG_FILE=$(grep -r logfile /etc/sudoers* | sed -e 's/.*logfile=//;s/,?
            .*//' -e 's/"//g' -e 's|/|\\/|g')
              [ -n "${SUDO_LOG_FILE}" ] && awk "/^ *-w/ \
              &&/"${SUDO_LOG_FILE}"/ \
              &&/ +-p *wa/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" /etc/audit/rules.d/*.rules \
              || printf "ERROR: Variable 'SUDO_LOG_FILE' is unset.\n"
            }
            Verify output of matches:
            -w /var/log/sudo.log -p wa -k sudo_log_file
            Running configuration
            Run the following command to check loaded rules:
            # {
              SUDO_LOG_FILE=$(grep -r logfile /etc/sudoers* | sed -e 's/.*logfile=//;s/,?
            .*//' -e 's/"//g' -e 's|/|\\/|g')
              [ -n "${SUDO_LOG_FILE}" ] && auditctl -l | awk "/^ *-w/ \
              &&/"${SUDO_LOG_FILE}"/ \
              &&/ +-p *wa/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" \
              || printf "ERROR: Variable 'SUDO_LOG_FILE' is unset.\n"
            }
            Verify output matches:
            -w /var/log/sudo.log -p wa -k sudo_log_file




                                                                                          Page 751

Internal Only - General
            Remediation:
            Note: This recommendation requires that the sudo logfile is configured. See guidance
            provided in the recommendation "Ensure sudo log file exists"
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor events that modify the sudo log file.
            Example:
            # {
            SUDO_LOG_FILE=$(grep -r logfile /etc/sudoers* | sed -e 's/.*logfile=//;s/,?
            .*//' -e 's/"//g')
            [ -n "${SUDO_LOG_FILE}" ] && printf "
            -w ${SUDO_LOG_FILE} -p wa -k sudo_log_file
            " >> /etc/audit/rules.d/50-sudo.rules || printf "ERROR: Variable
            'SUDO_LOG_FILE' is unset.\n"
            }
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          4.9 Log and Alert on Unsuccessful Administrative Account
                   v7     Login                                                                                        ●    ●
                            Configure systems to issue a log entry and alert on unsuccessful logins to an
                          administrative account.




                                                                                                                       Page 752

Internal Only - General
            6.2.3.4 Ensure events that modify date and time information are
            collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Capture events where the system date and/or time has been modified. The parameters
            in this section are set to determine if the;

                 •   adjtimex - tune kernel clock
                 •   settimeofday - set time using timeval and timezone structures
                 •   stime - using seconds since 1/1/1970
                 •   clock_settime - allows for the setting of several internal clocks and timers

            system calls have been executed. Further, ensure to write an audit record to the
            configured audit log file upon exit, tagging the records with a unique identifier such as
            "time-change".
            Rationale:
            Unexpected changes in system date and/or time could be a sign of malicious activity on
            the system.




                                                                                               Page 753

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # {
             awk '/^ *-a *always,exit/ \
             &&/ -F *arch=b(32|64)/ \
             &&/ -S/ \
             &&(/adjtimex/ \
                ||/settimeofday/ \
                ||/clock_settime/ ) \
             &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules

                awk '/^ *-w/ \
                &&/\/etc\/localtime/ \
                &&/ +-p *wa/ \
                &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules
            }
            Verify output of matches:
            -a always,exit -F arch=b64 -S adjtimex,settimeofday -k time-change
            -a always,exit -F arch=b32 -S adjtimex,settimeofday -k time-change
            -a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -k time-change
            -a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -k time-change
            -w /etc/localtime -p wa -k time-change
            Running configuration
            Run the following command to check loaded rules:
            # {
             auditctl -l | awk '/^ *-a *always,exit/ \
             &&/ -F *arch=b(32|64)/ \
             &&/ -S/ \
             &&(/adjtimex/ \
                ||/settimeofday/ \
                ||/clock_settime/ ) \
             &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'

                auditctl -l | awk '/^ *-w/ \
                &&/\/etc\/localtime/ \
                &&/ +-p *wa/ \
                &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'
            }
            Verify the output includes:
            -a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=time-change
            -a always,exit -F arch=b32 -S settimeofday,adjtimex -F key=time-change
            -a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -F key=time-change
            -a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -F key=time-change
            -w /etc/localtime -p wa -k time-change




                                                                                       Page 754

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor events that modify date and time information.
            Example:
            # printf "
            -a always,exit -F arch=b64 -S adjtimex,settimeofday -k time-change
            -a always,exit -F arch=b32 -S adjtimex,settimeofday -k time-change
            -a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -k time-change
            -a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -k time-change
            -w /etc/localtime -p wa -k time-change
            " >> /etc/audit/rules.d/50-time-change.rules
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3, CM-6

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 755

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          5.5 Implement Automated Configuration Monitoring
                          Systems
                   v7        Utilize a Security Content Automation Protocol (SCAP) compliant configuration             ●    ●
                          monitoring system to verify all security configuration elements, catalog approved
                          exceptions, and alert when unauthorized changes occur.




                                                                                                                       Page 756

Internal Only - General
            6.2.3.5 Ensure events that modify the system's network
            environment are collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Record changes to network environment files or system calls. The below parameters
            monitors the following system calls, and write an audit event on system call exit:

                 •   sethostname - set the systems host name
                 •   setdomainname - set the systems domain name

            The files being monitored are:

                 •   /etc/issue and /etc/issue.net - messages displayed pre-login
                 •   /etc/hosts - file containing host names and associated IP addresses
                 •   /etc/networks - symbolic names for networks
                 •   /etc/network/ - directory containing network interface scripts and
                     configurations files
                 •   /etc/netplan/ - central location for YAML networking configurations files

            Rationale:
            Monitoring system events that change network environments, such as sethostname
            and setdomainname, helps identify unauthorized alterations to host and domain names,
            which could compromise security settings reliant on these names. Changes to
            /etc/hosts can signal unauthorized attempts to alter machine associations with IP
            addresses, potentially redirecting users and processes to unintended destinations.
            Surveillance of /etc/issue and /etc/issue.net is crucial to detect intruders inserting
            false information to deceive users. Monitoring /etc/network/ reveals modifications to
            network interfaces or scripts that may jeopardize system availability or security.
            Additionally, tracking changes in the /etc/netplan/ directory ensures swift detection
            of unauthorized adjustments to network configurations. All audit records should be
            appropriately tagged for relevance
            Audit:
            On disk configuration
            Run the following commands to check the on disk rules:




                                                                                             Page 757

Internal Only - General
            # awk '/^ *-a *always,exit/ \
            &&/ -F *arch=b(32|64)/ \
            &&/ -S/ \
            &&(/sethostname/ \
              ||/setdomainname/) \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules

            # awk '/^ *-w/ \
            &&(/\/etc\/issue/ \
              ||/\/etc\/issue.net/ \
              ||/\/etc\/hosts/ \
              ||/\/etc\/network \
              ||/\/etc\/netplan) \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules
            Verify the output matches:
            -a always,exit -F arch=b64 -S sethostname,setdomainname -k system-locale
            -a always,exit -F arch=b32 -S sethostname,setdomainname -k system-locale
            -w /etc/issue -p wa -k system-locale
            -w /etc/issue.net -p wa -k system-locale
            -w /etc/hosts -p wa -k system-locale
            -w /etc/networks -p wa -k system-locale
            -w /etc/network -p wa -k system-locale
            -w /etc/netplan -p wa -k system-locale
            Running configuration
            Run the following command to check loaded rules:
            # auditctl -l | awk '/^ *-a *always,exit/ \
            &&/ -F *arch=b(32|64)/ \
            &&/ -S/ \
            &&(/sethostname/ \
              ||/setdomainname/) \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'

            # auditctl -l | awk '/^ *-w/ \
            &&(/\/etc\/issue/ \
              ||/\/etc\/issue.net/ \
              ||/\/etc\/hosts/ \
              ||/\/etc\/network \
              ||/\/etc\/netplan) \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'
            Verify the output includes:
            -a always,exit -F arch=b64 -S sethostname,setdomainname -F key=system-locale
            -a always,exit -F arch=b32 -S sethostname,setdomainname -F key=system-locale
            -w /etc/issue -p wa -k system-locale
            -w /etc/issue.net -p wa -k system-locale
            -w /etc/hosts -p wa -k system-locale
            -w /etc/networks -p wa -k system-locale
            -w /etc/network -p wa -k system-locale
            -w /etc/netplan -p wa -k system-locale




                                                                                   Page 758

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor events that modify the system's network environment.
            Example:
            # printf "
            -a always,exit -F arch=b64 -S sethostname,setdomainname -k system-locale
            -a always,exit -F arch=b32 -S sethostname,setdomainname -k system-locale
            -w /etc/issue -p wa -k system-locale
            -w /etc/issue.net -p wa -k system-locale
            -w /etc/hosts -p wa -k system-locale
            -w /etc/networks -p wa -k system-locale
            -w /etc/network -p wa -k system-locale
            -w /etc/netplan -p wa -k system-locale
            " >> /etc/audit/rules.d/50-system_locale.rules
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3, CM-6
                 2. https://netplan.io/faq

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 759

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          5.5 Implement Automated Configuration Monitoring
                          Systems
                   v7        Utilize a Security Content Automation Protocol (SCAP) compliant configuration             ●    ●
                          monitoring system to verify all security configuration elements, catalog approved
                          exceptions, and alert when unauthorized changes occur.




                                                                                                                       Page 760

Internal Only - General
            6.2.3.6 Ensure use of privileged commands are collected
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor privileged programs, those that have the setuid and/or setgid bit set on
            execution, to determine if unprivileged users are running these commands.
            Rationale:
            Execution of privileged commands by non-privileged users could be an indication of
            someone trying to gain unauthorized access to the system.
            Impact:
            Both the audit and remediation section of this recommendation will traverse all mounted
            file systems that is not mounted with either noexec or nosuid mount options. If there
            are large file systems without these mount options, such traversal will be significantly
            detrimental to the performance of the system.
            Before running either the audit or remediation section, inspect the output of the following
            command to determine exactly which file systems will be traversed:
            # findmnt -n -l -k -it $(awk '/nodev/ { print $2 }' /proc/filesystems | paste
            -sd,) | grep -Pv "noexec|nosuid"
            To exclude a particular file system due to adverse performance impacts, update the
            audit and remediation sections by adding a sufficiently unique string to the grep
            statement. The above command can be used to test the modified exclusions.




                                                                                              Page 761

Internal Only - General
            Audit:
            On disk configuration
            Run the following script to check on disk rules:
            #!/usr/bin/env bash

            {
               for PARTITION in $(findmnt -n -l -k -it $(awk '/nodev/ { print $2 }'
            /proc/filesystems | paste -sd,) | grep -Pv "noexec|nosuid" | awk '{print
            $1}'); do
                  for PRIVILEGED in $(find "${PARTITION}" -xdev -perm /6000 -type f); do
                      grep -qr "${PRIVILEGED}" /etc/audit/rules.d && printf "OK:
            '${PRIVILEGED}' found in auditing rules.\n" || printf "Warning:
            '${PRIVILEGED}' not found in on disk configuration.\n"
                  done
               done
            }
            Verify that all output is OK.
            Running configuration
            Run the following script to check loaded rules:
            #!/usr/bin/env bash

            {
               RUNNING=$(auditctl -l)
               [ -n "${RUNNING}" ] && for PARTITION in $(findmnt -n -l -k -it $(awk
            '/nodev/ { print $2 }' /proc/filesystems | paste -sd,) | grep -Pv
            "noexec|nosuid" | awk '{print $1}'); do
                  for PRIVILEGED in $(find "${PARTITION}" -xdev -perm /6000 -type f); do
                      printf -- "${RUNNING}" | grep -q "${PRIVILEGED}" && printf "OK:
            '${PRIVILEGED}' found in auditing rules.\n" || printf "Warning:
            '${PRIVILEGED}' not found in running configuration.\n"
                  done
               done \
               || printf "ERROR: Variable 'RUNNING' is unset.\n"
            }
            Verify that all output is OK.
            Special mount points
            If there are any special mount points that are not visible by default from findmnt as per
            the above audit, said file systems would have to be manually audited.




                                                                                             Page 762

Internal Only - General
            Remediation:
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor the use of privileged commands.
            Example script:
            #!/usr/bin/env bash

            {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              AUDIT_RULE_FILE="/etc/audit/rules.d/50-privileged.rules"
              NEW_DATA=()
              for PARTITION in $(findmnt -n -l -k -it $(awk '/nodev/ { print $2 }'
            /proc/filesystems | paste -sd,) | grep -Pv "noexec|nosuid" | awk '{print
            $1}'); do
                readarray -t DATA < <(find "${PARTITION}" -xdev -perm /6000 -type f | awk
            -v UID_MIN=${UID_MIN} '{print "-a always,exit -F path=" $1 " -F perm=x -F
            auid>="UID_MIN" -F auid!=unset -k privileged" }')
                   for ENTRY in "${DATA[@]}"; do
                     NEW_DATA+=("${ENTRY}")
                   done
              done
              readarray &> /dev/null -t OLD_DATA < "${AUDIT_RULE_FILE}"
              COMBINED_DATA=( "${OLD_DATA[@]}" "${NEW_DATA[@]}" )
              printf '%s\n' "${COMBINED_DATA[@]}" | sort -u > "${AUDIT_RULE_FILE}"
            }
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi
            Special mount points
            If there are any special mount points that are not visible by default from just scanning /,
            change the PARTITION variable to the appropriate partition and re-run the remediation.

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3, AU-3(1)




                                                                                               Page 763

Internal Only - General
            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          6.2 Activate audit logging
                   v7        Ensure that local logging has been enabled on all systems and networking             ●    ●    ●
                          devices.




                                                                                                                       Page 764

Internal Only - General
            6.2.3.7 Ensure unsuccessful file access attempts are collected
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor for unsuccessful attempts to access files. The following parameters are
            associated with system calls that control files:

                 •   creation - creat
                 •   opening - open , openat
                 •   truncation - truncate , ftruncate

            An audit log record will only be written if all of the following criteria is met for the user
            when trying to access a file:

                 •   a non-privileged user (auid>=UID_MIN)
                 •   is not a Daemon event (auid=4294967295/unset/-1)
                 •   if the system call returned EACCES (permission denied) or EPERM (some other
                     permanent error associated with the specific system call)

            Rationale:
            Failed attempts to open, create or truncate files could be an indication that an individual
            or process is trying to gain unauthorized access to the system.
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && awk "/^ *-a *always,exit/ \
              &&/ -F *arch=b(32|64)/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&(/ -F *exit=-EACCES/||/ -F *exit=-EPERM/) \
              &&/ -S/ \
              &&/creat/ \
              &&/open/ \
              &&/truncate/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" /etc/audit/rules.d/*.rules \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output includes:


                                                                                                    Page 765

Internal Only - General
            -a always,exit -F arch=b64 -S creat,open,openat,truncate,ftruncate -F exit=-
            EACCES -F auid>=1000 -F auid!=unset -k access
            -a always,exit -F arch=b64 -S creat,open,openat,truncate,ftruncate -F exit=-
            EPERM -F auid>=1000 -F auid!=unset -k access
            -a always,exit -F arch=b32 -S creat,open,openat,truncate,ftruncate -F exit=-
            EACCES -F auid>=1000 -F auid!=unset -k access
            -a always,exit -F arch=b32 -S creat,open,openat,truncate,ftruncate -F exit=-
            EPERM -F auid>=1000 -F auid!=unset -k access
            Running configuration
            Run the following command to check loaded rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && auditctl -l | awk "/^ *-a *always,exit/ \
              &&/ -F *arch=b(32|64)/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&(/ -F *exit=-EACCES/||/ -F *exit=-EPERM/) \
              &&/ -S/ \
              &&/creat/ \
              &&/open/ \
              &&/truncate/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output includes:
            -a always,exit -F arch=b64 -S open,truncate,ftruncate,creat,openat -F exit=-
            EACCES -F auid>=1000 -F auid!=-1 -F key=access
            -a always,exit -F arch=b64 -S open,truncate,ftruncate,creat,openat -F exit=-
            EPERM -F auid>=1000 -F auid!=-1 -F key=access
            -a always,exit -F arch=b32 -S open,truncate,ftruncate,creat,openat -F exit=-
            EACCES -F auid>=1000 -F auid!=-1 -F key=access
            -a always,exit -F arch=b32 -S open,truncate,ftruncate,creat,openat -F exit=-
            EPERM -F auid>=1000 -F auid!=-1 -F key=access




                                                                                   Page 766

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor unsuccessful file access attempts.
            Example:
            # {
            UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
            [ -n "${UID_MIN}" ] && printf "
            -a always,exit -F arch=b64 -S creat,open,openat,truncate,ftruncate -F exit=-
            EACCES -F auid>=${UID_MIN} -F auid!=unset -k access
            -a always,exit -F arch=b64 -S creat,open,openat,truncate,ftruncate -F exit=-
            EPERM -F auid>=${UID_MIN} -F auid!=unset -k access
            -a always,exit -F arch=b32 -S creat,open,openat,truncate,ftruncate -F exit=-
            EACCES -F auid>=${UID_MIN} -F auid!=unset -k access
            -a always,exit -F arch=b32 -S creat,open,openat,truncate,ftruncate -F exit=-
            EPERM -F auid>=${UID_MIN} -F auid!=unset -k access
            " >> /etc/audit/rules.d/50-access.rules || printf "ERROR: Variable 'UID_MIN'
            is unset.\n"
            }
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 767

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          14.9 Enforce Detail Logging for Access or Changes to
                          Sensitive Data
                   v7         Enforce detailed audit logging for access to sensitive data or changes to                     ●
                          sensitive data (utilizing tools such as File Integrity Monitoring or Security
                          Information and Event Monitoring).




                                                                                                                       Page 768

Internal Only - General
            6.2.3.8 Ensure events that modify user/group information are
            collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Record events affecting the modification of user or group information, including that of
            passwords and old passwords if in use.

                 •   /etc/group - system groups
                 •   /etc/passwd - system users
                 •   /etc/gshadow - encrypted password for each group
                 •   /etc/shadow - system user passwords
                 •   /etc/security/opasswd - storage of old passwords if the relevant PAM module
                     is in use
                 •   /etc/nsswitch.conf - file configures how the system uses various databases
                     and name resolution mechanisms
                 •   /etc/pam.conf - file determines the authentication services to be used, and the
                     order in which the services are used.
                 •   /etc/pam.d - directory contains the PAM configuration files for each PAM-aware
                     application.

            The parameters in this section will watch the files to see if they have been opened for
            write or have had attribute changes (e.g. permissions) and tag them with the identifier
            "identity" in the audit log file.
            Rationale:
            Unexpected changes to these files could be an indication that the system has been
            compromised and that an unauthorized user is attempting to hide their activities or
            compromise additional accounts.




                                                                                              Page 769

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # awk '/^ *-w/ \
            &&(/\/etc\/group/ \
              ||/\/etc\/passwd/ \
              ||/\/etc\/gshadow/ \
              ||/\/etc\/shadow/ \
              ||/\/etc\/security\/opasswd/ \
              ||/\/etc\/nsswitch.conf/ \
              ||/\/etc\/pam.conf/ \
              ||/\/etc\/pam.d/) \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules
            Verify the output matches:
            -w /etc/group -p wa -k identity
            -w /etc/passwd -p wa -k identity
            -w /etc/gshadow -p wa -k identity
            -w /etc/shadow -p wa -k identity
            -w /etc/security/opasswd -p wa -k identity
            -w /etc/nsswitch.conf -p wa -k identity
            -w /etc/pam.conf -p wa -k identity
            -w /etc/pam.d -p wa -k identity
            Running configuration
            Run the following command to check loaded rules:
            # auditctl -l | awk '/^ *-w/ \
            &&(/\/etc\/group/ \
              ||/\/etc\/passwd/ \
              ||/\/etc\/gshadow/ \
              ||/\/etc\/shadow/ \
              ||/\/etc\/security\/opasswd/ \
              ||/\/etc\/nsswitch.conf/ \
              ||/\/etc\/pam.conf/ \
              ||/\/etc\/pam.d/) \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'
            Verify the output matches:
            -w /etc/group -p wa -k identity
            -w /etc/passwd -p wa -k identity
            -w /etc/gshadow -p wa -k identity
            -w /etc/shadow -p wa -k identity
            -w /etc/security/opasswd -p wa -k identity
            -w /etc/nsswitch.conf -p wa -k identity
            -w /etc/pam.conf -p wa -k identity
            -w /etc/pam.d -p wa -k identity




                                                                                   Page 770

Internal Only - General
            Remediation:
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor events that modify user/group information.
            Example:
            # printf "
            -w /etc/group -p wa -k identity
            -w /etc/passwd -p wa -k identity
            -w /etc/gshadow -p wa -k identity
            -w /etc/shadow -p wa -k identity
            -w /etc/security/opasswd -p wa -k identity
            -w /etc/nsswitch.conf -p wa -k identity
            -w /etc/pam.conf -p wa -k identity
            -w /etc/pam.d -p wa -k identity
            " >> /etc/audit/rules.d/50-identity.rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3
                 2. https://manpages.debian.org/bookworm/manpages/nsswitch.conf.5.en.html
                 3. https://access.redhat.com/documentation/en-
                    us/red_hat_enterprise_linux/6/html/managing_smart_cards/pam_configuration_fil
                    es

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 771

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          4.8 Log and Alert on Changes to Administrative Group
                   v7     Membership                                                                                   ●    ●
                              Configure systems to issue a log entry and alert when an account is added to
                          or removed from any group assigned administrative privileges.




                                                                                                                       Page 772

Internal Only - General
            6.2.3.9 Ensure discretionary access control permission
            modification events are collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor changes to file permissions, attributes, ownership and group. The parameters in
            this section track changes for system calls that affect file permissions and attributes.
            The following commands and system calls effect the permissions, ownership and
            various attributes of files.

                 •   chmod
                 •   fchmod
                 •   fchmodat
                 •   chown
                 •   fchown
                 •   fchownat
                 •   lchown
                 •   setxattr
                 •   lsetxattr
                 •   fsetxattr
                 •   removexattr
                 •   lremovexattr
                 •   fremovexattr

            In all cases, an audit record will only be written for non-system user ids and will ignore
            Daemon events. All audit records will be tagged with the identifier "perm_mod."
            Rationale:
            Monitoring for changes in file attributes could alert a system administrator to activity that
            could indicate intruder activity or policy violation.
            Audit:
            Note: Output showing all audited syscalls, e.g. (-a always,exit -F arch=b64 -S
            chmod,fchmod,fchmodat,chmod,fchmod,fchmodat,setxattr,lsetxattr,fsetxattr,removexattr
            ,lremovexattr,fremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod) is also
            acceptable. These have been separated by function on the displayed output for clarity.
            On disk configuration
            Run the following command to check the on disk rules:




                                                                                                Page 773

Internal Only - General
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && awk "/^ *-a *always,exit/ \
              &&/ -F *arch=b(32|64)/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -S/ \
              &&/ -F *auid>=${UID_MIN}/ \
              &&(/chmod/||/fchmod/||/fchmodat/ \
                ||/chown/||/fchown/||/fchownat/||/lchown/ \
                ||/setxattr/||/lsetxattr/||/fsetxattr/ \
                ||/removexattr/||/lremovexattr/||/fremovexattr/) \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" /etc/audit/rules.d/*.rules \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -F arch=b64 -S chmod,fchmod,fchmodat -F auid>=1000 -F
            auid!=unset -F key=perm_mod
            -a always,exit -F arch=b64 -S chown,fchown,lchown,fchownat -F auid>=1000 -F
            auid!=unset -F key=perm_mod
            -a always,exit -F arch=b32 -S chmod,fchmod,fchmodat -F auid>=1000 -F
            auid!=unset -F key=perm_mod
            -a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F auid>=1000 -F
            auid!=unset -F key=perm_mod
            -a always,exit -F arch=b64 -S
            setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F
            auid>=1000 -F auid!=unset -F key=perm_mod
            -a always,exit -F arch=b32 -S
            setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F
            auid>=1000 -F auid!=unset -F key=perm_mod
            Running configuration
            Run the following command to check loaded rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && auditctl -l | awk "/^ *-a *always,exit/ \
              &&/ -F *arch=b(32|64)/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -S/ \
              &&/ -F *auid>=${UID_MIN}/ \
              &&(/chmod/||/fchmod/||/fchmodat/ \
                ||/chown/||/fchown/||/fchownat/||/lchown/ \
                ||/setxattr/||/lsetxattr/||/fsetxattr/ \
                ||/removexattr/||/lremovexattr/||/fremovexattr/) \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:




                                                                                   Page 774

Internal Only - General
            -a always,exit -F arch=b64 -S chmod,fchmod,fchmodat -F auid>=1000 -F auid!=-1
            -F key=perm_mod
            -a always,exit -F arch=b64 -S chown,fchown,lchown,fchownat -F auid>=1000 -F
            auid!=-1 -F key=perm_mod
            -a always,exit -F arch=b32 -S chmod,fchmod,fchmodat -F auid>=1000 -F auid!=-1
            -F key=perm_mod
            -a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F auid>=1000 -F
            auid!=-1 -F key=perm_mod
            -a always,exit -F arch=b64 -S
            setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F
            auid>=1000 -F auid!=-1 -F key=perm_mod
            -a always,exit -F arch=b32 -S
            setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F
            auid>=1000 -F auid!=-1 -F key=perm_mod




                                                                                  Page 775

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor discretionary access control permission modification
            events.
            Example:
            # {
            UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
            [ -n "${UID_MIN}" ] && printf "
            -a always,exit -F arch=b64 -S chmod,fchmod,fchmodat -F auid>=${UID_MIN} -F
            auid!=unset -F key=perm_mod
            -a always,exit -F arch=b64 -S chown,fchown,lchown,fchownat -F
            auid>=${UID_MIN} -F auid!=unset -F key=perm_mod
            -a always,exit -F arch=b32 -S chmod,fchmod,fchmodat -F auid>=${UID_MIN} -F
            auid!=unset -F key=perm_mod
            -a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F
            auid>=${UID_MIN} -F auid!=unset -F key=perm_mod
            -a always,exit -F arch=b64 -S
            setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F
            auid>=${UID_MIN} -F auid!=unset -F key=perm_mod
            -a always,exit -F arch=b32 -S
            setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F
            auid>=${UID_MIN} -F auid!=unset -F key=perm_mod
            " >> /etc/audit/rules.d/50-perm_mod.rules || printf "ERROR: Variable
            'UID_MIN' is unset.\n"
            }
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3, CM-6




                                                                                           Page 776

Internal Only - General
            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          5.5 Implement Automated Configuration Monitoring
                          Systems
                   v7        Utilize a Security Content Automation Protocol (SCAP) compliant configuration             ●    ●
                          monitoring system to verify all security configuration elements, catalog approved
                          exceptions, and alert when unauthorized changes occur.




                                                                                                                       Page 777

Internal Only - General
            6.2.3.10 Ensure successful file system mounts are collected
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor the use of the mount system call. The mount (and umount ) system call controls
            the mounting and unmounting of file systems. The parameters below configure the
            system to create an audit record when the mount system call is used by a non-
            privileged user
            Rationale:
            It is highly unusual for a non privileged user to mount file systems to the system. While
            tracking mount commands gives the system administrator evidence that external media
            may have been mounted (based on a review of the source of the mount and confirming
            it's an external media type), it does not conclusively indicate that data was exported to
            the media. System administrators who wish to determine if data were exported, would
            also have to track successful open, creat and truncate system calls requiring write
            access to a file under the mount point of the external media file system. This could give
            a fair indication that a write occurred. The only way to truly prove it, would be to track
            successful writes to the external media. Tracking write system calls could quickly fill up
            the audit log and is not recommended. Recommendations on configuration options to
            track data export to media is beyond the scope of this document.




                                                                                              Page 778

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && awk "/^ *-a *always,exit/ \
              &&/ -F *arch=b(32|64)/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -S/ \
              &&/mount/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" /etc/audit/rules.d/*.rules \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -F arch=b64 -S mount -F auid>=1000 -F auid!=unset -k mounts
            -a always,exit -F arch=b32 -S mount -F auid>=1000 -F auid!=unset -k mounts
            Running configuration
            Run the following command to check loaded rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && auditctl -l | awk "/^ *-a *always,exit/ \
              &&/ -F *arch=b(32|64)/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -S/ \
              &&/mount/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -F arch=b64 -S mount -F auid>=1000 -F auid!=-1 -F key=mounts
            -a always,exit -F arch=b32 -S mount -F auid>=1000 -F auid!=-1 -F key=mounts




                                                                                   Page 779

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor successful file system mounts.
            Example:
            # {
            UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
            [ -n "${UID_MIN}" ] && printf "
            -a always,exit -F arch=b32 -S mount -F auid>=$UID_MIN -F auid!=unset -k
            mounts
            -a always,exit -F arch=b64 -S mount -F auid>=$UID_MIN -F auid!=unset -k
            mounts
            " >> /etc/audit/rules.d/50-mounts.rules || printf "ERROR: Variable 'UID_MIN'
            is unset.\n"
            }
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: CM-6

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 780

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          6.3 Enable Detailed Logging
                   v7        Enable system logging to include detailed information such as an event source,
                          date, user, timestamp, source addresses, destination addresses, and other useful
                                                                                                                       ●    ●
                          elements.




                                                                                                                       Page 781

Internal Only - General
            6.2.3.11 Ensure session initiation information is collected
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor session initiation events. The parameters in this section track changes to the
            files associated with session events.

                 •   /var/run/utmp - tracks all currently logged in users.
                 •   /var/log/wtmp - file tracks logins, logouts, shutdown, and reboot events.
                 •   /var/log/btmp - keeps track of failed login attempts and can be read by
                     entering the command /usr/bin/last -f /var/log/btmp.

            All audit records will be tagged with the identifier "session."
            Rationale:
            Monitoring these files for changes could alert a system administrator to logins occurring
            at unusual hours, which could indicate intruder activity (i.e. a user logging in at a time
            when they do not normally log in).




                                                                                              Page 782

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # awk '/^ *-w/ \
            &&(/\/var\/run\/utmp/ \
              ||/\/var\/log\/wtmp/ \
              ||/\/var\/log\/btmp/) \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules
            Verify the output matches:
            -w /var/run/utmp -p wa -k session
            -w /var/log/wtmp -p wa -k session
            -w /var/log/btmp -p wa -k session
            Running configuration
            Run the following command to check loaded rules:
            # auditctl -l | awk '/^ *-w/ \
            &&(/\/var\/run\/utmp/ \
              ||/\/var\/log\/wtmp/ \
              ||/\/var\/log\/btmp/) \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'
            Verify the output matches:
            -w /var/run/utmp -p wa -k session
            -w /var/log/wtmp -p wa -k session
            -w /var/log/btmp -p wa -k session

            Remediation:
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor session initiation information.
            Example:
            # printf "
            -w /var/run/utmp -p wa -k session
            -w /var/log/wtmp -p wa -k session
            -w /var/log/btmp -p wa -k session
            " >> /etc/audit/rules.d/50-session.rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi




                                                                                           Page 783

Internal Only - General
            References:

                 1. NIST SP 800-53 Rev. 5: AU-3
                 2. STIG ID: UBTU-20-010279 | RULE ID: SV-238317r991581 | CAT II
                 3. STIG ID: UBTU-20-010278 | RULE ID: SV-238316r991581 | CAT II
                 4. STIG ID: UBTU-20-010277 | RULE ID: SV-238315r991581 | CAT II
                 5. STIG ID: UBTU-22-654195 | RULE ID: SV-260641r991581 | CAT II
                 6. STIG ID: UBTU-22-654200 | RULE ID: SV-260642r991581 | CAT II
                 7. STIG ID: UBTU-22-654205 | RULE ID: SV-260643r991581 | CAT II

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          4.9 Log and Alert on Unsuccessful Administrative Account
                   v7     Login                                                                                        ●    ●
                            Configure systems to issue a log entry and alert on unsuccessful logins to an
                          administrative account.

                          16.13 Alert on Account Login Behavior Deviation
                   v7       Alert when users deviate from normal login behavior, such as time-of-day,                       ●
                          workstation location and duration.




                                                                                                                       Page 784

Internal Only - General
            6.2.3.12 Ensure login and logout events are collected
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor login and logout events. The parameters below track changes to files
            associated with login/logout events.

                 •   /var/log/lastlog - maintain records of the last time a user successfully logged
                     in.
                 •   /var/run/faillock - directory maintains records of login failures via the
                     pam_faillock module.

            Rationale:
            Monitoring login/logout events could provide a system administrator with information
            associated with brute force attacks against user logins.
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # awk '/^ *-w/ \
            &&(/\/var\/log\/lastlog/ \
              ||/\/var\/run\/faillock/) \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules
            Verify the output matches:
            -w /var/log/lastlog -p wa -k logins
            -w /var/run/faillock -p wa -k logins
            Running configuration
            Run the following command to check loaded rules:
            # auditctl -l | awk '/^ *-w/ \
            &&(/\/var\/log\/lastlog/ \
              ||/\/var\/run\/faillock/) \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'
            Verify the output matches:
            -w /var/log/lastlog -p wa -k logins
            -w /var/run/faillock -p wa -k logins




                                                                                            Page 785

Internal Only - General
            Remediation:
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor login and logout events.
            Example:
            # printf "
            -w /var/log/lastlog -p wa -k logins
            -w /var/run/faillock -p wa -k logins
            " >> /etc/audit/rules.d/50-login.rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 786

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          4.9 Log and Alert on Unsuccessful Administrative Account
                   v7     Login                                                                                        ●    ●
                            Configure systems to issue a log entry and alert on unsuccessful logins to an
                          administrative account.

                   v7     16.11 Lock Workstation Sessions After Inactivity                                        ●    ●    ●
                             Automatically lock workstation sessions after a standard period of inactivity.

                          16.13 Alert on Account Login Behavior Deviation
                   v7       Alert when users deviate from normal login behavior, such as time-of-day,                       ●
                          workstation location and duration.




                                                                                                                       Page 787

Internal Only - General
            6.2.3.13 Ensure file deletion events by users are collected
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor the use of system calls associated with the deletion or renaming of files and file
            attributes. This configuration statement sets up monitoring for:

                 •   unlink - remove a file
                 •   unlinkat - remove a file attribute
                 •   rename - rename a file
                 •   renameat rename a file attribute

                     system calls and tags them with the identifier "delete".
            Rationale:
            Monitoring these calls from non-privileged users could provide a system administrator
            with evidence that inappropriate removal of files and file attributes associated with
            protected files is occurring. While this audit option will look at all events, system
            administrators will want to look for specific privileged files that are being deleted or
            altered.




                                                                                              Page 788

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && awk "/^ *-a *always,exit/ \
              &&/ -F *arch=b(32|64)/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -S/ \
              &&(/unlink/||/rename/||/unlinkat/||/renameat/) \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" /etc/audit/rules.d/*.rules \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -F arch=b64 -S unlink,unlinkat,rename,renameat -F auid>=1000 -
            F auid!=unset -k delete
            -a always,exit -F arch=b32 -S unlink,unlinkat,rename,renameat -F auid>=1000 -
            F auid!=unset -k delete
            Running configuration
            Run the following command to check loaded rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && auditctl -l | awk "/^ *-a *always,exit/ \
              &&/ -F *arch=b(32|64)/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -S/ \
              &&(/unlink/||/rename/||/unlinkat/||/renameat/) \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -F arch=b64 -S rename,unlink,unlinkat,renameat -F auid>=1000 -
            F auid!=-1 -F key=delete
            -a always,exit -F arch=b32 -S unlink,rename,unlinkat,renameat -F auid>=1000 -
            F auid!=-1 -F key=delete




                                                                                   Page 789

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor file deletion events by users.
            Example:
            # {
            UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
            [ -n "${UID_MIN}" ] && printf "
            -a always,exit -F arch=b64 -S rename,unlink,unlinkat,renameat -F
            auid>=${UID_MIN} -F auid!=unset -F key=delete
            -a always,exit -F arch=b32 -S rename,unlink,unlinkat,renameat -F
            auid>=${UID_MIN} -F auid!=unset -F key=delete
            " >> /etc/audit/rules.d/50-delete.rules || printf "ERROR: Variable 'UID_MIN'
            is unset.\n"
            }
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-12, SC-7
                 2. STIG ID: UBTU-20-010267 | Rule ID: SV-238310r991577 | CAT II
                 3. STIG ID: UBTU-22-654185 | Rule ID: SV-260639r991577 | CAT II

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 790

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          6.2 Activate audit logging
                   v7        Ensure that local logging has been enabled on all systems and networking             ●    ●    ●
                          devices.




                                                                                                                       Page 791

Internal Only - General
            6.2.3.14 Ensure events that modify the system's Mandatory
            Access Controls are collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor AppArmor, an implementation of mandatory access controls. The parameters
            below monitor any write access (potential additional, deletion or modification of files in
            the directory) or attribute changes to the /etc/apparmor/ and /etc/apparmor.d/
            directories.
            Note: If a different Mandatory Access Control method is used, changes to the
            corresponding directories should be audited.
            Rationale:
            Changes to files in the /etc/apparmor/ and /etc/apparmor.d/ directories could
            indicate that an unauthorized user is attempting to modify access controls and change
            security contexts, leading to a compromise of the system.




                                                                                                Page 792

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # awk '/^ *-w/ \
            &&(/\/etc\/apparmor/ \
              ||/\/etc\/apparmor.d/) \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules
            Verify the output matches:
            -w /etc/apparmor/ -p wa -k MAC-policy
            -w /etc/apparmor.d/ -p wa -k MAC-policy
            Running configuration
            Run the following command to check loaded rules:
            # auditctl -l | awk '/^ *-w/ \
            &&(/\/etc\/apparmor/ \
              ||/\/etc\/apparmor.d/) \
            &&/ +-p *wa/ \
            &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'
            Verify the output matches:
            -w /etc/apparmor/ -p wa -k MAC-policy
            -w /etc/apparmor.d/ -p wa -k MAC-policy

            Remediation:
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor events that modify the system's Mandatory Access
            Controls.
            Example:
            # printf "
            -w /etc/apparmor/ -p wa -k MAC-policy
            -w /etc/apparmor.d/ -p wa -k MAC-policy
            " >> /etc/audit/rules.d/50-MAC-policy.rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3, CM-6




                                                                                           Page 793

Internal Only - General
            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          5.5 Implement Automated Configuration Monitoring
                          Systems
                   v7        Utilize a Security Content Automation Protocol (SCAP) compliant configuration             ●    ●
                          monitoring system to verify all security configuration elements, catalog approved
                          exceptions, and alert when unauthorized changes occur.




                                                                                                                       Page 794

Internal Only - General
            6.2.3.15 Ensure successful and unsuccessful attempts to use the
            chcon command are collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The operating system must generate audit records for successful/unsuccessful uses of
            the chcon command.

            Rationale:
            The chcon command is used to change file security context. Without generating audit
            records that are specific to the security and mission needs of the organization, it would
            be difficult to establish, correlate, and investigate the events relating to an incident or
            identify those responsible for one.
            Audit records can be generated from various components within the information system
            (e.g., module or policy filter).




                                                                                               Page 795

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && awk "/^ *-a *always,exit/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -F *perm=x/ \
              &&/ -F *path=\/usr\/bin\/chcon/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" /etc/audit/rules.d/*.rules \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -F path=/usr/bin/chcon -F perm=x -F auid>=1000 -F auid!=unset
            -k perm_chng
            Running configuration
            Run the following command to check loaded rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && auditctl -l | awk "/^ *-a *always,exit/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -F *perm=x/ \
              &&/ -F *path=\/usr\/bin\/chcon/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -S all -F path=/usr/bin/chcon -F perm=x -F auid>=1000 -F
            auid!=-1 -F key=perm_chng




                                                                                   Page 796

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor successful and unsuccessful attempts to use the
            chcon command.
            Example:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && printf "
            -a always,exit -F path=/usr/bin/chcon -F perm=x -F auid>=${UID_MIN} -F
            auid!=unset -k perm_chng
            " >> /etc/audit/rules.d/50-perm_chng.rules || printf "ERROR: Variable
            'UID_MIN' is unset.\n"
            }
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-12, SI-5

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 797

Internal Only - General
            CIS Controls:

                Controls
                                                               Control                                    IG 1 IG 2 IG 3
                Version
                            8.2 Collect Audit Logs
                    v8        Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                            management process, has been enabled across enterprise assets.

