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V-282710

CAT II (Medium)

TOSS 5 SSH public host key files must have mode 0644 or less permissive.

Rule ID

SV-282710r1201371_rule

STIG

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

Version

V1R1

CCIs

CCI-000366

Discussion

If a public host key file is modified by an unauthorized user, the SSH service may be compromised.

Check Content

Verify the SSH public host key files have a mode of "0644" or less permissive using 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

Change the mode of public host key files under "/etc/ssh" to "0644" using 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