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-238233r653874_rule		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	2021-11-19

Details

Check Text ( C-41443r653872_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.

Check Text ( C-41443r653872_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-41402r653873_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".

Fix Text (F-41402r653873_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".