                            6.2 Activate audit logging
                    v7         Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                            devices.




                                                                                                                Page 798

Internal Only - General
            6.2.3.16 Ensure successful and unsuccessful attempts to use the
            setfacl command are collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The operating system must generate audit records for successful/unsuccessful uses of
            the setfacl command

            Rationale:
            This utility sets Access Control Lists (ACLs) of files and directories. Without generating
            audit records that are specific to the security and mission needs of the organization, it
            would be difficult to establish, correlate, and investigate the events relating to an
            incident or identify those responsible for one.
            Audit records can be generated from various components within the information system
            (e.g., module or policy filter).




                                                                                              Page 799

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && awk "/^ *-a *always,exit/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -F *perm=x/ \
              &&/ -F *path=\/usr\/bin\/setfacl/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" /etc/audit/rules.d/*.rules ||
            printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -F path=/usr/bin/setfacl -F perm=x -F auid>=1000 -F
            auid!=unset -k perm_chng
            Running configuration
            Run the following command to check loaded rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && auditctl -l | awk "/^ *-a *always,exit/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -F *perm=x/ \
              &&/ -F *path=\/usr\/bin\/setfacl/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -S all -F path=/usr/bin/setfacl -F perm=x -F auid>=1000 -F
            auid!=-1 -F key=perm_chng




                                                                                   Page 800

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor successful and unsuccessful attempts to use the
            setfacl command.
            Example:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && printf "
            -a always,exit -F path=/usr/bin/setfacl -F perm=x -F auid>=${UID_MIN} -F
            auid!=unset -k perm_chng
            " >> /etc/audit/rules.d/50-perm_chng.rules || printf "ERROR: Variable
            'UID_MIN' is unset.\n"
            }
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-12, SI-5

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 801

Internal Only - General
            CIS Controls:

                Controls
                                                               Control                                    IG 1 IG 2 IG 3
                Version
                            8.2 Collect Audit Logs
                    v8        Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                            management process, has been enabled across enterprise assets.

                            6.2 Activate audit logging
                    v7         Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                            devices.




                                                                                                                Page 802

Internal Only - General
            6.2.3.17 Ensure successful and unsuccessful attempts to use the
            chacl command are collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The operating system must generate audit records for successful/unsuccessful uses of
            the chacl command.
            chacl is an IRIX-compatibility command, and is maintained for those users who are
            familiar with its use from either XFS or IRIX.
            Rationale:
            chacl changes the ACL(s) for a file or directory. Without generating audit records that
            are specific to the security and mission needs of the organization, it would be difficult to
            establish, correlate, and investigate the events relating to an incident or identify those
            responsible for one.
            Audit records can be generated from various components within the information system
            (e.g., module or policy filter).




                                                                                                Page 803

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && awk "/^ *-a *always,exit/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -F *perm=x/ \
              &&/ -F *path=\/usr\/bin\/chacl/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" /etc/audit/rules.d/*.rules \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -F path=/usr/bin/chacl -F perm=x -F auid>=1000 -F auid!=unset
            -k perm_chng
            Running configuration
            Run the following command to check loaded rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && auditctl -l | awk "/^ *-a *always,exit/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -F *perm=x/ \
              &&/ -F *path=\/usr\/bin\/chacl/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -S all -F path=/usr/bin/chacl -F perm=x -F auid>=1000 -F
            auid!=-1 -F key=perm_chng




                                                                                   Page 804

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor successful and unsuccessful attempts to use the
            chacl command.
            Example:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && printf "
            -a always,exit -F path=/usr/bin/chacl -F perm=x -F auid>=${UID_MIN} -F
            auid!=unset -k perm_chng
            " >> /etc/audit/rules.d/50-perm_chng.rules || printf "ERROR: Variable
            'UID_MIN' is unset.\n"
            }
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-12, SI-5

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 805

Internal Only - General
            CIS Controls:

                Controls
                                                               Control                                    IG 1 IG 2 IG 3
                Version
                            8.2 Collect Audit Logs
                    v8        Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                            management process, has been enabled across enterprise assets.

                            6.2 Activate audit logging
                    v7         Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                            devices.




                                                                                                                Page 806

Internal Only - General
            6.2.3.18 Ensure successful and unsuccessful attempts to use the
            usermod command are collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The operating system must generate audit records for successful/unsuccessful uses of
            the usermod command.

            Rationale:
            The usermod command modifies the system account files to reflect the changes that are
            specified on the command line. Without generating audit records that are specific to the
            security and mission needs of the organization, it would be difficult to establish,
            correlate, and investigate the events relating to an incident or identify those responsible
            for one.
            Audit records can be generated from various components within the information system
            (e.g., module or policy filter).




                                                                                              Page 807

Internal Only - General
            Audit:
            On disk configuration
            Run the following command to check the on disk rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && awk "/^ *-a *always,exit/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -F *perm=x/ \
              &&/ -F *path=\/usr\/sbin\/usermod/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" /etc/audit/rules.d/*.rules \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -F path=/usr/sbin/usermod -F perm=x -F auid>=1000 -F
            auid!=unset -k usermod
            Running configuration
            Run the following command to check loaded rules:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && auditctl -l | awk "/^ *-a *always,exit/ \
              &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
              &&/ -F *auid>=${UID_MIN}/ \
              &&/ -F *perm=x/ \
              &&/ -F *path=\/usr\/sbin\/usermod/ \
              &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" \
              || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -S all -F path=/usr/sbin/usermod -F perm=x -F auid>=1000 -F
            auid!=-1 -F key=usermod




                                                                                   Page 808

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor successful and unsuccessful attempts to use the
            usermod command.
            Example:
            # {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && printf "
            -a always,exit -F path=/usr/sbin/usermod -F perm=x -F auid>=${UID_MIN} -F
            auid!=unset -k usermod
            " >> /etc/audit/rules.d/50-usermod.rules || printf "ERROR: Variable 'UID_MIN'
            is unset.\n"
            }
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2, AU-12, SI-5

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 809

Internal Only - General
            CIS Controls:

                Controls
                                                               Control                                    IG 1 IG 2 IG 3
                Version
                            8.2 Collect Audit Logs
                    v8        Collect audit logs. Ensure that logging, per the enterprise’s audit log      ●    ●    ●
                            management process, has been enabled across enterprise assets.

                            6.2 Activate audit logging
                    v7         Ensure that local logging has been enabled on all systems and networking    ●    ●    ●
                            devices.




                                                                                                                Page 810

Internal Only - General
            6.2.3.19 Ensure kernel module loading unloading and
            modification is collected (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Monitor the loading and unloading of kernel modules. All the loading / listing /
            dependency checking of modules is done by kmod via symbolic links.
            The following system calls control loading and unloading of modules:

                 •   init_module - load a module
                 •   finit_module - load a module (used when the overhead of using
                     cryptographically signed modules to determine the authenticity of a module can
                     be avoided)
                 •   delete_module - delete a module
                 •   query_module - query the kernel for various bits pertaining to modules

            Any execution of the loading and unloading module programs and system calls will
            trigger an audit record with an identifier of modules.

            Rationale:
            Monitoring the use of all the various ways to manipulate kernel modules could provide
            system administrators with evidence that an unauthorized change was made to a kernel
            module, possibly compromising the security of the system.
            Audit:
            On disk configuration
            Run the following script to check the on disk rules:




                                                                                               Page 811

Internal Only - General
            #!/usr/bin/env bash

            {
                awk '/^ *-a *always,exit/ \
                &&/ -F *arch=b(32|64)/ \
                &&(/ -F auid!=unset/||/ -F auid!=-1/||/ -F auid!=4294967295/) \
                &&/ -S/ \
                &&(/init_module/ \
                  ||/finit_module/ \
                  ||/delete_module/ \
                  ||/query_module/) \
                &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules

                UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
                [ -n "${UID_MIN}" ] && awk "/^ *-a *always,exit/ \
                &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
                &&/ -F *auid>=${UID_MIN}/ \
                &&/ -F *perm=x/ \
                &&/ -F *path=\/usr\/bin\/kmod/ \
                &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" /etc/audit/rules.d/*.rules \
                || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output matches:
            -a always,exit -F arch=b64 -S
            init_module,finit_module,delete_module,query_module -F auid>=1000 -F
            auid!=unset -k kernel_modules
            -a always,exit -F path=/usr/bin/kmod -F perm=x -F auid>=1000 -F auid!=unset -
            k kernel_modules
            Running configuration
            Run the following script to check loaded rules:
            #!/usr/bin/env bash

            {
                auditctl -l | awk '/^ *-a *always,exit/ \
                &&/ -F *arch=b(32|64)/ \
                &&(/ -F auid!=unset/||/ -F auid!=-1/||/ -F auid!=4294967295/) \
                &&/ -S/ \
                &&(/init_module/ \
                  ||/finit_module/ \
                  ||/delete_module/ \
                  ||/query_module/) \
                &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'

                UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
                [ -n "${UID_MIN}" ] && auditctl -l | awk "/^ *-a *always,exit/ \
                &&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
                &&/ -F *auid>=${UID_MIN}/ \
                &&/ -F *perm=x/ \
                &&/ -F *path=\/usr\/bin\/kmod/ \
                &&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)" \
                || printf "ERROR: Variable 'UID_MIN' is unset.\n"
            }
            Verify the output includes:



                                                                                       Page 812

Internal Only - General
            -a always,exit -F arch=b64 -S
            init_module,delete_module,query_module,finit_module -F auid>=1000 -F auid!=-1
            -F key=kernel_modules
            -a always,exit -S all -F path=/usr/bin/kmod -F perm=x -F auid>=1000 -F
            auid!=-1 -F key=kernel_modules
            Symlink audit
            Run the following script to audit if the symlinks kmod accepts are indeed pointing at it:
            #!/usr/bin/env bash

            {
               a_files=("/usr/sbin/lsmod" "/usr/sbin/rmmod" "/usr/sbin/insmod"
            "/usr/sbin/modinfo" "/usr/sbin/modprobe" "/usr/sbin/depmod")
               for l_file in "${a_files[@]}"; do
                  if [ "$(readlink -f "$l_file")" = "$(readlink -f /bin/kmod)" ]; then
                     printf "OK: \"$l_file\"\n"
                  else
                     printf "Issue with symlink for file: \"$l_file\"\n"
                  fi
               done
            }
            Verify the output states OK. If there is a symlink pointing to a different location it should
            be investigated




                                                                                                  Page 813

Internal Only - General
            Remediation:
            Create audit rules
            Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension,
            with the relevant rules to monitor kernel module modification.
            Example:
            #!/usr/bin/env bash

            {
              UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
              [ -n "${UID_MIN}" ] && printf "
              -a always,exit -F arch=b64 -S
            init_module,finit_module,delete_module,query_module -F auid>=${UID_MIN} -F
            auid!=unset -k kernel_modules
              -a always,exit -F path=/usr/bin/kmod -F perm=x -F auid>=${UID_MIN} -F
            auid!=unset -k kernel_modules
              " >> /etc/audit/rules.d/50-kernel_modules.rules || printf "ERROR: Variable
            'UID_MIN' is unset.\n"
            }
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3, CM-6
                 2. STIG ID: UBTU-20-010296 | RULE ID: SV-238318r991586 | CAT II
                 3. STIG ID: UBTU-22-654060 | RULE ID: SV-260614r991586 | CAT II

            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            System call structure
            For performance (man 7 audit.rules) reasons it is preferable to have all the system
            calls on one line. However, your configuration may have them on one line each or some
            other combination. This is important to understand for both the auditing and remediation
            sections as the examples given are optimized for performance as per the man page.




                                                                                            Page 814

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          6.2 Activate audit logging
                   v7        Ensure that local logging has been enabled on all systems and networking             ●    ●    ●
                          devices.




                                                                                                                       Page 815

Internal Only - General
            6.2.3.20 Ensure the audit configuration is immutable (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Set system audit so that audit rules cannot be modified with auditctl . Setting the flag
            "-e 2" forces audit to be put in immutable mode. Audit changes can only be made on
            system reboot.
            Note: This setting will require the system to be rebooted to update the active auditd
            configuration settings.
            Rationale:
            In immutable mode, unauthorized users cannot execute changes to the audit system to
            potentially hide malicious activity and then put the audit rules back. Users would most
            likely notice a system reboot and that could alert administrators of an attempt to make
            unauthorized audit changes.
            Audit:
            Run the following command and verify output matches:
            # grep -Ph -- '^\h*-e\h+2\b' /etc/audit/rules.d/*.rules | tail -1

            -e 2

            Remediation:
            Edit or create the file /etc/audit/rules.d/99-finalize.rules and add the line -e
            2 at the end of the file:
            Example:
            # printf '\n%s' "-e 2" >> /etc/audit/rules.d/99-finalize.rules
            Load audit rules
            Merge and load the rules into active configuration:
            # augenrules --load
            Check if reboot is required.
            # if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot
            required to load rules\n"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, AU-3, AU-12, MP-2




                                                                                            Page 816

Internal Only - General
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                  ●    ●    ●
                          systems, databases, and applications.

                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          6.2 Activate audit logging
                   v7        Ensure that local logging has been enabled on all systems and networking             ●    ●    ●
                          devices.

                          6.3 Enable Detailed Logging
                   v7        Enable system logging to include detailed information such as an event source,
                          date, user, timestamp, source addresses, destination addresses, and other useful
                                                                                                                       ●    ●
                          elements.




                                                                                                                       Page 817

Internal Only - General
            6.2.3.21 Ensure the running and on disk configuration is the same
            (Manual)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The Audit system have both on disk and running configuration. It is possible for these
            configuration settings to differ.
            Note: Due to the limitations of augenrules and auditctl, it is not absolutely
            guaranteed that loading the rule sets via augenrules --load will result in all rules
            being loaded or even that the user will be informed if there was a problem loading the
            rules.
            Rationale:
            Configuration differences between what is currently running and what is on disk could
            cause unexpected problems or may give a false impression of compliance
            requirements.
            Audit:
            Merged rule sets
            Ensure that all rules in /etc/audit/rules.d have been merged into
            /etc/audit/audit.rules:
            # augenrules --check

            /usr/sbin/augenrules: No change
            Should there be any drift, run augenrules --load to merge and load all rules.

            Remediation:
            If the rules are not aligned across all three () areas, run the following command to
            merge and load all rules:
            # augenrules --load
            Check if reboot is required.
            if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then echo "Reboot required
            to load rules"; fi

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3




                                                                                              Page 818

Internal Only - General
            Additional Information:
            Potential reboot required
            If the auditing configuration is locked (-e 2), then augenrules will not warn in any way
            that rules could not be loaded into the running configuration. A system reboot will be
            required to load the rules into the running configuration.
            CIS Controls:

              Controls
                                                              Control                                            IG 1 IG 2 IG 3
              Version
                          8.5 Collect Detailed Audit Logs
                   v8        Configure detailed audit logging for enterprise assets containing sensitive data.
                          Include event source, date, username, timestamp, source addresses, destination
                                                                                                                       ●    ●
                          addresses, and other useful elements that could assist in a forensic investigation.

                          6.3 Enable Detailed Logging
                   v7        Enable system logging to include detailed information such as an event source,
                          date, user, timestamp, source addresses, destination addresses, and other useful
                                                                                                                       ●    ●
                          elements.




                                                                                                                       Page 819

Internal Only - General
            6.2.4 Configure auditd File Access

            Without the capability to restrict which roles and individuals can select which events are
            audited, unauthorized personnel may be able to prevent the auditing of critical events.




                                                                                              Page 820

Internal Only - General
            6.2.4.1 Ensure audit log files mode is configured (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Audit log files contain information about the system and system activity.
            Rationale:
            Access to audit records can reveal system and configuration data to attackers,
            potentially compromising its confidentiality.




                                                                                             Page 821

Internal Only - General
            Audit:
            Run the following script to verify audit log files are mode 0640 or more restrictive:
            #!/usr/bin/env bash

            {
               l_perm_mask="0137"
               if [ -e "/etc/audit/auditd.conf" ]; then
                  l_audit_log_directory="$(dirname "$(awk -F= '/^\s*log_file\s*/{print
            $2}' /etc/audit/auditd.conf | xargs)")"
                  if [ -d "$l_audit_log_directory" ]; then
                     l_maxperm="$(printf '%o' $(( 0777 & ~$l_perm_mask )) )"
                     a_files=()
                     while IFS= read -r -d $'\0' l_file; do
                        [ -e "$l_file" ] && a_files+=("$l_file")
                     done < <(find "$l_audit_log_directory" -maxdepth 1 -type f -perm
            /"$l_perm_mask" -print0)
                             if (( "${#a_files[@]}" > 0 )); then
                        for l_file in "${a_files[@]}"; do
                           l_file_mode="$(stat -Lc '%#a' "$l_file")"
                           echo -e "\n- Audit Result:\n ** FAIL **\n - File:
            \"$l_file\" is mode: \"$l_file_mode\"\n      (should be mode: \"$l_maxperm\"
            or more restrictive)\n"
                        done
                     else
                        echo -e "\n- Audit Result:\n ** PASS **\n - All files in
            \"$l_audit_log_directory\" are mode: \"$l_maxperm\" or more restrictive"
                     fi
                  else
                     echo -e "\n- Audit Result:\n ** FAIL **\n - Log file directory not
            set in \"/etc/audit/auditd.conf\" please set log file directory"
                  fi
               else
                  echo -e "\n- Audit Result:\n ** FAIL **\n - File:
            \"/etc/audit/auditd.conf\" not found.\n - ** Verify auditd is installed **"
               fi
            }

            Remediation:
            Run the following command to remove more permissive mode than 0640 from audit log
            files:
            # [ -f /etc/audit/auditd.conf ] && find "$(dirname $(awk -F "="
            '/^\s*log_file/ {print $2}' /etc/audit/auditd.conf | xargs))" -type f -perm
            /0137 -exec chmod u-x,g-wx,o-rwx {} +

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3




                                                                                                Page 822

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 823

Internal Only - General
            6.2.4.2 Ensure audit log files owner is configured (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Audit log files contain information about the system and system activity.
            Rationale:
            Access to audit records can reveal system and configuration data to attackers,
            potentially compromising its confidentiality.
            Audit:
            Run the following script to verify audit log files are owned by the root user:
            #!/usr/bin/env bash

            {
               l_output="" l_output2=""
               if [ -e "/etc/audit/auditd.conf" ]; then
                  l_audit_log_directory="$(dirname "$(awk -F= '/^\s*log_file\s*/{print
            $2}' /etc/audit/auditd.conf | xargs)")"
                  if [ -d "$l_audit_log_directory" ]; then
                     while IFS= read -r -d $'\0' l_file; do
                        l_output2="$l_output2\n - File: \"$l_file\" is owned by user:
            \"$(stat -Lc '%U' "$l_file")\"\n     (should be owned by user: \"root\")\n"
                     done < <(find "$l_audit_log_directory" -maxdepth 1 -type f ! -user
            root -print0)
                  else
                     l_output2="$l_output2\n - Log file directory not set in
            \"/etc/audit/auditd.conf\" please set log file directory"
                  fi
               else
                  l_output2="$l_output2\n - File: \"/etc/audit/auditd.conf\" not
            found.\n - ** Verify auditd is installed **"
               fi
               if [ -z "$l_output2" ]; then
                  l_output="$l_output\n - All files in \"$l_audit_log_directory\" are
            owned by user: \"root\"\n"
                  echo -e "\n- Audit Result:\n ** PASS **\n - * Correctly configured *
            :$l_output"
               else
                  echo -e "\n- Audit Result:\n ** FAIL **\n - * Reasons for audit
            failure * :$l_output2\n"
               fi
            }




                                                                                             Page 824

Internal Only - General
            Remediation:
            Run the following command to configure the audit log files to be owned by the root
            user:
            # [ -f /etc/audit/auditd.conf ] && find "$(dirname $(awk -F "="
            '/^\s*log_file/ {print $2}' /etc/audit/auditd.conf | xargs))" -type f ! -user
            root -exec chown root {} +

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 825

Internal Only - General
            6.2.4.3 Ensure audit log files group owner is configured
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Audit log files contain information about the system and system activity.
            Rationale:
            Access to audit records can reveal system and configuration data to attackers,
            potentially compromising its confidentiality.
            Audit:
            Run the following command to verify log_group parameter is set to either adm or root
            in /etc/audit/auditd.conf:
            # grep -Piws -- '^\h*log_group\h*=\h*\H+\b' /etc/audit/auditd.conf | grep -
            Pvi -- '(adm)'
            Nothing should be returned
            Using the path of the directory containing the audit logs, verify audit log files are owned
            by the "root" or "adm" group by running the following script:
            #!/usr/bin/env bash

            {
              if [ -e /etc/audit/auditd.conf ]; then
                  l_fpath="$(dirname "$(awk -F "=" '/^\s*log_file/ {print $2}'
            /etc/audit/auditd.conf | xargs)")"
                  find -L "$l_fpath" -maxdepth 1 -not -path "$l_fpath"/lost+found -type f
            \( ! -group root -a ! -group adm \) -exec ls -l {} +
               fi
            }
            Nothing should be returned




                                                                                                Page 826

Internal Only - General
            Remediation:
            Run the following command to configure the audit log files to be group owned by adm:
            # find $(dirname $(awk -F"=" '/^\s*log_file/ {print $2}'
            /etc/audit/auditd.conf | xargs)) -type f \( ! -group adm -a ! -group root \)
            -exec chgrp adm {} +
            Run the following command to set the log_group parameter in the audit configuration
            file to log_group = adm:
            # sed -ri 's/^\s*#?\s*log_group\s*=\s*\S+(\s*#.*)?.*$/log_group = adm\1/'
            /etc/audit/auditd.conf
            Run the following command to restart the audit daemon to reload the configuration file:
            # systemctl restart auditd

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 827

Internal Only - General
            6.2.4.4 Ensure the audit log file directory mode is configured
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            The audit log directory contains audit log files.
            Rationale:
            Audit information includes all information including: audit records, audit settings and
            audit reports. This information is needed to successfully audit system activity. This
            information must be protected from unauthorized modification or deletion. If this
            information were to be compromised, forensic analysis and discovery of the true source
            of potentially malicious system activity is impossible to achieve.
            Audit:
            Run the following script to verify the audit log directory is mode 0750 or more restrictive:
            #!/usr/bin/env bash

            {
               l_perm_mask="0027"
               if [ -e "/etc/audit/auditd.conf" ]; then
                  l_audit_log_directory="$(dirname "$(awk -F= '/^\s*log_file\s*/{print
            $2}' /etc/audit/auditd.conf | xargs)")"
                  if [ -d "$l_audit_log_directory" ]; then
                     l_maxperm="$(printf '%o' $(( 0777 & ~$l_perm_mask )) )"
                     l_directory_mode="$(stat -Lc '%#a' "$l_audit_log_directory")"
                     if [ $(( $l_directory_mode & $l_perm_mask )) -gt 0 ]; then
                        echo -e "\n- Audit Result:\n ** FAIL **\n - Directory:
            \"$l_audit_log_directory\" is mode: \"$l_directory_mode\"\n      (should be
            mode: \"$l_maxperm\" or more restrictive)\n"
                     else
                        echo -e "\n- Audit Result:\n ** PASS **\n - Directory:
            \"$l_audit_log_directory\" is mode: \"$l_directory_mode\"\n      (should be
            mode: \"$l_maxperm\" or more restrictive)\n"
                     fi
                  else
                     echo -e "\n- Audit Result:\n ** FAIL **\n - Log file directory not
            set in \"/etc/audit/auditd.conf\" please set log file directory"
                  fi
               else
                  echo -e "\n- Audit Result:\n ** FAIL **\n - File:
            \"/etc/audit/auditd.conf\" not found\n - ** Verify auditd is installed **"
               fi
            }




                                                                                                Page 828

Internal Only - General
            Remediation:
            Run the following command to configure the audit log directory to have a mode of
            "0750" or less permissive:
            # chmod g-w,o-rwx "$(dirname "$(awk -F= '/^\s*log_file\s*/{print $2}'
            /etc/audit/auditd.conf | xargs)")"

            Default Value:
            750
            References:

                 1. NIST SP 800-53 Rev. 5: AU-3

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 829

Internal Only - General
            6.2.4.5 Ensure audit configuration files mode is configured
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Audit configuration files control auditd and what events are audited.
            Rationale:
            Access to the audit configuration files could allow unauthorized personnel to prevent the
            auditing of critical events.
            Misconfigured audit configuration files may prevent the auditing of critical events or
            impact the system's performance by overwhelming the audit log. Misconfiguration of the
            audit configuration files may also make it more difficult to establish and investigate
            events relating to an incident.
            Audit:
            Run the following script to verify that the audit configuration files are mode 0640 or more
            restrictive:
            #!/usr/bin/env bash

            {
               l_output="" l_output2="" l_perm_mask="0137"
               l_maxperm="$( printf '%o' $(( 0777 & ~$l_perm_mask )) )"
               while IFS= read -r -d $'\0' l_fname; do
                  l_mode=$(stat -Lc '%#a' "$l_fname")
                  if [ $(( "$l_mode" & "$l_perm_mask" )) -gt 0 ]; then
                     l_output2="$l_output2\n - file: \"$l_fname\" is mode: \"$l_mode\"
            (should be mode: \"$l_maxperm\" or more restrictive)"
                  fi
               done < <(find /etc/audit/ -type f \( -name "*.conf" -o -name '*.rules' \)
            -print0)
               if [ -z "$l_output2" ]; then
                  echo -e "\n- Audit Result:\n ** PASS **\n - All audit configuration
            files are mode: \"$l_maxperm\" or more restrictive"
               else
                  echo -e "\n- Audit Result:\n ** FAIL **\n$l_output2"
               fi
            }




                                                                                              Page 830

Internal Only - General
            Remediation:
            Run the following command to remove more permissive mode than 0640 from the audit
            configuration files:
            # find /etc/audit/ -type f \( -name '*.conf' -o -name '*.rules' \) -exec
            chmod u-x,g-wx,o-rwx {} +

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 831

Internal Only - General
            6.2.4.6 Ensure audit configuration files owner is configured
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Audit configuration files control auditd and what events are audited.
            Rationale:
            Access to the audit configuration files could allow unauthorized personnel to prevent the
            auditing of critical events.
            Misconfigured audit configuration files may prevent the auditing of critical events or
            impact the system's performance by overwhelming the audit log. Misconfiguration of the
            audit configuration files may also make it more difficult to establish and investigate
            events relating to an incident.
            Audit:
            Run the following command to verify that the audit configuration files are owned by the
            root user:
            # find /etc/audit/ -type f \( -name '*.conf' -o -name '*.rules' \) ! -user
            root
            Nothing should be returned
            Remediation:
            Run the following command to change ownership to root user:
            # find /etc/audit/ -type f \( -name '*.conf' -o -name '*.rules' \) ! -user
            root -exec chown root {} +

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3




                                                                                             Page 832

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 833

Internal Only - General
            6.2.4.7 Ensure audit configuration files group owner is configured
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Audit configuration files control auditd and what events are audited.
            Rationale:
            Access to the audit configuration files could allow unauthorized personnel to prevent the
            auditing of critical events.
            Misconfigured audit configuration files may prevent the auditing of critical events or
            impact the system's performance by overwhelming the audit log. Misconfiguration of the
            audit configuration files may also make it more difficult to establish and investigate
            events relating to an incident.
            Audit:
            Run the following command to verify that the audit configuration files are owned by the
            group root:
            # find /etc/audit/ -type f \( -name '*.conf' -o -name '*.rules' \) ! -group
            root
            Nothing should be returned
            Remediation:
            Run the following command to change group to root:
            # find /etc/audit/ -type f \( -name '*.conf' -o -name '*.rules' \) ! -group
            root -exec chgrp root {} +

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3




                                                                                             Page 834

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 835

Internal Only - General
            6.2.4.8 Ensure audit tools mode is configured (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Audit tools include, but are not limited to, vendor-provided and open source audit tools
            needed to successfully view and manipulate audit information system activity and
            records. Audit tools include custom queries and report generators.
            Rationale:
            Protecting audit information includes identifying and protecting the tools used to view
            and manipulate log data. Protecting audit tools is necessary to prevent unauthorized
            operation on audit information.
            Audit:
            Run the following script to verify the audit tools are mode 0755 or more restrictive:
            #!/usr/bin/env bash

            {
               l_output="" l_output2="" l_perm_mask="0022"
               l_maxperm="$( printf '%o' $(( 0777 & ~$l_perm_mask )) )"
               a_audit_tools=("/sbin/auditctl" "/sbin/aureport" "/sbin/ausearch"
            "/sbin/autrace" "/sbin/auditd" "/sbin/augenrules")
               for l_audit_tool in "${a_audit_tools[@]}"; do
                  l_mode="$(stat -Lc '%#a' "$l_audit_tool")"
                  if [ $(( "$l_mode" & "$l_perm_mask" )) -gt 0 ]; then
                     l_output2="$l_output2\n - Audit tool \"$l_audit_tool\" is mode:
            \"$l_mode\" and should be mode: \"$l_maxperm\" or more restrictive"
                  else
                     l_output="$l_output\n - Audit tool \"$l_audit_tool\" is correctly
            configured to mode: \"$l_mode\""
                  fi
               done
               if [ -z "$l_output2" ]; then
                  echo -e "\n- Audit Result:\n ** PASS **\n - * Correctly configured *
            :$l_output"
               else
                  echo -e "\n- Audit Result:\n ** FAIL **\n - * Reasons for audit
            failure * :$l_output2\n"
                  [ -n "$l_output" ] && echo -e "\n - * Correctly configured *
            :\n$l_output\n"
               fi
               unset a_audit_tools
            }




                                                                                               Page 836

Internal Only - General
            Remediation:
            Run the following command to remove more permissive mode from the audit tools:
            # chmod go-w /sbin/auditctl /sbin/aureport /sbin/ausearch /sbin/autrace
            /sbin/auditd /sbin/augenrules

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 837

Internal Only - General
            6.2.4.9 Ensure audit tools owner is configured (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Audit tools include, but are not limited to, vendor-provided and open source audit tools
            needed to successfully view and manipulate audit information system activity and
            records. Audit tools include custom queries and report generators.
            Rationale:
            Protecting audit information includes identifying and protecting the tools used to view
            and manipulate log data. Protecting audit tools is necessary to prevent unauthorized
            operation on audit information.
            Audit:
            Run the following command to verify the audit tools are owned by the root user:
            # stat -Lc "%n %U" /sbin/auditctl /sbin/aureport /sbin/ausearch /sbin/autrace
            /sbin/auditd /sbin/augenrules | awk '$2 != "root" {print}'
            Nothing should be returned
            Remediation:
            Run the following command to change the owner of the audit tools to the root user:
            # chown root /sbin/auditctl /sbin/aureport /sbin/ausearch /sbin/autrace
            /sbin/auditd /sbin/augenrules

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.



                                                                                                                      Page 838

Internal Only - General
            6.2.4.10 Ensure audit tools group owner is configured
            (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Audit tools include, but are not limited to, vendor-provided and open source audit tools
            needed to successfully view and manipulate audit information system activity and
            records. Audit tools include custom queries and report generators.
            Rationale:
            Protecting audit information includes identifying and protecting the tools used to view
            and manipulate log data. Protecting audit tools is necessary to prevent unauthorized
            operation on audit information.
            Audit:
            Run the following command to verify the audit tools are owned by the group root
            # stat -Lc "%n %G" /sbin/auditctl /sbin/aureport /sbin/ausearch /sbin/autrace
            /sbin/auditd /sbin/augenrules | awk '$2 != "root" {print}'
            Nothing should be returned
            Remediation:
            Run the following command to change group ownership to the group root:
            # chgrp root /sbin/auditctl /sbin/aureport /sbin/ausearch /sbin/autrace
            /sbin/auditd /sbin/augenrules

            References:

                 1. NIST SP 800-53 Rev. 5: AU-3




                                                                                              Page 839

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 840

Internal Only - General
            6.3 Configure Filesystem Integrity Checking

            AIDE is a file integrity checking tool. While it cannot prevent intrusions, it can detect
            unauthorized changes to configuration files by alerting when the files are changed.
            When setting up AIDE, decide internally what the site policy will be concerning integrity
            checking. Review the AIDE quick start guide and AIDE documentation before
            proceeding.
            Note: - IF - another local site approved solution is used, and configured to provide the
            capabilities covered by AIDE in this section, this section may be skipped.




                                                                                              Page 841

Internal Only - General
            6.3.1 Ensure AIDE is installed (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            AIDE takes a snapshot of filesystem state including modification times, permissions,
            and file hashes which can then be used to compare against the current state of the
            filesystem to detect modifications to the system.
            Rationale:
            By monitoring the filesystem state compromised files can be detected to prevent or limit
            the exposure of accidental or malicious misconfigurations or modified binaries.
            Audit:
            Run the following command to verify aide is installed:
            # dpkg-query -s aide &>/dev/null && echo "aide is installed"

            aide is installed
            Run the following command to verify aide-common is installed:
            # dpkg-query -s aide-common &>/dev/null && echo "aide-common is installed"

            aide-common is installed

            Remediation:
            Install AIDE using the appropriate package manager or manual installation:
            # apt install aide aide-common
            Configure AIDE as appropriate for your environment. Consult the AIDE documentation
            for options.
            Run the following commands to initialize AIDE:
            # aideinit
            # mv /var/lib/aide/aide.db.new /var/lib/aide/aide.db

            References:

                 1. NIST SP 800-53 Rev. 5: AU-2

            Additional Information:
            The prelinking feature can interfere with AIDE because it alters binaries to speed up
            their start up times. Run prelink -ua to restore the binaries to their prelinked state,
            thus avoiding false positives from AIDE.


                                                                                              Page 842

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                      IG 1 IG 2 IG 3
               Version

                    v8    3.14 Log Sensitive Data Access                                                             ●
                             Log sensitive data access, including modification and disposal.

                          14.9 Enforce Detail Logging for Access or Changes to
                          Sensitive Data
                    v7        Enforce detailed audit logging for access to sensitive data or changes to              ●
                          sensitive data (utilizing tools such as File Integrity Monitoring or Security
                          Information and Event Monitoring).




                                                                                                                Page 843

Internal Only - General
            6.3.2 Ensure filesystem integrity is regularly checked (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Periodic checking of the filesystem integrity is needed to detect changes to the
            filesystem.
            Rationale:
            Periodic file checking allows the system administrator to determine on a regular basis if
            critical files have been changed in an unauthorized fashion.
            Audit:
            Run the following commands to verify a cron job scheduled to run the aide check.
            # grep -Prs '^([^#\n\r]+\h+)?(\/usr\/s?bin\/|^\h*)aide(\.wrapper)?\h+(--
            (check|update)|([^#\n\r]+\h+)?\$AIDEARGS)\b' /etc/cron.* /etc/crontab
            /var/spool/cron/
            Ensure a cron job in compliance with site policy is returned.
            - OR -
            Run the following commands to verify that aidecheck.service and aidecheck.timer
            are enabled and aidecheck.timer is running
            # systemctl is-enabled aidecheck.service

            # systemctl is-enabled aidecheck.timer
            # systemctl status aidecheck.timer




                                                                                               Page 844

Internal Only - General
            Remediation:
            If cron will be used to schedule and run aide check:
            Run the following command:
            # crontab -u root -e
            Add the following line to the crontab:
            0 5 * * * /usr/bin/aide.wrapper --config /etc/aide/aide.conf --update
            - OR - If aidecheck.service and aidecheck.timer will be used to schedule and run aide
            check:
            Create or edit the file /etc/systemd/system/aidecheck.service and add the
            following lines:
            [Unit]
            Description=Aide Check

            [Service]
            Type=simple
            ExecStart=/usr/bin/aide.wrapper --config /etc/aide/aide.conf --update

            [Install]
            WantedBy=multi-user.target
            Create or edit the file /etc/systemd/system/aidecheck.timer and add the following
            lines:
            [Unit]
            Description=Aide check every day at 5AM

            [Timer]
            OnCalendar=*-*-* 05:00:00
            Unit=aidecheck.service

            [Install]
            WantedBy=multi-user.target
            Run the following commands:
            # chown root:root /etc/systemd/system/aidecheck.*
            # chmod 0644 /etc/systemd/system/aidecheck.*

            # systemctl daemon-reload

            # systemctl enable aidecheck.service
            # systemctl --now enable aidecheck.timer

            References:

                 1. https://github.com/konstruktoid/hardening/blob/master/config/aidecheck.service
                 2. https://github.com/konstruktoid/hardening/blob/master/config/aidecheck.timer




                                                                                            Page 845

Internal Only - General
            Additional Information:
            The checking in this recommendation occurs every day at 5am. Alter the frequency and
            time of the checks in compliance with site policy
            systemd timers, timer file aidecheck.timer and service file aidecheck.service, have
            been included as an optional alternative to using cron
            Ubuntu advises using /usr/bin/aide.wrapper rather than calling /usr/bin/aide
            directly in order to protect the database and prevent conflicts
            CIS Controls:

               Controls
                                                             Control                                      IG 1 IG 2 IG 3
               Version

                    v8    3.14 Log Sensitive Data Access                                                             ●
                             Log sensitive data access, including modification and disposal.

                          14.9 Enforce Detail Logging for Access or Changes to
                          Sensitive Data
                    v7        Enforce detailed audit logging for access to sensitive data or changes to              ●
                          sensitive data (utilizing tools such as File Integrity Monitoring or Security
                          Information and Event Monitoring).




