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Verify Group 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 group-owned by root group.

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_groupownership_sshd_pub_key
Severity
Medium
Updated



Remediation - Ansible

- name: Find /etc/ssh/ file(s) matching ^.*\.pub$
  command: find -H /etc/ssh/ -maxdepth 1 -type f ! -group 0 -regex "^.*\.pub$"
  register: files_found
  changed_when: false
  failed_when: false
  check_mode: false

Remediation - Shell Script

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

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

else