DISA STIGS Viewer

OL 9 SSH private host key files must have mode 0640 or less permissive.

Overview

Finding ID Version Rule ID IA Controls Severity
V-271771 OL09-00-002502 SV-271771r1092025_rule   Medium
Description
If an unauthorized user obtains the private SSH host key file, the host could be impersonated.
STIG Date
Oracle Linux 9 Security Technical Implementation Guide 2025-05-08

Details

Check Text (C-75821r1092023_chk)
Verify that OL 9 SSH private host key files have a mode of "0640" or less permissive with the following command:

$ ls -l /etc/ssh/*_key
640 /etc/ssh/ssh_host_dsa_key
640 /etc/ssh/ssh_host_ecdsa_key
640 /etc/ssh/ssh_host_ed25519_key
640 /etc/ssh/ssh_host_rsa_key

If any private host key file has a mode more permissive than "0640", this is a finding.
Fix Text (F-75728r1092024_fix)
Configure the mode of SSH private host key files under "/etc/ssh" to "0640" with the following command:

$ sudo chmod 0640 /etc/ssh/ssh_host*key

Restart the SSH daemon for the changes to take effect:

$ sudo systemctl restart sshd.service