Vulnerability Discussion

Passwords must be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised. Passwords that are encrypted with a weak algorithm are no more protected than if they are kept in plain text.

This setting ensures user and group account administration utilities are configured to store only encrypted representations of passwords. Additionally, the "crypt_style" configuration option ensures the use of a strong hashing algorithm that makes password cracking attacks more difficult.

The default for Red Hat 10 is yescrypt. Although yescrypt is structurally built using an outer layer of SHA-256 (which is a NIST-approved algorithm), the yescrypt algorithm as a whole is not recognized or validated by the National Institute of Standards and Technology (NIST) Cryptographic Module Validation Program (CMVP).

Check

Verify RHEL 10 is configured so that the shadow file stores only encrypted representations of passwords with a hash value of SHA512 with the following command:

$ sudo grep -i encrypt_method /etc/login.defs
ENCRYPT_METHOD SHA512

If "ENCRYPT_METHOD" does not have a value of "SHA512", or the line is commented out, this is a finding.

Fix

Configure RHEL 10 to store only SHA512 encrypted representations of passwords.

Add or update the following line in the "/etc/login.defs" file:

ENCRYPT_METHOD SHA512