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

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-253108	SRG-OS-000480-GPOS-00227	TOSS-04-040670	SV-253108r991589_rule	2024-05-30	2

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

ℹ️ Check
Verify the SSH public host key files have mode "0644" or less permissive with the following command: $ sudo ls -l /etc/ssh/*.pub -rw-r--r-- 1 root root 618 Nov 28 06:43 ssh_host_dsa_key.pub -rw-r--r-- 1 root root 347 Nov 28 06:43 ssh_host_key.pub -rw-r--r-- 1 root root 238 Nov 28 06:43 ssh_host_rsa_key.pub If any key.pub file has a mode more permissive than "0644", this is a finding. Note: SSH public key files may be found in other directories on the system depending on the installation.

ℹ️ Check

Verify the SSH public host key files have mode "0644" or less permissive with the following command: $ sudo ls -l /etc/ssh/*.pub -rw-r--r-- 1 root root 618 Nov 28 06:43 ssh_host_dsa_key.pub -rw-r--r-- 1 root root 347 Nov 28 06:43 ssh_host_key.pub -rw-r--r-- 1 root root 238 Nov 28 06:43 ssh_host_rsa_key.pub If any key.pub file has a mode more permissive than "0644", this is a finding. Note: SSH public key files may be found in other directories on the system depending on the installation.

✔️ 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 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