Verify Owner on SSH Server Configuration Files

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Description

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

$ sudo chown root /etc/ssh/sshd_config.d

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 "$newown" ]]; then
  >&2 echo "0 is not a defined user on the system"
else
find -P /etc/ssh/sshd_config.d/ -maxdepth 0 -type d  ! -user 0 -exec chown --no-dereference "$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-89747-0
  - NIST-800-53-AC-17(a)
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - directory_owner_sshd_config_d
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Set the directory_owner_sshd_config_d_newown variable if represented by uid
  ansible.builtin.set_fact:
    directory_owner_sshd_config_d_newown: '0'
  when: '"kernel-core" in ansible_facts.packages'
  tags:
  - CCE-89747-0
  - NIST-800-53-AC-17(a)
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - directory_owner_sshd_config_d
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure owner on directory /etc/ssh/sshd_config.d/
  ansible.builtin.file:
    path: /etc/ssh/sshd_config.d/
    follow: false
    state: directory
    owner: '{{ directory_owner_sshd_config_d_newown }}'
  when: '"kernel-core" in ansible_facts.packages'
  tags:
  - CCE-89747-0
  - NIST-800-53-AC-17(a)
  - NIST-800-53-AC-6(1)
  - NIST-800-53-CM-6(a)
  - configure_strategy
  - directory_owner_sshd_config_d
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed