The Ubuntu operating system must not allow unattended or automatic login via SSH.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-238218 | UBTU-20-010047 | SV-238218r991591_rule | CCI-000366 | high |
| Description | ||||
| Failure to restrict system access to authenticated users negatively impacts Ubuntu operating system security. | ||||
| STIG | Date | |||
| Canonical Ubuntu 20.04 LTS Security Technical Implementation Guide | 2025-05-16 | |||
Details
Check Text (C-238218r991591_chk)
Verify that unattended or automatic login via SSH is disabled with the following command:
$ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iEH '^\s*(permit(.*?)(passwords|environment))'
PermitEmptyPasswords no
PermitUserEnvironment no
If "PermitEmptyPasswords" or "PermitUserEnvironment" keywords are not set to "no", are missing completely, or are commented out, this is a finding.
If conflicting results are returned, this is a finding.
Fix Text (F-41387r653828_fix)
Configure the Ubuntu operating system 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