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V-282709

CAT II (Medium)

TOSS 5 SSH private host key files must have mode 0640 or less permissive.

Rule ID

SV-282709r1201369_rule

STIG

Tri-Lab Operating System Stack (TOSS) 5 Security Technical Implementation Guide

Version

V1R1

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 a mode of "0640" or less permissive using 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

Configure the mode of SSH private host key files under "/etc/ssh" to "0640" using 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