Enable SSH Print Last Log

An XCCDF Rule

Description

Ensure that SSH will display the date and time of the last successful account logon.
The default SSH configuration enables print of the date and time of the last login. The appropriate configuration is used if no value is set for PrintLastLog.
To explicitly enable LastLog in SSH, add or correct the following line in /etc/ssh/sshd_config:

PrintLastLog yes

Rationale

Providing users feedback on when account accesses last occurred facilitates user recognition and reporting of unauthorized account use.

ID: xccdf_org.ssgproject.content_rule_sshd_print_last_log
Severity: Medium
References: 1 12 15 16

DSS05.04 DSS05.10 DSS06.10

CCI-000052

4.3.3.6.1 4.3.3.6.2 4.3.3.6.3 4.3.3.6.4 4.3.3.6.5 4.3.3.6.6 4.3.3.6.7 4.3.3.6.8 4.3.3.6.9

SR 1.1 SR 1.10 SR 1.2 SR 1.5 SR 1.7 SR 1.8 SR 1.9

A.18.1.4 A.9.2.1 A.9.2.4 A.9.3.1 A.9.4.2 A.9.4.3

AC-9 AC-9(1)

PR.AC-7

SRG-OS-000480-GPOS-00227

OL08-00-020350

SV-248718r858584_rule
Updated: about 1 year ago

# Remediation is applicable only in certain platforms
if [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; then

# Find the include keyword, extract from the line the glob expression representing included files.
# And if it is a relative path prepend '/etc/ssh/'
included_files=$(grep -oP "^\s*(?i)include.*" /etc/ssh/sshd_config | sed -e 's/\s*include\s*//I' | sed -e 's|^[^/]|/etc/ssh/&|')for included_file in ${included_files} ; do
    
    LC_ALL=C sed -i "/^\s*PrintLastLog/Id" "$included_file"
done

if [ -e "/etc/ssh/sshd_config" ] ; then
    
    LC_ALL=C sed -i "/^\s*PrintLastLog\s\+/Id" "/etc/ssh/sshd_config"
else
    touch "/etc/ssh/sshd_config"
fi
# make sure file has newline at the end
sed -i -e '$a\' "/etc/ssh/sshd_config"

cp "/etc/ssh/sshd_config" "/etc/ssh/sshd_config.bak"
# Insert at the beginning of the file
printf '%s\n' "PrintLastLog yes" > "/etc/ssh/sshd_config"
cat "/etc/ssh/sshd_config.bak" >> "/etc/ssh/sshd_config"
# Clean up after ourselves.
rm "/etc/ssh/sshd_config.bak"

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

- name: Find sshd_config included files
  shell: |-
    included_files=$(grep -oP "^\s*(?i)include.*" /etc/ssh/sshd_config | sed -e 's/\s*Include\s*//i' | sed -e 's|^[^/]|/etc/ssh/&|')
    [[ -n $included_files ]] && ls $included_files || true
  register: sshd_config_included_files
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]  tags:
  - DISA-STIG-OL08-00-020350
  - NIST-800-53-AC-9
  - NIST-800-53-AC-9(1)
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sshd_print_last_log

- name: Comment conf from included files
  replace:
    path: '{{ item }}'
    regexp: ^(\s*PrintLastLog.*)$
    replace: '# \1'
  loop: '{{ sshd_config_included_files.stdout_lines }}'
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - DISA-STIG-OL08-00-020350
  - NIST-800-53-AC-9
  - NIST-800-53-AC-9(1)
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sshd_print_last_log

- name: Enable SSH Print Last Log
  block:

  - name: Check for duplicate values
    lineinfile:
      path: /etc/ssh/sshd_config
      create: true
      regexp: (?i)^\s*PrintLastLog\s+
      state: absent
    check_mode: true
    changed_when: false
    register: dupes

  - name: Deduplicate values from /etc/ssh/sshd_config
    lineinfile:
      path: /etc/ssh/sshd_config
      create: true
      regexp: (?i)^\s*PrintLastLog\s+
      state: absent
    when: dupes.found is defined and dupes.found > 1

  - name: Insert correct line to /etc/ssh/sshd_config
    lineinfile:
      path: /etc/ssh/sshd_config
      create: true
      regexp: (?i)^\s*PrintLastLog\s+
      line: PrintLastLog yes
      state: present
      insertbefore: BOF
      validate: /usr/sbin/sshd -t -f %s
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - DISA-STIG-OL08-00-020350
  - NIST-800-53-AC-9
  - NIST-800-53-AC-9(1)
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - restrict_strategy
  - sshd_print_last_log

Enable SSH Print Last Log

Description

Rationale

Remediation - Shell Script

Remediation - Ansible