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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-238362	UBTU-20-010441	SV-238362r654261_rule		Low

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If cached authentication information is out-of-date, the validity of the authentication information may be questionable.

STIG	Date
Canonical Ubuntu 20.04 LTS Security Technical Implementation Guide	2021-03-23

Details

Check Text ( C-41572r654259_chk )
If smart card authentication is not being used on the system, this s Not Applicable. Verify that PAM prohibits the use of cached authentications after one day with the following command: $ sudo grep offline_credentials_expiration /etc/sssd/sssd.conf /etc/sssd/conf.d/*.conf offline_credentials_expiration = 1 If "offline_credentials_expiration" is not set to a value of "1" in "/etc/sssd/sssd.conf" or in a file with a name ending in .conf in the "/etc/sssd/conf.d/" directory, this is a finding.

Check Text ( C-41572r654259_chk )

If smart card authentication is not being used on the system, this s Not Applicable.

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

$ sudo grep offline_credentials_expiration /etc/sssd/sssd.conf /etc/sssd/conf.d/*.conf

offline_credentials_expiration = 1

If "offline_credentials_expiration" is not set to a value of "1" in "/etc/sssd/sssd.conf" or in a file with a name ending in .conf in the "/etc/sssd/conf.d/" directory, this is a finding.

Fix Text (F-41531r654260_fix)
Configure PAM to prohibit the use of cached authentications after one day. Add or change the following line in "/etc/sssd/sssd.conf" 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.

Fix Text (F-41531r654260_fix)

Configure PAM to prohibit the use of cached authentications after one day. Add or change the following line in "/etc/sssd/sssd.conf" 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.