Vulnerability Discussion

Using an authentication device, such as a Common Access Card (CAC) or token that is separate from the information system, ensures that even if the information system is compromised, that compromise will not affect credentials stored on the authentication device.

Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards such as the U.S. Government Personal Identity Verification card and the DoD CAC.

There are various methods of implementing multifactor authentication for RHEL 8. Some methods include a local system multifactor account mapping or joining the system to a domain and utilizing a Red Hat idM server or Microsoft Windows Active Directory server. Any of these methods will require that the client operating system handle the multifactor authentication correctly.

Satisfies: SRG-OS-000105-GPOS-00052, SRG-OS-000106-GPOS-00053, SRG-OS-000107-GPOS-00054, SRG-OS-000108-GPOS-00055

Check

Verify RHEL 8 uses multifactor authentication for local access to accounts.

Note: If the System Administrator demonstrates the use of an approved alternate multifactor authentication method, this requirement is not applicable.

Check that the "pam_cert_auth" setting is set to "true" in the "/etc/sssd/sssd.conf" file.

Check that the "try_cert_auth" or "require_cert_auth" options are configured in both "/etc/pam.d/system-auth" and "/etc/pam.d/smartcard-auth" files with the following command:

$ sudo grep -ir cert_auth /etc/sssd/sssd.conf /etc/sssd/conf.d/*.conf /etc/pam.d/*
/etc/sssd/sssd.conf:pam_cert_auth = True
/etc/pam.d/smartcard-auth:auth sufficient pam_sss.so try_cert_auth
/etc/pam.d/system-auth:auth [success=done authinfo_unavail=ignore ignore=ignore default=die] pam_sss.so try_cert_auth

If "pam_cert_auth" is not set to "true" in "/etc/sssd/sssd.conf", this is a finding.

If "pam_sss.so" is not set to "try_cert_auth" or "require_cert_auth" in both the "/etc/pam.d/smartcard-auth" and "/etc/pam.d/system-auth" files, this is a finding.

Fix

Configure RHEL 8 to use multifactor authentication for local access to accounts.

Add or update the "pam_cert_auth" setting in the "/etc/sssd/sssd.conf" file to match the following line:

[pam]
pam_cert_auth = True

Add or update "pam_sss.so" with "try_cert_auth" or "require_cert_auth" in the "/etc/pam.d/system-auth" and "/etc/pam.d/smartcard-auth" files based on the following examples:

/etc/pam.d/smartcard-auth:auth sufficient pam_sss.so try_cert_auth

/etc/pam.d/system-auth:auth [success=done authinfo_unavail=ignore ignore=ignore default=die] pam_sss.so try_cert_auth

The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command:

$ sudo systemctl restart sssd.service