                                                                                                                Page 846

Internal Only - General
            6.3.3 Ensure cryptographic mechanisms are used to protect the
            integrity of audit tools (Automated)
            Profile Applicability:

            • Level 2 - Server
            • Level 2 - Workstation
            Description:
            Audit tools include, but are not limited to, vendor-provided and open source audit tools
            needed to successfully view and manipulate audit information system activity and
            records. Audit tools include custom queries and report generators.
            Rationale:
            Protecting the integrity of the tools used for auditing purposes is a critical step toward
            ensuring the integrity of audit information. Audit information includes all information
            (e.g., audit records, audit settings, and audit reports) needed to successfully audit
            information system activity.
            Attackers may replace the audit tools or inject code into the existing tools with the
            purpose of providing the capability to hide or erase system activity from the audit logs.
            Audit tools should be cryptographically signed in order to provide the capability to
            identify when the audit tools have been modified, manipulated, or replaced. An example
            is a checksum hash of the file or files.
            Audit:
            Verify that Advanced Intrusion Detection Environment (AIDE) is properly configured .
            Run the following script to verify:

                 •   AIDE is configured to use cryptographic mechanisms to protect the integrity of
                     audit tools:
                 •   The following audit tool files include the options "p, i, n, u, g, s, b, acl, xattrs and
                     sha512"
                        o auditctl
                        o auditd
                        o ausearch
                        o aureport
                        o autrace
                        o augenrules




                                                                                                      Page 847

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output=();a_output2=();a_output3=();a_parlist=()
               l_systemd_analyze="$(readlink -e /bin/systemd-analyze || readlink -e
            /usr/bin/systemd-analyze)"
               a_audit_files=("auditctl" "auditd" "ausearch" "aureport" "autrace"
            "augenrules")
               f_parameter_chk()
               {
                   for l_tool_file in "${a_parlist[@]}"; do
                      if grep -Pq -- '\b'"$l_tool_file"'\b' <<< "${!A_out[*]}"; then
                         for l_string in "${!A_out[@]}"; do
                            l_check="$(grep -Po --
            '^\h*(\/usr)?\/sbin\/'"$l_tool_file"'\b' <<< "$l_string")"
                            if [ -n "$l_check" ]; then
                               l_fname="$(printf '%s' "${A_out[$l_string]}")"
                               [ "$l_check" != "$(readlink -f "$l_check")" ] && \
                               a_output3+=(" - \"$l_check\" should be updated to:
            \"$(readlink -e "$l_check")\"" "     in: \"$l_fname\"")
                               a_missing=()
                               for l_var in "${a_items[@]}"; do
                                  if ! grep -Pq -- "\b$l_var\b" <<< "$l_string"; then
                                     a_missing+=("\"$l_var\"")
                                  fi
                               done
                               if [ "${#a_missing[@]}" -gt 0 ]; then
                                  a_output2+=(" - Option(s): ( ${a_missing[*]} ) are
            missing from: \"$l_tool_file\" in: \"$l_fname\"")
                               else
                                  a_output+=(" - Audit tool file \"$l_tool_file\" exists
            as:" "    \"$l_string\"" "   in the configuration file: \"$l_fname\"")
                               fi
                            fi
                         done
                      else
                         a_output2+=(" - Audit tool file \"$l_tool_file\" doesn't exist in
            an AIDE configuration file")
                      fi
                   done
               }
               f_aide_conf()
               {
                   l_config_file="$(readlink -e /etc/aide/aide.conf || readlink -e
            /etc/aide.conf)"
                   if [ -f "$l_config_file" ]; then
                      a_items=("p" "i" "n" "u" "g" "s" "b" "acl" "xattrs" "sha512")
                      declare -A A_out
                      while IFS= read -r l_out; do
                         if grep -Pq -- '^\h*\#\h*\/[^#\n\r]+\.conf\b' <<< "$l_out"; then
                            l_file="${l_out//# /}"
                         else
                            for i in "${a_parlist[@]}"; do
                               grep -Pq -- '^\h*(\/usr)?\/sbin\/'"$i"'\b' <<< "$l_out" &&
            A_out+=(["$l_out"]="$l_file")
                            done
                         fi


                                                                                   Page 848

Internal Only - General
                     done < <("$l_systemd_analyze" cat-config "$l_config_file" | grep -
            Pio '^\h*([^#\n\r]+|#\h*\/[^#\n\r\h]+\.conf\b)')
                     if [ "${#A_out[@]}" -gt 0 ]; then
                        f_parameter_chk
                     else
                        a_output2+=(" - No audit tool files are configured in an AIDE
            configuration file")
                     fi
                  else
                     a_output2+=(" - AIDE configuration file not found." "   Please
            verify AIDE is installed on the system")
                  fi
               }
               for l_audit_file in "${a_audit_files[@]}"; do
                  if [ -f "$(readlink -f "/sbin/$l_audit_file")" ]; then
                     a_parlist+=("$l_audit_file")
                  else
                     a_output+=(" - Audit tool file \"$(readlink -f
            "/sbin/$l_audit_file")\" doesn't exist")
                  fi
               done
               [ "${#a_parlist[@]}" -gt 0 ] && f_aide_conf
               if [ "${#a_output2[@]}" -le 0 ]; then
                  printf '%s\n' "" "- Audit Result:" " ** PASS **" "${a_output[@]}"
                  [ "${#a_output3[@]}" -gt 0 ] && printf '%s\n' "" " ** WARNING **"
            "${a_output3[@]}"
               else
                  printf '%s\n' "" "- Audit Result:" " ** FAIL **" " * Reasons for
            audit failure *" "${a_output2[@]}" ""
                  [ "${#a_output3[@]}" -gt 0 ] && printf '%s\n' "" " ** WARNING **"
            "${a_output3[@]}"
                  [ "${#a_output[@]}" -gt 0 ] && printf '%s\n' "- Correctly set:"
            "${a_output[@]}"
               fi
            }
            Note: The script is written to read the "winning" configuration setting, to include any
            configuration settings in files included as part of the @@x_include setting.




                                                                                               Page 849

Internal Only - General
            Remediation:
            Run the following command to determine the absolute path to the non-symlinked
            version on the audit tools:
            # readlink -e /sbin
            The output will be either /usr/sbin - OR - /sbin. Ensure the correct path is used.
            Edit /etc/aide/aide.conf and add or update the following selection lines replacing
            <PATH> with the correct path returned in the command above:
            # Audit Tools
            <PATH>/auditctl p+i+n+u+g+s+b+acl+xattrs+sha512
            <PATH>/auditd p+i+n+u+g+s+b+acl+xattrs+sha512
            <PATH>/ausearch p+i+n+u+g+s+b+acl+xattrs+sha512
            <PATH>/aureport p+i+n+u+g+s+b+acl+xattrs+sha512
            <PATH>/autrace p+i+n+u+g+s+b+acl+xattrs+sha512
            <PATH>/augenrules p+i+n+u+g+s+b+acl+xattrs+sha512
            Example
            # printf '%s\n' "" "# Audit Tools" "$(readlink -e /sbin/auditctl)
            p+i+n+u+g+s+b+acl+xattrs+sha512" "$(readlink -e /sbin/auditd)
            p+i+n+u+g+s+b+acl+xattrs+sha512" "$(readlink -e /sbin/ausearch)
            p+i+n+u+g+s+b+acl+xattrs+sha512" "$(readlink -e /sbin/aureport)
            p+i+n+u+g+s+b+acl+xattrs+sha512" "$(readlink -e /sbin/autrace)
            p+i+n+u+g+s+b+acl+xattrs+sha512" "$(readlink -e /sbin/augenrules)
            p+i+n+u+g+s+b+acl+xattrs+sha512" >> "$(readlink -e /etc/aide/aide.conf ||
            readlink -e /etc/aide.conf)"
            Note: - IF - /etc/aide/aide.conf includes a @@x_include statement:
            Example:
            @@x_include /etc/aide/aide.conf.d ^[a-zA-Z0-9_-]+$

                 •   @@x_include FILE
                 •   @@x_include DIRECTORY REGEX
                        o @x_include is identical to @@include, except that if a config file is
                          executable it is run and the output is used as config.
                        o If the executable file exits with status greater than zero or writes to stderr
                          aide stops with an error.
                        o For security reasons DIRECTORY and each executable config file must
                          be owned by the current user and must not be group or world-writable.

            References:

                 1. AIDE.CONF(5)
                 2. STIG ID: UBTU-20-010205 | RULE ID: SV-238303r991567 | CAT II
                 3. STIG ID: UBTU-22-651030 | RULE ID: SV-260586r1044779 | CAT II
                 4. STIG ID: UBTU-24-90890 | RULE ID: SV-270831r1066982 | CAT II




                                                                                                 Page 850

Internal Only - General
            CIS Controls:

                 Controls Version                      Control            IG 1 IG 2 IG 3

                          v8          0.0 Explicitly Not Mapped
                                        Explicitly Not Mapped

                          v7          0.0 Explicitly Not Mapped
                                        Explicitly Not Mapped




            7 System Maintenance
            Recommendations in this section are intended as maintenance and are intended to be
            checked on a frequent basis to ensure system stability. Many recommendations do not
            have quick remediations and require investigation into the cause and best fix available
            and may indicate an attempted breach of system security.




                                                                                            Page 851

Internal Only - General
            7.1 Configure system file and directory access

            This section provides guidance on securing aspects of system files and directories.




                                                                                            Page 852

Internal Only - General
            7.1.1 Ensure access to /etc/passwd is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/passwd file contains user account information that is used by many system
            utilities and therefore must be readable for these utilities to operate.
            Rationale:
            It is critical to ensure that the /etc/passwd file is protected from unauthorized write
            access. Although it is protected by default, the file permissions could be changed either
            inadvertently or through malicious actions.
            Audit:
            Run the following command to verify /etc/passwd is mode 644 or more restrictive, Uid
            is 0/root and Gid is 0/root:
            # stat -Lc 'Access: (%#a/%A)         Uid: ( %u/ %U) Gid: ( %g/ %G)'    /etc/passwd

            Access: (0644/-rw-r--r--)        Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            Run the following commands to remove excess permissions, set owner, and set group
            on /etc/passwd:
            # chmod u-x,go-wx /etc/passwd
            # chown root:root /etc/passwd

            Default Value:
            Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2




                                                                                             Page 853

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 854

Internal Only - General
            7.1.2 Ensure access to /etc/passwd- is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/passwd- file contains backup user account information.

            Rationale:
            It is critical to ensure that the /etc/passwd- file is protected from unauthorized access.
            Although it is protected by default, the file permissions could be changed either
            inadvertently or through malicious actions.
            Audit:
            Run the following command to verify /etc/passwd- is mode 644 or more restrictive,
            Uid is 0/root and Gid is 0/root:
            # stat -Lc 'Access: (%#a/%A)         Uid: ( %u/ %U) Gid: { %g/ %G)' /etc/passwd-

            Access: (0644/-rw-r--r--)        Uid: ( 0/ root) Gid: { 0/ root)

            Remediation:
            Run the following commands to remove excess permissions, set owner, and set group
            on /etc/passwd-:
            # chmod u-x,go-wx /etc/passwd-
            # chown root:root /etc/passwd-

            Default Value:
            Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: { 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2




                                                                                              Page 855

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 856

Internal Only - General
            7.1.3 Ensure access to /etc/group is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/group file contains a list of all the valid groups defined in the system. The
            command below allows read/write access for root and read access for everyone else.
            Rationale:
            The /etc/group file needs to be protected from unauthorized changes by non-
            privileged users, but needs to be readable as this information is used with many non-
            privileged programs.
            Audit:
            Run the following command to verify /etc/group is mode 644 or more restrictive, Uid
            is 0/root and Gid is 0/root:
            # stat -Lc 'Access: (%#a/%A)         Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/group

            Access: (0644/-rw-r--r--)        Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            Run the following commands to remove excess permissions, set owner, and set group
            on /etc/group:
            # chmod u-x,go-wx /etc/group
            # chown root:root /etc/group

            Default Value:
            Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2




                                                                                            Page 857

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 858

Internal Only - General
            7.1.4 Ensure access to /etc/group- is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/group- file contains a backup list of all the valid groups defined in the
            system.
            Rationale:
            It is critical to ensure that the /etc/group- file is protected from unauthorized access.
            Although it is protected by default, the file permissions could be changed either
            inadvertently or through malicious actions.
            Audit:
            Run the following command to verify /etc/group- is mode 644 or more restrictive, Uid
            is 0/root and Gid is 0/root:
            # stat -Lc 'Access: (%#a/%A)         Uid: ( %u/ %U) Gid: ( %g/ %G)'     /etc/group-

            Access: (0644/-rw-r--r--)        Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            Run the following commands to remove excess permissions, set owner, and set group
            on /etc/group-:
            # chmod u-x,go-wx /etc/group-
            # chown root:root /etc/group-

            Default Value:
            Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2




                                                                                              Page 859

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 860

Internal Only - General
            7.1.5 Ensure access to /etc/shadow is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/shadow file is used to store the information about user accounts that is critical
            to the security of those accounts, such as the hashed password and other security
            information.
            Rationale:
            If attackers can gain read access to the /etc/shadow file, they can easily run a
            password cracking program against the hashed password to break it. Other security
            information that is stored in the /etc/shadow file (such as expiration) could also be
            useful to subvert the user accounts.
            Audit:
            Run the following command to verify /etc/shadow is mode 640 or more restrictive, Uid
            is 0/root and Gid is 0/root or ({GID}/ shadow):
            # stat -Lc 'Access: (%#a/%A)       Uid: ( %u/ %U) Gid: ( %g/ %G)'      /etc/shadow
            Example:
            Access: (0640/-rw-r-----)       Uid: ( 0/ root) Gid: ( 42/ shadow)

            Remediation:
            Run one of the following commands to set ownership of /etc/shadow to root and
            group to either root or shadow:
            # chown root:shadow /etc/shadow
              -OR-
            # chown root:root /etc/shadow
            Run the following command to remove excess permissions form /etc/shadow:
            # chmod u-x,g-wx,o-rwx /etc/shadow

            Default Value:
            Access: (0640/-rw-r-----) Uid: ( 0/ root) Gid: ( 42/ shadow)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2




                                                                                              Page 861

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 862

Internal Only - General
            7.1.6 Ensure access to /etc/shadow- is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/shadow- file is used to store backup information about user accounts that is
            critical to the security of those accounts, such as the hashed password and other
            security information.
            Rationale:
            It is critical to ensure that the /etc/shadow- file is protected from unauthorized access.
            Although it is protected by default, the file permissions could be changed either
            inadvertently or through malicious actions.
            Audit:
            Run the following command to verify /etc/shadow- is mode 640 or more restrictive,
            Uid is 0/root and Gid is 0/root or {GID}/shadow:
            # stat -Lc 'Access: (%#a/%A)       Uid: ( %u/ %U) Gid: ( %g/ %G)'       /etc/shadow-
            Example:
            Access: (0640/-rw-r-----)       Uid: ( 0/ root) Gid: ( 42/ shadow)

            Remediation:
            Run one of the following commands to set ownership of /etc/shadow- to root and
            group to either root or shadow:
            # chown root:shadow /etc/shadow-
              -OR-
            # chown root:root /etc/shadow-
            Run the following command to remove excess permissions form /etc/shadow-:
            # chmod u-x,g-wx,o-rwx /etc/shadow-

            Default Value:
            Access: (0640/-rw-r-----) Uid: ( 0/ root) Gid: ( 42/ shadow)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2




                                                                                              Page 863

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 864

Internal Only - General
            7.1.7 Ensure access to /etc/gshadow is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/gshadow file is used to store the information about groups that is critical to
            the security of those accounts, such as the hashed password and other security
            information.
            Rationale:
            If attackers can gain read access to the /etc/gshadow file, they can easily run a
            password cracking program against the hashed password to break it. Other security
            information that is stored in the /etc/gshadow file (such as group administrators) could
            also be useful to subvert the group.
            Audit:
            Run the following command to verify /etc/gshadow is mode 640 or more restrictive,
            Uid is 0/root and Gid is 0/root or `{GID}/shadow:
            # stat -Lc 'Access: (%#a/%A)       Uid: ( %u/ %U) Gid: ( %g/ %G)'       /etc/gshadow
            Example:
            Access: (0640/-rw-r-----)       Uid: ( 0/ root) Gid: ( 42/ shadow)

            Remediation:
            Run one of the following commands to set ownership of /etc/gshadow to root and
            group to either root or shadow:
            # chown root:shadow /etc/gshadow
              -OR-
            # chown root:root /etc/gshadow
            Run the following command to remove excess permissions form /etc/gshadow:
            # chmod u-x,g-wx,o-rwx /etc/gshadow

            Default Value:
            Access: (0640/-rw-r-----) Uid: ( 0/ root) Gid: ( 42/ shadow)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2




                                                                                              Page 865

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 866

Internal Only - General
            7.1.8 Ensure access to /etc/gshadow- is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The /etc/gshadow- file is used to store backup information about groups that is critical
            to the security of those accounts, such as the hashed password and other security
            information.
            Rationale:
            It is critical to ensure that the /etc/gshadow- file is protected from unauthorized
            access. Although it is protected by default, the file permissions could be changed either
            inadvertently or through malicious actions.
            Audit:
            Run the following command to verify /etc/gshadow- is mode 640 or more restrictive,
            Uid is 0/root and Gid is 0/root or {GID}/shadow:
            # stat -Lc 'Access: (%#a/%A)       Uid: ( %u/ %U) Gid: ( %g/ %G)'      /etc/gshadow-
            Example:
            Access: (0640/-rw-r-----)       Uid: ( 0/ root) Gid: ( 42/ shadow)

            Remediation:
            Run one of the following commands to set ownership of /etc/gshadow- to root and
            group to either root or shadow:
            # chown root:shadow /etc/gshadow-
              -OR-
            # chown root:root /etc/gshadow-
            Run the following command to remove excess permissions form /etc/gshadow-:
            # chmod u-x,g-wx,o-rwx /etc/gshadow-

            Default Value:
            Access: (0640/-rw-r-----) Uid: ( 0/ root) Gid: ( 42/ shadow)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2




                                                                                             Page 867

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 868

Internal Only - General
            7.1.9 Ensure access to /etc/shells is configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            /etc/shells is a text file which contains the full pathnames of valid login shells. This
            file is consulted by chsh and available to be queried by other programs.

            Rationale:
            It is critical to ensure that the /etc/shells file is protected from unauthorized access.
            Although it is protected by default, the file permissions could be changed either
            inadvertently or through malicious actions.
            Audit:
            Run the following command to verify /etc/shells is mode 644 or more restrictive, Uid
            is 0/root and Gid is 0/root:
            # stat -Lc 'Access: (%#a/%A)         Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/shells

            Access: (0644/-rw-r--r--)        Uid: ( 0/ root) Gid: ( 0/ root)

            Remediation:
            Run the following commands to remove excess permissions, set owner, and set group
            on /etc/shells:
            # chmod u-x,go-wx /etc/shells
            # chown root:root /etc/shells

            Default Value:
            Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2




                                                                                              Page 869

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 870

Internal Only - General
            7.1.10 Ensure access to /etc/security/opasswd is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            /etc/security/opasswd and it's backup /etc/security/opasswd.old hold user's
            previous passwords if pam_unix or pam_pwhistory is in use on the system

            Rationale:
            It is critical to ensure that /etc/security/opasswd is protected from unauthorized
            access. Although it is protected by default, the file permissions could be changed either
            inadvertently or through malicious actions.
            Audit:
            Run the following commands to verify /etc/security/opasswd and
            /etc/security/opasswd.old are mode 600 or more restrictive, Uid is 0/root and
            Gid is 0/root if they exist:
            # [ -e "/etc/security/opasswd" ] && stat -Lc '%n Access: (%#a/%A)             Uid: (
            %u/ %U) Gid: ( %g/ %G)' /etc/security/opasswd

            /etc/security/opasswd Access: (0600/-rw-------) Uid: ( 0/ root) Gid: ( 0/
            root)
             -OR-
            Nothing is returned
            # [ -e "/etc/security/opasswd.old" ] && stat -Lc '%n Access: (%#a/%A) Uid:
            ( %u/ %U) Gid: ( %g/ %G)' /etc/security/opasswd.old

            /etc/security/opasswd.old Access: (0600/-rw-------)          Uid: ( 0/ root) Gid: (
            0/ root)
             -OR-
            Nothing is returned




                                                                                             Page 871

Internal Only - General
            Remediation:
            Run the following commands to remove excess permissions, set owner, and set group
            on /etc/security/opasswd and /etc/security/opasswd.old is they exist:
            # [ -e "/etc/security/opasswd" ] && chmod u-x,go-rwx /etc/security/opasswd
            # [ -e "/etc/security/opasswd" ] && chown root:root /etc/security/opasswd
            # [ -e "/etc/security/opasswd.old" ] && chmod u-x,go-rwx
            /etc/security/opasswd.old
            # [ -e "/etc/security/opasswd.old" ] && chown root:root
            /etc/security/opasswd.old

            Default Value:
            /etc/security/opasswd Access: (0600/-rw-------) Uid: ( 0/ root) Gid: ( 0/ root)
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3, MP-2

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 872

Internal Only - General
            7.1.11 Ensure world writable files and directories are secured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            World writable files are the least secure. Data in world-writable files can be modified and
            compromised by any user on the system. World writable files may also indicate an
            incorrectly written script or program that could potentially be the cause of a larger
            compromise to the system's integrity. See the chmod(2) man page for more
            information.
            Setting the sticky bit on world writable directories prevents users from deleting or
            renaming files in that directory that are not owned by them.
            Rationale:
            Data in world-writable files can be modified and compromised by any user on the
            system. World writable files may also indicate an incorrectly written script or program
            that could potentially be the cause of a larger compromise to the system's integrity.
            This feature prevents the ability to delete or rename files in world writable directories
            (such as /tmp ) that are owned by another user.




                                                                                                Page 873

Internal Only - General
            Audit:
            Run the following script to verify:

                 •   No world writable files exist
                 •   No world writable directories without the sticky bit exist

            #!/usr/bin/env bash

            {
               a_output=() a_output2=() a_file=() a_dir=() l_smask='01000'
               l_exclude="nfs|proc|cifs|smb|vfat|iso9660|efivarfs|selinuxfs|ncpfs"
               l_exclude2="\/run|\/tmp|\/var\/tmp"
               a_path=(-path "*/containers/storage/*" -o -path "*/containerd/*" -o -path
            "*/kubelet/*" -o -path "/sys/*" -o -path "/snap/*" -o -path "/boot/efi/*")
               while IFS= read -r l_mount; do
                  while IFS= read -r -d $'\0' l_file; do
                     if [ -e "$l_file" ]; then
                         [ -f "$l_file" ] && a_file+=("$l_file")
                         if [ -d "$l_file" ]; then
                            l_mode="$(stat -Lc '%#a' "$l_file")"
                            [ ! $(( $l_mode & $l_smask )) -gt 0 ] && a_dir+=("$l_file")
                         fi
                     fi
                  done < <(find "$l_mount" -mount -xdev \( "${a_path[@]}" \) \
                  -prune -o \( -type f -o -type d \) -perm -0002 -print0 2> /dev/null)
               done < <(findmnt -Dkerno fstype,target | \
               awk '($1 !~ /^\s*('"$l_exclude"')/ && $2 !~
            /^('"$l_exclude2"')(\/|$)/){print $2}')
               if [ "${#a_file[@]}" -le 0 ]; then
                  printf '%s\n' "" " - No world writable files exist on the local
            filesystem."
               else
                  printf '%s\n' "" " - There are \"${#a_file[@]}\" World writable files
            on the system." \
                  "   - The following is a list of World writable files:" \
                  "${a_file[@]}" "    - end of list"
               fi
               if [ "${#a_dir[@]}" -le 0 ]; then
                  printf '%s\n' "" \
                  " - Sticky bit is set on world writable directories on the local
            filesystem."
               else
                  printf '%s\n' "" " - There are \"${#a_dir[@]}\" World writable
            directories" \
                  "     without the sticky bit on the system." \
                  "   - The following is a list of World writable directories without the
            sticky bit:" \
                  "${a_dir[@]}" "    - end of list"
               fi
            }
            Note: On systems with a large number of files and/or directories, this audit may be a
            long running process



                                                                                            Page 874

Internal Only - General
            Remediation:

                 •   World Writable Files:
                       o It is recommended that write access is removed from other with the
                           command ( chmod o-w <filename> ), but always consult relevant vendor
                           documentation to avoid breaking any application dependencies on a given
                           file.
                 •   World Writable Directories:
                       o Set the sticky bit on all world writable directories with the command (
                           chmod a+t <directory_name> )

            Run the following script to:

                 •   Remove other write permission from any world writable files
                 •   Add the sticky bit to all world writable directories

            #!/usr/bin/env bash

            {
               l_smask='01000' a_file=() a_dir=()
               a_path=(-path "*/containers/storage/*" -o -path "*/containerd/*" -o -path
            "*/kubelet/*" -o -path "/sys/*" -o -path "/snap/*" -o -path "/boot/efi/*")
               l_exclude="nfs|proc|cifs|smb|vfat|iso9660|efivarfs|selinuxfs|ncpfs"
               l_exclude2="\/run|\/tmp|\/var\/tmp"
               while IFS= read -r l_mount; do
                  while IFS= read -r -d $'\0' l_file; do
                     l_mode="$(stat -Lc '%#a' "$l_file" 2>/dev/null)"
                     if [ -f "$l_file" ]; then # Remove excess permissions from WW files
                        printf '%s\n' "" " - File: \"$l_file\" is mode: \"$l_mode\"" \
                        " - removing write permission on \"$l_file\" from \"other\""
                        chmod o-w "$l_file"
                     fi
                     if [ -d "$l_file" ]; then # Add sticky bit
                        if [ ! $(( $l_mode & $l_smask )) -gt 0 ]; then
                           printf '%s\n' "" " - Directory: \"$l_file\" is mode:
            \"$l_mode\"" \
                           "    and doesn't have the sticky bit set" \
                           " - Adding the sticky bit"
                           chmod a+t "$l_file"
                        fi
                     fi
                  done < <(find "$l_mount" -mount -xdev \( "${a_path[@]}" \) \
                  -prune -o \( -type f -o -type d \) -perm -0002 -print0 2> /dev/null)
               done < <(findmnt -Dkerno fstype,target | \
               awk '($1 !~ /^\s*('"$l_exclude"')/ && $2 !~
            /^('"$l_exclude2"')(\/|$)/){print $2}')
            }
            References:
               1. NIST SP 800-53 Rev. 5: AC-3. MP-2
               2. STIG ID: UBTU-20-010411 | Rule ID: SV-238332r958524 | CAT ||
               3. STIG ID: UBTU-22-232145 | Rule ID: SV-260513r958524 | CAT ||



                                                                                          Page 875

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 876

Internal Only - General
            7.1.12 Ensure no files or directories without an owner and a group
            exist (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Administrators may delete users or groups from the system and neglect to remove all
            files and/or directories owned by those users or groups.
            Rationale:
            A new user or group who is assigned a deleted user's user ID or group ID may then end
            up "owning" a deleted user or group's files, and thus have more access on the system
            than was intended.
            Audit:
            Run the following script to verify no unowned or ungrouped files or directories exist:




                                                                                              Page 877

Internal Only - General
            #!/usr/bin/env bash

            {
               l_output="" l_output2=""
               a_nouser=(); a_nogroup=() # Initialize arrays
               a_path=(! -path "/run/user/*" -a ! -path "/proc/*" -a ! -path
            "*/containerd/*" -a ! -path "*/kubelet/pods/*" -a ! -path
            "*/kubelet/plugins/*" -a ! -path "/sys/fs/cgroup/memory/*" -a ! -path
            "/var/*/private/*")
               while IFS= read -r l_mount; do
                   while IFS= read -r -d $'\0' l_file; do
                      if [ -e "$l_file" ]; then
                         while IFS=: read -r l_user l_group; do
                            [ "$l_user" = "UNKNOWN" ] && a_nouser+=("$l_file")
                            [ "$l_group" = "UNKNOWN" ] && a_nogroup+=("$l_file")
                         done < <(stat -Lc '%U:%G' "$l_file")
                      fi
                   done < <(find "$l_mount" -xdev \( "${a_path[@]}" \) \( -type f -o -type
            d \) \( -nouser -o -nogroup \) -print0 2> /dev/null)
               done < <(findmnt -Dkerno fstype,target | awk '($1 !~
            /^\s*(nfs|proc|smb|vfat|iso9660|efivarfs|selinuxfs)/ && $2 !~
            /^\/run\/user\//){print $2}')
               if ! (( ${#a_nouser[@]} > 0 )); then
                   l_output="$l_output\n - No files or directories without a owner exist
            on the local filesystem."
               else
                   l_output2="$l_output2\n - There are \"$(printf '%s'
            "${#a_nouser[@]}")\" unowned files or directories on the system.\n    - The
            following is a list of unowned files and/or directories:\n$(printf '%s\n'
            "${a_nouser[@]}")\n    - end of list"
               fi
               if ! (( ${#a_nogroup[@]} > 0 )); then
                   l_output="$l_output\n - No files or directories without a group exist
            on the local filesystem."
               else
                   l_output2="$l_output2\n - There are \"$(printf '%s'
            "${#a_nogroup[@]}")\" ungrouped files or directories on the system.\n    - The
            following is a list of ungrouped files and/or directories:\n$(printf '%s\n'
            "${a_nogroup[@]}")\n    - end of list"
               fi
               unset a_path; unset a_arr ; unset a_nouser; unset a_nogroup # Remove
            arrays
               if [ -z "$l_output2" ]; then # If l_output2 is empty, we pass
                   echo -e "\n- Audit Result:\n ** PASS **\n - * Correctly configured *
            :\n$l_output\n"
               else
                   echo -e "\n- Audit Result:\n ** FAIL **\n - * Reasons for audit
            failure * :\n$l_output2"
                   [ -n "$l_output" ] && echo -e "\n- * Correctly configured *
            :\n$l_output\n"
               fi
            }
            Note: On systems with a large number of files and/or directories, this audit may be a
            long running process




                                                                                            Page 878

Internal Only - General
            Remediation:
            Remove or set ownership and group ownership of these files and/or directories to an
            active user on the system as appropriate.
            References:

                 1. NIST SP 800-53 Rev. 5: AC-3. MP-2

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 879

Internal Only - General
            7.1.13 Ensure SUID and SGID files are reviewed (Manual)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The owner of a file can set the file's permissions to run with the owner's or group's
            permissions, even if the user running the program is not the owner or a member of the
            group. The most common reason for a SUID or SGID program is to enable users to
            perform functions (such as changing their password) that require root privileges.
            Rationale:
            There are valid reasons for SUID and SGID programs, but it is important to identify and
            review such programs to ensure they are legitimate. Review the files returned by the
            action in the audit section and check to see if system binaries have a different
            checksum than what from the package. This is an indication that the binary may have
            been replaced.
            Audit:
            Run the following script to generate a list of SUID and SGID files:




                                                                                            Page 880

Internal Only - General
            #!/usr/bin/env bash

            {
               l_output="" l_output2=""
               a_suid=(); a_sgid=() # initialize arrays
               while IFS= read -r l_mount; do
                  while IFS= read -r -d $'\0' l_file; do
                     if [ -e "$l_file" ]; then
                        l_mode="$(stat -Lc '%#a' "$l_file")"
                        [ $(( $l_mode & 04000 )) -gt 0 ] && a_suid+=("$l_file")
                        [ $(( $l_mode & 02000 )) -gt 0 ] && a_sgid+=("$l_file")
                     fi
                  done < <(find "$l_mount" -xdev -type f \( -perm -2000 -o -perm -4000 \)
            -print0 2>/dev/null)
               done < <(findmnt -Dkerno fstype,target,options | awk '($1 !~
            /^\s*(nfs|proc|smb|vfat|iso9660|efivarfs|selinuxfs)/ && $2 !~
            /^\/run\/user\// && $3 !~/noexec/ && $3 !~/nosuid/) {print $2}')
               if ! (( ${#a_suid[@]} > 0 )); then
                  l_output="$l_output\n - No executable SUID files exist on the system"
               else
                  l_output2="$l_output2\n - List of \"$(printf '%s' "${#a_suid[@]}")\"
            SUID executable files:\n$(printf '%s\n' "${a_suid[@]}")\n - end of list -\n"
               fi
               if ! (( ${#a_sgid[@]} > 0 )); then
                  l_output="$l_output\n - No SGID files exist on the system"
               else
                  l_output2="$l_output2\n - List of \"$(printf '%s' "${#a_sgid[@]}")\"
            SGID executable files:\n$(printf '%s\n' "${a_sgid[@]}")\n - end of list -\n"
               fi
               [ -n "$l_output2" ] && l_output2="$l_output2\n- Review the preceding
            list(s) of SUID and/or SGID files to\n- ensure that no rogue programs have
            been introduced onto the system.\n"
               unset a_arr; unset a_suid; unset a_sgid # Remove arrays
               # If l_output2 is empty, Nothing to report
               if [ -z "$l_output2" ]; then
                  echo -e "\n- Audit Result:\n$l_output\n"
               else
                  echo -e "\n- Audit Result:\n$l_output2\n"
                  [ -n "$l_output" ] && echo -e "$l_output\n"
               fi
            }
            Note: on systems with a large number of files, this may be a long running process




                                                                                           Page 881

Internal Only - General
            Remediation:
            Ensure that no rogue SUID or SGID programs have been introduced into the system.
            Review the files returned by the action in the Audit section and confirm the integrity of
            these binaries.
            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5, AC-3, MP-2

            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 882

Internal Only - General
            7.2 Local User and Group Settings

            This section provides guidance on securing aspects of the local users and groups.
            Note: The recommendations in this section check local users and groups. Any users or
            groups from other sources such as LDAP will not be audited. In a domain environment
            similar checks should be performed against domain users and groups.




                                                                                         Page 883

Internal Only - General
            7.2.1 Ensure accounts in /etc/passwd use shadowed passwords
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Local accounts can uses shadowed passwords. With shadowed passwords, The
            passwords are saved in shadow password file, /etc/shadow, encrypted by a salted
            one-way hash. Accounts with a shadowed password have an x in the second field in
            /etc/passwd.

            Rationale:
            The /etc/passwd file also contains information like user ID's and group ID's that are
            used by many system programs. Therefore, the /etc/passwd file must remain world
            readable. In spite of encoding the password with a randomly-generated one-way hash
            function, an attacker could still break the system if they got access to the /etc/passwd
            file. This can be mitigated by using shadowed passwords, thus moving the passwords in
            the /etc/passwd file to /etc/shadow. The /etc/shadow file is set so only root will be
            able to read and write. This helps mitigate the risk of an attacker gaining access to the
            encoded passwords with which to perform a dictionary attack.
            Note:

                 •   All accounts must have passwords or be locked to prevent the account from
                     being used by an unauthorized user.
                 •   A user account with an empty second field in /etc/passwd allows the account to
                     be logged into by providing only the username.

            Audit:
            Run the following command and verify that no output is returned:
            # awk -F: '($2 != "x" ) { print "User: \"" $1 "\" is not set to shadowed
            passwords "}' /etc/passwd

            Remediation:
            Run the following command to set accounts to use shadowed passwords and migrate
            passwords in /etc/passwd to /etc/shadow:
            # pwconv
            Investigate to determine if the account is logged in and what it is being used for, to
            determine if it needs to be forced off.




                                                                                               Page 884

Internal Only - General
            References:

                 1. NIST SP 800-53 Rev. 5: IA-5
                 2. PWCONV(8)

            Additional Information:
            The pwconv command creates shadow from passwd and an optionally existing shadow.

                 •        The pwunconv command creates passwd from passwd and shadow and then
                          removes shadow.
                 •        The grpconv command creates gshadow from group and an optionally existing
                          gshadow.
                 •        The grpunconv command creates group from group and gshadow and then
                          removes gshadow.

            These four programs all operate on the normal and shadow password and group files:
            /etc/passwd, /etc/group, /etc/shadow, and /etc/gshadow.
            Each program acquires the necessary locks before conversion. pwconv and grpconv
            are similar. First, entries in the shadowed file which don't exist in the main file are
            removed. Then, shadowed entries which don't have x' as the password in the
            main file are updated. Any missing shadowed entries are added.
            Finally, passwords in the main file are replaced with x'. These programs
            can be used for initial conversion as well to update the shadowed file if the main file is
            edited by hand.
            pwconv will use the values of PASS_MIN_DAYS, PASS_MAX_DAYS, and PASS_WARN_AGE
            from /etc/login.defs when adding new entries to /etc/shadow.
            pwunconv and grpunconv are similar. Passwords in the main file are updated from the
            shadowed file. Entries which exist in the main file but not in the shadowed file are left
            alone. Finally, the shadowed file is removed. Some password aging information is lost
            by pwunconv. It will convert what it can.

            CIS Controls:

              Controls
                                                                   Control                                           IG 1 IG 2 IG 3
              Version
                              3.11 Encrypt Sensitive Data at Rest
                                 Encrypt sensitive data at rest on servers, applications, and databases containing
                              sensitive data. Storage-layer encryption, also known as server-side encryption,
                     v8       meets the minimum requirement of this Safeguard. Additional encryption methods               ●    ●
                              may include application-layer encryption, also known as client-side encryption,
                              where access to the data storage device(s) does not permit access to the plain-text
                              data.

                     v7       16.4 Encrypt or Hash all Authentication Credentials                                          ●    ●
                                 Encrypt or hash with a salt all authentication credentials when stored.




                                                                                                                           Page 885

Internal Only - General
            7.2.2 Ensure /etc/shadow password fields are not empty
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            An account with an empty password field means that anybody may log in as that user
            without providing a password.
            Rationale:
            All accounts must have passwords or be locked to prevent the account from being used
            by an unauthorized user.
            Audit:
            Run the following command and verify that no output is returned:
            # awk -F: '($2 == "" ) { print $1 " does not have a password "}' /etc/shadow

            Remediation:
            If any accounts in the /etc/shadow file do not have a password, run the following
            command to lock the account until it can be determined why it does not have a
            password:
            # passwd -l <username>
            Also, check to see if the account is logged in and investigate what it is being used for to
            determine if it needs to be forced off.
            References:

                 1. NIST SP 800-53 Rev. 5: IA-5
                 2. NIST SP 800-53 Revision 5 :: CM-6 b
                 3. NIST SP 800-53A :: CM-6.1 (iv)




                                                                                               Page 886

Internal Only - General
            Additional Information:
            Red Hat Enterprise Linux 8 Security Technical Implementation Guide
            Version 1, Release: 14 Benchmark Date: 24 APR 2024

            Vul ID: V-251706
            Rule ID: SV-251706r809342
            STIG ID: RHEL-08-010121
            Severity: CAT II

            CIS Controls:

               Controls
                                                             Control                                            IG 1 IG 2 IG 3
               Version
                          5.2 Use Unique Passwords
                   v8         Use unique passwords for all enterprise assets. Best practice implementation
                          includes, at a minimum, an 8-character password for accounts using MFA and a
                                                                                                                 ●    ●    ●
                          14-character password for accounts not using MFA.

                          4.4 Use Unique Passwords
                   v7        Where multi-factor authentication is not supported (such as local administrator,
                          root, or service accounts), accounts will use passwords that are unique to that
                                                                                                                      ●    ●
                          system.




                                                                                                                      Page 887

Internal Only - General
            7.2.3 Ensure all groups in /etc/passwd exist in /etc/group
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Over time, system administration errors and changes can lead to groups being defined
            in /etc/passwd but not in /etc/group .

            Rationale:
            Groups defined in the /etc/passwd file but not in the /etc/group file pose a threat to
            system security since group permissions are not properly managed.
            Audit:
            Run the following script to verify all GIDs in /etc/passwd exist in /etc/group:
            #!/usr/bin/env bash

            {
               a_passwd_group_gid=("$(awk -F: '{print $4}' /etc/passwd | sort -u)")
               a_group_gid=("$(awk -F: '{print $3}' /etc/group | sort -u)")
               a_passwd_group_diff=("$(printf '%s\n' "${a_group_gid[@]}"
            "${a_passwd_group_gid[@]}" | sort | uniq -u)")
               while IFS= read -r l_gid; do
                  awk -F: '($4 == '"$l_gid"') {print " - User: \"" $1 "\" has GID: \""
            $4 "\" which does not exist in /etc/group" }' /etc/passwd
               done < <(printf '%s\n' "${a_passwd_group_gid[@]}"
            "${a_passwd_group_diff[@]}" | sort | uniq -D | uniq)
               unset a_passwd_group_gid; unset a_group_gid; unset a_passwd_group_diff
            }
            Nothing should be returned
            Remediation:
            Analyze the output of the Audit step above and perform the appropriate action to correct
            any discrepancies found.
            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5




                                                                                              Page 888

Internal Only - General
            CIS Controls:

               Controls
                                                             Control                                         IG 1 IG 2 IG 3
               Version
                          3.3 Configure Data Access Control Lists
                   v8         Configure data access control lists based on a user’s need to know. Apply
                          data access control lists, also known as access permissions, to local and remote
                                                                                                              ●    ●    ●
                          file systems, databases, and applications.

                          14.6 Train Workforce Members on Recognizing and
                   v8     Reporting Security Incidents                                                        ●    ●    ●
                             Train workforce members to be able to recognize a potential incident and be
                          able to report such an incident.




