Title

The SSH public host key files must have mode 0644 or less permissive. (Cat II impact)

Discussion

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

Check Content

Verify the SSH public host key files have mode "0644" or less permissive. Note: SSH public key files may be found in other directories on the system depending on the installation. The following command will find all SSH public key files on the system: # ls -l /etc/ssh/*.pub -rw-r--r-- 1 root wheel 618 Nov 28 06:43 ssh_host_dsa_key.pub -rw-r--r-- 1 root wheel 347 Nov 28 06:43 ssh_host_key.pub -rw-r--r-- 1 root wheel 238 Nov 28 06:43 ssh_host_rsa_key.pub If any key.pub file has a mode more permissive than "0644", this is a finding.

Fix Text

Note: SSH public key files may be found in other directories on the system depending on the installation. Change the mode of public host key files under "/etc/ssh" to "0644" with the following command: # sudo chmod 0644 /etc/ssh/*key.pub The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command: # sudo systemctl restart sshd.service

Additional Identifiers

Rule ID: SV-215132r610931_rule

Vulnerability ID: V-215132

Group Title: SRG-OS-000480-GPOS-00227

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.