RHEL 9 pam_unix.so module must be configured in the password-auth file to use a FIPS 140-3 approved cryptographic hashing algorithm for system authentication.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-258233	SRG-OS-000073-GPOS-00041	RHEL-09-671025	SV-258233r1015136_rule	2025-02-27	2

Description
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 9 systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules. FIPS 140-3 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.

Description

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 9 systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules. FIPS 140-3 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.

ℹ️ Check
Verify that the pam_unix.so module is configured to use sha512 in /etc/pam.d/password-auth with the following command: $ grep "^password.pam_unix.so.sha512" /etc/pam.d/password-auth password sufficient pam_unix.so sha512 If "sha512" is missing, or the line is commented out, this is a finding. If the system administrator (SA) can demonstrate that the required configuration is contained in a PAM configuration file included or substacked from the system-auth file, this is not a finding.

ℹ️ Check

Verify that the pam_unix.so module is configured to use sha512 in /etc/pam.d/password-auth with the following command: $ grep "^password.*pam_unix.so.*sha512" /etc/pam.d/password-auth password sufficient pam_unix.so sha512 If "sha512" is missing, or the line is commented out, this is a finding. If the system administrator (SA) can demonstrate that the required configuration is contained in a PAM configuration file included or substacked from the system-auth file, this is not a finding.

✔️ Fix
Configure RHEL 9 to use a FIPS 140-3 approved cryptographic hashing algorithm for system authentication. Edit/modify the following line in the "/etc/pam.d/password-auth" file to include the sha512 option for pam_unix.so: password sufficient pam_unix.so sha512