Ubuntu 22.04 LTS must be configured such that Pluggable Authentication Module (PAM) prohibits the use of cached authentications after one day.

STIG ID: UBTU-22-631015  |  SRG: SRG-OS-000383-GPOS-00166 | Severity: low |  CCI: CCI-002007

Vulnerability Discussion

If cached authentication information is out-of-date, the validity of the authentication information may be questionable.

Check

Verify that PAM prohibits the use of cached authentications after one day by using the following command:

Note: If smart card authentication is not being used on the system, this requirement is not applicable.

$ sudo grep -i '^\s*offline_credentials_expiration' /etc/sssd/sssd.conf /etc/sssd/conf.d/*.conf
/etc/sssd/sssd.conf:offline_credentials_expiration = 1

If "offline_credentials_expiration" is not set to "1", is commented out, is missing, or conflicting results are returned, this is a finding.

Fix

Configure PAM to prohibit the use of cached authentications after one day.

Add or modify the following line in the "/etc/sssd/sssd.conf" file, just below the line "[pam]":

offline_credentials_expiration = 1

Note: It is valid for this configuration to be in a file with a name that ends with ".conf" and does not begin with a "." in the "/etc/sssd/conf.d/" directory instead of the "/etc/sssd/sssd.conf" file.