                                                                                                                   Page 889

Internal Only - General
            7.2.4 Ensure shadow group is empty (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The shadow group allows system programs which require access the ability to read the
            /etc/shadow file. No users should be assigned to the shadow group.
            Rationale:
            Any users assigned to the shadow group would be granted read access to the
            /etc/shadow file. If attackers can gain read access to the /etc/shadow file, they can
            easily run a password cracking program against the hashed passwords to break them.
            Other security information that is stored in the /etc/shadow file (such as expiration)
            could also be useful to subvert additional user accounts.
            Audit:
            Run the following commands and verify no results are returned:
            # awk -F: '($1=="shadow") {print $NF}' /etc/group
            # awk -F: '($4 == '"$(getent group shadow | awk -F: '{print $3}' | xargs)"')
            {print " - user: \"" $1 "\" primary group is the shadow group"}' /etc/passwd

            Remediation:
            Run the following command to remove all users from the shadow group
            # sed -ri 's/(^shadow:[^:]*:[^:]*:)([^:]+$)/\1/' /etc/group
            Change the primary group of any users with shadow as their primary group.
            # usermod -g <primary group> <user>

            References:

                 1. NIST SP 800-53 Rev. 5: IA-5




                                                                                           Page 890

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 891

Internal Only - General
            7.2.5 Ensure no duplicate UIDs exist (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Although the useradd program will not let you create a duplicate User ID (UID), it is
            possible for an administrator to manually edit the /etc/passwd file and change the UID
            field.
            Rationale:
            Users must be assigned unique UIDs for accountability and to ensure appropriate
            access protections.
            Satisfies: SRG-OS-000104-GPOS-00051, SRG-OS-000121-GPOS-00062, SRG-OS-
            000042-GPOS-00020
            Audit:
            Run the following script and verify no results are returned:
            #!/usr/bin/env bash

            {
              while read -r l_count l_uid; do
                if [ "$l_count" -gt 1 ]; then
                   echo -e "Duplicate UID: \"$l_uid\" Users: \"$(awk -F: '($3 == n) {
            print $1 }' n=$l_uid /etc/passwd | xargs)\""
                fi
              done < <(cut -f3 -d":" /etc/passwd | sort -n | uniq -c)
            }

            Remediation:
            Based on the results of the audit script, establish unique UIDs and review all files owned
            by the shared UIDs to determine which UID they are supposed to belong to.
            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5
                 2. NIST SP 800-53A :: IA-2.1




                                                                                             Page 892

Internal Only - General
            Additional Information:
            Red Hat Enterprise Linux 8 Security Technical Implementation Guide
            Version 1, Release: 14 Benchmark Date: 24 APR 2024

            Vul ID: V-230371
            Rule ID: SV-230371r627750
            STIG ID: RHEL-08-020240
            Severity: CAT II

            CIS Controls:

                 Controls Version                      Control     IG 1 IG 2 IG 3

                          v8          0.0 Explicitly Not Mapped
                                        Explicitly Not Mapped

                          v7          0.0 Explicitly Not Mapped
                                        Explicitly Not Mapped




                                                                                    Page 893

Internal Only - General
            7.2.6 Ensure no duplicate GIDs exist (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Although the groupadd program will not let you create a duplicate Group ID (GID), it is
            possible for an administrator to manually edit the /etc/group file and change the GID
            field.
            Rationale:
            User groups must be assigned unique GIDs for accountability and to ensure appropriate
            access protections.
            Audit:
            Run the following script and verify no results are returned:
            #!/usr/bin/env bash

            {
               while read -r l_count l_gid; do
                   if [ "$l_count" -gt 1 ]; then
                   echo -e "Duplicate GID: \"$l_gid\" Groups: \"$(awk -F: '($3 == n) {
            print $1 }' n=$l_gid /etc/group | xargs)\""
                fi
              done < <(cut -f3 -d":" /etc/group | sort -n | uniq -c)
            }

            Remediation:
            Based on the results of the audit script, establish unique GIDs and review all files
            owned by the shared GID to determine which group they are supposed to belong to.
            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

            Additional Information:
            You can also use the grpck command to check for other inconsistencies in the
            /etc/group file.




                                                                                            Page 894

Internal Only - General
            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 895

Internal Only - General
            7.2.7 Ensure no duplicate user names exist (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Although the useradd program will not let you create a duplicate user name, it is
            possible for an administrator to manually edit the /etc/passwd file and change the user
            name.
            Rationale:
            If a user is assigned a duplicate user name, it will create and have access to files with
            the first UID for that username in /etc/passwd . For example, if "test4" has a UID of
            1000 and a subsequent "test4" entry has a UID of 2000, logging in as "test4" will use
            UID 1000. Effectively, the UID is shared, which is a security problem.
            Audit:
            Run the following script and verify no results are returned:
            #!/usr/bin/env bash

            {
               while read -r l_count l_user; do
                  if [ "$l_count" -gt 1 ]; then
                     echo -e "Duplicate User: \"$l_user\" Users: \"$(awk -F: '($1 == n) {
            print $1 }' n=$l_user /etc/passwd | xargs)\""
                  fi
               done < <(cut -f1 -d":" /etc/passwd | sort -n | uniq -c)
            }

            Remediation:
            Based on the results of the audit script, establish unique user names for the users. File
            ownerships will automatically reflect the change as long as the users have unique UIDs.
            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5




                                                                                               Page 896

Internal Only - General
            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 897

Internal Only - General
            7.2.8 Ensure no duplicate group names exist (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            Although the groupadd program will not let you create a duplicate group name, it is
            possible for an administrator to manually edit the /etc/group file and change the group
            name.
            Rationale:
            If a group is assigned a duplicate group name, it will create and have access to files
            with the first GID for that group in /etc/group . Effectively, the GID is shared, which is
            a security problem.
            Audit:
            Run the following script and verify no results are returned:
            #!/usr/bin/env bash

            {
               while read -r l_count l_group; do
                  if [ "$l_count" -gt 1 ]; then
                     echo -e "Duplicate Group: \"$l_group\" Groups: \"$(awk -F: '($1 ==
            n) { print $1 }' n=$l_group /etc/group | xargs)\""
                  fi
               done < <(cut -f1 -d":" /etc/group | sort -n | uniq -c)
            }

            Remediation:
            Based on the results of the audit script, establish unique names for the user groups. File
            group ownerships will automatically reflect the change as long as the groups have
            unique GIDs.
            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5




                                                                                               Page 898

Internal Only - General
            CIS Controls:

                 Controls Version                    Control    IG 1 IG 2 IG 3

                          v8        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped

                          v7        0.0 Explicitly Not Mapped
                                      Explicitly Not Mapped




                                                                                 Page 899

Internal Only - General
            7.2.9 Ensure local interactive user home directories are
            configured (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            The user home directory is space defined for the particular user to set local environment
            variables and to store personal files. While the system administrator can establish
            secure permissions for users' home directories, the users can easily override these.
            Users can be defined in /etc/passwd without a home directory or with a home directory
            that does not actually exist.
            Rationale:
            Since the user is accountable for files stored in the user home directory, the user must
            be the owner of the directory. Group or world-writable user home directories may enable
            malicious users to steal or modify other users' data or to gain another user's system
            privileges. If the user's home directory does not exist or is unassigned, the user will be
            placed in "/" and will not be able to write any files or have local environment variables
            set.
            Audit:
            Run the following script to Ensure:

                 •   local interactive user home directories exist
                 •   Ensure local interactive users own their home directories
                 •   Ensure local interactive user home directories are mode 750 or more restrictive




                                                                                              Page 900

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output=() a_output2=() a_exists2=() a_mode2=() a_owner2=()
               l_valid_shells="^($( awk -F\/ '$NF != "nologin" {print}' /etc/shells | sed
            -rn '/^\//{s,/,\\\\/,g;p}' | paste -s -d '|' - ))$"
               l_mask='0027'; l_max="$( printf '%o' $(( 0777 & ~$l_mask)) )"
               l_users="$(awk -v pat="$l_valid_shells" -F: '$(NF) ~ pat { print $1 " "
            $(NF-1) }' /etc/passwd | wc -l)"
               [ "$l_users" -gt 10000 ] && printf '%s\n' "" " ** INFO **" \
               " $l_users Local interactive users found on the system" " This may be a
            long running check" " **********"
               while IFS=" " read -r l_user l_home; do
                  if [ -d "$l_home" ]; then
                     while IFS=: read -r l_own l_mode; do
                        [ "$l_user" != "$l_own" ] && a_owner2+=(" - User: \"$l_user\"
            Home \"$l_home\" is owned by: \"$l_own\"")
                        [ $(( $l_mode & $l_mask )) -gt 0 ] && a_mode2+=(" - User:
            \"$l_user\" Home \"$l_home\" is mode: \"$l_mode\"" \
                        "    should be mode: \"$l_max\" or more restrictive")
                     done <<< "$(stat -Lc '%U:%#a' "$l_home")"
                  else
                     a_exists2+=(" - User: \"$l_user\" Home Directory: \"$l_home\"
            Doesn't exist")
                  fi
               done <<< "$(awk -v pat="$l_valid_shells" -F: '$(NF) ~ pat { print $1 " "
            $(NF-1) }' /etc/passwd)"
               [ "${#a_exists2[@]}" -gt 0 ] && a_output2+=("${a_exists2[@]}") || \
               a_output+=(" - All interactive users home directories exist")
               [ "${#a_mode2[@]}" -gt 0 ] && a_output2+=("${a_mode2[@]}") || \
               a_output+=(" - All interactive users home directories are mode \"$l_max\"
            or more restrictive")
               [ "${#a_owner2[@]}" -gt 0 ] && a_output2+=("${a_owner2[@]}") || \
               a_output+=(" - All interactive users own their home directory")
               if [ "${#a_output2[@]}" -le 0 ]; then
                  printf '%s\n' "" "- Audit Result:" " ** PASS **" "${a_output[@]}"
               else
                  printf '%s\n' "" "- Audit Result:" " ** FAIL **" " - Reason(s) for
            audit failure:" "${a_output2[@]}"
                  [ "${#a_output[@]}" -gt 0 ] && printf '%s\n' "- Correctly set:"
            "${a_output[@]}"
               fi
            }




                                                                                  Page 901

Internal Only - General
            Remediation:
            If a local interactive users' home directory is undefined and/or doesn't exist, follow local
            site policy and perform one of the following:

                 •   Lock the user account
                 •   Remove the user from the system
                 •   create a directory for the user. If undefined, edit /etc/passwd and add the
                     absolute path to the directory to the last field of the user.

            Run the following script to:

                 •   Remove excessive permissions from local interactive users home directories
                 •   Update the home directory's owner




                                                                                                Page 902

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output=() a_output2=() a_exists2=() a_mode2=() a_owner2=()
               l_valid_shells="^($( awk -F\/ '$NF != "nologin" {print}' /etc/shells | sed
            -rn '/^\//{s,/,\\\\/,g;p}' | paste -s -d '|' - ))$"
               l_mask='0027'; l_max="$( printf '%o' $(( 0777 & ~$l_mask)) )"
               l_users="$(awk -v pat="$l_valid_shells" -F: '$(NF) ~ pat { print $1 " "
            $(NF-1) }' /etc/passwd | wc -l)"
               [ "$l_users" -gt 10000 ] && printf '%s\n' "" " ** INFO **" \
               " $l_users Local interactive users found on the system" " This may be a
            long running process" " **********"
               while IFS=" " read -r l_user l_home; do
                  if [ -d "$l_home" ]; then
                      while IFS=: read -r l_own l_mode; do
                         if [ "$l_user" != "$l_own" ]; then
                            a_owner2+=(" - User: \"$l_user\" Home \"$l_home\" is owned
            by: \"$l_own\"" \
                            "    changing owner to: \"$l_user\"") && chown "$l_user"
            "$l_home"
                         fi
                         if [ $(( $l_mode & $l_mask )) -gt 0 ]; then
                            a_mode2+=(" - User: \"$l_user\" Home \"$l_home\" is mode:
            \"$l_mode\"" \
                            "    changing to mode: \"$l_max\" or more restrictive")
                            chmod g-w,o-rwx "$l_home"
                         fi
                      done <<< "$(stat -Lc '%U:%#a' "$l_home")"
                  else
                      a_exists2+=(" - User: \"$l_user\" Home Directory: \"$l_home\"
            Doesn't exist")
                  fi
               done <<< "$(awk -v pat="$l_valid_shells" -F: '$(NF) ~ pat { print $1 " "
            $(NF-1) }' /etc/passwd)"
               [ "${#a_exists2[@]}" -gt 0 ] && a_output2+=("${a_exists2[@]}")
               [ "${#a_mode2[@]}" -gt 0 ] && a_output2+=("${a_mode2[@]}")
               [ "${#a_owner2[@]}" -gt 0 ] && a_output2+=("${a_owner2[@]}")
               if [ "${#a_output2[@]}" -gt 0 ]; then
                  printf '%s\n' "" "${a_output2[@]}"
               else
                  printf '%s\n' "" "- No changes required"
               fi
            }

            References:

                 1. NIST SP 800-53 Revision 5 :: CM-6 b
                 2. NIST SP 800-53A :: CM-6.1 (iv)




                                                                                  Page 903

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 904

Internal Only - General
            7.2.10 Ensure local interactive user dot files access is configured
            (Automated)
            Profile Applicability:

            • Level 1 - Server
            • Level 1 - Workstation
            Description:
            While the system administrator can establish secure permissions for users' "dot" files,
            the users can easily override these.

                 •   .forward file specifies an email address to forward the user's mail to.
                 •   .rhost file provides the "remote authentication" database for the rcp, rlogin, and
                     rsh commands and the rcmd() function. These files bypass the standard
                     password-based user authentication mechanism. They specify remote hosts and
                     users that are considered trusted (i.e. are allowed to access the local system
                     without supplying a password)
                 •   .netrc file contains data for logging into a remote host or passing authentication
                     to an API.
                 •   .bash_history file keeps track of the user’s commands.

            Rationale:
            User configuration files with excessive or incorrect access may enable malicious users
            to steal or modify other users' data or to gain another user's system privileges.
            Audit:
            Run the following script to verify local interactive user dot files:

                 •   Don't include .forward, .rhost, or .netrc files
                 •   Are mode 0644 or more restrictive
                 •   Are owned by the local interactive user
                 •   Are group owned by the user's primary group
                 •   .bash_history is mode 0600 or more restrictive

            Note: If a .netrc file is required, and follows local site policy, it should be mode 0600 or
            more restrictive.




                                                                                               Page 905

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output2=(); a_output3=()
               l_maxsize="1000" # Maximum number of local interactive users before warning (Default 1,000)
               l_valid_shells="^($( awk -F\/ '$NF != "nologin" {print}' /etc/shells | sed -rn '/^\//{s,/,\\\\/,g;p}' |
            paste -s -d '|' - ))$"
               a_user_and_home=() # Create array with local users and their home directories
               while read -r l_local_user l_local_user_home; do # Populate array with users and user home location
                  [[ -n "$l_local_user" && -n "$l_local_user_home" ]] &&
            a_user_and_home+=("$l_local_user:$l_local_user_home")
               done <<< "$(awk -v pat="$l_valid_shells" -F: '$(NF) ~ pat { print $1 " " $(NF-1) }' /etc/passwd)"
               l_asize="${#a_user_and_home[@]}" # Here if we want to look at number of users before proceeding
               [ "${#a_user_and_home[@]}" -gt "$l_maxsize" ] && printf '%s\n' "" " ** INFO **" \
               " - \"$l_asize\" Local interactive users found on the system" \
               " - This may be a long running check" ""
               file_access_chk()
               {
                  a_access_out=()
                  l_max="$( printf '%o' $(( 0777 & ~$l_mask)) )"
                  if [ $(( $l_mode & $l_mask )) -gt 0 ]; then
                     a_access_out+=(" - File: \"$l_hdfile\" is mode: \"$l_mode\" and should be mode: \"$l_max\" or more
            restrictive")
                  fi
                  if [[ ! "$l_owner" =~ ($l_user) ]]; then
                     a_access_out+=(" - File: \"$l_hdfile\" owned by: \"$l_owner\" and should be owned by \"${l_user//|/
            or }\"")
                  fi
                  if [[ ! "$l_gowner" =~ ($l_group) ]]; then
                     a_access_out+=(" - File: \"$l_hdfile\" group owned by: \"$l_gowner\" and should be group owned by
            \"${l_group//|/ or }\"")
                  fi
               }
               while IFS=: read -r l_user l_home; do
                  a_dot_file=(); a_netrc=(); a_netrc_warn=(); a_bhout=(); a_hdirout=()
                  if [ -d "$l_home" ]; then
                     l_group="$(id -gn "$l_user" | xargs)";l_group="${l_group// /|}"
                     while IFS= read -r -d $'\0' l_hdfile; do
                        while read -r l_mode l_owner l_gowner; do
                           case "$(basename "$l_hdfile")" in
                              .forward | .rhost )
                                  a_dot_file+=(" - File: \"$l_hdfile\" exists") ;;
                              .netrc )
                                  l_mask='0177'; file_access_chk
                                  if [ "${#a_access_out[@]}" -gt 0 ]; then
                                     a_netrc+=("${a_access_out[@]}")
                                  else
                                     a_netrc_warn+=("   - File: \"$l_hdfile\" exists")
                                  fi ;;
                              .bash_history )
                                  l_mask='0177'; file_access_chk
                                  [ "${#a_access_out[@]}" -gt 0 ] && a_bhout+=("${a_access_out[@]}") ;;
                              * )
                                  l_mask='0133'; file_access_chk
                                  [ "${#a_access_out[@]}" -gt 0 ] && a_hdirout+=("${a_access_out[@]}") ;;
                           esac
                        done < <(stat -Lc '%#a %U %G' "$l_hdfile")
                     done < <(find "$l_home" -xdev -type f -name '.*' -print0)
                  fi
                  if [[ "${#a_dot_file[@]}" -gt 0 || "${#a_netrc[@]}" -gt 0 || "${#a_bhout[@]}" -gt 0 || "${#a_hdirout[@]}"
            -gt 0 ]]; then
                     a_output2+=(" - User: \"$l_user\" Home Directory: \"$l_home\"" "${a_dot_file[@]}" "${a_netrc[@]}"
            "${a_bhout[@]}" "${a_hdirout[@]}")
                  fi
                  [ "${#a_netrc_warn[@]}" -gt 0 ] && a_output3+=(" - User: \"$l_user\" Home Directory: \"$l_home\""
            "${a_netrc_warn[@]}")
               done <<< "$(printf '%s\n' "${a_user_and_home[@]}")"
               if [ "${#a_output2[@]}" -le 0 ]; then # If l_output2 is empty, we pass
                  [ "${#a_output3[@]}" -gt 0 ] && printf '%s\n' " ** WARNING **" "${a_output3[@]}"
                  printf '%s\n' "- Audit Result:" " ** PASS **"
               else
                  printf '%s\n' "- Audit Result:" " ** FAIL **" " - * Reasons for audit failure * :" "${a_output2[@]}" ""
                  [ "${#a_output3[@]}" -gt 0 ] && printf '%s\n' " ** WARNING **" "${a_output3[@]}"
               fi
            }




                                                                                                                 Page 906

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            Remediation:
            Making global modifications to users' files without alerting the user community can result
            in unexpected outages and unhappy users. Therefore, it is recommended that a
            monitoring policy be established to report user dot file permissions and determine the
            action to be taken in accordance with site policy.
            The following script will:

                 •   remove excessive permissions on dot files within interactive users' home
                     directories
                 •   change ownership of dot files within interactive users' home directories to the
                     user
                 •   change group ownership of dot files within interactive users' home directories to
                     the user's primary group
                 •   list .forward and .rhost files to be investigated and manually deleted




                                                                                               Page 907

Internal Only - General
            #!/usr/bin/env bash

            {
               a_output2=(); a_output3=()
               l_maxsize="1000" # Maximum number of local interactive users before warning (Default 1,000)
               l_valid_shells="^($( awk -F\/ '$NF != "nologin" {print}' /etc/shells | sed -rn '/^\//{s,/,\\\\/,g;p}' |
            paste -s -d '|' - ))$"
               a_user_and_home=() # Create array with local users and their home directories
               while read -r l_local_user l_local_user_home; do # Populate array with users and user home location
                  [[ -n "$l_local_user" && -n "$l_local_user_home" ]] &&
            a_user_and_home+=("$l_local_user:$l_local_user_home")
               done <<< "$(awk -v pat="$l_valid_shells" -F: '$(NF) ~ pat { print $1 " " $(NF-1) }' /etc/passwd)"
               l_asize="${#a_user_and_home[@]}" # Here if we want to look at number of users before proceeding
               [ "${#a_user_and_home[@]}" -gt "$l_maxsize" ] && printf '%s\n' "" " ** INFO **" \
               " - \"$l_asize\" Local interactive users found on the system" \
               " - This may be a long running check" ""
               file_access_fix()
               {
                  a_access_out=()
                  l_max="$( printf '%o' $(( 0777 & ~$l_mask)) )"
                  if [ $(( $l_mode & $l_mask )) -gt 0 ]; then
                      printf '%s\n' "" " - File: \"$l_hdfile\" is mode: \"$l_mode\" and should be mode: \"$l_max\" or more
            restrictive" \
                      "     Updating file: \"$l_hdfile\" to be mode: \"$l_max\" or more restrictive"
                      chmod "$l_change" "$l_hdfile"
                  fi
                  if [[ ! "$l_owner" =~ ($l_user) ]]; then
                      printf '%s\n' "" " - File: \"$l_hdfile\" owned by: \"$l_owner\" and should be owned by \"${l_user//|/
            or }\"" \
                      "     Updating file: \"$l_hdfile\" to be owned by \"${l_user//|/ or }\""
                      chown "$l_user" "$l_hdfile"
                  fi
                  if [[ ! "$l_gowner" =~ ($l_group) ]]; then
                      printf '%s\n' "" " - File: \"$l_hdfile\" group owned by: \"$l_gowner\" and should be group owned by
            \"${l_group//|/ or }\"" \
                      "     Updating file: \"$l_hdfile\" to be group owned by \"${l_group//|/ or }\""
                      chgrp "$l_group" "$l_hdfile"
                  fi
               }
               while IFS=: read -r l_user l_home; do
                  a_dot_file=(); a_netrc=(); a_netrc_warn=(); a_bhout=(); a_hdirout=()
                  if [ -d "$l_home" ]; then
                      l_group="$(id -gn "$l_user" | xargs)";l_group="${l_group// /|}"
                      while IFS= read -r -d $'\0' l_hdfile; do
                         while read -r l_mode l_owner l_gowner; do
                            case "$(basename "$l_hdfile")" in
                               .forward | .rhost )
                                   a_dot_file+=(" - File: \"$l_hdfile\" exists" "     Please review and manually delete this
            file") ;;
                               .netrc )
                                   l_mask='0177'; l_change="u-x,go-rwx"; file_access_fix
                                   a_netrc_warn+=("   - File: \"$l_hdfile\" exists") ;;
                               .bash_history )
                                   l_mask='0177'; l_change="u-x,go-rwx"; file_access_fix ;;
                               * )
                                   l_mask='0133'; l_change="u-x,go-wx"; file_access_fix ;;
                            esac
                         done < <(stat -Lc '%#a %U %G' "$l_hdfile")
                      done < <(find "$l_home" -xdev -type f -name '.*' -print0)
                  fi
                  [ "${#a_dot_file[@]}" -gt 0 ] && a_output2+=(" - User: \"$l_user\" Home Directory: \"$l_home\""
            "${a_dot_file[@]}")
                  [ "${#a_netrc_warn[@]}" -gt 0 ] && a_output3+=(" - User: \"$l_user\" Home Directory: \"$l_home\""
            "${a_netrc_warn[@]}")
               done <<< "$(printf '%s\n' "${a_user_and_home[@]}")"
               [ "${#a_output3[@]}" -gt 0 ] && printf '%s\n' "" " ** WARNING **" "${a_output3[@]}" ""
               [ "${#a_output2[@]}" -gt 0 ] && printf '%s\n' "" "${a_output2[@]}"
            }


            References:

                 1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5




                                                                                                                  Page 908

Internal Only - General
            CIS Controls:

              Controls
                                                               Control                                          IG 1 IG 2 IG 3
              Version
                          3.3 Configure Data Access Control Lists
                   v8        Configure data access control lists based on a user’s need to know. Apply data
                          access control lists, also known as access permissions, to local and remote file
                                                                                                                 ●    ●    ●
                          systems, databases, and applications.

                          14.6 Protect Information through Access Control Lists
                              Protect all information stored on systems with file system, network share,
                   v7     claims, application, or database specific access control lists. These controls will
                          enforce the principle that only authorized individuals should have access to the
                                                                                                                 ●    ●    ●
                          information based on their need to access the information as a part of their
                          responsibilities.




                                                                                                                      Page 909

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            Appendix: Summary Table
                            CIS Benchmark Recommendation                               Set
                                                                                     Correctly
                                                                                     Yes      No
              1           Initial Setup
              1.1         Filesystem
              1.1.1       Configure Filesystem Kernel Modules
              1.1.1.1     Ensure cramfs kernel module is not available                      
                          (Automated)
              1.1.1.2     Ensure freevxfs kernel module is not available                    
                          (Automated)
              1.1.1.3     Ensure hfs kernel module is not available (Automated)             
              1.1.1.4     Ensure hfsplus kernel module is not available                     
                          (Automated)
              1.1.1.5     Ensure jffs2 kernel module is not available (Automated)           
              1.1.1.6     Ensure overlay kernel module is not available                     
                          (Automated)
              1.1.1.7     Ensure squashfs kernel module is not available                    
                          (Automated)
              1.1.1.8     Ensure udf kernel module is not available (Automated)             
              1.1.1.9     Ensure usb-storage kernel module is not available                 
                          (Automated)
              1.1.1.10    Ensure unused filesystems kernel modules are not                  
                          available (Manual)
              1.1.1.11    Ensure firewire-core kernel module is not available               
                          (Automated)
              1.1.2       Configure Filesystem Partitions
              1.1.2.1     Configure /tmp
              1.1.2.1.1   Ensure /tmp is tmpfs or a separate partition (Automated)          
              1.1.2.1.2   Ensure nodev option set on /tmp partition (Automated)             
              1.1.2.1.3   Ensure nosuid option set on /tmp partition (Automated)            
              1.1.2.1.4   Ensure noexec option set on /tmp partition (Automated)            
              1.1.2.2     Configure /dev/shm
              1.1.2.2.1   Ensure /dev/shm is tmpfs or a separate partition                  
                          (Automated)



                                                                                           Page 910

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                            CIS Benchmark Recommendation                                Set
                                                                                      Correctly
                                                                                      Yes     No
              1.1.2.2.2   Ensure nodev option set on /dev/shm partition                      
                          (Automated)
              1.1.2.2.3   Ensure nosuid option set on /dev/shm partition                     
                          (Automated)
              1.1.2.2.4   Ensure noexec option set on /dev/shm partition                     
                          (Automated)
              1.1.2.3     Configure /home
              1.1.2.3.1   Ensure separate partition exists for /home (Automated)             
              1.1.2.3.2   Ensure nodev option set on /home partition (Automated)             
              1.1.2.3.3   Ensure nosuid option set on /home partition (Automated)            
              1.1.2.4     Configure /var
              1.1.2.4.1   Ensure separate partition exists for /var (Automated)              
              1.1.2.4.2   Ensure nodev option set on /var partition (Automated)              
              1.1.2.4.3   Ensure nosuid option set on /var partition (Automated)             
              1.1.2.5     Configure /var/tmp
              1.1.2.5.1   Ensure separate partition exists for /var/tmp (Automated)          
              1.1.2.5.2   Ensure nodev option set on /var/tmp partition                      
                          (Automated)
              1.1.2.5.3   Ensure nosuid option set on /var/tmp partition                     
                          (Automated)
              1.1.2.5.4   Ensure noexec option set on /var/tmp partition                     
                          (Automated)
              1.1.2.6     Configure /var/log
              1.1.2.6.1   Ensure separate partition exists for /var/log (Automated)          
              1.1.2.6.2   Ensure nodev option set on /var/log partition                      
                          (Automated)
              1.1.2.6.3   Ensure nosuid option set on /var/log partition                     
                          (Automated)
              1.1.2.6.4   Ensure noexec option set on /var/log partition                     
                          (Automated)
              1.1.2.7     Configure /var/log/audit
              1.1.2.7.1   Ensure separate partition exists for /var/log/audit                
                          (Automated)
              1.1.2.7.2   Ensure nodev option set on /var/log/audit partition                
                          (Automated)


                                                                                            Page 911

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                            CIS Benchmark Recommendation                             Set
                                                                                   Correctly
                                                                                   Yes     No
              1.1.2.7.3   Ensure nosuid option set on /var/log/audit partition            
                          (Automated)
              1.1.2.7.4   Ensure noexec option set on /var/log/audit partition            
                          (Automated)
              1.2         Package Management
              1.2.1       Configure Package Repositories
              1.2.1.1     Ensure GPG keys are configured (Manual)                         
              1.2.1.2     Ensure package manager repositories are configured              
                          (Manual)
              1.2.2       Configure Package Updates
              1.2.2.1     Ensure updates, patches, and additional security                
                          software are installed (Manual)
              1.3         Mandatory Access Control
              1.3.1       Configure AppArmor
              1.3.1.1     Ensure the apparmor packages are installed                      
                          (Automated)
              1.3.1.2     Ensure AppArmor is enabled (Automated)                          
              1.3.1.3     Ensure all AppArmor Profiles are not disabled                   
                          (Automated)
              1.3.1.4     Ensure all AppArmor Profiles are enforcing (Automated)          
              1.4         Configure Bootloader
              1.4.1       Ensure bootloader password is set (Automated)                   
              1.4.2       Ensure access to bootloader config is configured                
                          (Automated)
              1.5         Configure Additional Process Hardening
              1.5.1       Ensure randomize_va_space is configured (Automated)             
              1.5.2       Ensure ptrace_scope is configured (Automated)                   
              1.5.3       Ensure suid_dumpable is configured (Automated)                  
              1.5.4       Ensure core file size is configured (Automated)                 
              1.5.5       Ensure prelink is not installed (Automated)                     
              1.5.6       Ensure Automatic Error Reporting is configured                  
                          (Automated)
              1.6         Configure Command Line Warning Banners
              1.6.1       Ensure /etc/motd is configured (Automated)                      



                                                                                         Page 912

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                            CIS Benchmark Recommendation                             Set
                                                                                   Correctly
                                                                                   Yes     No
              1.6.2       Ensure /etc/issue is configured (Automated)                     
              1.6.3       Ensure /etc/issue.net is configured (Automated)                 
              1.6.4       Ensure access to /etc/motd is configured (Automated)            
              1.6.5       Ensure access to /etc/issue is configured (Automated)           
              1.6.6       Ensure access to /etc/issue.net is configured                   
                          (Automated)
              1.7         Configure GNOME Display Manager
              1.7.1       Ensure GDM is removed (Automated)                               
              1.7.2       Ensure GDM login banner is configured (Automated)               
              1.7.3       Ensure GDM disable-user-list option is enabled                  
                          (Automated)
              1.7.4       Ensure GDM screen locks when the user is idle                   
                          (Automated)
              1.7.5       Ensure GDM screen locks cannot be overridden                    
                          (Automated)
              1.7.6       Ensure GDM automatic mounting of removable media is             
                          disabled (Automated)
              1.7.7       Ensure GDM disabling automatic mounting of removable            
                          media is not overridden (Automated)
              1.7.8       Ensure GDM autorun-never is enabled (Automated)                 
              1.7.9       Ensure GDM autorun-never is not overridden                      
                          (Automated)
              1.7.10      Ensure XDMCP is not enabled (Automated)                         
              1.7.11      Ensure Xwayland is configured (Automated)                       
              2           Services
              2.1         Configure Server Services
              2.1.1       Ensure autofs services are not in use (Automated)               
              2.1.2       Ensure avahi daemon services are not in use                     
                          (Automated)
              2.1.3       Ensure dhcp server services are not in use (Automated)          
              2.1.4       Ensure dns server services are not in use (Automated)           
              2.1.5       Ensure dnsmasq services are not in use (Automated)              
              2.1.6       Ensure ftp server services are not in use (Automated)           
              2.1.7       Ensure ldap server services are not in use (Automated)          



                                                                                         Page 913

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                            CIS Benchmark Recommendation                                Set
                                                                                      Correctly
                                                                                      Yes     No
              2.1.8       Ensure message access server services are not in use               
                          (Automated)
              2.1.9       Ensure network file system services are not in use                 
                          (Automated)
              2.1.10      Ensure nis server services are not in use (Automated)              
              2.1.11      Ensure print server services are not in use (Automated)            
              2.1.12      Ensure rpcbind services are not in use (Automated)                 
              2.1.13      Ensure rsync services are not in use (Automated)                   
              2.1.14      Ensure samba file server services are not in use                   
                          (Automated)
              2.1.15      Ensure snmp services are not in use (Automated)                    
              2.1.16      Ensure tftp server services are not in use (Automated)             
              2.1.17      Ensure web proxy server services are not in use                    
                          (Automated)
              2.1.18      Ensure web server services are not in use (Automated)              
              2.1.19      Ensure xinetd services are not in use (Automated)                  
              2.1.20      Ensure X window server services are not in use                     
                          (Automated)
              2.1.21      Ensure mail transfer agents are configured for local-only          
                          mode (Automated)
              2.1.22      Ensure only approved services are listening on a                   
                          network interface (Manual)
              2.2         Configure Client Services
              2.2.1       Ensure nis client is not installed (Automated)                     
              2.2.2       Ensure rsh client is not installed (Automated)                     
              2.2.3       Ensure talk client is not installed (Automated)                    
              2.2.4       Ensure telnet client is not installed (Automated)                  
              2.2.5       Ensure ldap client is not installed (Automated)                    
              2.2.6       Ensure ftp client is not installed (Automated)                     
              2.3         Configure Time Synchronization
              2.3.1       Ensure time synchronization is in use
              2.3.1.1     Ensure a single time synchronization daemon is in use              
                          (Automated)
              2.3.2       Configure systemd-timesyncd


                                                                                            Page 914

Internal Only - General
                            CIS Benchmark Recommendation                               Set
                                                                                     Correctly
                                                                                     Yes     No
              2.3.2.1     Ensure systemd-timesyncd configured with authorized               
                          timeserver (Automated)
              2.3.2.2     Ensure systemd-timesyncd is enabled and running                   
                          (Automated)
              2.3.3       Configure chrony
              2.3.3.1     Ensure chrony is configured with authorized timeserver            
                          (Automated)
              2.3.3.2     Ensure chrony is running as user _chrony (Automated)              
              2.3.3.3     Ensure chrony is enabled and running (Automated)                  
              2.4         Job Schedulers
              2.4.1       Configure cron
              2.4.1.1     Ensure cron daemon is enabled and active (Automated)              
              2.4.1.2     Ensure access to /etc/crontab is configured (Automated)           
              2.4.1.3     Ensure access to /etc/cron.hourly is configured                   
                          (Automated)
              2.4.1.4     Ensure access to /etc/cron.daily is configured                    
                          (Automated)
              2.4.1.5     Ensure access to /etc/cron.weekly is configured                   
                          (Automated)
              2.4.1.6     Ensure access to /etc/cron.monthly is configured                  
                          (Automated)
              2.4.1.7     Ensure access to /etc/cron.yearly is configured                   
                          (Automated)
              2.4.1.8     Ensure access to /etc/cron.d is configured (Automated)            
              2.4.1.9     Ensure access to crontab is configured (Automated)                
              2.4.2       Configure at
              2.4.2.1     Ensure access to at is configured (Automated)                     
              3           Network
              3.1         Configure Network Devices
              3.1.1       Ensure IPv6 status is identified (Manual)                         
              3.1.2       Ensure wireless interfaces are not available (Automated)          
              3.1.3       Ensure bluetooth services are not in use (Automated)              
              3.2         Configure Network Kernel Modules
              3.2.1       Ensure dccp kernel module is not available (Automated)            



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                            CIS Benchmark Recommendation                             Set
                                                                                   Correctly
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              3.2.2       Ensure tipc kernel module is not available (Automated)          
              3.2.3       Ensure rds kernel module is not available (Automated)           
              3.2.4       Ensure sctp kernel module is not available (Automated)          
              3.3         Configure Network Kernel Parameters
              3.3.1       Configure IPv4 parameters
              3.3.1.1     Ensure net.ipv4.ip_forward is configured (Automated)            
              3.3.1.2     Ensure net.ipv4.conf.all.forwarding is configured               
                          (Automated)
              3.3.1.3     Ensure net.ipv4.conf.default.forwarding is configured           
                          (Automated)
              3.3.1.4     Ensure net.ipv4.conf.all.send_redirects is configured           
                          (Automated)
              3.3.1.5     Ensure net.ipv4.conf.default.send_redirects is configured       
                          (Automated)
              3.3.1.6     Ensure net.ipv4.icmp_ignore_bogus_error_responses is            
                          configured (Automated)
              3.3.1.7     Ensure net.ipv4.icmp_echo_ignore_broadcasts is                  
                          configured (Automated)
              3.3.1.8     Ensure net.ipv4.conf.all.accept_redirects is configured         
                          (Automated)
              3.3.1.9     Ensure net.ipv4.conf.default.accept_redirects is                
                          configured (Automated)
              3.3.1.10    Ensure net.ipv4.conf.all.secure_redirects is configured         
                          (Automated)
              3.3.1.11    Ensure net.ipv4.conf.default.secure_redirects is                
                          configured (Automated)
              3.3.1.12    Ensure net.ipv4.conf.all.rp_filter is configured                
                          (Automated)
              3.3.1.13    Ensure net.ipv4.conf.default.rp_filter is configured            
                          (Automated)
              3.3.1.14    Ensure net.ipv4.conf.all.accept_source_route is                 
                          configured (Automated)
              3.3.1.15    Ensure net.ipv4.conf.default.accept_source_route is             
                          configured (Automated)
              3.3.1.16    Ensure net.ipv4.conf.all.log_martians is configured             
                          (Automated)


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                                                                                    Correctly
                                                                                    Yes     No
              3.3.1.17    Ensure net.ipv4.conf.default.log_martians is configured          
                          (Automated)
              3.3.1.18    Ensure net.ipv4.tcp_syncookies is configured                     
                          (Automated)
              3.3.2       Configure IPv6 parameters
              3.3.2.1     Ensure net.ipv6.conf.all.forwarding is configured                
                          (Automated)
              3.3.2.2     Ensure net.ipv6.conf.default.forwarding is configured            
                          (Automated)
              3.3.2.3     Ensure net.ipv6.conf.all.accept_redirects is configured          
                          (Automated)
              3.3.2.4     Ensure net.ipv6.conf.default.accept_redirects is                 
                          configured (Automated)
              3.3.2.5     Ensure net.ipv6.conf.all.accept_source_route is                  
                          configured (Automated)
              3.3.2.6     Ensure net.ipv6.conf.default.accept_source_route is              
                          configured (Automated)
              3.3.2.7     Ensure net.ipv6.conf.all.accept_ra is configured                 
                          (Automated)
              3.3.2.8     Ensure net.ipv6.conf.default.accept_ra is configured             
                          (Automated)
              4           Host Based Firewall
              4.1         Configure Uncomplicated Firewall
              4.1.1       Ensure ufw is installed (Automated)                              
              4.1.2       Ensure ufw service is configured (Automated)                     
              4.1.3       Ensure ufw incoming default is configured (Automated)            
              4.1.4       Ensure ufw outgoing default is configured (Automated)            
              4.1.5       Ensure ufw routed default is configured (Automated)              
              5           Access Control
              5.1         Configure SSH Server
              5.1.1       Ensure access to /etc/ssh/sshd_config is configured              
                          (Automated)
              5.1.2       Ensure access to SSH private host key files is                   
                          configured (Automated)




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                                                                                     Correctly
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              5.1.3       Ensure access to SSH public host key files is configured          
                          (Automated)
              5.1.4       Ensure sshd access is configured (Automated)                      
              5.1.5       Ensure sshd Banner is configured (Automated)                      
              5.1.6       Ensure sshd Ciphers are configured (Automated)                    
              5.1.7       Ensure sshd ClientAliveInterval and                               
                          ClientAliveCountMax are configured (Automated)
              5.1.8       Ensure sshd DisableForwarding is enabled (Automated)              
              5.1.9       Ensure sshd GSSAPIAuthentication is disabled                      
                          (Automated)
              5.1.10      Ensure sshd HostbasedAuthentication is disabled                   
                          (Automated)
              5.1.11      Ensure sshd IgnoreRhosts is enabled (Automated)                   
              5.1.12      Ensure sshd KexAlgorithms is configured (Automated)               
              5.1.13      Ensure sshd LoginGraceTime is configured (Automated)              
              5.1.14      Ensure sshd LogLevel is configured (Automated)                    
              5.1.15      Ensure sshd MACs are configured (Automated)                       
              5.1.16      Ensure sshd MaxAuthTries is configured (Automated)                
              5.1.17      Ensure sshd MaxSessions is configured (Automated)                 
              5.1.18      Ensure sshd MaxStartups is configured (Automated)                 
              5.1.19      Ensure sshd PermitEmptyPasswords is disabled                      
                          (Automated)
              5.1.20      Ensure sshd PermitRootLogin is disabled (Automated)               
              5.1.21      Ensure sshd PermitUserEnvironment is disabled                     
                          (Automated)
              5.1.22      Ensure sshd UsePAM is enabled (Automated)                         
              5.2         Configure privilege escalation
              5.2.1       Ensure sudo is installed (Automated)                              
              5.2.2       Ensure sudo commands use pty (Automated)                          
              5.2.3       Ensure sudo log file exists (Automated)                           
              5.2.4       Ensure users must provide password for escalation                 
                          (Automated)
              5.2.5       Ensure re-authentication for privilege escalation is not          
                          disabled globally (Automated)


