Ubuntu OS must not allow unattended or automatic login via SSH.

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

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

     $ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iEH '(permit(.*?)(passwords|environment))' 
     /etc/ssh/sshd_config:PermitEmptyPasswords no 
     /etc/ssh/sshd_config:PermitUserEnvironment no 

If "PermitEmptyPasswords" and "PermitUserEnvironment" are not set to "no", are commented out, are missing, or conflicting results are returned, this is a finding.

Configure the SSH server to not allow unattended or automatic login to the system.

Add or modify 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