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V-253107

CAT II (Medium)

The TOSS SSH private host key files must have mode 0600 or less permissive.

Rule ID

SV-253107r991589_rule

STIG

Tri-Lab Operating System Stack (TOSS) 4 Security Technical Implementation Guide

Version

V2R5

CCIs

CCI-000366

Discussion

If an unauthorized user obtains the private SSH host key file, the host could be impersonated.

Check Content

Verify the SSH private host key files have mode "0600" or less permissive with the following command:

$ sudo ls -l /etc/ssh/ssh_host*key

-rw------- 1 root ssh_keys 668 Nov 28 06:43 ssh_host_dsa_key
-rw------- 1 root ssh_keys 582 Nov 28 06:43 ssh_host_key
-rw------- 1 root ssh_keys 887 Nov 28 06:43 ssh_host_rsa_key

If any private host key file has a mode more permissive than "0600", this is a finding.

Fix Text

Configure the mode of SSH private host key files under "/etc/ssh" to "0600" with the following command:

$ sudo chmod 0600 /etc/ssh/ssh_host*key

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