The TOSS SSH public host key files must have mode 0644 or less permissive.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-253108 | TOSS-04-040670 | SV-253108r991589_rule | CCI-000366 | medium |
| Description | ||||
| If a public host key file is modified by an unauthorized user, the SSH service may be compromised. | ||||
| STIG | Date | |||
| Tri-Lab Operating System Stack (TOSS) 4 Security Technical Implementation Guide | 2025-05-08 | |||
Details
Check Text (C-253108r991589_chk)
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.
Fix Text (F-56511r824995_fix)
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