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 -ir permituserenvironment /etc/ssh/sshd_config /etc/ssh/sshd_config.d/*

PermitUserEnvironment no

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

If the required value is not set, this is a finding.

Fix

Configure the RHEL 9 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

Restart the SSH daemon for the setting to take effect:

$ sudo systemctl restart sshd.service