RHEL 9 crypto policy must not be overridden.

STIG ID: RHEL-09-672020  |  SRG: SRG-OS-000396-GPOS-00176 |  Severity: medium |  CCI: CCI-002450,CCI-002890,CCI-003123 |  Vulnerability Id: V-258236

Vulnerability Discussion

Centralized cryptographic policies simplify applying secure ciphers across an operating system and the applications that run on that operating system. Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data.

Satisfies: SRG-OS-000396-GPOS-00176, SRG-OS-000393-GPOS-00173, SRG-OS-000394-GPOS-00174

Check

Verify that RHEL 9 custom crypto policies are loaded correctly.

List all of the crypto backends configured on the system.

$ ls -l /etc/crypto-policies/back-ends/
lrwxrwxrwx. 1 root root 40 Oct 7 08:44 bind.config -> /usr/share/crypto-policies/FIPS/bind.txt
lrwxrwxrwx. 1 root root 42 Oct 7 08:44 gnutls.config -> /usr/share/crypto-policies/FIPS/gnutls.txt
lrwxrwxrwx. 1 root root 40 Oct 7 08:44 java.config -> /usr/share/crypto-policies/FIPS/java.txt
lrwxrwxrwx. 1 root root 46 Oct 7 08:44 javasystem.config -> /usr/share/crypto-policies/FIPS/javasystem.txt
lrwxrwxrwx. 1 root root 40 Oct 7 08:44 krb5.config -> /usr/share/crypto-policies/FIPS/krb5.txt
lrwxrwxrwx. 1 root root 45 Oct 7 08:44 libreswan.config -> /usr/share/crypto-policies/FIPS/libreswan.txt
lrwxrwxrwx. 1 root root 42 Oct 7 08:44 libssh.config -> /usr/share/crypto-policies/FIPS/libssh.txt
lrwxrwxrwx. 1 root root 39 Oct 7 08:44 nss.config -> /usr/share/crypto-policies/FIPS/nss.txt
lrwxrwxrwx. 1 root root 43 Oct 7 08:44 openssh.config -> /usr/share/crypto-policies/FIPS/openssh.txt
lrwxrwxrwx. 1 root root 49 Oct 7 08:44 opensshserver.config -> /usr/share/crypto-policies/FIPS/opensshserver.txt
lrwxrwxrwx. 1 root root 46 Oct 7 08:44 opensslcnf.config -> /usr/share/crypto-policies/FIPS/opensslcnf.txt
lrwxrwxrwx. 1 root root 43 Oct 7 08:44 openssl.config -> /usr/share/crypto-policies/FIPS/openssl.txt

If the paths do not point the respective files under /usr/share/crypto-policies/FIPS path, this is a finding.

Fix

Configure RHEL 9 to FIPS crypto policy.

$ sudo ln -s /usr/share/crypto-policies/FIPS/.txt /etc/crypto-policies/back-ends/.conf

Replace with every service that is not set to FIPS.

The system must be rebooted to make the changes to take effect.
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