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                            CIS Benchmark Recommendation                             Set
                                                                                   Correctly
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              5.2.6       Ensure sudo timestamp_timeout is configured                     
                          (Automated)
              5.2.7       Ensure access to the su command is restricted                   
                          (Automated)
              5.3         Pluggable Authentication Modules
              5.3.1       Configure PAM software packages
              5.3.1.1     Ensure latest version of pam is installed (Automated)           
              5.3.1.2     Ensure latest version of libpam-modules is installed            
                          (Automated)
              5.3.1.3     Ensure latest version of libpam-pwquality is installed          
                          (Automated)
              5.3.2       Configure pam-auth-update profiles
              5.3.2.1     Ensure pam_unix module is enabled (Automated)                   
              5.3.2.2     Ensure pam_faillock module is enabled (Automated)               
              5.3.2.3     Ensure pam_pwquality module is enabled (Automated)              
              5.3.2.4     Ensure pam_pwhistory module is enabled (Automated)              
              5.3.3       Configure PAM Arguments
              5.3.3.1     Configure pam_faillock module
              5.3.3.1.1   Ensure password failed attempts lockout is configured           
                          (Automated)
              5.3.3.1.2   Ensure password unlock time is configured (Automated)           
              5.3.3.1.3   Ensure password failed attempts lockout includes root           
                          account (Automated)
              5.3.3.2     Configure pam_pwquality module
              5.3.3.2.1   Ensure password number of changed characters is                 
                          configured (Automated)
              5.3.3.2.2   Ensure minimum password length is configured                    
                          (Automated)
              5.3.3.2.3   Ensure password complexity is configured (Manual)               
              5.3.3.2.4   Ensure password same consecutive characters is                  
                          configured (Automated)
              5.3.3.2.5   Ensure password maximum sequential characters is                
                          configured (Automated)
              5.3.3.2.6   Ensure password dictionary check is enabled                     
                          (Automated)


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                            CIS Benchmark Recommendation                             Set
                                                                                   Correctly
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              5.3.3.2.7   Ensure password quality checking is enforced                    
                          (Automated)
              5.3.3.2.8   Ensure password quality is enforced for the root user           
                          (Automated)
              5.3.3.3     Configure pam_pwhistory module
              5.3.3.3.1   Ensure password history remember is configured                  
                          (Automated)
              5.3.3.3.2   Ensure password history is enforced for the root user           
                          (Automated)
              5.3.3.3.3   Ensure pam_pwhistory includes use_authtok                       
                          (Automated)
              5.3.3.4     Configure pam_unix module
              5.3.3.4.1   Ensure pam_unix does not include nullok (Automated)             
              5.3.3.4.2   Ensure pam_unix does not include remember                       
                          (Automated)
              5.3.3.4.3   Ensure pam_unix includes a strong password hashing              
                          algorithm (Automated)
              5.3.3.4.4   Ensure pam_unix includes use_authtok (Automated)                
              5.4         User Accounts and Environment
              5.4.1       Configure shadow password suite parameters
              5.4.1.1     Ensure password expiration is configured (Automated)            
              5.4.1.2     Ensure minimum password days is configured (Manual)             
              5.4.1.3     Ensure password expiration warning days is configured           
                          (Automated)
              5.4.1.4     Ensure strong password hashing algorithm is configured          
                          (Automated)
              5.4.1.5     Ensure inactive password lock is configured (Automated)         
              5.4.1.6     Ensure all users last password change date is in the past       
                          (Automated)
              5.4.2       Configure root and system accounts and environment
              5.4.2.1     Ensure root is the only UID 0 account (Automated)               
              5.4.2.2     Ensure root is the only GID 0 account (Automated)               
              5.4.2.3     Ensure group root is the only GID 0 group (Automated)           
              5.4.2.4     Ensure root account access is controlled (Automated)            
              5.4.2.5     Ensure root path integrity (Automated)                          


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              5.4.2.6     Ensure root user umask is configured (Automated)                  
              5.4.2.7     Ensure system accounts do not have a valid login shell            
                          (Automated)
              5.4.2.8     Ensure accounts without a valid login shell are locked            
                          (Automated)
              5.4.3       Configure user default environment
              5.4.3.1     Ensure nologin is not listed in /etc/shells (Automated)           
              5.4.3.2     Ensure default user shell timeout is configured                   
                          (Automated)
              5.4.3.3     Ensure default user umask is configured (Automated)               
              6           Logging and Auditing
              6.1         System Logging
              6.1.1       Configure journald
              6.1.1.1     Configure systemd-journald service
              6.1.1.1.1   Ensure journald service is active (Automated)                     
              6.1.1.1.2   Ensure journald log file access is configured (Manual)            
              6.1.1.1.3   Ensure journald log file rotation is configured (Manual)          
              6.1.1.1.4   Ensure journald ForwardToSyslog is disabled                       
                          (Automated)
              6.1.1.1.5   Ensure journald Storage is configured (Automated)                 
              6.1.1.1.6   Ensure journald Compress is configured (Automated)                
              6.1.1.2     Configure systemd-journal-remote
              6.1.1.2.1   Ensure systemd-journal-remote is installed (Automated)            
              6.1.1.2.2   Ensure systemd-journal-upload authentication is                   
                          configured (Manual)
              6.1.1.2.3   Ensure systemd-journal-upload is enabled and active               
                          (Automated)
              6.1.1.2.4   Ensure systemd-journal-remote service is not in use               
                          (Automated)
              6.1.2       Configure rsyslog
              6.1.2.1     Ensure rsyslog is installed (Automated)                           
              6.1.2.2     Ensure rsyslog service is enabled and active                      
                          (Automated)




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                            CIS Benchmark Recommendation                                  Set
                                                                                        Correctly
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              6.1.2.3     Ensure journald is configured to send logs to rsyslog                
                          (Automated)
              6.1.2.4     Ensure rsyslog log file creation mode is configured                  
                          (Automated)
              6.1.2.5     Ensure rsyslog logging is configured (Manual)                        
              6.1.2.6     Ensure rsyslog is configured to send logs to a remote log            
                          host (Manual)
              6.1.2.7     Ensure rsyslog is not configured to receive logs from a              
                          remote client (Automated)
              6.1.2.8     Ensure logrotate is configured (Manual)                              
              6.1.3       Configure Logfiles
              6.1.3.1     Ensure access to all logfiles has been configured                    
                          (Automated)
              6.2         System Auditing
              6.2.1       Configure auditd Service
              6.2.1.1     Ensure auditd packages are installed (Automated)                     
              6.2.1.2     Ensure auditd service is enabled and active (Automated)              
              6.2.1.3     Ensure auditing for processes that start prior to auditd is          
                          enabled (Automated)
              6.2.1.4     Ensure audit_backlog_limit is configured (Automated)                 
              6.2.2       Configure Data Retention
              6.2.2.1     Ensure audit log storage size is configured (Automated)              
              6.2.2.2     Ensure audit logs are not automatically deleted                      
                          (Automated)
              6.2.2.3     Ensure system is disabled when audit logs are full                   
                          (Automated)
              6.2.2.4     Ensure system warns when audit logs are low on space                 
                          (Automated)
              6.2.3       Configure auditd Rules
              6.2.3.1     Ensure changes to system administration scope                        
                          (sudoers) is collected (Automated)
              6.2.3.2     Ensure actions as another user are always logged                     
                          (Automated)
              6.2.3.3     Ensure events that modify the sudo log file are collected            
                          (Automated)


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                            CIS Benchmark Recommendation                              Set
                                                                                    Correctly
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              6.2.3.4     Ensure events that modify date and time information are          
                          collected (Automated)
              6.2.3.5     Ensure events that modify the system's network                   
                          environment are collected (Automated)
              6.2.3.6     Ensure use of privileged commands are collected                  
                          (Automated)
              6.2.3.7     Ensure unsuccessful file access attempts are collected           
                          (Automated)
              6.2.3.8     Ensure events that modify user/group information are             
                          collected (Automated)
              6.2.3.9     Ensure discretionary access control permission                   
                          modification events are collected (Automated)
              6.2.3.10    Ensure successful file system mounts are collected               
                          (Automated)
              6.2.3.11    Ensure session initiation information is collected               
                          (Automated)
              6.2.3.12    Ensure login and logout events are collected                     
                          (Automated)
              6.2.3.13    Ensure file deletion events by users are collected               
                          (Automated)
              6.2.3.14    Ensure events that modify the system's Mandatory                 
                          Access Controls are collected (Automated)
              6.2.3.15    Ensure successful and unsuccessful attempts to use the           
                          chcon command are collected (Automated)
              6.2.3.16    Ensure successful and unsuccessful attempts to use the           
                          setfacl command are collected (Automated)
              6.2.3.17    Ensure successful and unsuccessful attempts to use the           
                          chacl command are collected (Automated)
              6.2.3.18    Ensure successful and unsuccessful attempts to use the           
                          usermod command are collected (Automated)
              6.2.3.19    Ensure kernel module loading unloading and                       
                          modification is collected (Automated)
              6.2.3.20    Ensure the audit configuration is immutable (Automated)          
              6.2.3.21    Ensure the running and on disk configuration is the same         
                          (Manual)
              6.2.4       Configure auditd File Access



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                            CIS Benchmark Recommendation                             Set
                                                                                   Correctly
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              6.2.4.1     Ensure audit log files mode is configured (Automated)           
              6.2.4.2     Ensure audit log files owner is configured (Automated)          
              6.2.4.3     Ensure audit log files group owner is configured                
                          (Automated)
              6.2.4.4     Ensure the audit log file directory mode is configured          
                          (Automated)
              6.2.4.5     Ensure audit configuration files mode is configured             
                          (Automated)
              6.2.4.6     Ensure audit configuration files owner is configured            
                          (Automated)
              6.2.4.7     Ensure audit configuration files group owner is                 
                          configured (Automated)
              6.2.4.8     Ensure audit tools mode is configured (Automated)               
              6.2.4.9     Ensure audit tools owner is configured (Automated)              
              6.2.4.10    Ensure audit tools group owner is configured                    
                          (Automated)
              6.3         Configure Filesystem Integrity Checking
              6.3.1       Ensure AIDE is installed (Automated)                            
              6.3.2       Ensure filesystem integrity is regularly checked                
                          (Automated)
              6.3.3       Ensure cryptographic mechanisms are used to protect             
                          the integrity of audit tools (Automated)
              7           System Maintenance
              7.1         Configure system file and directory access
              7.1.1       Ensure access to /etc/passwd is configured (Automated)          
              7.1.2       Ensure access to /etc/passwd- is configured                     
                          (Automated)
              7.1.3       Ensure access to /etc/group is configured (Automated)           
              7.1.4       Ensure access to /etc/group- is configured (Automated)          
              7.1.5       Ensure access to /etc/shadow is configured (Automated)          
              7.1.6       Ensure access to /etc/shadow- is configured                     
                          (Automated)
              7.1.7       Ensure access to /etc/gshadow is configured                     
                          (Automated)




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                                                                                    Correctly
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              7.1.8       Ensure access to /etc/gshadow- is configured                     
                          (Automated)
              7.1.9       Ensure access to /etc/shells is configured (Automated)           
              7.1.10      Ensure access to /etc/security/opasswd is configured             
                          (Automated)
              7.1.11      Ensure world writable files and directories are secured          
                          (Automated)
              7.1.12      Ensure no files or directories without an owner and a            
                          group exist (Automated)
              7.1.13      Ensure SUID and SGID files are reviewed (Manual)                 
              7.2         Local User and Group Settings
              7.2.1       Ensure accounts in /etc/passwd use shadowed                      
                          passwords (Automated)
              7.2.2       Ensure /etc/shadow password fields are not empty                 
                          (Automated)
              7.2.3       Ensure all groups in /etc/passwd exist in /etc/group             
                          (Automated)
              7.2.4       Ensure shadow group is empty (Automated)                         
              7.2.5       Ensure no duplicate UIDs exist (Automated)                       
              7.2.6       Ensure no duplicate GIDs exist (Automated)                       
              7.2.7       Ensure no duplicate user names exist (Automated)                 
              7.2.8       Ensure no duplicate group names exist (Automated)                
              7.2.9       Ensure local interactive user home directories are               
                          configured (Automated)
              7.2.10      Ensure local interactive user dot files access is                
                          configured (Automated)




                                                                                          Page 925

Internal Only - General
            Appendix: CIS Controls v7 IG 1 Mapped
            Recommendations
                                     Recommendation                                 Set
                                                                                 Correctly
                                                                                 Yes No
              1.1.2.1.1   Ensure /tmp is tmpfs or a separate partition                 
              1.1.2.1.2   Ensure nodev option set on /tmp partition                    
              1.1.2.1.3   Ensure nosuid option set on /tmp partition                   
              1.1.2.1.4   Ensure noexec option set on /tmp partition                   
              1.1.2.2.1   Ensure /dev/shm is tmpfs or a separate partition             
              1.1.2.2.2   Ensure nodev option set on /dev/shm partition                
              1.1.2.2.3   Ensure nosuid option set on /dev/shm partition               
              1.1.2.2.4   Ensure noexec option set on /dev/shm partition               
              1.1.2.3.1   Ensure separate partition exists for /home                   
              1.1.2.3.2   Ensure nodev option set on /home partition                   
              1.1.2.3.3   Ensure nosuid option set on /home partition                  
              1.1.2.4.1   Ensure separate partition exists for /var                    
              1.1.2.4.2   Ensure nodev option set on /var partition                    
              1.1.2.4.3   Ensure nosuid option set on /var partition                   
              1.1.2.5.1   Ensure separate partition exists for /var/tmp                
              1.1.2.5.2   Ensure nodev option set on /var/tmp partition                
              1.1.2.5.3   Ensure nosuid option set on /var/tmp partition               
              1.1.2.5.4   Ensure noexec option set on /var/tmp partition               
              1.1.2.6.2   Ensure nodev option set on /var/log partition                
              1.1.2.6.3   Ensure nosuid option set on /var/log partition               
              1.1.2.6.4   Ensure noexec option set on /var/log partition               
              1.1.2.7.2   Ensure nodev option set on /var/log/audit partition          
              1.1.2.7.3   Ensure nosuid option set on /var/log/audit partition         
              1.1.2.7.4   Ensure noexec option set on /var/log/audit partition         
              1.2.1.1     Ensure GPG keys are configured                               
              1.2.1.2     Ensure package manager repositories are configured           
              1.2.2.1     Ensure updates, patches, and additional security
                                                                                       
                          software are installed
              1.3.1.1     Ensure the apparmor packages are installed                   
              1.3.1.2     Ensure AppArmor is enabled                                   
              1.3.1.3     Ensure all AppArmor Profiles are not disabled                
              1.3.1.4     Ensure all AppArmor Profiles are enforcing                   
              1.4.1       Ensure bootloader password is set                            
              1.4.2       Ensure access to bootloader config is configured             
              1.6.4       Ensure access to /etc/motd is configured                     


                                                                                     Page 926

Internal Only - General
                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              1.6.5       Ensure access to /etc/issue is configured                         
              1.6.6       Ensure access to /etc/issue.net is configured                     
              1.7.4       Ensure GDM screen locks when the user is idle                     
              1.7.5       Ensure GDM screen locks cannot be overridden                      
              1.7.6       Ensure GDM automatic mounting of removable media is
                                                                                            
                          disabled
              1.7.8       Ensure GDM autorun-never is enabled                               
              1.7.9       Ensure GDM autorun-never is not overridden                        
              2.1.1       Ensure autofs services are not in use                             
              2.1.20      Ensure X window server services are not in use                    
              2.2.1       Ensure nis client is not installed                                
              2.4.1.2     Ensure access to /etc/crontab is configured                       
              2.4.1.3     Ensure access to /etc/cron.hourly is configured                   
              2.4.1.4     Ensure access to /etc/cron.daily is configured                    
              2.4.1.5     Ensure access to /etc/cron.weekly is configured                   
              2.4.1.6     Ensure access to /etc/cron.monthly is configured                  
              2.4.1.8     Ensure access to /etc/cron.d is configured                        
              2.4.1.9     Ensure access to crontab is configured                            
              2.4.2.1     Ensure access to at is configured                                 
              3.3.1.16    Ensure net.ipv4.conf.all.log_martians is configured               
              3.3.1.17    Ensure net.ipv4.conf.default.log_martians is configured           
              4.1.1       Ensure ufw is installed                                           
              4.1.2       Ensure ufw service is configured                                  
              4.1.3       Ensure ufw incoming default is configured                         
              4.1.4       Ensure ufw outgoing default is configured                         
              4.1.5       Ensure ufw routed default is configured                           
              5.1.1       Ensure access to /etc/ssh/sshd_config is configured               
              5.1.2       Ensure access to SSH private host key files is configured         
              5.1.3       Ensure access to SSH public host key files is configured          
              5.1.4       Ensure sshd access is configured                                  
              5.1.14      Ensure sshd LogLevel is configured                                
              5.1.20      Ensure sshd PermitRootLogin is disabled                           
              5.2.1       Ensure sudo is installed                                          
              5.2.2       Ensure sudo commands use pty                                      
              5.2.4       Ensure users must provide password for escalation                 
              5.2.5       Ensure re-authentication for privilege escalation is not
                                                                                            
                          disabled globally
              5.2.6       Ensure sudo timestamp_timeout is configured                       
              5.2.7       Ensure access to the su command is restricted                     
              5.3.2.1     Ensure pam_unix module is enabled                                 


                                                                                          Page 927

Internal Only - General
                                     Recommendation                                        Set
                                                                                        Correctly
                                                                                        Yes No
              5.4.2.1     Ensure root is the only UID 0 account                               
              5.4.2.2     Ensure root is the only GID 0 account                               
              5.4.2.3     Ensure group root is the only GID 0 group                           
              5.4.2.4     Ensure root account access is controlled                            
              5.4.2.6     Ensure root user umask is configured                                
              5.4.2.7     Ensure system accounts do not have a valid login shell              
              5.4.2.8     Ensure accounts without a valid login shell are locked              
              5.4.3.2     Ensure default user shell timeout is configured                     
              5.4.3.3     Ensure default user umask is configured                             
              6.1.1.1.1   Ensure journald service is active                                   
              6.1.1.1.2   Ensure journald log file access is configured                       
              6.1.1.1.3   Ensure journald log file rotation is configured                     
              6.1.1.1.5   Ensure journald Storage is configured                               
              6.1.1.1.6   Ensure journald Compress is configured                              
              6.1.1.2.1   Ensure systemd-journal-remote is installed                          
              6.1.1.2.2   Ensure systemd-journal-upload authentication is
                                                                                              
                          configured
              6.1.1.2.3   Ensure systemd-journal-upload is enabled and active                 
              6.1.2.1     Ensure rsyslog is installed                                         
              6.1.2.2     Ensure rsyslog service is enabled and active                        
              6.1.2.3     Ensure journald is configured to send logs to rsyslog               
              6.1.2.4     Ensure rsyslog log file creation mode is configured                 
              6.1.2.5     Ensure rsyslog logging is configured                                
              6.1.2.6     Ensure rsyslog is configured to send logs to a remote log
                                                                                              
                          host
              6.1.3.1     Ensure access to all logfiles has been configured                   
              6.2.1.1     Ensure auditd packages are installed                                
              6.2.1.2     Ensure auditd service is enabled and active                         
              6.2.1.3     Ensure auditing for processes that start prior to auditd is
                                                                                              
                          enabled
              6.2.1.4     Ensure audit_backlog_limit is configured                            
              6.2.2.4     Ensure system warns when audit logs are low on space                
              6.2.3.6     Ensure use of privileged commands are collected                     
              6.2.3.12    Ensure login and logout events are collected                        
              6.2.3.13    Ensure file deletion events by users are collected                  
              6.2.3.15    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chcon command are collected
              6.2.3.16    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          setfacl command are collected
              6.2.3.17    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chacl command are collected


                                                                                            Page 928

Internal Only - General
                                    Recommendation                                    Set
                                                                                    Correctly
                                                                                    Yes No
              6.2.3.18    Ensure successful and unsuccessful attempts to use the
                                                                                          
                          usermod command are collected
              6.2.3.19    Ensure kernel module loading unloading and modification
                                                                                          
                          is collected
              6.2.3.20    Ensure the audit configuration is immutable                     
              6.2.4.1     Ensure audit log files mode is configured                       
              6.2.4.2     Ensure audit log files owner is configured                      
              6.2.4.3     Ensure audit log files group owner is configured                
              6.2.4.4     Ensure the audit log file directory mode is configured          
              6.2.4.5     Ensure audit configuration files mode is configured             
              6.2.4.6     Ensure audit configuration files owner is configured            
              6.2.4.7     Ensure audit configuration files group owner is
                                                                                          
                          configured
              6.2.4.8     Ensure audit tools mode is configured                           
              6.2.4.9     Ensure audit tools owner is configured                          
              6.2.4.10    Ensure audit tools group owner is configured                    
              7.1.1       Ensure access to /etc/passwd is configured                      
              7.1.2       Ensure access to /etc/passwd- is configured                     
              7.1.3       Ensure access to /etc/group is configured                       
              7.1.4       Ensure access to /etc/group- is configured                      
              7.1.5       Ensure access to /etc/shadow is configured                      
              7.1.6       Ensure access to /etc/shadow- is configured                     
              7.1.7       Ensure access to /etc/gshadow is configured                     
              7.1.8       Ensure access to /etc/gshadow- is configured                    
              7.1.9       Ensure access to /etc/shells is configured                      
              7.1.10      Ensure access to /etc/security/opasswd is configured            
              7.1.11      Ensure world writable files and directories are secured         
              7.1.12      Ensure no files or directories without an owner and a
                                                                                          
                          group exist
              7.1.13      Ensure SUID and SGID files are reviewed                         
              7.2.4       Ensure shadow group is empty                                    
              7.2.9       Ensure local interactive user home directories are
                                                                                          
                          configured
              7.2.10      Ensure local interactive user dot files access is
                                                                                          
                          configured




                                                                                        Page 929

Internal Only - General
            Appendix: CIS Controls v7 IG 2 Mapped
            Recommendations
                                     Recommendation                                Set
                                                                                Correctly
                                                                                Yes No
              1.1.1.1     Ensure cramfs kernel module is not available                
              1.1.1.2     Ensure freevxfs kernel module is not available              
              1.1.1.3     Ensure hfs kernel module is not available                   
              1.1.1.4     Ensure hfsplus kernel module is not available               
              1.1.1.5     Ensure jffs2 kernel module is not available                 
              1.1.1.6     Ensure overlay kernel module is not available               
              1.1.1.7     Ensure squashfs kernel module is not available              
              1.1.1.8     Ensure udf kernel module is not available                   
              1.1.1.9     Ensure usb-storage kernel module is not available           
              1.1.1.10    Ensure unused filesystems kernel modules are not
                                                                                      
                          available
              1.1.1.11    Ensure firewire-core kernel module is not available         
              1.1.2.1.1   Ensure /tmp is tmpfs or a separate partition                
              1.1.2.1.2   Ensure nodev option set on /tmp partition                   
              1.1.2.1.3   Ensure nosuid option set on /tmp partition                  
              1.1.2.1.4   Ensure noexec option set on /tmp partition                  
              1.1.2.2.1   Ensure /dev/shm is tmpfs or a separate partition            
              1.1.2.2.2   Ensure nodev option set on /dev/shm partition               
              1.1.2.2.3   Ensure nosuid option set on /dev/shm partition              
              1.1.2.2.4   Ensure noexec option set on /dev/shm partition              
              1.1.2.3.1   Ensure separate partition exists for /home                  
              1.1.2.3.2   Ensure nodev option set on /home partition                  
              1.1.2.3.3   Ensure nosuid option set on /home partition                 
              1.1.2.4.1   Ensure separate partition exists for /var                   
              1.1.2.4.2   Ensure nodev option set on /var partition                   
              1.1.2.4.3   Ensure nosuid option set on /var partition                  
              1.1.2.5.1   Ensure separate partition exists for /var/tmp               
              1.1.2.5.2   Ensure nodev option set on /var/tmp partition               
              1.1.2.5.3   Ensure nosuid option set on /var/tmp partition              
              1.1.2.5.4   Ensure noexec option set on /var/tmp partition              
              1.1.2.6.1   Ensure separate partition exists for /var/log               
              1.1.2.6.2   Ensure nodev option set on /var/log partition               
              1.1.2.6.3   Ensure nosuid option set on /var/log partition              
              1.1.2.6.4   Ensure noexec option set on /var/log partition              
              1.1.2.7.1   Ensure separate partition exists for /var/log/audit         


                                                                                    Page 930

Internal Only - General
                                    Recommendation                                  Set
                                                                                 Correctly
                                                                                 Yes No
              1.1.2.7.2   Ensure nodev option set on /var/log/audit partition          
              1.1.2.7.3   Ensure nosuid option set on /var/log/audit partition         
              1.1.2.7.4   Ensure noexec option set on /var/log/audit partition         
              1.2.1.1     Ensure GPG keys are configured                               
              1.2.1.2     Ensure package manager repositories are configured           
              1.2.2.1     Ensure updates, patches, and additional security
                                                                                       
                          software are installed
              1.3.1.1     Ensure the apparmor packages are installed                   
              1.3.1.2     Ensure AppArmor is enabled                                   
              1.3.1.3     Ensure all AppArmor Profiles are not disabled                
              1.3.1.4     Ensure all AppArmor Profiles are enforcing                   
              1.4.1       Ensure bootloader password is set                            
              1.4.2       Ensure access to bootloader config is configured             
              1.5.1       Ensure randomize_va_space is configured                      
              1.5.2       Ensure ptrace_scope is configured                            
              1.5.6       Ensure Automatic Error Reporting is configured               
              1.6.4       Ensure access to /etc/motd is configured                     
              1.6.5       Ensure access to /etc/issue is configured                    
              1.6.6       Ensure access to /etc/issue.net is configured                
              1.7.1       Ensure GDM is removed                                        
              1.7.4       Ensure GDM screen locks when the user is idle                
              1.7.5       Ensure GDM screen locks cannot be overridden                 
              1.7.6       Ensure GDM automatic mounting of removable media is
                                                                                       
                          disabled
              1.7.8       Ensure GDM autorun-never is enabled                          
              1.7.9       Ensure GDM autorun-never is not overridden                   
              1.7.10      Ensure XDMCP is not enabled                                  
              1.7.11      Ensure Xwayland is configured                                
              2.1.1       Ensure autofs services are not in use                        
              2.1.2       Ensure avahi daemon services are not in use                  
              2.1.3       Ensure dhcp server services are not in use                   
              2.1.4       Ensure dns server services are not in use                    
              2.1.5       Ensure dnsmasq services are not in use                       
              2.1.6       Ensure ftp server services are not in use                    
              2.1.7       Ensure ldap server services are not in use                   
              2.1.8       Ensure message access server services are not in use         
              2.1.9       Ensure network file system services are not in use           
              2.1.10      Ensure nis server services are not in use                    
              2.1.11      Ensure print server services are not in use                  
              2.1.12      Ensure rpcbind services are not in use                       


                                                                                     Page 931

Internal Only - General
                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              2.1.13      Ensure rsync services are not in use                              
              2.1.14      Ensure samba file server services are not in use                  
              2.1.15      Ensure snmp services are not in use                               
              2.1.16      Ensure tftp server services are not in use                        
              2.1.17      Ensure web proxy server services are not in use                   
              2.1.18      Ensure web server services are not in use                         
              2.1.19      Ensure xinetd services are not in use                             
              2.1.20      Ensure X window server services are not in use                    
              2.1.21      Ensure mail transfer agents are configured for local-only
                                                                                            
                          mode
              2.1.22      Ensure only approved services are listening on a network
                                                                                            
                          interface
              2.2.1       Ensure nis client is not installed                                
              2.2.2       Ensure rsh client is not installed                                
              2.2.3       Ensure talk client is not installed                               
              2.2.4       Ensure telnet client is not installed                             
              2.2.5       Ensure ldap client is not installed                               
              2.2.6       Ensure ftp client is not installed                                
              2.3.1.1     Ensure a single time synchronization daemon is in use             
              2.3.2.1     Ensure systemd-timesyncd configured with authorized
                                                                                            
                          timeserver
              2.3.2.2     Ensure systemd-timesyncd is enabled and running                   
              2.3.3.1     Ensure chrony is configured with authorized timeserver            
              2.3.3.3     Ensure chrony is enabled and running                              
              2.4.1.2     Ensure access to /etc/crontab is configured                       
              2.4.1.3     Ensure access to /etc/cron.hourly is configured                   
              2.4.1.4     Ensure access to /etc/cron.daily is configured                    
              2.4.1.5     Ensure access to /etc/cron.weekly is configured                   
              2.4.1.6     Ensure access to /etc/cron.monthly is configured                  
              2.4.1.8     Ensure access to /etc/cron.d is configured                        
              2.4.1.9     Ensure access to crontab is configured                            
              2.4.2.1     Ensure access to at is configured                                 
              3.1.1       Ensure IPv6 status is identified                                  
              3.1.3       Ensure bluetooth services are not in use                          
              3.2.1       Ensure dccp kernel module is not available                        
              3.2.2       Ensure tipc kernel module is not available                        
              3.2.3       Ensure rds kernel module is not available                         
              3.2.4       Ensure sctp kernel module is not available                        
              3.3.1.1     Ensure net.ipv4.ip_forward is configured                          
              3.3.1.2     Ensure net.ipv4.conf.all.forwarding is configured                 



                                                                                          Page 932

Internal Only - General
                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              3.3.1.3     Ensure net.ipv4.conf.default.forwarding is configured             
              3.3.1.4     Ensure net.ipv4.conf.all.send_redirects is configured             
              3.3.1.5     Ensure net.ipv4.conf.default.send_redirects is configured         
              3.3.1.6     Ensure net.ipv4.icmp_ignore_bogus_error_responses is
                                                                                            
                          configured
              3.3.1.7     Ensure net.ipv4.icmp_echo_ignore_broadcasts is
                                                                                            
                          configured
              3.3.1.8     Ensure net.ipv4.conf.all.accept_redirects is configured           
              3.3.1.9     Ensure net.ipv4.conf.default.accept_redirects is
                                                                                            
                          configured
              3.3.1.10    Ensure net.ipv4.conf.all.secure_redirects is configured           
              3.3.1.11    Ensure net.ipv4.conf.default.secure_redirects is
                                                                                            
                          configured
              3.3.1.12    Ensure net.ipv4.conf.all.rp_filter is configured                  
              3.3.1.13    Ensure net.ipv4.conf.default.rp_filter is configured              
              3.3.1.14    Ensure net.ipv4.conf.all.accept_source_route is
                                                                                            
                          configured
              3.3.1.15    Ensure net.ipv4.conf.default.accept_source_route is
                                                                                            
                          configured
              3.3.1.16    Ensure net.ipv4.conf.all.log_martians is configured               
              3.3.1.17    Ensure net.ipv4.conf.default.log_martians is configured           
              3.3.1.18    Ensure net.ipv4.tcp_syncookies is configured                      
              3.3.2.1     Ensure net.ipv6.conf.all.forwarding is configured                 
              3.3.2.2     Ensure net.ipv6.conf.default.forwarding is configured             
              3.3.2.3     Ensure net.ipv6.conf.all.accept_redirects is configured           
              3.3.2.4     Ensure net.ipv6.conf.default.accept_redirects is
                                                                                            
                          configured
              3.3.2.5     Ensure net.ipv6.conf.all.accept_source_route is
                                                                                            
                          configured
              3.3.2.6     Ensure net.ipv6.conf.default.accept_source_route is
                                                                                            
                          configured
              3.3.2.7     Ensure net.ipv6.conf.all.accept_ra is configured                  
              3.3.2.8     Ensure net.ipv6.conf.default.accept_ra is configured              
              4.1.1       Ensure ufw is installed                                           
              4.1.2       Ensure ufw service is configured                                  
              4.1.3       Ensure ufw incoming default is configured                         
              4.1.4       Ensure ufw outgoing default is configured                         
              4.1.5       Ensure ufw routed default is configured                           
              5.1.1       Ensure access to /etc/ssh/sshd_config is configured               
              5.1.2       Ensure access to SSH private host key files is configured         
              5.1.3       Ensure access to SSH public host key files is configured          


                                                                                          Page 933

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                                     Recommendation                                     Set
                                                                                     Correctly
                                                                                     Yes No
              5.1.4       Ensure sshd access is configured                                 
              5.1.6       Ensure sshd Ciphers are configured                               
              5.1.8       Ensure sshd DisableForwarding is enabled                         
              5.1.9       Ensure sshd GSSAPIAuthentication is disabled                     
              5.1.10      Ensure sshd HostbasedAuthentication is disabled                  
              5.1.11      Ensure sshd IgnoreRhosts is enabled                              
              5.1.12      Ensure sshd KexAlgorithms is configured                          
              5.1.14      Ensure sshd LogLevel is configured                               
              5.1.15      Ensure sshd MACs are configured                                  
              5.1.19      Ensure sshd PermitEmptyPasswords is disabled                     
              5.1.20      Ensure sshd PermitRootLogin is disabled                          
              5.1.22      Ensure sshd UsePAM is enabled                                    
              5.2.1       Ensure sudo is installed                                         
              5.2.2       Ensure sudo commands use pty                                     
              5.2.3       Ensure sudo log file exists                                      
              5.2.4       Ensure users must provide password for escalation                
              5.2.5       Ensure re-authentication for privilege escalation is not
                                                                                           
                          disabled globally
              5.2.6       Ensure sudo timestamp_timeout is configured                      
              5.2.7       Ensure access to the su command is restricted                    
              5.3.1.3     Ensure latest version of libpam-pwquality is installed           
              5.3.2.1     Ensure pam_unix module is enabled                                
              5.3.2.2     Ensure pam_faillock module is enabled                            
              5.3.2.3     Ensure pam_pwquality module is enabled                           
              5.3.2.4     Ensure pam_pwhistory module is enabled                           
              5.3.3.1.1   Ensure password failed attempts lockout is configured            
              5.3.3.1.2   Ensure password unlock time is configured                        
              5.3.3.1.3   Ensure password failed attempts lockout includes root
                                                                                           
                          account
              5.3.3.2.1   Ensure password number of changed characters is
                                                                                           
                          configured
              5.3.3.2.2   Ensure minimum password length is configured                     
              5.3.3.2.3   Ensure password complexity is configured                         
              5.3.3.2.4   Ensure password same consecutive characters is
                                                                                           
                          configured
              5.3.3.2.5   Ensure password maximum sequential characters is
                                                                                           
                          configured
              5.3.3.2.6   Ensure password dictionary check is enabled                      
              5.3.3.2.7   Ensure password quality checking is enforced                     
              5.3.3.2.8   Ensure password quality is enforced for the root user            
              5.3.3.3.1   Ensure password history remember is configured                   

                                                                                         Page 934

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                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              5.3.3.3.2   Ensure password history is enforced for the root user             
              5.3.3.3.3   Ensure pam_pwhistory includes use_authtok                         
              5.3.3.4.1   Ensure pam_unix does not include nullok                           
              5.3.3.4.2   Ensure pam_unix does not include remember                         
              5.3.3.4.3   Ensure pam_unix includes a strong password hashing
                                                                                            
                          algorithm
              5.3.3.4.4   Ensure pam_unix includes use_authtok                              
              5.4.1.1     Ensure password expiration is configured                          
              5.4.1.2     Ensure minimum password days is configured                        
              5.4.1.3     Ensure password expiration warning days is configured             
              5.4.1.4     Ensure strong password hashing algorithm is configured            
              5.4.1.5     Ensure inactive password lock is configured                       
              5.4.1.6     Ensure all users last password change date is in the past         
              5.4.2.1     Ensure root is the only UID 0 account                             
              5.4.2.2     Ensure root is the only GID 0 account                             
              5.4.2.3     Ensure group root is the only GID 0 group                         
              5.4.2.4     Ensure root account access is controlled                          
              5.4.2.6     Ensure root user umask is configured                              
              5.4.2.7     Ensure system accounts do not have a valid login shell            
              5.4.2.8     Ensure accounts without a valid login shell are locked            
              5.4.3.2     Ensure default user shell timeout is configured                   
              5.4.3.3     Ensure default user umask is configured                           
              6.1.1.1.1   Ensure journald service is active                                 
              6.1.1.1.2   Ensure journald log file access is configured                     
              6.1.1.1.3   Ensure journald log file rotation is configured                   
              6.1.1.1.4   Ensure journald ForwardToSyslog is disabled                       
              6.1.1.1.5   Ensure journald Storage is configured                             
              6.1.1.1.6   Ensure journald Compress is configured                            
              6.1.1.2.1   Ensure systemd-journal-remote is installed                        
              6.1.1.2.2   Ensure systemd-journal-upload authentication is
                                                                                            
                          configured
              6.1.1.2.3   Ensure systemd-journal-upload is enabled and active               
              6.1.1.2.4   Ensure systemd-journal-remote service is not in use               
              6.1.2.1     Ensure rsyslog is installed                                       
              6.1.2.2     Ensure rsyslog service is enabled and active                      
              6.1.2.3     Ensure journald is configured to send logs to rsyslog             
              6.1.2.4     Ensure rsyslog log file creation mode is configured               
              6.1.2.5     Ensure rsyslog logging is configured                              
              6.1.2.6     Ensure rsyslog is configured to send logs to a remote log
                                                                                            
                          host



                                                                                          Page 935

Internal Only - General
                                     Recommendation                                       Set
                                                                                        Correctly
                                                                                        Yes No
              6.1.2.7     Ensure rsyslog is not configured to receive logs from a
                                                                                              
                          remote client
              6.1.2.8     Ensure logrotate is configured                                      
              6.1.3.1     Ensure access to all logfiles has been configured                   
              6.2.1.1     Ensure auditd packages are installed                                
              6.2.1.2     Ensure auditd service is enabled and active                         
              6.2.1.3     Ensure auditing for processes that start prior to auditd is
                                                                                              
                          enabled
              6.2.1.4     Ensure audit_backlog_limit is configured                            
              6.2.2.1     Ensure audit log storage size is configured                         
              6.2.2.2     Ensure audit logs are not automatically deleted                     
              6.2.2.4     Ensure system warns when audit logs are low on space                
              6.2.3.1     Ensure changes to system administration scope
                                                                                              
                          (sudoers) is collected
              6.2.3.2     Ensure actions as another user are always logged                    
              6.2.3.3     Ensure events that modify the sudo log file are collected           
              6.2.3.4     Ensure events that modify date and time information are
                                                                                              
                          collected
              6.2.3.5     Ensure events that modify the system's network
                                                                                              
                          environment are collected
              6.2.3.6     Ensure use of privileged commands are collected                     
              6.2.3.8     Ensure events that modify user/group information are
                                                                                              
                          collected
              6.2.3.9     Ensure discretionary access control permission
                                                                                              
                          modification events are collected
              6.2.3.10    Ensure successful file system mounts are collected                  
              6.2.3.11    Ensure session initiation information is collected                  
              6.2.3.12    Ensure login and logout events are collected                        
              6.2.3.13    Ensure file deletion events by users are collected                  
              6.2.3.14    Ensure events that modify the system's Mandatory
                                                                                              
