The Red Hat Enterprise Linux operating system must be configured so that the SSH public host key files have mode 0644 or less permissive.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-204596	RHEL-07-040410	SV-204596r603261_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 7 Security Technical Implementation Guide	2020-12-08

Details

Check Text ( C-4720r88980_chk )
Verify the SSH public host key files have mode "0644" or less permissive. Note: SSH public key files may be found in other directories on the system depending on the installation. The following command will find all SSH public key files on the system: # find /etc/ssh -name '*.pub' -exec ls -lL {} \; -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 file has a mode more permissive than "0644", this is a finding.

Check Text ( C-4720r88980_chk )

Verify the SSH public host key files have mode "0644" or less permissive.

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

The following command will find all SSH public key files on the system:

# find /etc/ssh -name '*.pub' -exec ls -lL {} \;

-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 file has a mode more permissive than "0644", this is a finding.

Fix Text (F-4720r88981_fix)
Note: SSH public key files may be found in other directories on the system depending on the installation. Change the mode of public host key files under "/etc/ssh" to "0644" with the following command: # chmod 0644 /etc/ssh/*.key.pub