Vulnerability Discussion

SSH environment options potentially allow users to bypass access restriction in some configurations.

Check

Verify that unattended or automatic logon via ssh is disabled with the following command:

$ sudo grep -i PermitUserEnvironment /etc/ssh/sshd_config

PermitUserEnvironment no

If "PermitUserEnvironment" is set to "yes", is missing completely, or is commented out, this is a finding.

Fix

Configure RHEL 8 to allow the SSH daemon to not allow unattended or automatic logon to the system.

Add or edit the following line in the "/etc/ssh/sshd_config" file:

PermitUserEnvironment no

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