                          Access Controls are collected
              6.2.3.15    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chcon command are collected
              6.2.3.16    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          setfacl command are collected
              6.2.3.17    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chacl command are collected
              6.2.3.18    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          usermod command are collected
              6.2.3.19    Ensure kernel module loading unloading and modification
                                                                                              
                          is collected


                                                                                            Page 936

Internal Only - General
                                     Recommendation                                     Set
                                                                                     Correctly
                                                                                     Yes No
              6.2.3.20    Ensure the audit configuration is immutable                      
              6.2.3.21    Ensure the running and on disk configuration is the same         
              6.2.4.1     Ensure audit log files mode is configured                        
              6.2.4.2     Ensure audit log files owner is configured                       
              6.2.4.3     Ensure audit log files group owner is configured                 
              6.2.4.4     Ensure the audit log file directory mode is configured           
              6.2.4.5     Ensure audit configuration files mode is configured              
              6.2.4.6     Ensure audit configuration files owner is configured             
              6.2.4.7     Ensure audit configuration files group owner is
                                                                                           
                          configured
              6.2.4.8     Ensure audit tools mode is configured                            
              6.2.4.9     Ensure audit tools owner is configured                           
              6.2.4.10    Ensure audit tools group owner is configured                     
              7.1.1       Ensure access to /etc/passwd is configured                       
              7.1.2       Ensure access to /etc/passwd- is configured                      
              7.1.3       Ensure access to /etc/group is configured                        
              7.1.4       Ensure access to /etc/group- is configured                       
              7.1.5       Ensure access to /etc/shadow is configured                       
              7.1.6       Ensure access to /etc/shadow- is configured                      
              7.1.7       Ensure access to /etc/gshadow is configured                      
              7.1.8       Ensure access to /etc/gshadow- is configured                     
              7.1.9       Ensure access to /etc/shells is configured                       
              7.1.10      Ensure access to /etc/security/opasswd is configured             
              7.1.11      Ensure world writable files and directories are secured          
              7.1.12      Ensure no files or directories without an owner and a
                                                                                           
                          group exist
              7.1.13      Ensure SUID and SGID files are reviewed                          
              7.2.1       Ensure accounts in /etc/passwd use shadowed
                                                                                           
                          passwords
              7.2.2       Ensure /etc/shadow password fields are not empty                 
              7.2.4       Ensure shadow group is empty                                     
              7.2.9       Ensure local interactive user home directories are
                                                                                           
                          configured
              7.2.10      Ensure local interactive user dot files access is
                                                                                           
                          configured




                                                                                         Page 937

Internal Only - General
            Appendix: CIS Controls v7 IG 3 Mapped
            Recommendations
                                     Recommendation                                Set
                                                                                Correctly
                                                                                Yes No
              1.1.1.1     Ensure cramfs kernel module is not available                
              1.1.1.2     Ensure freevxfs kernel module is not available              
              1.1.1.3     Ensure hfs kernel module is not available                   
              1.1.1.4     Ensure hfsplus kernel module is not available               
              1.1.1.5     Ensure jffs2 kernel module is not available                 
              1.1.1.6     Ensure overlay kernel module is not available               
              1.1.1.7     Ensure squashfs kernel module is not available              
              1.1.1.8     Ensure udf kernel module is not available                   
              1.1.1.9     Ensure usb-storage kernel module is not available           
              1.1.1.10    Ensure unused filesystems kernel modules are not
                                                                                      
                          available
              1.1.1.11    Ensure firewire-core kernel module is not available         
              1.1.2.1.1   Ensure /tmp is tmpfs or a separate partition                
              1.1.2.1.2   Ensure nodev option set on /tmp partition                   
              1.1.2.1.3   Ensure nosuid option set on /tmp partition                  
              1.1.2.1.4   Ensure noexec option set on /tmp partition                  
              1.1.2.2.1   Ensure /dev/shm is tmpfs or a separate partition            
              1.1.2.2.2   Ensure nodev option set on /dev/shm partition               
              1.1.2.2.3   Ensure nosuid option set on /dev/shm partition              
              1.1.2.2.4   Ensure noexec option set on /dev/shm partition              
              1.1.2.3.1   Ensure separate partition exists for /home                  
              1.1.2.3.2   Ensure nodev option set on /home partition                  
              1.1.2.3.3   Ensure nosuid option set on /home partition                 
              1.1.2.4.1   Ensure separate partition exists for /var                   
              1.1.2.4.2   Ensure nodev option set on /var partition                   
              1.1.2.4.3   Ensure nosuid option set on /var partition                  
              1.1.2.5.1   Ensure separate partition exists for /var/tmp               
              1.1.2.5.2   Ensure nodev option set on /var/tmp partition               
              1.1.2.5.3   Ensure nosuid option set on /var/tmp partition              
              1.1.2.5.4   Ensure noexec option set on /var/tmp partition              
              1.1.2.6.1   Ensure separate partition exists for /var/log               
              1.1.2.6.2   Ensure nodev option set on /var/log partition               
              1.1.2.6.3   Ensure nosuid option set on /var/log partition              
              1.1.2.6.4   Ensure noexec option set on /var/log partition              
              1.1.2.7.1   Ensure separate partition exists for /var/log/audit         


                                                                                    Page 938

Internal Only - General
                                    Recommendation                                  Set
                                                                                 Correctly
                                                                                 Yes No
              1.1.2.7.2   Ensure nodev option set on /var/log/audit partition          
              1.1.2.7.3   Ensure nosuid option set on /var/log/audit partition         
              1.1.2.7.4   Ensure noexec option set on /var/log/audit partition         
              1.2.1.1     Ensure GPG keys are configured                               
              1.2.1.2     Ensure package manager repositories are configured           
              1.2.2.1     Ensure updates, patches, and additional security
                                                                                       
                          software are installed
              1.3.1.1     Ensure the apparmor packages are installed                   
              1.3.1.2     Ensure AppArmor is enabled                                   
              1.3.1.3     Ensure all AppArmor Profiles are not disabled                
              1.3.1.4     Ensure all AppArmor Profiles are enforcing                   
              1.4.1       Ensure bootloader password is set                            
              1.4.2       Ensure access to bootloader config is configured             
              1.5.1       Ensure randomize_va_space is configured                      
              1.5.2       Ensure ptrace_scope is configured                            
              1.5.5       Ensure prelink is not installed                              
              1.5.6       Ensure Automatic Error Reporting is configured               
              1.6.4       Ensure access to /etc/motd is configured                     
              1.6.5       Ensure access to /etc/issue is configured                    
              1.6.6       Ensure access to /etc/issue.net is configured                
              1.7.1       Ensure GDM is removed                                        
              1.7.4       Ensure GDM screen locks when the user is idle                
              1.7.5       Ensure GDM screen locks cannot be overridden                 
              1.7.6       Ensure GDM automatic mounting of removable media is
                                                                                       
                          disabled
              1.7.8       Ensure GDM autorun-never is enabled                          
              1.7.9       Ensure GDM autorun-never is not overridden                   
              1.7.10      Ensure XDMCP is not enabled                                  
              1.7.11      Ensure Xwayland is configured                                
              2.1.1       Ensure autofs services are not in use                        
              2.1.2       Ensure avahi daemon services are not in use                  
              2.1.3       Ensure dhcp server services are not in use                   
              2.1.4       Ensure dns server services are not in use                    
              2.1.5       Ensure dnsmasq services are not in use                       
              2.1.6       Ensure ftp server services are not in use                    
              2.1.7       Ensure ldap server services are not in use                   
              2.1.8       Ensure message access server services are not in use         
              2.1.9       Ensure network file system services are not in use           
              2.1.10      Ensure nis server services are not in use                    
              2.1.11      Ensure print server services are not in use                  


                                                                                     Page 939

Internal Only - General
                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              2.1.12      Ensure rpcbind services are not in use                            
              2.1.13      Ensure rsync services are not in use                              
              2.1.14      Ensure samba file server services are not in use                  
              2.1.15      Ensure snmp services are not in use                               
              2.1.16      Ensure tftp server services are not in use                        
              2.1.17      Ensure web proxy server services are not in use                   
              2.1.18      Ensure web server services are not in use                         
              2.1.19      Ensure xinetd services are not in use                             
              2.1.20      Ensure X window server services are not in use                    
              2.1.21      Ensure mail transfer agents are configured for local-only
                                                                                            
                          mode
              2.1.22      Ensure only approved services are listening on a network
                                                                                            
                          interface
              2.2.1       Ensure nis client is not installed                                
              2.2.2       Ensure rsh client is not installed                                
              2.2.3       Ensure talk client is not installed                               
              2.2.4       Ensure telnet client is not installed                             
              2.2.5       Ensure ldap client is not installed                               
              2.2.6       Ensure ftp client is not installed                                
              2.3.1.1     Ensure a single time synchronization daemon is in use             
              2.3.2.1     Ensure systemd-timesyncd configured with authorized
                                                                                            
                          timeserver
              2.3.2.2     Ensure systemd-timesyncd is enabled and running                   
              2.3.3.1     Ensure chrony is configured with authorized timeserver            
              2.3.3.3     Ensure chrony is enabled and running                              
              2.4.1.2     Ensure access to /etc/crontab is configured                       
              2.4.1.3     Ensure access to /etc/cron.hourly is configured                   
              2.4.1.4     Ensure access to /etc/cron.daily is configured                    
              2.4.1.5     Ensure access to /etc/cron.weekly is configured                   
              2.4.1.6     Ensure access to /etc/cron.monthly is configured                  
              2.4.1.8     Ensure access to /etc/cron.d is configured                        
              2.4.1.9     Ensure access to crontab is configured                            
              2.4.2.1     Ensure access to at is configured                                 
              3.1.1       Ensure IPv6 status is identified                                  
              3.1.2       Ensure wireless interfaces are not available                      
              3.1.3       Ensure bluetooth services are not in use                          
              3.2.1       Ensure dccp kernel module is not available                        
              3.2.2       Ensure tipc kernel module is not available                        
              3.2.3       Ensure rds kernel module is not available                         
              3.2.4       Ensure sctp kernel module is not available                        



                                                                                          Page 940

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                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              3.3.1.1     Ensure net.ipv4.ip_forward is configured                          
              3.3.1.2     Ensure net.ipv4.conf.all.forwarding is configured                 
              3.3.1.3     Ensure net.ipv4.conf.default.forwarding is configured             
              3.3.1.4     Ensure net.ipv4.conf.all.send_redirects is configured             
              3.3.1.5     Ensure net.ipv4.conf.default.send_redirects is configured         
              3.3.1.6     Ensure net.ipv4.icmp_ignore_bogus_error_responses is
                                                                                            
                          configured
              3.3.1.7     Ensure net.ipv4.icmp_echo_ignore_broadcasts is
                                                                                            
                          configured
              3.3.1.8     Ensure net.ipv4.conf.all.accept_redirects is configured           
              3.3.1.9     Ensure net.ipv4.conf.default.accept_redirects is
                                                                                            
                          configured
              3.3.1.10    Ensure net.ipv4.conf.all.secure_redirects is configured           
              3.3.1.11    Ensure net.ipv4.conf.default.secure_redirects is
                                                                                            
                          configured
              3.3.1.12    Ensure net.ipv4.conf.all.rp_filter is configured                  
              3.3.1.13    Ensure net.ipv4.conf.default.rp_filter is configured              
              3.3.1.14    Ensure net.ipv4.conf.all.accept_source_route is
                                                                                            
                          configured
              3.3.1.15    Ensure net.ipv4.conf.default.accept_source_route is
                                                                                            
                          configured
              3.3.1.16    Ensure net.ipv4.conf.all.log_martians is configured               
              3.3.1.17    Ensure net.ipv4.conf.default.log_martians is configured           
              3.3.1.18    Ensure net.ipv4.tcp_syncookies is configured                      
              3.3.2.1     Ensure net.ipv6.conf.all.forwarding is configured                 
              3.3.2.2     Ensure net.ipv6.conf.default.forwarding is configured             
              3.3.2.3     Ensure net.ipv6.conf.all.accept_redirects is configured           
              3.3.2.4     Ensure net.ipv6.conf.default.accept_redirects is
                                                                                            
                          configured
              3.3.2.5     Ensure net.ipv6.conf.all.accept_source_route is
                                                                                            
                          configured
              3.3.2.6     Ensure net.ipv6.conf.default.accept_source_route is
                                                                                            
                          configured
              3.3.2.7     Ensure net.ipv6.conf.all.accept_ra is configured                  
              3.3.2.8     Ensure net.ipv6.conf.default.accept_ra is configured              
              4.1.1       Ensure ufw is installed                                           
              4.1.2       Ensure ufw service is configured                                  
              4.1.3       Ensure ufw incoming default is configured                         
              4.1.4       Ensure ufw outgoing default is configured                         
              4.1.5       Ensure ufw routed default is configured                           
              5.1.1       Ensure access to /etc/ssh/sshd_config is configured               


                                                                                          Page 941

Internal Only - General
                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              5.1.2       Ensure access to SSH private host key files is configured         
              5.1.3       Ensure access to SSH public host key files is configured          
              5.1.4       Ensure sshd access is configured                                  
              5.1.6       Ensure sshd Ciphers are configured                                
              5.1.8       Ensure sshd DisableForwarding is enabled                          
              5.1.9       Ensure sshd GSSAPIAuthentication is disabled                      
              5.1.10      Ensure sshd HostbasedAuthentication is disabled                   
              5.1.11      Ensure sshd IgnoreRhosts is enabled                               
              5.1.12      Ensure sshd KexAlgorithms is configured                           
              5.1.14      Ensure sshd LogLevel is configured                                
              5.1.15      Ensure sshd MACs are configured                                   
              5.1.16      Ensure sshd MaxAuthTries is configured                            
              5.1.19      Ensure sshd PermitEmptyPasswords is disabled                      
              5.1.20      Ensure sshd PermitRootLogin is disabled                           
              5.1.22      Ensure sshd UsePAM is enabled                                     
              5.2.1       Ensure sudo is installed                                          
              5.2.2       Ensure sudo commands use pty                                      
              5.2.3       Ensure sudo log file exists                                       
              5.2.4       Ensure users must provide password for escalation                 
              5.2.5       Ensure re-authentication for privilege escalation is not
                                                                                            
                          disabled globally
              5.2.6       Ensure sudo timestamp_timeout is configured                       
              5.2.7       Ensure access to the su command is restricted                     
              5.3.1.3     Ensure latest version of libpam-pwquality is installed            
              5.3.2.1     Ensure pam_unix module is enabled                                 
              5.3.2.2     Ensure pam_faillock module is enabled                             
              5.3.2.3     Ensure pam_pwquality module is enabled                            
              5.3.2.4     Ensure pam_pwhistory module is enabled                            
              5.3.3.1.1   Ensure password failed attempts lockout is configured             
              5.3.3.1.2   Ensure password unlock time is configured                         
              5.3.3.1.3   Ensure password failed attempts lockout includes root
                                                                                            
                          account
              5.3.3.2.1   Ensure password number of changed characters is
                                                                                            
                          configured
              5.3.3.2.2   Ensure minimum password length is configured                      
              5.3.3.2.3   Ensure password complexity is configured                          
              5.3.3.2.4   Ensure password same consecutive characters is
                                                                                            
                          configured
              5.3.3.2.5   Ensure password maximum sequential characters is
                                                                                            
                          configured
              5.3.3.2.6   Ensure password dictionary check is enabled                       

                                                                                          Page 942

Internal Only - General
                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              5.3.3.2.7   Ensure password quality checking is enforced                      
              5.3.3.2.8   Ensure password quality is enforced for the root user             
              5.3.3.3.1   Ensure password history remember is configured                    
              5.3.3.3.2   Ensure password history is enforced for the root user             
              5.3.3.3.3   Ensure pam_pwhistory includes use_authtok                         
              5.3.3.4.1   Ensure pam_unix does not include nullok                           
              5.3.3.4.2   Ensure pam_unix does not include remember                         
              5.3.3.4.3   Ensure pam_unix includes a strong password hashing
                                                                                            
                          algorithm
              5.3.3.4.4   Ensure pam_unix includes use_authtok                              
              5.4.1.1     Ensure password expiration is configured                          
              5.4.1.2     Ensure minimum password days is configured                        
              5.4.1.3     Ensure password expiration warning days is configured             
              5.4.1.4     Ensure strong password hashing algorithm is configured            
              5.4.1.5     Ensure inactive password lock is configured                       
              5.4.1.6     Ensure all users last password change date is in the past         
              5.4.2.1     Ensure root is the only UID 0 account                             
              5.4.2.2     Ensure root is the only GID 0 account                             
              5.4.2.3     Ensure group root is the only GID 0 group                         
              5.4.2.4     Ensure root account access is controlled                          
              5.4.2.6     Ensure root user umask is configured                              
              5.4.2.7     Ensure system accounts do not have a valid login shell            
              5.4.2.8     Ensure accounts without a valid login shell are locked            
              5.4.3.2     Ensure default user shell timeout is configured                   
              5.4.3.3     Ensure default user umask is configured                           
              6.1.1.1.1   Ensure journald service is active                                 
              6.1.1.1.2   Ensure journald log file access is configured                     
              6.1.1.1.3   Ensure journald log file rotation is configured                   
              6.1.1.1.4   Ensure journald ForwardToSyslog is disabled                       
              6.1.1.1.5   Ensure journald Storage is configured                             
              6.1.1.1.6   Ensure journald Compress is configured                            
              6.1.1.2.1   Ensure systemd-journal-remote is installed                        
              6.1.1.2.2   Ensure systemd-journal-upload authentication is
                                                                                            
                          configured
              6.1.1.2.3   Ensure systemd-journal-upload is enabled and active               
              6.1.1.2.4   Ensure systemd-journal-remote service is not in use               
              6.1.2.1     Ensure rsyslog is installed                                       
              6.1.2.2     Ensure rsyslog service is enabled and active                      
              6.1.2.3     Ensure journald is configured to send logs to rsyslog             
              6.1.2.4     Ensure rsyslog log file creation mode is configured               


                                                                                          Page 943

Internal Only - General
                                     Recommendation                                        Set
                                                                                        Correctly
                                                                                        Yes No
              6.1.2.5     Ensure rsyslog logging is configured                                
              6.1.2.6     Ensure rsyslog is configured to send logs to a remote log
                                                                                              
                          host
              6.1.2.7     Ensure rsyslog is not configured to receive logs from a
                                                                                              
                          remote client
              6.1.2.8     Ensure logrotate is configured                                      
              6.1.3.1     Ensure access to all logfiles has been configured                   
              6.2.1.1     Ensure auditd packages are installed                                
              6.2.1.2     Ensure auditd service is enabled and active                         
              6.2.1.3     Ensure auditing for processes that start prior to auditd is
                                                                                              
                          enabled
              6.2.1.4     Ensure audit_backlog_limit is configured                            
              6.2.2.1     Ensure audit log storage size is configured                         
              6.2.2.2     Ensure audit logs are not automatically deleted                     
              6.2.2.4     Ensure system warns when audit logs are low on space                
              6.2.3.1     Ensure changes to system administration scope
                                                                                              
                          (sudoers) is collected
              6.2.3.2     Ensure actions as another user are always logged                    
              6.2.3.3     Ensure events that modify the sudo log file are collected           
              6.2.3.4     Ensure events that modify date and time information are
                                                                                              
                          collected
              6.2.3.5     Ensure events that modify the system's network
                                                                                              
                          environment are collected
              6.2.3.6     Ensure use of privileged commands are collected                     
              6.2.3.7     Ensure unsuccessful file access attempts are collected              
              6.2.3.8     Ensure events that modify user/group information are
                                                                                              
                          collected
              6.2.3.9     Ensure discretionary access control permission
                                                                                              
                          modification events are collected
              6.2.3.10    Ensure successful file system mounts are collected                  
              6.2.3.11    Ensure session initiation information is collected                  
              6.2.3.12    Ensure login and logout events are collected                        
              6.2.3.13    Ensure file deletion events by users are collected                  
              6.2.3.14    Ensure events that modify the system's Mandatory
                                                                                              
                          Access Controls are collected
              6.2.3.15    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chcon command are collected
              6.2.3.16    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          setfacl command are collected
              6.2.3.17    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chacl command are collected


                                                                                            Page 944

Internal Only - General
                                     Recommendation                                    Set
                                                                                     Correctly
                                                                                     Yes No
              6.2.3.18    Ensure successful and unsuccessful attempts to use the
                                                                                           
                          usermod command are collected
              6.2.3.19    Ensure kernel module loading unloading and modification
                                                                                           
                          is collected
              6.2.3.20    Ensure the audit configuration is immutable                      
              6.2.3.21    Ensure the running and on disk configuration is the same         
              6.2.4.1     Ensure audit log files mode is configured                        
              6.2.4.2     Ensure audit log files owner is configured                       
              6.2.4.3     Ensure audit log files group owner is configured                 
              6.2.4.4     Ensure the audit log file directory mode is configured           
              6.2.4.5     Ensure audit configuration files mode is configured              
              6.2.4.6     Ensure audit configuration files owner is configured             
              6.2.4.7     Ensure audit configuration files group owner is
                                                                                           
                          configured
              6.2.4.8     Ensure audit tools mode is configured                            
              6.2.4.9     Ensure audit tools owner is configured                           
              6.2.4.10    Ensure audit tools group owner is configured                     
              6.3.1       Ensure AIDE is installed                                         
              6.3.2       Ensure filesystem integrity is regularly checked                 
              7.1.1       Ensure access to /etc/passwd is configured                       
              7.1.2       Ensure access to /etc/passwd- is configured                      
              7.1.3       Ensure access to /etc/group is configured                        
              7.1.4       Ensure access to /etc/group- is configured                       
              7.1.5       Ensure access to /etc/shadow is configured                       
              7.1.6       Ensure access to /etc/shadow- is configured                      
              7.1.7       Ensure access to /etc/gshadow is configured                      
              7.1.8       Ensure access to /etc/gshadow- is configured                     
              7.1.9       Ensure access to /etc/shells is configured                       
              7.1.10      Ensure access to /etc/security/opasswd is configured             
              7.1.11      Ensure world writable files and directories are secured          
              7.1.12      Ensure no files or directories without an owner and a
                                                                                           
                          group exist
              7.1.13      Ensure SUID and SGID files are reviewed                          
              7.2.1       Ensure accounts in /etc/passwd use shadowed
                                                                                           
                          passwords
              7.2.2       Ensure /etc/shadow password fields are not empty                 
              7.2.4       Ensure shadow group is empty                                     
              7.2.9       Ensure local interactive user home directories are
                                                                                           
                          configured
              7.2.10      Ensure local interactive user dot files access is
                                                                                           
                          configured


                                                                                         Page 945

Internal Only - General
                          Page 946

Internal Only - General
            Appendix: CIS Controls v7 Unmapped
            Recommendations
                                    Recommendation                                  Set
                                                                                 Correctly
                                                                                 Yes No
              1.7.2       Ensure GDM login banner is configured                        
              1.7.3       Ensure GDM disable-user-list option is enabled               
              1.7.7       Ensure GDM disabling automatic mounting of removable
                                                                                       
                          media is not overridden
              2.4.1.7     Ensure access to /etc/cron.yearly is configured              
              6.2.2.3     Ensure system is disabled when audit logs are full           
              7.2.3       Ensure all groups in /etc/passwd exist in /etc/group         




                                                                                     Page 947

Internal Only - General
            Appendix: CIS Controls v8 IG 1 Mapped
            Recommendations
                                     Recommendation                                 Set
                                                                                 Correctly
                                                                                 Yes No
              1.1.1.9     Ensure usb-storage kernel module is not available            
              1.1.2.1.1   Ensure /tmp is tmpfs or a separate partition                 
              1.1.2.1.2   Ensure nodev option set on /tmp partition                    
              1.1.2.1.3   Ensure nosuid option set on /tmp partition                   
              1.1.2.1.4   Ensure noexec option set on /tmp partition                   
              1.1.2.2.1   Ensure /dev/shm is tmpfs or a separate partition             
              1.1.2.2.2   Ensure nodev option set on /dev/shm partition                
              1.1.2.2.3   Ensure nosuid option set on /dev/shm partition               
              1.1.2.2.4   Ensure noexec option set on /dev/shm partition               
              1.1.2.3.1   Ensure separate partition exists for /home                   
              1.1.2.3.2   Ensure nodev option set on /home partition                   
              1.1.2.3.3   Ensure nosuid option set on /home partition                  
              1.1.2.4.1   Ensure separate partition exists for /var                    
              1.1.2.4.2   Ensure nodev option set on /var partition                    
              1.1.2.4.3   Ensure nosuid option set on /var partition                   
              1.1.2.5.1   Ensure separate partition exists for /var/tmp                
              1.1.2.5.2   Ensure nodev option set on /var/tmp partition                
              1.1.2.5.3   Ensure nosuid option set on /var/tmp partition               
              1.1.2.5.4   Ensure noexec option set on /var/tmp partition               
              1.1.2.6.1   Ensure separate partition exists for /var/log                
              1.1.2.6.2   Ensure nodev option set on /var/log partition                
              1.1.2.6.3   Ensure nosuid option set on /var/log partition               
              1.1.2.6.4   Ensure noexec option set on /var/log partition               
              1.1.2.7.1   Ensure separate partition exists for /var/log/audit          
              1.1.2.7.2   Ensure nodev option set on /var/log/audit partition          
              1.1.2.7.3   Ensure nosuid option set on /var/log/audit partition         
              1.1.2.7.4   Ensure noexec option set on /var/log/audit partition         
              1.2.1.1     Ensure GPG keys are configured                               
              1.2.1.2     Ensure package manager repositories are configured           
              1.2.2.1     Ensure updates, patches, and additional security
                                                                                       
                          software are installed
              1.3.1.1     Ensure the apparmor packages are installed                   
              1.3.1.2     Ensure AppArmor is enabled                                   
              1.3.1.3     Ensure all AppArmor Profiles are not disabled                
              1.3.1.4     Ensure all AppArmor Profiles are enforcing                   


                                                                                     Page 948

Internal Only - General
                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              1.4.1       Ensure bootloader password is set                                 
              1.4.2       Ensure access to bootloader config is configured                  
              1.6.4       Ensure access to /etc/motd is configured                          
              1.6.5       Ensure access to /etc/issue is configured                         
              1.6.6       Ensure access to /etc/issue.net is configured                     
              1.7.4       Ensure GDM screen locks when the user is idle                     
              1.7.5       Ensure GDM screen locks cannot be overridden                      
              1.7.6       Ensure GDM automatic mounting of removable media is
                                                                                            
                          disabled
              1.7.8       Ensure GDM autorun-never is enabled                               
              1.7.9       Ensure GDM autorun-never is not overridden                        
              2.1.1       Ensure autofs services are not in use                             
              2.4.1.2     Ensure access to /etc/crontab is configured                       
              2.4.1.3     Ensure access to /etc/cron.hourly is configured                   
              2.4.1.4     Ensure access to /etc/cron.daily is configured                    
              2.4.1.5     Ensure access to /etc/cron.weekly is configured                   
              2.4.1.6     Ensure access to /etc/cron.monthly is configured                  
              2.4.1.8     Ensure access to /etc/cron.d is configured                        
              2.4.1.9     Ensure access to crontab is configured                            
              2.4.2.1     Ensure access to at is configured                                 
              4.1.1       Ensure ufw is installed                                           
              4.1.2       Ensure ufw service is configured                                  
              4.1.3       Ensure ufw incoming default is configured                         
              4.1.4       Ensure ufw outgoing default is configured                         
              4.1.5       Ensure ufw routed default is configured                           
              5.1.1       Ensure access to /etc/ssh/sshd_config is configured               
              5.1.2       Ensure access to SSH private host key files is configured         
              5.1.3       Ensure access to SSH public host key files is configured          
              5.1.4       Ensure sshd access is configured                                  
              5.1.9       Ensure sshd GSSAPIAuthentication is disabled                      
              5.1.10      Ensure sshd HostbasedAuthentication is disabled                   
              5.1.11      Ensure sshd IgnoreRhosts is enabled                               
              5.1.14      Ensure sshd LogLevel is configured                                
              5.1.19      Ensure sshd PermitEmptyPasswords is disabled                      
              5.1.20      Ensure sshd PermitRootLogin is disabled                           
              5.1.22      Ensure sshd UsePAM is enabled                                     
              5.2.1       Ensure sudo is installed                                          
              5.2.2       Ensure sudo commands use pty                                      
              5.2.4       Ensure users must provide password for escalation                 




                                                                                          Page 949

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                                     Recommendation                                     Set
                                                                                      Correctly
                                                                                      Yes No
              5.2.5       Ensure re-authentication for privilege escalation is not
                                                                                            
                          disabled globally
              5.2.6       Ensure sudo timestamp_timeout is configured                       
              5.2.7       Ensure access to the su command is restricted                     
              5.3.1.3     Ensure latest version of libpam-pwquality is installed            
              5.3.2.1     Ensure pam_unix module is enabled                                 
              5.3.2.2     Ensure pam_faillock module is enabled                             
              5.3.2.3     Ensure pam_pwquality module is enabled                            
              5.3.2.4     Ensure pam_pwhistory module is enabled                            
              5.3.3.1.1   Ensure password failed attempts lockout is configured             
              5.3.3.1.2   Ensure password unlock time is configured                         
              5.3.3.1.3   Ensure password failed attempts lockout includes root
                                                                                            
                          account
              5.3.3.2.1   Ensure password number of changed characters is
                                                                                            
                          configured
              5.3.3.2.2   Ensure minimum password length is configured                      
              5.3.3.2.3   Ensure password complexity is configured                          
              5.3.3.2.4   Ensure password same consecutive characters is
                                                                                            
                          configured
              5.3.3.2.5   Ensure password maximum sequential characters is
                                                                                            
                          configured
              5.3.3.2.6   Ensure password dictionary check is enabled                       
              5.3.3.2.7   Ensure password quality checking is enforced                      
              5.3.3.2.8   Ensure password quality is enforced for the root user             
              5.3.3.3.1   Ensure password history remember is configured                    
              5.3.3.3.2   Ensure password history is enforced for the root user             
              5.3.3.4.1   Ensure pam_unix does not include nullok                           
              5.3.3.4.2   Ensure pam_unix does not include remember                         
              5.4.1.1     Ensure password expiration is configured                          
              5.4.1.2     Ensure minimum password days is configured                        
              5.4.1.3     Ensure password expiration warning days is configured             
              5.4.1.5     Ensure inactive password lock is configured                       
              5.4.1.6     Ensure all users last password change date is in the past         
              5.4.2.1     Ensure root is the only UID 0 account                             
              5.4.2.2     Ensure root is the only GID 0 account                             
              5.4.2.3     Ensure group root is the only GID 0 group                         
              5.4.2.4     Ensure root account access is controlled                          
              5.4.2.6     Ensure root user umask is configured                              
              5.4.2.7     Ensure system accounts do not have a valid login shell            
              5.4.2.8     Ensure accounts without a valid login shell are locked            
              5.4.3.2     Ensure default user shell timeout is configured                   

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Internal Only - General
                                     Recommendation                                        Set
                                                                                        Correctly
                                                                                        Yes No
              5.4.3.3     Ensure default user umask is configured                             
              6.1.1.1.1   Ensure journald service is active                                   
              6.1.1.1.2   Ensure journald log file access is configured                       
              6.1.1.1.3   Ensure journald log file rotation is configured                     
              6.1.1.1.4   Ensure journald ForwardToSyslog is disabled                         
              6.1.1.1.5   Ensure journald Storage is configured                               
              6.1.1.1.6   Ensure journald Compress is configured                              
              6.1.1.2.1   Ensure systemd-journal-remote is installed                          
              6.1.1.2.2   Ensure systemd-journal-upload authentication is
                                                                                              
                          configured
              6.1.1.2.3   Ensure systemd-journal-upload is enabled and active                 
              6.1.2.1     Ensure rsyslog is installed                                         
              6.1.2.2     Ensure rsyslog service is enabled and active                        
              6.1.2.3     Ensure journald is configured to send logs to rsyslog               
              6.1.2.4     Ensure rsyslog log file creation mode is configured                 
              6.1.2.5     Ensure rsyslog logging is configured                                
              6.1.2.6     Ensure rsyslog is configured to send logs to a remote log
                                                                                              
                          host
              6.1.2.8     Ensure logrotate is configured                                      
              6.1.3.1     Ensure access to all logfiles has been configured                   
              6.2.1.2     Ensure auditd service is enabled and active                         
              6.2.1.3     Ensure auditing for processes that start prior to auditd is
                                                                                              
                          enabled
              6.2.1.4     Ensure audit_backlog_limit is configured                            
              6.2.2.1     Ensure audit log storage size is configured                         
              6.2.2.2     Ensure audit logs are not automatically deleted                     
              6.2.2.3     Ensure system is disabled when audit logs are full                  
              6.2.2.4     Ensure system warns when audit logs are low on space                
              6.2.3.15    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chcon command are collected
              6.2.3.16    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          setfacl command are collected
              6.2.3.17    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chacl command are collected
              6.2.3.18    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          usermod command are collected
              6.2.3.20    Ensure the audit configuration is immutable                         
              6.2.4.1     Ensure audit log files mode is configured                           
              6.2.4.2     Ensure audit log files owner is configured                          
              6.2.4.3     Ensure audit log files group owner is configured                    
              6.2.4.4     Ensure the audit log file directory mode is configured              


                                                                                            Page 951

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                                     Recommendation                                    Set
                                                                                    Correctly
                                                                                    Yes No
              6.2.4.5     Ensure audit configuration files mode is configured             
              6.2.4.6     Ensure audit configuration files owner is configured            
              6.2.4.7     Ensure audit configuration files group owner is
                                                                                          
                          configured
              6.2.4.8     Ensure audit tools mode is configured                           
              6.2.4.9     Ensure audit tools owner is configured                          
              6.2.4.10    Ensure audit tools group owner is configured                    
              7.1.1       Ensure access to /etc/passwd is configured                      
              7.1.2       Ensure access to /etc/passwd- is configured                     
              7.1.3       Ensure access to /etc/group is configured                       
              7.1.4       Ensure access to /etc/group- is configured                      
              7.1.5       Ensure access to /etc/shadow is configured                      
              7.1.6       Ensure access to /etc/shadow- is configured                     
              7.1.7       Ensure access to /etc/gshadow is configured                     
              7.1.8       Ensure access to /etc/gshadow- is configured                    
              7.1.9       Ensure access to /etc/shells is configured                      
              7.1.10      Ensure access to /etc/security/opasswd is configured            
              7.1.11      Ensure world writable files and directories are secured         
              7.1.12      Ensure no files or directories without an owner and a
                                                                                          
                          group exist
              7.1.13      Ensure SUID and SGID files are reviewed                         
              7.2.2       Ensure /etc/shadow password fields are not empty                
              7.2.3       Ensure all groups in /etc/passwd exist in /etc/group            
              7.2.4       Ensure shadow group is empty                                    
              7.2.9       Ensure local interactive user home directories are
                                                                                          
                          configured
              7.2.10      Ensure local interactive user dot files access is
                                                                                          
                          configured




                                                                                        Page 952

Internal Only - General
            Appendix: CIS Controls v8 IG 2 Mapped
            Recommendations
                                     Recommendation                                Set
                                                                                Correctly
                                                                                Yes No
              1.1.1.1     Ensure cramfs kernel module is not available                
              1.1.1.2     Ensure freevxfs kernel module is not available              
              1.1.1.3     Ensure hfs kernel module is not available                   
              1.1.1.4     Ensure hfsplus kernel module is not available               
              1.1.1.5     Ensure jffs2 kernel module is not available                 
              1.1.1.6     Ensure overlay kernel module is not available               
              1.1.1.7     Ensure squashfs kernel module is not available              
              1.1.1.8     Ensure udf kernel module is not available                   
              1.1.1.9     Ensure usb-storage kernel module is not available           
              1.1.1.10    Ensure unused filesystems kernel modules are not
                                                                                      
                          available
              1.1.1.11    Ensure firewire-core kernel module is not available         
              1.1.2.1.1   Ensure /tmp is tmpfs or a separate partition                
              1.1.2.1.2   Ensure nodev option set on /tmp partition                   
              1.1.2.1.3   Ensure nosuid option set on /tmp partition                  
              1.1.2.1.4   Ensure noexec option set on /tmp partition                  
              1.1.2.2.1   Ensure /dev/shm is tmpfs or a separate partition            
              1.1.2.2.2   Ensure nodev option set on /dev/shm partition               
              1.1.2.2.3   Ensure nosuid option set on /dev/shm partition              
              1.1.2.2.4   Ensure noexec option set on /dev/shm partition              
              1.1.2.3.1   Ensure separate partition exists for /home                  
              1.1.2.3.2   Ensure nodev option set on /home partition                  
              1.1.2.3.3   Ensure nosuid option set on /home partition                 
              1.1.2.4.1   Ensure separate partition exists for /var                   
              1.1.2.4.2   Ensure nodev option set on /var partition                   
              1.1.2.4.3   Ensure nosuid option set on /var partition                  
              1.1.2.5.1   Ensure separate partition exists for /var/tmp               
              1.1.2.5.2   Ensure nodev option set on /var/tmp partition               
              1.1.2.5.3   Ensure nosuid option set on /var/tmp partition              
              1.1.2.5.4   Ensure noexec option set on /var/tmp partition              
              1.1.2.6.1   Ensure separate partition exists for /var/log               
              1.1.2.6.2   Ensure nodev option set on /var/log partition               
              1.1.2.6.3   Ensure nosuid option set on /var/log partition              
              1.1.2.6.4   Ensure noexec option set on /var/log partition              
              1.1.2.7.1   Ensure separate partition exists for /var/log/audit         


                                                                                    Page 953

Internal Only - General
                                    Recommendation                                  Set
                                                                                 Correctly
                                                                                 Yes No
              1.1.2.7.2   Ensure nodev option set on /var/log/audit partition          
              1.1.2.7.3   Ensure nosuid option set on /var/log/audit partition         
              1.1.2.7.4   Ensure noexec option set on /var/log/audit partition         
              1.2.1.1     Ensure GPG keys are configured                               
              1.2.1.2     Ensure package manager repositories are configured           
              1.2.2.1     Ensure updates, patches, and additional security
                                                                                       
                          software are installed
              1.3.1.1     Ensure the apparmor packages are installed                   
              1.3.1.2     Ensure AppArmor is enabled                                   
              1.3.1.3     Ensure all AppArmor Profiles are not disabled                
              1.3.1.4     Ensure all AppArmor Profiles are enforcing                   
              1.4.1       Ensure bootloader password is set                            
              1.4.2       Ensure access to bootloader config is configured             
              1.5.1       Ensure randomize_va_space is configured                      
              1.5.2       Ensure ptrace_scope is configured                            
              1.5.6       Ensure Automatic Error Reporting is configured               
              1.6.4       Ensure access to /etc/motd is configured                     
              1.6.5       Ensure access to /etc/issue is configured                    
              1.6.6       Ensure access to /etc/issue.net is configured                
              1.7.1       Ensure GDM is removed                                        
              1.7.4       Ensure GDM screen locks when the user is idle                
              1.7.5       Ensure GDM screen locks cannot be overridden                 
              1.7.6       Ensure GDM automatic mounting of removable media is
                                                                                       
                          disabled
              1.7.8       Ensure GDM autorun-never is enabled                          
              1.7.9       Ensure GDM autorun-never is not overridden                   
              1.7.10      Ensure XDMCP is not enabled                                  
              1.7.11      Ensure Xwayland is configured                                
              2.1.1       Ensure autofs services are not in use                        
              2.1.2       Ensure avahi daemon services are not in use                  
              2.1.3       Ensure dhcp server services are not in use                   
              2.1.4       Ensure dns server services are not in use                    
              2.1.5       Ensure dnsmasq services are not in use                       
              2.1.6       Ensure ftp server services are not in use                    
              2.1.7       Ensure ldap server services are not in use                   
              2.1.8       Ensure message access server services are not in use         
              2.1.9       Ensure network file system services are not in use           
              2.1.10      Ensure nis server services are not in use                    
              2.1.11      Ensure print server services are not in use                  
              2.1.12      Ensure rpcbind services are not in use                       


