UBTU-22-255065 Ubuntu 22.04 LTS must use strong authenticators in establishing nonlocal maintenance and diagnostic sessions.
All changes in this version
Maps to MA-4 via CCI-000877
Title
Ubuntu 22.04 LTS must use strong authenticators in establishing nonlocal maintenance and diagnostic sessions.
Control
Verify Ubuntu 22.04 LTS is configured to use strong authenticators in the establishment of nonlocal maintenance and diagnostic maintenance by using the following command: $ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH 'usepam' /etc/ssh/sshd_config:UsePAM yes If "UsePAM" is not set to "yes", is commented out, is missing, or conflicting results are returned, this is a finding.
Discussion
Nonlocal maintenance and diagnostic activities are conducted by individuals communicating through either an external network (e.g., the internet) or an internal network. Local maintenance and diagnostic activities are carried out by individuals physically present at the information system or information system component and not communicating across a network connection. Typically, strong authentication requires authenticators that are resistant to replay attacks and employ multifactor authentication. Strong authenticators include, for example, PKI where certificates are stored on a token protected by a password, passphrase, or biometric.
Related controls
CCI-000877
Fix
Configure Ubuntu 22.04 LTS to use strong authentication when establishing nonlocal maintenance and diagnostic sessions. Add or modify the following line to /etc/ssh/sshd_config: UsePAM yes Restart SSH for the changes to take effect: $ sudo systemctl restart ssh