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RHEL 9 SSH public host key files must have mode 0644 or less permissive.


Overview

Finding ID Version Rule ID IA Controls Severity
V-258001 RHEL-09-255125 SV-258001r991589_rule Medium
Description
If a public host key file is modified by an unauthorized user, the SSH service may be compromised.
STIG Date
Red Hat Enterprise Linux 9 Security Technical Implementation Guide 2024-06-04

Details

Check Text ( C-61742r925988_chk )
Verify the SSH public host key files have a mode of "0644" or less permissive with the following command:

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

$ sudo stat -c "%a %n" /etc/ssh/*.pub

644 /etc/ssh/ssh_host_dsa_key.pub
644 /etc/ssh/ssh_host_ecdsa_key.pub
644 /etc/ssh/ssh_host_ed25519_key.pub
644 /etc/ssh/ssh_host_rsa_key.pub

If any key.pub file has a mode more permissive than "0644", this is a finding.
Fix Text (F-61666r925989_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

Restart the SSH daemon for the changes to take effect:

$ sudo systemctl restart sshd.service