The RHEL 8 SSH public host key files must have mode 0644 or less permissive.

STIG ID: RHEL-08-010480 |  SRG: SRG-OS-000480-GPOS-00227 |  Severity: medium |  CCI:  | Vulnerability Id: V-230286

Vulnerability Discussion

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

Check

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

Fix

Verify the SSH public host key files have mode "0644" or less permissive with the following command:

$ sudo ls -l /etc/ssh/*.pub

-rw-r--r-- 1 root root 618 Nov 28 06:43 ssh_host_dsa_key.pub
-rw-r--r-- 1 root root 347 Nov 28 06:43 ssh_host_key.pub
-rw-r--r-- 1 root root 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.

Note: SSH public key files may be found in other directories on the system depending on the installation.