                                                                                     Page 954

Internal Only - General
                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              2.1.13      Ensure rsync services are not in use                              
              2.1.14      Ensure samba file server services are not in use                  
              2.1.15      Ensure snmp services are not in use                               
              2.1.16      Ensure tftp server services are not in use                        
              2.1.17      Ensure web proxy server services are not in use                   
              2.1.18      Ensure web server services are not in use                         
              2.1.19      Ensure xinetd services are not in use                             
              2.1.20      Ensure X window server services are not in use                    
              2.1.21      Ensure mail transfer agents are configured for local-only
                                                                                            
                          mode
              2.1.22      Ensure only approved services are listening on a network
                                                                                            
                          interface
              2.2.1       Ensure nis client is not installed                                
              2.2.2       Ensure rsh client is not installed                                
              2.2.3       Ensure talk client is not installed                               
              2.2.4       Ensure telnet client is not installed                             
              2.2.5       Ensure ldap client is not installed                               
              2.2.6       Ensure ftp client is not installed                                
              2.3.1.1     Ensure a single time synchronization daemon is in use             
              2.3.2.1     Ensure systemd-timesyncd configured with authorized
                                                                                            
                          timeserver
              2.3.2.2     Ensure systemd-timesyncd is enabled and running                   
              2.3.3.1     Ensure chrony is configured with authorized timeserver            
              2.3.3.3     Ensure chrony is enabled and running                              
              2.4.1.2     Ensure access to /etc/crontab is configured                       
              2.4.1.3     Ensure access to /etc/cron.hourly is configured                   
              2.4.1.4     Ensure access to /etc/cron.daily is configured                    
              2.4.1.5     Ensure access to /etc/cron.weekly is configured                   
              2.4.1.6     Ensure access to /etc/cron.monthly is configured                  
              2.4.1.8     Ensure access to /etc/cron.d is configured                        
              2.4.1.9     Ensure access to crontab is configured                            
              2.4.2.1     Ensure access to at is configured                                 
              3.1.1       Ensure IPv6 status is identified                                  
              3.1.2       Ensure wireless interfaces are not available                      
              3.1.3       Ensure bluetooth services are not in use                          
              3.2.1       Ensure dccp kernel module is not available                        
              3.2.2       Ensure tipc kernel module is not available                        
              3.2.3       Ensure rds kernel module is not available                         
              3.2.4       Ensure sctp kernel module is not available                        
              3.3.1.1     Ensure net.ipv4.ip_forward is configured                          



                                                                                          Page 955

Internal Only - General
                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              3.3.1.2     Ensure net.ipv4.conf.all.forwarding is configured                 
              3.3.1.3     Ensure net.ipv4.conf.default.forwarding is configured             
              3.3.1.4     Ensure net.ipv4.conf.all.send_redirects is configured             
              3.3.1.5     Ensure net.ipv4.conf.default.send_redirects is configured         
              3.3.1.6     Ensure net.ipv4.icmp_ignore_bogus_error_responses is
                                                                                            
                          configured
              3.3.1.7     Ensure net.ipv4.icmp_echo_ignore_broadcasts is
                                                                                            
                          configured
              3.3.1.8     Ensure net.ipv4.conf.all.accept_redirects is configured           
              3.3.1.9     Ensure net.ipv4.conf.default.accept_redirects is
                                                                                            
                          configured
              3.3.1.10    Ensure net.ipv4.conf.all.secure_redirects is configured           
              3.3.1.11    Ensure net.ipv4.conf.default.secure_redirects is
                                                                                            
                          configured
              3.3.1.12    Ensure net.ipv4.conf.all.rp_filter is configured                  
              3.3.1.13    Ensure net.ipv4.conf.default.rp_filter is configured              
              3.3.1.14    Ensure net.ipv4.conf.all.accept_source_route is
                                                                                            
                          configured
              3.3.1.15    Ensure net.ipv4.conf.default.accept_source_route is
                                                                                            
                          configured
              3.3.1.16    Ensure net.ipv4.conf.all.log_martians is configured               
              3.3.1.17    Ensure net.ipv4.conf.default.log_martians is configured           
              3.3.1.18    Ensure net.ipv4.tcp_syncookies is configured                      
              3.3.2.1     Ensure net.ipv6.conf.all.forwarding is configured                 
              3.3.2.2     Ensure net.ipv6.conf.default.forwarding is configured             
              3.3.2.3     Ensure net.ipv6.conf.all.accept_redirects is configured           
              3.3.2.4     Ensure net.ipv6.conf.default.accept_redirects is
                                                                                            
                          configured
              3.3.2.5     Ensure net.ipv6.conf.all.accept_source_route is
                                                                                            
                          configured
              3.3.2.6     Ensure net.ipv6.conf.default.accept_source_route is
                                                                                            
                          configured
              3.3.2.7     Ensure net.ipv6.conf.all.accept_ra is configured                  
              3.3.2.8     Ensure net.ipv6.conf.default.accept_ra is configured              
              4.1.1       Ensure ufw is installed                                           
              4.1.2       Ensure ufw service is configured                                  
              4.1.3       Ensure ufw incoming default is configured                         
              4.1.4       Ensure ufw outgoing default is configured                         
              4.1.5       Ensure ufw routed default is configured                           
              5.1.1       Ensure access to /etc/ssh/sshd_config is configured               
              5.1.2       Ensure access to SSH private host key files is configured         


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                                     Recommendation                                     Set
                                                                                     Correctly
                                                                                     Yes No
              5.1.3       Ensure access to SSH public host key files is configured         
              5.1.4       Ensure sshd access is configured                                 
              5.1.6       Ensure sshd Ciphers are configured                               
              5.1.8       Ensure sshd DisableForwarding is enabled                         
              5.1.9       Ensure sshd GSSAPIAuthentication is disabled                     
              5.1.10      Ensure sshd HostbasedAuthentication is disabled                  
              5.1.11      Ensure sshd IgnoreRhosts is enabled                              
              5.1.12      Ensure sshd KexAlgorithms is configured                          
              5.1.14      Ensure sshd LogLevel is configured                               
              5.1.15      Ensure sshd MACs are configured                                  
              5.1.16      Ensure sshd MaxAuthTries is configured                           
              5.1.19      Ensure sshd PermitEmptyPasswords is disabled                     
              5.1.20      Ensure sshd PermitRootLogin is disabled                          
              5.1.22      Ensure sshd UsePAM is enabled                                    
              5.2.1       Ensure sudo is installed                                         
              5.2.2       Ensure sudo commands use pty                                     
              5.2.3       Ensure sudo log file exists                                      
              5.2.4       Ensure users must provide password for escalation                
              5.2.5       Ensure re-authentication for privilege escalation is not
                                                                                           
                          disabled globally
              5.2.6       Ensure sudo timestamp_timeout is configured                      
              5.2.7       Ensure access to the su command is restricted                    
              5.3.1.3     Ensure latest version of libpam-pwquality is installed           
              5.3.2.1     Ensure pam_unix module is enabled                                
              5.3.2.2     Ensure pam_faillock module is enabled                            
              5.3.2.3     Ensure pam_pwquality module is enabled                           
              5.3.2.4     Ensure pam_pwhistory module is enabled                           
              5.3.3.1.1   Ensure password failed attempts lockout is configured            
              5.3.3.1.2   Ensure password unlock time is configured                        
              5.3.3.1.3   Ensure password failed attempts lockout includes root
                                                                                           
                          account
              5.3.3.2.1   Ensure password number of changed characters is
                                                                                           
                          configured
              5.3.3.2.2   Ensure minimum password length is configured                     
              5.3.3.2.3   Ensure password complexity is configured                         
              5.3.3.2.4   Ensure password same consecutive characters is
                                                                                           
                          configured
              5.3.3.2.5   Ensure password maximum sequential characters is
                                                                                           
                          configured
              5.3.3.2.6   Ensure password dictionary check is enabled                      
              5.3.3.2.7   Ensure password quality checking is enforced                     

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                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              5.3.3.2.8   Ensure password quality is enforced for the root user             
              5.3.3.3.1   Ensure password history remember is configured                    
              5.3.3.3.2   Ensure password history is enforced for the root user             
              5.3.3.3.3   Ensure pam_pwhistory includes use_authtok                         
              5.3.3.4.1   Ensure pam_unix does not include nullok                           
              5.3.3.4.2   Ensure pam_unix does not include remember                         
              5.3.3.4.3   Ensure pam_unix includes a strong password hashing
                                                                                            
                          algorithm
              5.3.3.4.4   Ensure pam_unix includes use_authtok                              
              5.4.1.1     Ensure password expiration is configured                          
              5.4.1.2     Ensure minimum password days is configured                        
              5.4.1.3     Ensure password expiration warning days is configured             
              5.4.1.4     Ensure strong password hashing algorithm is configured            
              5.4.1.5     Ensure inactive password lock is configured                       
              5.4.1.6     Ensure all users last password change date is in the past         
              5.4.2.1     Ensure root is the only UID 0 account                             
              5.4.2.2     Ensure root is the only GID 0 account                             
              5.4.2.3     Ensure group root is the only GID 0 group                         
              5.4.2.4     Ensure root account access is controlled                          
              5.4.2.6     Ensure root user umask is configured                              
              5.4.2.7     Ensure system accounts do not have a valid login shell            
              5.4.2.8     Ensure accounts without a valid login shell are locked            
              5.4.3.2     Ensure default user shell timeout is configured                   
              5.4.3.3     Ensure default user umask is configured                           
              6.1.1.1.1   Ensure journald service is active                                 
              6.1.1.1.2   Ensure journald log file access is configured                     
              6.1.1.1.3   Ensure journald log file rotation is configured                   
              6.1.1.1.4   Ensure journald ForwardToSyslog is disabled                       
              6.1.1.1.5   Ensure journald Storage is configured                             
              6.1.1.1.6   Ensure journald Compress is configured                            
              6.1.1.2.1   Ensure systemd-journal-remote is installed                        
              6.1.1.2.2   Ensure systemd-journal-upload authentication is
                                                                                            
                          configured
              6.1.1.2.3   Ensure systemd-journal-upload is enabled and active               
              6.1.1.2.4   Ensure systemd-journal-remote service is not in use               
              6.1.2.1     Ensure rsyslog is installed                                       
              6.1.2.2     Ensure rsyslog service is enabled and active                      
              6.1.2.3     Ensure journald is configured to send logs to rsyslog             
              6.1.2.4     Ensure rsyslog log file creation mode is configured               
              6.1.2.5     Ensure rsyslog logging is configured                              


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                                     Recommendation                                       Set
                                                                                        Correctly
                                                                                        Yes No
              6.1.2.6     Ensure rsyslog is configured to send logs to a remote log
                                                                                              
                          host
              6.1.2.7     Ensure rsyslog is not configured to receive logs from a
                                                                                              
                          remote client
              6.1.2.8     Ensure logrotate is configured                                      
              6.1.3.1     Ensure access to all logfiles has been configured                   
              6.2.1.1     Ensure auditd packages are installed                                
              6.2.1.2     Ensure auditd service is enabled and active                         
              6.2.1.3     Ensure auditing for processes that start prior to auditd is
                                                                                              
                          enabled
              6.2.1.4     Ensure audit_backlog_limit is configured                            
              6.2.2.1     Ensure audit log storage size is configured                         
              6.2.2.2     Ensure audit logs are not automatically deleted                     
              6.2.2.3     Ensure system is disabled when audit logs are full                  
              6.2.2.4     Ensure system warns when audit logs are low on space                
              6.2.3.1     Ensure changes to system administration scope
                                                                                              
                          (sudoers) is collected
              6.2.3.2     Ensure actions as another user are always logged                    
              6.2.3.3     Ensure events that modify the sudo log file are collected           
              6.2.3.4     Ensure events that modify date and time information are
                                                                                              
                          collected
              6.2.3.5     Ensure events that modify the system's network
                                                                                              
                          environment are collected
              6.2.3.6     Ensure use of privileged commands are collected                     
              6.2.3.7     Ensure unsuccessful file access attempts are collected              
              6.2.3.8     Ensure events that modify user/group information are
                                                                                              
                          collected
              6.2.3.9     Ensure discretionary access control permission
                                                                                              
                          modification events are collected
              6.2.3.10    Ensure successful file system mounts are collected                  
              6.2.3.11    Ensure session initiation information is collected                  
              6.2.3.12    Ensure login and logout events are collected                        
              6.2.3.13    Ensure file deletion events by users are collected                  
              6.2.3.14    Ensure events that modify the system's Mandatory
                                                                                              
                          Access Controls are collected
              6.2.3.15    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chcon command are collected
              6.2.3.16    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          setfacl command are collected
              6.2.3.17    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chacl command are collected


                                                                                            Page 959

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                                     Recommendation                                    Set
                                                                                     Correctly
                                                                                     Yes No
              6.2.3.18    Ensure successful and unsuccessful attempts to use the
                                                                                           
                          usermod command are collected
              6.2.3.19    Ensure kernel module loading unloading and modification
                                                                                           
                          is collected
              6.2.3.20    Ensure the audit configuration is immutable                      
              6.2.3.21    Ensure the running and on disk configuration is the same         
              6.2.4.1     Ensure audit log files mode is configured                        
              6.2.4.2     Ensure audit log files owner is configured                       
              6.2.4.3     Ensure audit log files group owner is configured                 
              6.2.4.4     Ensure the audit log file directory mode is configured           
              6.2.4.5     Ensure audit configuration files mode is configured              
              6.2.4.6     Ensure audit configuration files owner is configured             
              6.2.4.7     Ensure audit configuration files group owner is
                                                                                           
                          configured
              6.2.4.8     Ensure audit tools mode is configured                            
              6.2.4.9     Ensure audit tools owner is configured                           
              6.2.4.10    Ensure audit tools group owner is configured                     
              7.1.1       Ensure access to /etc/passwd is configured                       
              7.1.2       Ensure access to /etc/passwd- is configured                      
              7.1.3       Ensure access to /etc/group is configured                        
              7.1.4       Ensure access to /etc/group- is configured                       
              7.1.5       Ensure access to /etc/shadow is configured                       
              7.1.6       Ensure access to /etc/shadow- is configured                      
              7.1.7       Ensure access to /etc/gshadow is configured                      
              7.1.8       Ensure access to /etc/gshadow- is configured                     
              7.1.9       Ensure access to /etc/shells is configured                       
              7.1.10      Ensure access to /etc/security/opasswd is configured             
              7.1.11      Ensure world writable files and directories are secured          
              7.1.12      Ensure no files or directories without an owner and a
                                                                                           
                          group exist
              7.1.13      Ensure SUID and SGID files are reviewed                          
              7.2.1       Ensure accounts in /etc/passwd use shadowed
                                                                                           
                          passwords
              7.2.2       Ensure /etc/shadow password fields are not empty                 
              7.2.3       Ensure all groups in /etc/passwd exist in /etc/group             
              7.2.4       Ensure shadow group is empty                                     
              7.2.9       Ensure local interactive user home directories are
                                                                                           
                          configured
              7.2.10      Ensure local interactive user dot files access is
                                                                                           
                          configured



                                                                                         Page 960

Internal Only - General
            Appendix: CIS Controls v8 IG 3 Mapped
            Recommendations
                                     Recommendation                                Set
                                                                                Correctly
                                                                                Yes No
              1.1.1.1     Ensure cramfs kernel module is not available                
              1.1.1.2     Ensure freevxfs kernel module is not available              
              1.1.1.3     Ensure hfs kernel module is not available                   
              1.1.1.4     Ensure hfsplus kernel module is not available               
              1.1.1.5     Ensure jffs2 kernel module is not available                 
              1.1.1.6     Ensure overlay kernel module is not available               
              1.1.1.7     Ensure squashfs kernel module is not available              
              1.1.1.8     Ensure udf kernel module is not available                   
              1.1.1.9     Ensure usb-storage kernel module is not available           
              1.1.1.10    Ensure unused filesystems kernel modules are not
                                                                                      
                          available
              1.1.1.11    Ensure firewire-core kernel module is not available         
              1.1.2.1.1   Ensure /tmp is tmpfs or a separate partition                
              1.1.2.1.2   Ensure nodev option set on /tmp partition                   
              1.1.2.1.3   Ensure nosuid option set on /tmp partition                  
              1.1.2.1.4   Ensure noexec option set on /tmp partition                  
              1.1.2.2.1   Ensure /dev/shm is tmpfs or a separate partition            
              1.1.2.2.2   Ensure nodev option set on /dev/shm partition               
              1.1.2.2.3   Ensure nosuid option set on /dev/shm partition              
              1.1.2.2.4   Ensure noexec option set on /dev/shm partition              
              1.1.2.3.1   Ensure separate partition exists for /home                  
              1.1.2.3.2   Ensure nodev option set on /home partition                  
              1.1.2.3.3   Ensure nosuid option set on /home partition                 
              1.1.2.4.1   Ensure separate partition exists for /var                   
              1.1.2.4.2   Ensure nodev option set on /var partition                   
              1.1.2.4.3   Ensure nosuid option set on /var partition                  
              1.1.2.5.1   Ensure separate partition exists for /var/tmp               
              1.1.2.5.2   Ensure nodev option set on /var/tmp partition               
              1.1.2.5.3   Ensure nosuid option set on /var/tmp partition              
              1.1.2.5.4   Ensure noexec option set on /var/tmp partition              
              1.1.2.6.1   Ensure separate partition exists for /var/log               
              1.1.2.6.2   Ensure nodev option set on /var/log partition               
              1.1.2.6.3   Ensure nosuid option set on /var/log partition              
              1.1.2.6.4   Ensure noexec option set on /var/log partition              
              1.1.2.7.1   Ensure separate partition exists for /var/log/audit         


                                                                                    Page 961

Internal Only - General
                                    Recommendation                                  Set
                                                                                 Correctly
                                                                                 Yes No
              1.1.2.7.2   Ensure nodev option set on /var/log/audit partition          
              1.1.2.7.3   Ensure nosuid option set on /var/log/audit partition         
              1.1.2.7.4   Ensure noexec option set on /var/log/audit partition         
              1.2.1.1     Ensure GPG keys are configured                               
              1.2.1.2     Ensure package manager repositories are configured           
              1.2.2.1     Ensure updates, patches, and additional security
                                                                                       
                          software are installed
              1.3.1.1     Ensure the apparmor packages are installed                   
              1.3.1.2     Ensure AppArmor is enabled                                   
              1.3.1.3     Ensure all AppArmor Profiles are not disabled                
              1.3.1.4     Ensure all AppArmor Profiles are enforcing                   
              1.4.1       Ensure bootloader password is set                            
              1.4.2       Ensure access to bootloader config is configured             
              1.5.1       Ensure randomize_va_space is configured                      
              1.5.2       Ensure ptrace_scope is configured                            
              1.5.5       Ensure prelink is not installed                              
              1.5.6       Ensure Automatic Error Reporting is configured               
              1.6.4       Ensure access to /etc/motd is configured                     
              1.6.5       Ensure access to /etc/issue is configured                    
              1.6.6       Ensure access to /etc/issue.net is configured                
              1.7.1       Ensure GDM is removed                                        
              1.7.4       Ensure GDM screen locks when the user is idle                
              1.7.5       Ensure GDM screen locks cannot be overridden                 
              1.7.6       Ensure GDM automatic mounting of removable media is
                                                                                       
                          disabled
              1.7.8       Ensure GDM autorun-never is enabled                          
              1.7.9       Ensure GDM autorun-never is not overridden                   
              1.7.10      Ensure XDMCP is not enabled                                  
              1.7.11      Ensure Xwayland is configured                                
              2.1.1       Ensure autofs services are not in use                        
              2.1.2       Ensure avahi daemon services are not in use                  
              2.1.3       Ensure dhcp server services are not in use                   
              2.1.4       Ensure dns server services are not in use                    
              2.1.5       Ensure dnsmasq services are not in use                       
              2.1.6       Ensure ftp server services are not in use                    
              2.1.7       Ensure ldap server services are not in use                   
              2.1.8       Ensure message access server services are not in use         
              2.1.9       Ensure network file system services are not in use           
              2.1.10      Ensure nis server services are not in use                    
              2.1.11      Ensure print server services are not in use                  


                                                                                     Page 962

Internal Only - General
                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              2.1.12      Ensure rpcbind services are not in use                            
              2.1.13      Ensure rsync services are not in use                              
              2.1.14      Ensure samba file server services are not in use                  
              2.1.15      Ensure snmp services are not in use                               
              2.1.16      Ensure tftp server services are not in use                        
              2.1.17      Ensure web proxy server services are not in use                   
              2.1.18      Ensure web server services are not in use                         
              2.1.19      Ensure xinetd services are not in use                             
              2.1.20      Ensure X window server services are not in use                    
              2.1.21      Ensure mail transfer agents are configured for local-only
                                                                                            
                          mode
              2.1.22      Ensure only approved services are listening on a network
                                                                                            
                          interface
              2.2.1       Ensure nis client is not installed                                
              2.2.2       Ensure rsh client is not installed                                
              2.2.3       Ensure talk client is not installed                               
              2.2.4       Ensure telnet client is not installed                             
              2.2.5       Ensure ldap client is not installed                               
              2.2.6       Ensure ftp client is not installed                                
              2.3.1.1     Ensure a single time synchronization daemon is in use             
              2.3.2.1     Ensure systemd-timesyncd configured with authorized
                                                                                            
                          timeserver
              2.3.2.2     Ensure systemd-timesyncd is enabled and running                   
              2.3.3.1     Ensure chrony is configured with authorized timeserver            
              2.3.3.3     Ensure chrony is enabled and running                              
              2.4.1.2     Ensure access to /etc/crontab is configured                       
              2.4.1.3     Ensure access to /etc/cron.hourly is configured                   
              2.4.1.4     Ensure access to /etc/cron.daily is configured                    
              2.4.1.5     Ensure access to /etc/cron.weekly is configured                   
              2.4.1.6     Ensure access to /etc/cron.monthly is configured                  
              2.4.1.8     Ensure access to /etc/cron.d is configured                        
              2.4.1.9     Ensure access to crontab is configured                            
              2.4.2.1     Ensure access to at is configured                                 
              3.1.1       Ensure IPv6 status is identified                                  
              3.1.2       Ensure wireless interfaces are not available                      
              3.1.3       Ensure bluetooth services are not in use                          
              3.2.1       Ensure dccp kernel module is not available                        
              3.2.2       Ensure tipc kernel module is not available                        
              3.2.3       Ensure rds kernel module is not available                         
              3.2.4       Ensure sctp kernel module is not available                        



                                                                                          Page 963

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                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              3.3.1.1     Ensure net.ipv4.ip_forward is configured                          
              3.3.1.2     Ensure net.ipv4.conf.all.forwarding is configured                 
              3.3.1.3     Ensure net.ipv4.conf.default.forwarding is configured             
              3.3.1.4     Ensure net.ipv4.conf.all.send_redirects is configured             
              3.3.1.5     Ensure net.ipv4.conf.default.send_redirects is configured         
              3.3.1.6     Ensure net.ipv4.icmp_ignore_bogus_error_responses is
                                                                                            
                          configured
              3.3.1.7     Ensure net.ipv4.icmp_echo_ignore_broadcasts is
                                                                                            
                          configured
              3.3.1.8     Ensure net.ipv4.conf.all.accept_redirects is configured           
              3.3.1.9     Ensure net.ipv4.conf.default.accept_redirects is
                                                                                            
                          configured
              3.3.1.10    Ensure net.ipv4.conf.all.secure_redirects is configured           
              3.3.1.11    Ensure net.ipv4.conf.default.secure_redirects is
                                                                                            
                          configured
              3.3.1.12    Ensure net.ipv4.conf.all.rp_filter is configured                  
              3.3.1.13    Ensure net.ipv4.conf.default.rp_filter is configured              
              3.3.1.14    Ensure net.ipv4.conf.all.accept_source_route is
                                                                                            
                          configured
              3.3.1.15    Ensure net.ipv4.conf.default.accept_source_route is
                                                                                            
                          configured
              3.3.1.16    Ensure net.ipv4.conf.all.log_martians is configured               
              3.3.1.17    Ensure net.ipv4.conf.default.log_martians is configured           
              3.3.1.18    Ensure net.ipv4.tcp_syncookies is configured                      
              3.3.2.1     Ensure net.ipv6.conf.all.forwarding is configured                 
              3.3.2.2     Ensure net.ipv6.conf.default.forwarding is configured             
              3.3.2.3     Ensure net.ipv6.conf.all.accept_redirects is configured           
              3.3.2.4     Ensure net.ipv6.conf.default.accept_redirects is
                                                                                            
                          configured
              3.3.2.5     Ensure net.ipv6.conf.all.accept_source_route is
                                                                                            
                          configured
              3.3.2.6     Ensure net.ipv6.conf.default.accept_source_route is
                                                                                            
                          configured
              3.3.2.7     Ensure net.ipv6.conf.all.accept_ra is configured                  
              3.3.2.8     Ensure net.ipv6.conf.default.accept_ra is configured              
              4.1.1       Ensure ufw is installed                                           
              4.1.2       Ensure ufw service is configured                                  
              4.1.3       Ensure ufw incoming default is configured                         
              4.1.4       Ensure ufw outgoing default is configured                         
              4.1.5       Ensure ufw routed default is configured                           
              5.1.1       Ensure access to /etc/ssh/sshd_config is configured               


                                                                                          Page 964

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                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              5.1.2       Ensure access to SSH private host key files is configured         
              5.1.3       Ensure access to SSH public host key files is configured          
              5.1.4       Ensure sshd access is configured                                  
              5.1.6       Ensure sshd Ciphers are configured                                
              5.1.8       Ensure sshd DisableForwarding is enabled                          
              5.1.9       Ensure sshd GSSAPIAuthentication is disabled                      
              5.1.10      Ensure sshd HostbasedAuthentication is disabled                   
              5.1.11      Ensure sshd IgnoreRhosts is enabled                               
              5.1.12      Ensure sshd KexAlgorithms is configured                           
              5.1.14      Ensure sshd LogLevel is configured                                
              5.1.15      Ensure sshd MACs are configured                                   
              5.1.16      Ensure sshd MaxAuthTries is configured                            
              5.1.19      Ensure sshd PermitEmptyPasswords is disabled                      
              5.1.20      Ensure sshd PermitRootLogin is disabled                           
              5.1.22      Ensure sshd UsePAM is enabled                                     
              5.2.1       Ensure sudo is installed                                          
              5.2.2       Ensure sudo commands use pty                                      
              5.2.3       Ensure sudo log file exists                                       
              5.2.4       Ensure users must provide password for escalation                 
              5.2.5       Ensure re-authentication for privilege escalation is not
                                                                                            
                          disabled globally
              5.2.6       Ensure sudo timestamp_timeout is configured                       
              5.2.7       Ensure access to the su command is restricted                     
              5.3.1.3     Ensure latest version of libpam-pwquality is installed            
              5.3.2.1     Ensure pam_unix module is enabled                                 
              5.3.2.2     Ensure pam_faillock module is enabled                             
              5.3.2.3     Ensure pam_pwquality module is enabled                            
              5.3.2.4     Ensure pam_pwhistory module is enabled                            
              5.3.3.1.1   Ensure password failed attempts lockout is configured             
              5.3.3.1.2   Ensure password unlock time is configured                         
              5.3.3.1.3   Ensure password failed attempts lockout includes root
                                                                                            
                          account
              5.3.3.2.1   Ensure password number of changed characters is
                                                                                            
                          configured
              5.3.3.2.2   Ensure minimum password length is configured                      
              5.3.3.2.3   Ensure password complexity is configured                          
              5.3.3.2.4   Ensure password same consecutive characters is
                                                                                            
                          configured
              5.3.3.2.5   Ensure password maximum sequential characters is
                                                                                            
                          configured
              5.3.3.2.6   Ensure password dictionary check is enabled                       

                                                                                          Page 965

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                                     Recommendation                                      Set
                                                                                      Correctly
                                                                                      Yes No
              5.3.3.2.7   Ensure password quality checking is enforced                      
              5.3.3.2.8   Ensure password quality is enforced for the root user             
              5.3.3.3.1   Ensure password history remember is configured                    
              5.3.3.3.2   Ensure password history is enforced for the root user             
              5.3.3.3.3   Ensure pam_pwhistory includes use_authtok                         
              5.3.3.4.1   Ensure pam_unix does not include nullok                           
              5.3.3.4.2   Ensure pam_unix does not include remember                         
              5.3.3.4.3   Ensure pam_unix includes a strong password hashing
                                                                                            
                          algorithm
              5.3.3.4.4   Ensure pam_unix includes use_authtok                              
              5.4.1.1     Ensure password expiration is configured                          
              5.4.1.2     Ensure minimum password days is configured                        
              5.4.1.3     Ensure password expiration warning days is configured             
              5.4.1.4     Ensure strong password hashing algorithm is configured            
              5.4.1.5     Ensure inactive password lock is configured                       
              5.4.1.6     Ensure all users last password change date is in the past         
              5.4.2.1     Ensure root is the only UID 0 account                             
              5.4.2.2     Ensure root is the only GID 0 account                             
              5.4.2.3     Ensure group root is the only GID 0 group                         
              5.4.2.4     Ensure root account access is controlled                          
              5.4.2.6     Ensure root user umask is configured                              
              5.4.2.7     Ensure system accounts do not have a valid login shell            
              5.4.2.8     Ensure accounts without a valid login shell are locked            
              5.4.3.2     Ensure default user shell timeout is configured                   
              5.4.3.3     Ensure default user umask is configured                           
              6.1.1.1.1   Ensure journald service is active                                 
              6.1.1.1.2   Ensure journald log file access is configured                     
              6.1.1.1.3   Ensure journald log file rotation is configured                   
              6.1.1.1.4   Ensure journald ForwardToSyslog is disabled                       
              6.1.1.1.5   Ensure journald Storage is configured                             
              6.1.1.1.6   Ensure journald Compress is configured                            
              6.1.1.2.1   Ensure systemd-journal-remote is installed                        
              6.1.1.2.2   Ensure systemd-journal-upload authentication is
                                                                                            
                          configured
              6.1.1.2.3   Ensure systemd-journal-upload is enabled and active               
              6.1.1.2.4   Ensure systemd-journal-remote service is not in use               
              6.1.2.1     Ensure rsyslog is installed                                       
              6.1.2.2     Ensure rsyslog service is enabled and active                      
              6.1.2.3     Ensure journald is configured to send logs to rsyslog             
              6.1.2.4     Ensure rsyslog log file creation mode is configured               


                                                                                          Page 966

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                                     Recommendation                                        Set
                                                                                        Correctly
                                                                                        Yes No
              6.1.2.5     Ensure rsyslog logging is configured                                
              6.1.2.6     Ensure rsyslog is configured to send logs to a remote log
                                                                                              
                          host
              6.1.2.7     Ensure rsyslog is not configured to receive logs from a
                                                                                              
                          remote client
              6.1.2.8     Ensure logrotate is configured                                      
              6.1.3.1     Ensure access to all logfiles has been configured                   
              6.2.1.1     Ensure auditd packages are installed                                
              6.2.1.2     Ensure auditd service is enabled and active                         
              6.2.1.3     Ensure auditing for processes that start prior to auditd is
                                                                                              
                          enabled
              6.2.1.4     Ensure audit_backlog_limit is configured                            
              6.2.2.1     Ensure audit log storage size is configured                         
              6.2.2.2     Ensure audit logs are not automatically deleted                     
              6.2.2.3     Ensure system is disabled when audit logs are full                  
              6.2.2.4     Ensure system warns when audit logs are low on space                
              6.2.3.1     Ensure changes to system administration scope
                                                                                              
                          (sudoers) is collected
              6.2.3.2     Ensure actions as another user are always logged                    
              6.2.3.3     Ensure events that modify the sudo log file are collected           
              6.2.3.4     Ensure events that modify date and time information are
                                                                                              
                          collected
              6.2.3.5     Ensure events that modify the system's network
                                                                                              
                          environment are collected
              6.2.3.6     Ensure use of privileged commands are collected                     
              6.2.3.7     Ensure unsuccessful file access attempts are collected              
              6.2.3.8     Ensure events that modify user/group information are
                                                                                              
                          collected
              6.2.3.9     Ensure discretionary access control permission
                                                                                              
                          modification events are collected
              6.2.3.10    Ensure successful file system mounts are collected                  
              6.2.3.11    Ensure session initiation information is collected                  
              6.2.3.12    Ensure login and logout events are collected                        
              6.2.3.13    Ensure file deletion events by users are collected                  
              6.2.3.14    Ensure events that modify the system's Mandatory
                                                                                              
                          Access Controls are collected
              6.2.3.15    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          chcon command are collected
              6.2.3.16    Ensure successful and unsuccessful attempts to use the
                                                                                              
                          setfacl command are collected



                                                                                            Page 967

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                                     Recommendation                                    Set
                                                                                     Correctly
                                                                                     Yes No
              6.2.3.17    Ensure successful and unsuccessful attempts to use the
                                                                                           
                          chacl command are collected
              6.2.3.18    Ensure successful and unsuccessful attempts to use the
                                                                                           
                          usermod command are collected
              6.2.3.19    Ensure kernel module loading unloading and modification
                                                                                           
                          is collected
              6.2.3.20    Ensure the audit configuration is immutable                      
              6.2.3.21    Ensure the running and on disk configuration is the same         
              6.2.4.1     Ensure audit log files mode is configured                        
              6.2.4.2     Ensure audit log files owner is configured                       
              6.2.4.3     Ensure audit log files group owner is configured                 
              6.2.4.4     Ensure the audit log file directory mode is configured           
              6.2.4.5     Ensure audit configuration files mode is configured              
              6.2.4.6     Ensure audit configuration files owner is configured             
              6.2.4.7     Ensure audit configuration files group owner is
                                                                                           
                          configured
              6.2.4.8     Ensure audit tools mode is configured                            
              6.2.4.9     Ensure audit tools owner is configured                           
              6.2.4.10    Ensure audit tools group owner is configured                     
              6.3.1       Ensure AIDE is installed                                         
              6.3.2       Ensure filesystem integrity is regularly checked                 
              7.1.1       Ensure access to /etc/passwd is configured                       
              7.1.2       Ensure access to /etc/passwd- is configured                      
              7.1.3       Ensure access to /etc/group is configured                        
              7.1.4       Ensure access to /etc/group- is configured                       
              7.1.5       Ensure access to /etc/shadow is configured                       
              7.1.6       Ensure access to /etc/shadow- is configured                      
              7.1.7       Ensure access to /etc/gshadow is configured                      
              7.1.8       Ensure access to /etc/gshadow- is configured                     
              7.1.9       Ensure access to /etc/shells is configured                       
              7.1.10      Ensure access to /etc/security/opasswd is configured             
              7.1.11      Ensure world writable files and directories are secured          
              7.1.12      Ensure no files or directories without an owner and a
                                                                                           
                          group exist
              7.1.13      Ensure SUID and SGID files are reviewed                          
              7.2.1       Ensure accounts in /etc/passwd use shadowed
                                                                                           
                          passwords
              7.2.2       Ensure /etc/shadow password fields are not empty                 
              7.2.3       Ensure all groups in /etc/passwd exist in /etc/group             
              7.2.4       Ensure shadow group is empty                                     



                                                                                         Page 968

Internal Only - General
                                     Recommendation                              Set
                                                                               Correctly
                                                                               Yes No
              7.2.9       Ensure local interactive user home directories are
                                                                                     
                          configured
              7.2.10      Ensure local interactive user dot files access is
                                                                                     
                          configured




                                                                                   Page 969

Internal Only - General
            Appendix: CIS Controls v8 Unmapped
            Recommendations
                                    Recommendation                                  Set
                                                                                 Correctly
                                                                                 Yes No
              1.7.2       Ensure GDM login banner is configured                        
              1.7.3       Ensure GDM disable-user-list option is enabled               
              1.7.7       Ensure GDM disabling automatic mounting of removable
                                                                                       
                          media is not overridden
              2.4.1.7     Ensure access to /etc/cron.yearly is configured              




                                                                                     Page 970

Internal Only - General
            Appendix: Change History
              Date           Version Changes for this version
              ADDED:
                                      ADDED RECOMMENDATION: 1.1.1.10 - Ensure unused filesystems kernel modules are not
                10/30/2025    3.0.0   available
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.1.1.11 - Ensure firewire-core kernel module is not available
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.1.1.6 - Ensure overlay kernel module is not available
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.1.2.1.1 - Ensure /tmp is tmpfs or a separate partition
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.1.2.2.1 - Ensure /dev/shm is tmpfs or a separate partition
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.3.1.1 - Ensure the apparmor packages are installed
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.3.1.2 - Ensure AppArmor is enabled
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.3.1.3 - Ensure all AppArmor Profiles are not disabled
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.5.1 - Ensure randomize_va_space is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.5.2 - Ensure ptrace_scope is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.5.3 - Ensure suid_dumpable is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.5.4 - Ensure core file size is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.5.6 - Ensure Automatic Error Reporting is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.6.1 - Ensure /etc/motd is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.6.2 - Ensure /etc/issue is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.6.3 - Ensure /etc/issue.net is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.7.10 - Ensure XDMCP is not enabled
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 1.7.11 - Ensure Xwayland is configured
                                      ADDED RECOMMENDATION: 2.1.21 - Ensure mail transfer agents are configured for local-
                10/30/2025    3.0.0   only mode
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 2.2.1 - Ensure nis client is not installed
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 2.4.1.2 - Ensure access to /etc/crontab is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 2.4.1.3 - Ensure access to /etc/cron.hourly is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 2.4.1.4 - Ensure access to /etc/cron.daily is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 2.4.1.5 - Ensure access to /etc/cron.weekly is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 2.4.1.6 - Ensure access to /etc/cron.monthly is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 2.4.1.7 - Ensure access to /etc/cron.yearly is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 2.4.1.8 - Ensure access to /etc/cron.d is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 2.4.1.9 - Ensure access to crontab is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 2.4.2.1 - Ensure access to at is configured
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 3.1.2 - Ensure wireless interfaces are not available
                10/30/2025    3.0.0   ADDED RECOMMENDATION: 3.3.1.1 - Ensure net.ipv4.ip_forward is configured
                                      ADDED RECOMMENDATION: 3.3.1.10 - Ensure net.ipv4.conf.all.secure_redirects is
                10/30/2025 3.0.0      configured
                                      ADDED RECOMMENDATION: 3.3.1.11 - Ensure net.ipv4.conf.default.secure_redirects is
                10/30/2025 3.0.0      configured


                                                                                                         Page 971

Internal Only - General
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.1.12 - Ensure net.ipv4.conf.all.rp_filter is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.1.13 - Ensure net.ipv4.conf.default.rp_filter is configured
                                 ADDED RECOMMENDATION: 3.3.1.14 - Ensure net.ipv4.conf.all.accept_source_route is
                10/30/2025 3.0.0 configured
                                 ADDED RECOMMENDATION: 3.3.1.15 - Ensure net.ipv4.conf.default.accept_source_route is
                10/30/2025 3.0.0 configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.1.16 - Ensure net.ipv4.conf.all.log_martians is configured
                                 ADDED RECOMMENDATION: 3.3.1.17 - Ensure net.ipv4.conf.default.log_martians is
                10/30/2025 3.0.0 configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.1.18 - Ensure net.ipv4.tcp_syncookies is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.1.2 - Ensure net.ipv4.conf.all.forwarding is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.1.3 - Ensure net.ipv4.conf.default.forwarding is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.1.4 - Ensure net.ipv4.conf.all.send_redirects is configured
                                 ADDED RECOMMENDATION: 3.3.1.5 - Ensure net.ipv4.conf.default.send_redirects is
                10/30/2025 3.0.0 configured
                                 ADDED RECOMMENDATION: 3.3.1.6 - Ensure net.ipv4.icmp_ignore_bogus_error_responses
                10/30/2025 3.0.0 is configured
                                 ADDED RECOMMENDATION: 3.3.1.7 - Ensure net.ipv4.icmp_echo_ignore_broadcasts is
                10/30/2025 3.0.0 configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.1.8 - Ensure net.ipv4.conf.all.accept_redirects is configured
                                 ADDED RECOMMENDATION: 3.3.1.9 - Ensure net.ipv4.conf.default.accept_redirects is
                10/30/2025 3.0.0 configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.2.1 - Ensure net.ipv6.conf.all.forwarding is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.2.2 - Ensure net.ipv6.conf.default.forwarding is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.2.3 - Ensure net.ipv6.conf.all.accept_redirects is configured
                                 ADDED RECOMMENDATION: 3.3.2.4 - Ensure net.ipv6.conf.default.accept_redirects is
                10/30/2025 3.0.0 configured
                                 ADDED RECOMMENDATION: 3.3.2.5 - Ensure net.ipv6.conf.all.accept_source_route is
                10/30/2025 3.0.0 configured
                                 ADDED RECOMMENDATION: 3.3.2.6 - Ensure net.ipv6.conf.default.accept_source_route is
                10/30/2025 3.0.0 configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.2.7 - Ensure net.ipv6.conf.all.accept_ra is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 3.3.2.8 - Ensure net.ipv6.conf.default.accept_ra is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 4.1.2 - Ensure ufw service is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 4.1.3 - Ensure ufw incoming default is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 4.1.4 - Ensure ufw outgoing default is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 4.1.5 - Ensure ufw routed default is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 5.1.1 - Ensure access to /etc/ssh/sshd_config is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 5.1.2 - Ensure access to SSH private host key files is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 5.1.3 - Ensure access to SSH public host key files is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 5.2.4 - Ensure users must provide password for escalation
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 5.2.6 - Ensure sudo timestamp_timeout is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 5.3.1.2 - Ensure latest version of libpam-modules is installed
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 5.3.1.3 - Ensure latest version of libpam-pwquality is installed


