Vulnerability Discussion

Unapproved mechanisms that are used for authentication to the cryptographic module are not verified and therefore cannot be relied upon to provide confidentiality or integrity, and DoD data may be compromised.

RHEL 8 systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules.

FIPS 140-2 is the current standard for validating that mechanisms used to access cryptographic modules utilize authentication that meets DoD requirements. This allows for Security Levels 1, 2, 3, or 4 for use on a general-purpose computing system.

Check

Verify that pam_unix.so auth is configured to use sha512.

Check that pam_unix.so auth is configured to use sha512 in both /etc/pam.d/password-auth and /etc/pam.d/system-auth with the following command:

$ sudo grep password /etc/pam.d/password-auth | grep pam_unix

password sufficient pam_unix.so sha512 rounds=5000

$ sudo grep password /etc/pam.d/system-auth | grep pam_unix

password sufficient pam_unix.so sha512 rounds=5000

If "sha512" is not an option in both outputs, or is commented out, this is a finding.

Fix

Configure RHEL 8 to use a FIPS 140-2 approved cryptographic hashing algorithm for system authentication.

Edit/modify the following line in the file "/etc/pam.d/password-auth" and "/etc/pam.d/system-auth" files to include the sha512 option for pam_unix.so:

password sufficient pam_unix.so sha512 rounds=5000 shadow remember=5