The Ubuntu operating system for PKI-based authentication, must implement a local cache of revocation data in case of the inability to access revocation information via the network.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-238233 | UBTU-20-010066 | SV-238233r1015151_rule | CCI-001991 | medium |
| Description | ||||
| Without configuring a local cache of revocation data, there is the potential to allow access to users who are no longer authorized (users with revoked certificates). | ||||
| STIG | Date | |||
| Canonical Ubuntu 20.04 LTS Security Technical Implementation Guide | 2025-05-16 | |||
Details
Check Text (C-238233r1015151_chk)
Verify the Ubuntu operating system, for PKI-based authentication, uses local revocation data when unable to access it from the network.
Verify that "crl_offline" or "crl_auto" is part of the "cert_policy" definition in "/etc/pam_pkcs11/pam_pkcs11.conf" using the following command:
# sudo grep cert_policy /etc/pam_pkcs11/pam_pkcs11.conf | grep -E -- 'crl_auto|crl_offline'
cert_policy = ca,signature,ocsp_on,crl_auto;
If "cert_policy" is not set to include "crl_auto" or "crl_offline", this is a finding.
Fix Text (F-41402r880869_fix)
Configure the Ubuntu operating system, for PKI-based authentication, to use local revocation data when unable to access the network to obtain it remotely.
Add or update the "cert_policy" option in "/etc/pam_pkcs11/pam_pkcs11.conf" to include "crl_auto" or "crl_offline".
cert_policy = ca,signature,ocsp_on, crl_auto;
If the system is missing an "/etc/pam_pkcs11/" directory and an "/etc/pam_pkcs11/pam_pkcs11.conf", find an example to copy into place and modify accordingly at "/usr/share/doc/libpam-pkcs11/examples/pam_pkcs11.conf.example.gz".