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                10/30/2025 3.0.0 ADDED RECOMMENDATION: 5.4.1.2 - Ensure minimum password days is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 5.4.2.4 - Ensure root account access is controlled
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 6.1.1.1.1 - Ensure journald service is active
                                 ADDED RECOMMENDATION: 6.1.1.2.2 - Ensure systemd-journal-upload authentication is
                10/30/2025 3.0.0 configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 6.1.2.1 - Ensure rsyslog is installed
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 6.1.2.2 - Ensure rsyslog service is enabled and active
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 6.1.2.3 - Ensure journald is configured to send logs to rsyslog
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 6.1.2.4 - Ensure rsyslog log file creation mode is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 6.1.2.5 - Ensure rsyslog logging is configured
                                 ADDED RECOMMENDATION: 6.1.2.6 - Ensure rsyslog is configured to send logs to a remote
                10/30/2025 3.0.0 log host
                                 ADDED RECOMMENDATION: 6.1.2.7 - Ensure rsyslog is not configured to receive logs from a
                10/30/2025 3.0.0 remote client
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 6.1.2.8 - Ensure logrotate is configured
                10/30/2025 3.0.0 ADDED RECOMMENDATION: 6.2.1.4 - Ensure audit_backlog_limit is configured
                                 ADDED RECOMMENDATION: 6.2.3.15 - Ensure successful and unsuccessful attempts to use
                10/30/2025 3.0.0 the chcon command are collected
                                 ADDED RECOMMENDATION: 6.2.3.16 - Ensure successful and unsuccessful attempts to use
                10/30/2025 3.0.0 the setfacl command are collected
                                 ADDED RECOMMENDATION: 6.2.3.17 - Ensure successful and unsuccessful attempts to use
                10/30/2025 3.0.0 the chacl command are collected
                                     ADDED RECOMMENDATION: 6.2.3.18 - Ensure successful and unsuccessful attempts to use
               10/30/2025    3.0.0   the usermod command are collected
               10/30/2025    3.0.0   ADDED RECOMMENDATION: 7.1.1 - Ensure access to /etc/passwd is configured
               10/30/2025    3.0.0   ADDED RECOMMENDATION: 7.1.10 - Ensure access to /etc/security/opasswd is configured
               10/30/2025    3.0.0   ADDED RECOMMENDATION: 7.1.2 - Ensure access to /etc/passwd- is configured
               10/30/2025    3.0.0   ADDED RECOMMENDATION: 7.1.3 - Ensure access to /etc/group is configured
               10/30/2025    3.0.0   ADDED RECOMMENDATION: 7.1.4 - Ensure access to /etc/group- is configured
               10/30/2025    3.0.0   ADDED RECOMMENDATION: 7.1.5 - Ensure access to /etc/shadow is configured
               10/30/2025    3.0.0   ADDED RECOMMENDATION: 7.1.6 - Ensure access to /etc/shadow- is configured
               10/30/2025    3.0.0   ADDED RECOMMENDATION: 7.1.7 - Ensure access to /etc/gshadow is configured
               10/30/2025    3.0.0   ADDED RECOMMENDATION: 7.1.8 - Ensure access to /etc/gshadow- is configured
               10/30/2025    3.0.0   ADDED RECOMMENDATION: 7.1.9 - Ensure access to /etc/shells is configured
               10/30/2025    3.0.0   ADDED SECTION: 3.3.1 - Configure IPv4 parameters
               10/30/2025    3.0.0   ADDED SECTION: 3.3.2 - Configure IPv6 parameters
               10/30/2025    3.0.0   ADDED SECTION: 4.1 - Configure Uncomplicated Firewall
               10/30/2025    3.0.0   ADDED SECTION: 6.1.2 - Configure rsyslog
               10/30/2025    3.0.0   ADDED SECTION: 7.1 - Configure system file and directory access
              DROPPED:
               10/30/2025    3.0.0 DROPPED RECOMMENDATION: 1.1.2.1.1 - Ensure /tmp is a separate partition
               10/30/2025    3.0.0 DROPPED RECOMMENDATION: 1.1.2.2.1 - Ensure /dev/shm is a separate partition
               10/30/2025    3.0.0 DROPPED RECOMMENDATION: 1.3.1.1 - Ensure AppArmor is installed


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                                     DROPPED RECOMMENDATION: 1.3.1.2 - Ensure AppArmor is enabled in the bootloader
                10/30/2025 3.0.0     configuration
                                     DROPPED RECOMMENDATION: 1.3.1.3 - Ensure all AppArmor Profiles are in enforce or
                10/30/2025 3.0.0     complain mode
                                     DROPPED RECOMMENDATION: 1.5.1 - Ensure address space layout randomization is
                10/30/2025   3.0.0   enabled
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 1.5.2 - Ensure ptrace_scope is restricted
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 1.5.3 - Ensure core dumps are restricted
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 1.5.5 - Ensure Automatic Error Reporting is not enabled
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 1.6.1 - Ensure message of the day is configured properly
                                     DROPPED RECOMMENDATION: 1.6.2 - Ensure local login warning banner is configured
                10/30/2025 3.0.0     properly
                                     DROPPED RECOMMENDATION: 1.6.3 - Ensure remote login warning banner is configured
                10/30/2025 3.0.0     properly
                10/30/2025 3.0.0     DROPPED RECOMMENDATION: 1.7.10 - Ensure XDCMP is not enabled
                                     DROPPED RECOMMENDATION: 2.1.21 - Ensure mail transfer agent is configured for local-
                10/30/2025 3.0.0     only mode
                10/30/2025 3.0.0     DROPPED RECOMMENDATION: 2.2.1 - Ensure NIS Client is not installed
                10/30/2025 3.0.0     DROPPED RECOMMENDATION: 2.4.1.2 - Ensure permissions on /etc/crontab are configured
                                     DROPPED RECOMMENDATION: 2.4.1.3 - Ensure permissions on /etc/cron.hourly are
                10/30/2025 3.0.0     configured
                                     DROPPED RECOMMENDATION: 2.4.1.4 - Ensure permissions on /etc/cron.daily are
                10/30/2025 3.0.0     configured
                                     DROPPED RECOMMENDATION: 2.4.1.5 - Ensure permissions on /etc/cron.weekly are
                10/30/2025 3.0.0     configured
                                     DROPPED RECOMMENDATION: 2.4.1.6 - Ensure permissions on /etc/cron.monthly are
                10/30/2025   3.0.0   configured
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 2.4.1.7 - Ensure permissions on /etc/cron.d are configured
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 2.4.1.8 - Ensure crontab is restricted to authorized users
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 2.4.2.1 - Ensure at is restricted to authorized users
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.1.2 - Ensure wireless interfaces are disabled
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.1 - Ensure ip forwarding is disabled
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.10 - Ensure tcp syn cookies is enabled
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.11 - Ensure ipv6 router advertisements are not accepted
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.2 - Ensure packet redirect sending is disabled
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.3 - Ensure bogus icmp responses are ignored
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.4 - Ensure broadcast icmp requests are ignored
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.5 - Ensure icmp redirects are not accepted
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.6 - Ensure secure icmp redirects are not accepted
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.7 - Ensure reverse path filtering is enabled
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.8 - Ensure source routed packets are not accepted
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 3.3.9 - Ensure suspicious packets are logged
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.1.2 - Ensure iptables-persistent is not installed with ufw
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.1.3 - Ensure ufw service is enabled


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                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.1.4 - Ensure ufw loopback traffic is configured
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.1.5 - Ensure ufw outbound connections are configured
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.1.6 - Ensure ufw firewall rules exist for all open ports
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.1.7 - Ensure ufw default deny firewall policy
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.2.1 - Ensure nftables is installed
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.2.10 - Ensure nftables rules are permanent
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.2.2 - Ensure ufw is uninstalled or disabled with nftables
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.2.3 - Ensure iptables are flushed with nftables
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.2.4 - Ensure a nftables table exists
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.2.5 - Ensure nftables base chains exist
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.2.6 - Ensure nftables loopback traffic is configured
                                     DROPPED RECOMMENDATION: 4.2.7 - Ensure nftables outbound and established
                10/30/2025   3.0.0   connections are configured
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.2.8 - Ensure nftables default deny firewall policy
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.2.9 - Ensure nftables service is enabled
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.3.1.1 - Ensure iptables packages are installed
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.3.1.2 - Ensure nftables is not installed with iptables
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.3.1.3 - Ensure ufw is uninstalled or disabled with iptables
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.3.2.1 - Ensure iptables default deny firewall policy
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.3.2.2 - Ensure iptables loopback traffic is configured
                                     DROPPED RECOMMENDATION: 4.3.2.3 - Ensure iptables outbound and established
                10/30/2025   3.0.0   connections are configured
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.3.2.4 - Ensure iptables firewall rules exist for all open ports
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.3.3.1 - Ensure ip6tables default deny firewall policy
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 4.3.3.2 - Ensure ip6tables loopback traffic is configured
                                     DROPPED RECOMMENDATION: 4.3.3.3 - Ensure ip6tables outbound and established
                10/30/2025 3.0.0     connections are configured
                                     DROPPED RECOMMENDATION: 4.3.3.4 - Ensure ip6tables firewall rules exist for all open
                10/30/2025 3.0.0     ports
                                     DROPPED RECOMMENDATION: 5.1.1 - Ensure permissions on /etc/ssh/sshd_config are
                10/30/2025 3.0.0     configured
                                     DROPPED RECOMMENDATION: 5.1.2 - Ensure permissions on SSH private host key files are
                10/30/2025 3.0.0     configured
                                     DROPPED RECOMMENDATION: 5.1.3 - Ensure permissions on SSH public host key files are
                10/30/2025 3.0.0     configured
                                     DROPPED RECOMMENDATION: 5.2.4 - Ensure users must provide password for privilege
                10/30/2025 3.0.0     escalation
                                     DROPPED RECOMMENDATION: 5.2.6 - Ensure sudo authentication timeout is configured
                10/30/2025   3.0.0   correctly
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 5.3.1.2 - Ensure libpam-modules is installed
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 5.3.1.3 - Ensure libpam-pwquality is installed
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 5.4.1.2 - Ensure minimum password age is configured
                10/30/2025   3.0.0   DROPPED RECOMMENDATION: 5.4.2.4 - Ensure root password is set



                                                                                                          Page 975

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                10/30/2025 3.0.0 DROPPED RECOMMENDATION: 6.2.1.1.1 - Ensure journald service is enabled and active
                                 DROPPED RECOMMENDATION: 6.2.1.2.2 - Ensure systemd-journal-remote authentication is
                10/30/2025 3.0.0 configured
                10/30/2025 3.0.0 DROPPED RECOMMENDATION: 6.3.1.4 - Ensure audit_backlog_limit is sufficient
                                 DROPPED RECOMMENDATION: 6.3.3.15 - Ensure successful and unsuccessful attempts to
                10/30/2025 3.0.0 use the chcon command are recorded
                                 DROPPED RECOMMENDATION: 6.3.3.16 - Ensure successful and unsuccessful attempts to
                10/30/2025 3.0.0 use the setfacl command are recorded
                                 DROPPED RECOMMENDATION: 6.3.3.17 - Ensure successful and unsuccessful attempts to
                10/30/2025 3.0.0 use the chacl command are recorded
                                    DROPPED RECOMMENDATION: 6.3.3.18 - Ensure successful and unsuccessful attempts to
                10/30/2025 3.0.0    use the usermod command are recorded
                10/30/2025 3.0.0    DROPPED RECOMMENDATION: 7.1.1 - Ensure permissions on /etc/passwd are configured
                                    DROPPED RECOMMENDATION: 7.1.10 - Ensure permissions on /etc/security/opasswd are
               10/30/2025   3.0.0   configured
               10/30/2025   3.0.0   DROPPED RECOMMENDATION: 7.1.2 - Ensure permissions on /etc/passwd- are configured
               10/30/2025   3.0.0   DROPPED RECOMMENDATION: 7.1.3 - Ensure permissions on /etc/group are configured
               10/30/2025   3.0.0   DROPPED RECOMMENDATION: 7.1.4 - Ensure permissions on /etc/group- are configured
               10/30/2025   3.0.0   DROPPED RECOMMENDATION: 7.1.5 - Ensure permissions on /etc/shadow are configured
               10/30/2025   3.0.0   DROPPED RECOMMENDATION: 7.1.6 - Ensure permissions on /etc/shadow- are configured
               10/30/2025   3.0.0   DROPPED RECOMMENDATION: 7.1.7 - Ensure permissions on /etc/gshadow are configured
               10/30/2025   3.0.0   DROPPED RECOMMENDATION: 7.1.8 - Ensure permissions on /etc/gshadow- are configured
               10/30/2025   3.0.0   DROPPED RECOMMENDATION: 7.1.9 - Ensure permissions on /etc/shells are configured
               10/30/2025   3.0.0   DROPPED SECTION: 4.1 - Configure UncomplicatedFirewall
               10/30/2025   3.0.0   DROPPED SECTION: 4.2 - Configure nftables
               10/30/2025   3.0.0   DROPPED SECTION: 4.3 - Configure iptables
               10/30/2025   3.0.0   DROPPED SECTION: 4.3.1 - Configure iptables software
               10/30/2025   3.0.0   DROPPED SECTION: 4.3.2 - Configure IPv4 iptables
               10/30/2025   3.0.0   DROPPED SECTION: 4.3.3 - Configure IPv6 ip6tables
               10/30/2025   3.0.0   DROPPED SECTION: 7.1 - System File Permissions
              MOVED:
                                 MOVED RECOMMENDATION: 1.1.1.7 - Ensure squashfs kernel module is not available moved
                10/30/2025 3.0.0 from 1.1.1.6 in 2.0.0
                                 MOVED RECOMMENDATION: 1.1.1.8 - Ensure udf kernel module is not available moved from
                10/30/2025 3.0.0 1.1.1.7 in 2.0.0
                                 MOVED RECOMMENDATION: 1.1.1.9 - Ensure usb-storage kernel module is not available
                10/30/2025 3.0.0 moved from 1.1.1.8 in 2.0.0
                10/30/2025 3.0.0 MOVED RECOMMENDATION: 1.5.5 - Ensure prelink is not installed moved from 1.5.4 in 2.0.0
                                 MOVED RECOMMENDATION: 6.1.1.1.2 - Ensure journald log file access is configured moved
                10/30/2025 3.0.0 from 6.2.1.1.2 in 2.0.0
                                 MOVED RECOMMENDATION: 6.1.1.1.3 - Ensure journald log file rotation is configured moved
                10/30/2025 3.0.0 from 6.2.1.1.3 in 2.0.0




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                                    MOVED RECOMMENDATION: 6.1.1.1.4 - Ensure journald ForwardToSyslog is disabled moved
                10/30/2025 3.0.0    from 6.2.1.1.4 in 2.0.0
                                    MOVED RECOMMENDATION: 6.1.1.1.5 - Ensure journald Storage is configured moved from
                10/30/2025 3.0.0    6.2.1.1.5 in 2.0.0
                                    MOVED RECOMMENDATION: 6.1.1.1.6 - Ensure journald Compress is configured moved from
                10/30/2025 3.0.0    6.2.1.1.6 in 2.0.0
                                    MOVED RECOMMENDATION: 6.1.1.2.1 - Ensure systemd-journal-remote is installed moved
                10/30/2025 3.0.0    from 6.2.1.2.1 in 2.0.0
                                    MOVED RECOMMENDATION: 6.1.1.2.3 - Ensure systemd-journal-upload is enabled and
                10/30/2025 3.0.0    active moved from 6.2.1.2.3 in 2.0.0
                                    MOVED RECOMMENDATION: 6.1.1.2.4 - Ensure systemd-journal-remote service is not in use
                10/30/2025 3.0.0    moved from 6.2.1.2.4 in 2.0.0
                                    MOVED RECOMMENDATION: 6.1.3.1 - Ensure access to all logfiles has been configured
                10/30/2025 3.0.0    moved from 6.2.2.1 in 2.0.0
                                    MOVED RECOMMENDATION: 6.2.1.1 - Ensure auditd packages are installed moved from
                10/30/2025 3.0.0    6.3.1.1 in 2.0.0
                                    MOVED RECOMMENDATION: 6.2.1.2 - Ensure auditd service is enabled and active moved
                10/30/2025 3.0.0    from 6.3.1.2 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.1.3 - Ensure auditing for processes that start prior to auditd
                10/30/2025 3.0.0 is enabled moved from 6.3.1.3 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.2.1 - Ensure audit log storage size is configured moved from
                10/30/2025 3.0.0 6.3.2.1 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.2.2 - Ensure audit logs are not automatically deleted moved
                10/30/2025 3.0.0 from 6.3.2.2 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.2.3 - Ensure system is disabled when audit logs are full
                10/30/2025 3.0.0 moved from 6.3.2.3 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.2.4 - Ensure system warns when audit logs are low on
                10/30/2025 3.0.0 space moved from 6.3.2.4 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.1 - Ensure changes to system administration scope
                10/30/2025 3.0.0 (sudoers) is collected moved from 6.3.3.1 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.10 - Ensure successful file system mounts are collected
                10/30/2025 3.0.0 moved from 6.3.3.10 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.11 - Ensure session initiation information is collected
                10/30/2025 3.0.0 moved from 6.3.3.11 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.12 - Ensure login and logout events are collected moved
                10/30/2025 3.0.0 from 6.3.3.12 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.13 - Ensure file deletion events by users are collected
                10/30/2025 3.0.0 moved from 6.3.3.13 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.14 - Ensure events that modify the system's Mandatory
                10/30/2025 3.0.0 Access Controls are collected moved from 6.3.3.14 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.19 - Ensure kernel module loading unloading and
                10/30/2025 3.0.0 modification is collected moved from 6.3.3.19 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.2 - Ensure actions as another user are always logged
                10/30/2025 3.0.0 moved from 6.3.3.2 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.20 - Ensure the audit configuration is immutable moved
                10/30/2025 3.0.0 from 6.3.3.20 in 2.0.0


                                                                                                      Page 977

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                                 MOVED RECOMMENDATION: 6.2.3.21 - Ensure the running and on disk configuration is the
                10/30/2025 3.0.0 same moved from 6.3.3.21 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.3 - Ensure events that modify the sudo log file are
                10/30/2025 3.0.0 collected moved from 6.3.3.3 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.4 - Ensure events that modify date and time information
                10/30/2025 3.0.0 are collected moved from 6.3.3.4 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.5 - Ensure events that modify the system's network
                10/30/2025 3.0.0 environment are collected moved from 6.3.3.5 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.6 - Ensure use of privileged commands are collected
                10/30/2025 3.0.0 moved from 6.3.3.6 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.7 - Ensure unsuccessful file access attempts are
                10/30/2025 3.0.0 collected moved from 6.3.3.7 in 2.0.0
                                 MOVED RECOMMENDATION: 6.2.3.8 - Ensure events that modify user/group information are
                10/30/2025 3.0.0 collected moved from 6.3.3.8 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.3.9 - Ensure discretionary access control permission
                10/30/2025 3.0.0     modification events are collected moved from 6.3.3.9 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.4.1 - Ensure audit log files mode is configured moved from
                10/30/2025 3.0.0     6.3.4.1 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.4.10 - Ensure audit tools group owner is configured moved
                10/30/2025 3.0.0     from 6.3.4.10 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.4.2 - Ensure audit log files owner is configured moved from
                10/30/2025 3.0.0     6.3.4.2 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.4.3 - Ensure audit log files group owner is configured moved
                10/30/2025 3.0.0     from 6.3.4.3 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.4.4 - Ensure the audit log file directory mode is configured
                10/30/2025 3.0.0     moved from 6.3.4.4 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.4.5 - Ensure audit configuration files mode is configured
                10/30/2025 3.0.0     moved from 6.3.4.5 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.4.6 - Ensure audit configuration files owner is configured
                10/30/2025 3.0.0     moved from 6.3.4.6 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.4.7 - Ensure audit configuration files group owner is
                10/30/2025 3.0.0     configured moved from 6.3.4.7 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.4.8 - Ensure audit tools mode is configured moved from
                10/30/2025 3.0.0     6.3.4.8 in 2.0.0
                                     MOVED RECOMMENDATION: 6.2.4.9 - Ensure audit tools owner is configured moved from
                10/30/2025 3.0.0     6.3.4.9 in 2.0.0
                10/30/2025 3.0.0     MOVED RECOMMENDATION: 6.3.1 - Ensure AIDE is installed moved from 6.1.1 in 2.0.0
                                     MOVED RECOMMENDATION: 6.3.2 - Ensure filesystem integrity is regularly checked moved
                10/30/2025 3.0.0     from 6.1.2 in 2.0.0
                                     MOVED RECOMMENDATION: 6.3.3 - Ensure cryptographic mechanisms are used to protect
                10/30/2025   3.0.0   the integrity of audit tools moved from 6.1.3 in 2.0.0
                10/30/2025   3.0.0   MOVED SECTION: 6.1 - System Logging moved from 6.2 in 2.0.0
                10/30/2025   3.0.0   MOVED SECTION: 6.1.1 - Configure journald moved from 6.2.1 in 2.0.0
                10/30/2025   3.0.0   MOVED SECTION: 6.1.1.1 - Configure systemd-journald service moved from 6.2.1.1 in 2.0.0
                10/30/2025   3.0.0   MOVED SECTION: 6.1.1.2 - Configure systemd-journal-remote moved from 6.2.1.2 in 2.0.0


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               10/30/2025    3.0.0   MOVED SECTION: 6.1.3 - Configure Logfiles moved from 6.2.2 in 2.0.0
               10/30/2025    3.0.0   MOVED SECTION: 6.2 - System Auditing moved from 6.3 in 2.0.0
               10/30/2025    3.0.0   MOVED SECTION: 6.2.1 - Configure auditd Service moved from 6.3.1 in 2.0.0
               10/30/2025    3.0.0   MOVED SECTION: 6.2.2 - Configure Data Retention moved from 6.3.2 in 2.0.0
               10/30/2025    3.0.0   MOVED SECTION: 6.2.3 - Configure auditd Rules moved from 6.3.3 in 2.0.0
               10/30/2025    3.0.0   MOVED SECTION: 6.2.4 - Configure auditd File Access moved from 6.3.4 in 2.0.0
               10/30/2025    3.0.0   MOVED SECTION: 6.3 - Configure Filesystem Integrity Checking moved from 6.1 in 2.0.0
              UPDATED:
                                 UPDATED RECOMMENDATION: 1.1.1.7 - Ensure squashfs kernel module is not available -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.1.8 - Ensure udf kernel module is not available - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.1.9 - Ensure usb-storage kernel module is not available -
                10/30/2025 3.0.0 Sections Modified: Rationale Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 6.1.1.1.2 - Ensure journald log file access is configured -
                10/30/2025 3.0.0 Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 6.1.1.1.3 - Ensure journald log file rotation is configured -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 6.1.1.1.4 - Ensure journald ForwardToSyslog is disabled -
                10/30/2025 3.0.0 Sections Modified: Rationale Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 6.1.1.1.5 - Ensure journald Storage is configured - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 6.1.1.1.6 - Ensure journald Compress is configured -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 6.1.1.2.1 - Ensure systemd-journal-remote is installed -
                10/30/2025 3.0.0 Sections Modified: Rationale Statement; Audit Procedure
                                 UPDATED RECOMMENDATION: 6.1.1.2.4 - Ensure systemd-journal-remote service is not in
                10/30/2025 3.0.0 use - Sections Modified: Description; Rationale Statement; Audit Procedure
                                 UPDATED RECOMMENDATION: 6.1.3.1 - Ensure access to all logfiles has been configured -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 6.2.3.1 - Ensure changes to system administration scope
                10/30/2025 3.0.0 (sudoers) is collected - Sections Modified: Remediation Procedure
                                 UPDATED RECOMMENDATION: 6.2.3.19 - Ensure kernel module loading unloading and
                                 modification is collected - Sections Modified: Description; Remediation Procedure; Audit
                10/30/2025 3.0.0 Procedure
                                 UPDATED RECOMMENDATION: 6.2.3.20 - Ensure the audit configuration is immutable -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure
                                 UPDATED RECOMMENDATION: 6.2.3.4 - Ensure events that modify date and time
                10/30/2025 3.0.0 information are collected - Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 6.2.3.5 - Ensure events that modify the system's network
                10/30/2025 3.0.0 environment are collected - Sections Modified: Remediation Procedure; Audit Procedure




                                                                                                          Page 979

Internal Only - General
                                 UPDATED RECOMMENDATION: 6.2.4.10 - Ensure audit tools group owner is configured -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure
                                 UPDATED RECOMMENDATION: 6.2.4.3 - Ensure audit log files group owner is configured -
                10/30/2025 3.0.0 Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 6.3.3 - Ensure cryptographic mechanisms are used to
                                 protect the integrity of audit tools - Sections Modified: Remediation Procedure; Audit
                10/30/2025 3.0.0 Procedure
                                 UPDATED RECOMMENDATION: 1.1.1.1 - Ensure cramfs kernel module is not available -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.1.2 - Ensure freevxfs kernel module is not available -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.1.3 - Ensure hfs kernel module is not available - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.1.4 - Ensure hfsplus kernel module is not available -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.1.5 - Ensure jffs2 kernel module is not available -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.2.1.3 - Ensure nosuid option set on /tmp partition -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.2.1.4 - Ensure noexec option set on /tmp partition -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.2.3.1 - Ensure separate partition exists for /home -
                10/30/2025 3.0.0 Sections Modified: Impact Statement; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.2.3.2 - Ensure nodev option set on /home partition -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.2.3.3 - Ensure nosuid option set on /home partition -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.2.4.1 - Ensure separate partition exists for /var - Sections
                10/30/2025 3.0.0 Modified: Rationale Statement; Impact Statement; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.2.4.2 - Ensure nodev option set on /var partition -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.2.4.3 - Ensure nosuid option set on /var partition -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.1.2.5.1 - Ensure separate partition exists for /var/tmp -
                10/30/2025 3.0.0 Sections Modified: Rationale Statement; Impact Statement
                                 UPDATED RECOMMENDATION: 1.1.2.7.1 - Ensure separate partition exists for /var/log/audit -
                10/30/2025 3.0.0 Sections Modified: Rationale Statement; Impact Statement
                                 UPDATED RECOMMENDATION: 1.2.1.1 - Ensure GPG keys are configured - Sections Modified:
                10/30/2025 3.0.0 Audit Procedure
                                 UPDATED RECOMMENDATION: 1.2.2.1 - Ensure updates, patches, and additional security
                10/30/2025 3.0.0 software are installed - Sections Modified: Remediation Procedure
                                 UPDATED RECOMMENDATION: 1.4.1 - Ensure bootloader password is set - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure


                                                                                                       Page 980

Internal Only - General
                                 UPDATED RECOMMENDATION: 1.7.1 - Ensure GDM is removed - Sections Modified:
                10/30/2025 3.0.0 Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.7.2 - Ensure GDM login banner is configured - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.7.3 - Ensure GDM disable-user-list option is enabled -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.7.4 - Ensure GDM screen locks when the user is idle -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.7.5 - Ensure GDM screen locks cannot be overridden -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.7.6 - Ensure GDM automatic mounting of removable media
                10/30/2025 3.0.0 is disabled - Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.7.7 - Ensure GDM disabling automatic mounting of
                                 removable media is not overridden - Sections Modified: Remediation Procedure; Audit
                10/30/2025 3.0.0 Procedure
                                 UPDATED RECOMMENDATION: 1.7.8 - Ensure GDM autorun-never is enabled - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 1.7.9 - Ensure GDM autorun-never is not overridden -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 2.1.18 - Ensure web server services are not in use - Sections
                10/30/2025 3.0.0 Modified: Impact Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 2.1.19 - Ensure xinetd services are not in use - Sections
                10/30/2025 3.0.0 Modified: Description; Rationale Statement
                                 UPDATED RECOMMENDATION: 2.1.4 - Ensure dns server services are not in use - Sections
                10/30/2025 3.0.0 Modified: Description; Impact Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 2.1.6 - Ensure ftp server services are not in use - Sections
                10/30/2025 3.0.0 Modified: Description; Audit Procedure
                                 UPDATED RECOMMENDATION: 2.2.6 - Ensure ftp client is not installed - Sections Modified:
                10/30/2025 3.0.0 Description; Rationale Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 2.3.1.1 - Ensure a single time synchronization daemon is in
                10/30/2025 3.0.0 use - Sections Modified: Description; Audit Procedure
                                 UPDATED RECOMMENDATION: 2.3.2.1 - Ensure systemd-timesyncd configured with
                10/30/2025 3.0.0 authorized timeserver - Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 2.3.2.2 - Ensure systemd-timesyncd is enabled and running -
                10/30/2025 3.0.0 Sections Modified: Assessment Status
                                 UPDATED RECOMMENDATION: 2.3.3.1 - Ensure chrony is configured with authorized
                10/30/2025 3.0.0 timeserver - Sections Modified: Assessment Status; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 3.1.1 - Ensure IPv6 status is identified - Sections Modified:
                10/30/2025 3.0.0 Description; Rationale Statement; Audit Procedure
                                 UPDATED RECOMMENDATION: 3.1.3 - Ensure bluetooth services are not in use - Sections
                10/30/2025 3.0.0 Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 3.2.1 - Ensure dccp kernel module is not available - Sections
                10/30/2025 3.0.0 Modified: Profile; Rationale Statement; Remediation Procedure; Audit Procedure


                                                                                                       Page 981

Internal Only - General
                                 UPDATED RECOMMENDATION: 3.2.2 - Ensure tipc kernel module is not available - Sections
                10/30/2025 3.0.0 Modified: Profile; Rationale Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 3.2.3 - Ensure rds kernel module is not available - Sections
                10/30/2025 3.0.0 Modified: Profile; Rationale Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 3.2.4 - Ensure sctp kernel module is not available - Sections
                10/30/2025 3.0.0 Modified: Profile; Rationale Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 4.1.1 - Ensure ufw is installed - Sections Modified: Rationale
                10/30/2025 3.0.0 Statement; Impact Statement; Remediation Procedure
                                    UPDATED RECOMMENDATION: 5.1.11 - Ensure sshd IgnoreRhosts is enabled - Sections
                10/30/2025 3.0.0    Modified: Remediation Procedure; Audit Procedure
                                    UPDATED RECOMMENDATION: 5.1.12 - Ensure sshd KexAlgorithms is configured - Sections
                10/30/2025 3.0.0    Modified: Audit Procedure
                                    UPDATED RECOMMENDATION: 5.1.15 - Ensure sshd MACs are configured - Sections
                10/30/2025 3.0.0    Modified: Audit Procedure
                                    UPDATED RECOMMENDATION: 5.1.17 - Ensure sshd MaxSessions is configured - Sections
                10/30/2025 3.0.0    Modified: Audit Procedure
                                    UPDATED RECOMMENDATION: 5.1.18 - Ensure sshd MaxStartups is configured - Sections
                10/30/2025 3.0.0    Modified: Audit Procedure
                                    UPDATED RECOMMENDATION: 5.1.21 - Ensure sshd PermitUserEnvironment is disabled -
                10/30/2025 3.0.0    Sections Modified: Audit Procedure
                                    UPDATED RECOMMENDATION: 5.1.22 - Ensure sshd UsePAM is enabled - Sections Modified:
                10/30/2025 3.0.0    Audit Procedure
                                    UPDATED RECOMMENDATION: 5.1.4 - Ensure sshd access is configured - Sections Modified:
                10/30/2025 3.0.0    Remediation Procedure
                                 UPDATED RECOMMENDATION: 5.1.5 - Ensure sshd Banner is configured - Sections Modified:
                10/30/2025 3.0.0 Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.1.8 - Ensure sshd DisableForwarding is enabled - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.2.2 - Ensure sudo commands use pty - Sections Modified:
                10/30/2025 3.0.0 Audit Procedure
                                 UPDATED RECOMMENDATION: 5.2.3 - Ensure sudo log file exists - Sections Modified:
                10/30/2025 3.0.0 Remediation Procedure
                                 UPDATED RECOMMENDATION: 5.3.1.1 - Ensure latest version of pam is installed - Sections
                10/30/2025 3.0.0 Modified: Description; Rationale Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.2.1 - Ensure pam_unix module is enabled - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.2.2 - Ensure pam_faillock module is enabled - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure
                                 UPDATED RECOMMENDATION: 5.3.2.3 - Ensure pam_pwquality module is enabled - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.2.4 - Ensure pam_pwhistory module is enabled - Sections
                10/30/2025 3.0.0 Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.1.1 - Ensure password failed attempts lockout is
                10/30/2025 3.0.0 configured - Sections Modified: Audit Procedure


                                                                                                      Page 982

Internal Only - General
                                 UPDATED RECOMMENDATION: 5.3.3.1.2 - Ensure password unlock time is configured -
                10/30/2025 3.0.0 Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.1.3 - Ensure password failed attempts lockout includes
                10/30/2025 3.0.0 root account - Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.2.1 - Ensure password number of changed characters
                10/30/2025 3.0.0 is configured - Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.2.2 - Ensure minimum password length is configured -
                10/30/2025 3.0.0 Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.2.3 - Ensure password complexity is configured -
                10/30/2025 3.0.0 Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.2.4 - Ensure password same consecutive characters is
                10/30/2025 3.0.0 configured - Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.2.5 - Ensure password maximum sequential characters
                10/30/2025 3.0.0 is configured - Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.2.6 - Ensure password dictionary check is enabled -
                10/30/2025 3.0.0 Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.2.8 - Ensure password quality is enforced for the root
                10/30/2025 3.0.0 user - Sections Modified: Remediation Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.3.1 - Ensure password history remember is configured -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.3.2 - Ensure password history is enforced for the root
                10/30/2025 3.0.0 user - Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.3.3 - Ensure pam_pwhistory includes use_authtok -
                10/30/2025 3.0.0 Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.4.1 - Ensure pam_unix does not include nullok -
                10/30/2025 3.0.0 Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.4.2 - Ensure pam_unix does not include remember -
                10/30/2025 3.0.0 Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.3.3.4.3 - Ensure pam_unix includes a strong password
                10/30/2025 3.0.0 hashing algorithm - Sections Modified: Remediation Procedure
                                 UPDATED RECOMMENDATION: 5.4.1.1 - Ensure password expiration is configured - Sections
                10/30/2025 3.0.0 Modified: Impact Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.4.1.4 - Ensure strong password hashing algorithm is
                10/30/2025 3.0.0 configured - Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.4.1.5 - Ensure inactive password lock is configured -
                10/30/2025 3.0.0 Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.4.1.6 - Ensure all users last password change date is in the
                10/30/2025 3.0.0 past - Sections Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.4.2.1 - Ensure root is the only UID 0 account - Sections
                10/30/2025 3.0.0 Modified: Rationale Statement
                                 UPDATED RECOMMENDATION: 5.4.2.5 - Ensure root path integrity - Sections Modified: Audit
                10/30/2025 3.0.0 Procedure
                                 UPDATED RECOMMENDATION: 5.4.2.6 - Ensure root user umask is configured - Sections
                10/30/2025 3.0.0 Modified: Description; Remediation Procedure; Audit Procedure


                                                                                                      Page 983

Internal Only - General
                                 UPDATED RECOMMENDATION: 5.4.3.1 - Ensure nologin is not listed in /etc/shells - Sections
                10/30/2025 3.0.0 Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 5.4.3.2 - Ensure default user shell timeout is configured -
                10/30/2025 3.0.0 Sections Modified: Description; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 5.4.3.3 - Ensure default user umask is configured - Sections
                10/30/2025 3.0.0 Modified: Rationale Statement; Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 7.1.11 - Ensure world writable files and directories are
                10/30/2025 3.0.0 secured - Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 7.1.13 - Ensure SUID and SGID files are reviewed - Sections
                10/30/2025 3.0.0 Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 7.2.10 - Ensure local interactive user dot files access is
                10/30/2025 3.0.0 configured - Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED RECOMMENDATION: 7.2.5 - Ensure no duplicate UIDs exist - Sections Modified:
                10/30/2025 3.0.0 Rationale Statement
                                 UPDATED RECOMMENDATION: 7.2.7 - Ensure no duplicate user names exist - Sections
                10/30/2025 3.0.0 Modified: Audit Procedure
                                 UPDATED RECOMMENDATION: 7.2.9 - Ensure local interactive user home directories are
                10/30/2025 3.0.0 configured - Sections Modified: Remediation Procedure; Audit Procedure
                                 UPDATED SECTION: 1.1.1 - Configure Filesystem Kernel Modules - Sections Modified:
                10/30/2025 3.0.0 Description
                10/30/2025 3.0.0 UPDATED SECTION: 1.1.2.3 - Configure /home - Sections Modified: Description
                10/30/2025 3.0.0 UPDATED SECTION: 1.2 - Package Management - Sections Modified: Description
                10/30/2025 3.0.0 UPDATED SECTION: 1.2.1 - Configure Package Repositories - Sections Modified: Description
                                 UPDATED SECTION: 1.7 - Configure GNOME Display Manager - Sections Modified:
                10/30/2025 3.0.0 Description
                10/30/2025 3.0.0 UPDATED SECTION: 2.3.2 - Configure systemd-timesyncd - Sections Modified: Description
                10/30/2025 3.0.0 UPDATED SECTION: 2.3.3 - Configure chrony - Sections Modified: Description
                10/30/2025 3.0.0 UPDATED SECTION: 2.4.1 - Configure cron - Sections Modified: Description
                                 UPDATED SECTION: 3.3 - Configure Network Kernel Parameters - Sections Modified:
                10/30/2025 3.0.0 Description
                10/30/2025 3.0.0 UPDATED SECTION: 4 - Host Based Firewall - Sections Modified: Description
                10/30/2025 3.0.0 UPDATED SECTION: 5.1 - Configure SSH Server - Sections Modified: Description
                10/30/2025 3.0.0 UPDATED SECTION: 5.3 - Pluggable Authentication Modules - Sections Modified: Description
                                 UPDATED SECTION: 5.3.1 - Configure PAM software packages - Sections Modified:
                10/30/2025 3.0.0 Description
                                 UPDATED SECTION: 5.4.1 - Configure shadow password suite parameters - Sections
                10/30/2025 3.0.0 Modified: Description
                10/30/2025 3.0.0 UPDATED SECTION: 6.1 - System Logging - Sections Modified: Description
                10/30/2025 3.0.0 UPDATED SECTION: 6.2.3 - Configure auditd Rules - Sections Modified: Description
                                 UPDATED SECTION: 6.3 - Configure Filesystem Integrity Checking - Sections Modified:
                10/30/2025 3.0.0 Description




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