Verify Owner on SSH Server Configuration Directory

Description

To properly set the owner of files in /etc/ssh/sshd_config.d, run the command:

find -H /etc/ssh/sshd_config.d -type d -exec chown -L root {} \;

Rationale

Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel-core; then

newown=""
if id "0" >/dev/null 2>&1; then
  newown="0"
fi

if [[ -z "$newown" ]]; then
  >&2 echo "0 is not a defined user on the system"
else

find -P /etc/ssh/sshd_config.d/ -maxdepth 1 -type f  ! -user 0 -regextype posix-extended -regex '^.*$' -exec chown --no-dereference "$newown" {} \;

fi

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

Ansible playbook

The following playbook can be run with Ansible to remediate the issue.

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CCE-86268-0
  - NIST-800-53-AC-17(a)
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - file_owner_sshd_drop_in_config
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Set the file_owner_sshd_drop_in_config_newown variable if represented by uid
  ansible.builtin.set_fact:
    file_owner_sshd_drop_in_config_newown: '0'
  when: '"kernel-core" in ansible_facts.packages'
  tags:
  - CCE-86268-0
  - NIST-800-53-AC-17(a)
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - file_owner_sshd_drop_in_config
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Find /etc/ssh/sshd_config.d/ file(s) matching ^.*$
  ansible.builtin.command: find -P /etc/ssh/sshd_config.d/ -maxdepth 1 -type f  !
    -user 0 -regextype posix-extended -regex "^.*$"
  register: files_found
  changed_when: false
  failed_when: false
  check_mode: false
  when: '"kernel-core" in ansible_facts.packages'
  tags:
  - CCE-86268-0
  - NIST-800-53-AC-17(a)
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - file_owner_sshd_drop_in_config
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure owner on /etc/ssh/sshd_config.d/ file(s) matching ^.*$
  ansible.builtin.file:
    path: '{{ item }}'
    follow: false
    owner: '{{ file_owner_sshd_drop_in_config_newown }}'
    state: file
  with_items:
  - '{{ files_found.stdout_lines }}'
  when: '"kernel-core" in ansible_facts.packages'
  tags:
  - CCE-86268-0
  - NIST-800-53-AC-17(a)
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - file_owner_sshd_drop_in_config
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed