Vulnerability Discussion

Failure to restrict system access to authenticated users negatively impacts Ubuntu 24.04 LTS security.

Check

Verify unattended or automatic login via SSH is disabled with the following command:

$ egrep -r '(Permit(.*?)(Passwords|Environment))' /etc/ssh/sshd_config
PermitEmptyPasswords no
PermitUserEnvironment no

If the "PermitEmptyPasswords" or "PermitUserEnvironment" keywords are set to a value other than "no", are commented out, are both missing, or conflicting results are returned, this is a finding.

Fix

Configure Ubuntu 24.04 LTS to allow the SSH daemon to not allow unattended or automatic login to the system.

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

PermitEmptyPasswords no
PermitUserEnvironment no

Restart the SSH daemon for the changes to take effect:

$ sudo systemctl restart sshd.service