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Verify Ownership on SSH Server Private *_key Key Files

An XCCDF Rule

Description

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

Rationale

If an unauthorized user obtains the private SSH host key file, the host could be impersonated.

ID
xccdf_org.ssgproject.content_rule_file_ownership_sshd_private_key
Severity
Medium
References
Updated

Remediation Templates

An Ansible Snippet

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

A Shell Script

# Remediation is applicable only in certain platforms
if [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; then
find /etc/ssh/ -maxdepth 1 -type f ! -uid 0 -regex '^.*_key$' -exec chown 0 {} \;

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