Verify Ownership on SSH Server Public *.pub Key Files

An XCCDF Rule

Description

SSH server public keys, files that match the /etc/ssh/*.pub glob, must be owned by root user.

Rationale

If a public host key file is modified by an unauthorized user, the SSH service may be compromised.

ID: xccdf_org.ssgproject.content_rule_file_ownership_sshd_pub_key
Severity: Medium
Updated: about 1 year ago

- name: Find /etc/ssh/ file(s) matching ^.*\.pub$
  command: find -H /etc/ssh/ -maxdepth 1 -type f ! -uid 0 -regex "^.*\.pub$"
  register: files_found
  changed_when: false
  failed_when: false
  check_mode: false  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - configure_strategy
  - file_ownership_sshd_pub_key
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure owner on /etc/ssh/ file(s) matching ^.*\.pub$
  file:
    path: '{{ item }}'
    owner: '0'
    state: file
  with_items:
  - '{{ files_found.stdout_lines }}'
  when: ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - configure_strategy
  - file_ownership_sshd_pub_key
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

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

find /etc/ssh/ -maxdepth 1 -type f ! -uid 0 -regex '^.*\.pub$' -exec chown 0 {} \;

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

Verify Ownership on SSH Server Public *.pub Key Files

Description

Rationale

Remediation - Ansible

Remediation - Shell Script