Vulnerability Discussion

Untrusted Certificate Authorities (CA) can issue certificates, but they may be issued by organizations or individuals that seek to compromise DOD systems or by organizations with insufficient security controls. If the CA used for verifying the certificate is not a DOD-approved CA, trust of this CA has not been established.

The DOD will only accept PKI-certificates obtained from a DOD-approved internal or external certificate authority. Reliance on CAs for the establishment of secure sessions includes, for example, the use of SSL/TLS certificates.

Check

Verify AlmaLinux OS 9 only allows the use of DOD PKI-established certificate authorities using the following command:

$ trust list

pkcs11:id=%7C%42%96%AE%DE%4B%48%3B%FA%92%F8%9E%8C%CF%6D%8B%A9%72%37%95;type=cert
type: certificate
label: ISRG Root X2
trust: anchor
category: authority

If any nonapproved CAs are returned, this is a finding.

Fix

Configure AlmaLinux OS 9 to only allow the use of DOD PKI-established certificate authorities.

For each untrusted CA, export the certificate to a file and add it to the blocklist:

$ trust dump --filter "pkcs11:id=%7C%42%96%AE%DE%4B%48%3B%FA%92%F8%9E%8C%CF%6D%8B%A9%72%37%95;type=cert" > /etc/pki/ca-trust/source/blocklist/ISRGRootX2

$ update-ca-trust

Verify that the certificate is in the blocklist:

$ trust list --filter=blocklist
p11-kit: overriding trust for anchor in blocklist: ISRGRootX2
pkcs11:id=%7C%42%96%AE%DE%4B%48%3B%FA%92%F8%9E%8C%CF%6D%8B%A9%72%37%95;type=cert
type: certificate
label: ISRG Root X2
trust: distrusted
category: authority

pkcs11:id=%88%68%BF%E0%8E%35%C4%3B%38%6B%62%F7%28%3B%84%81%C8%0C%D7%4D;type=cert
type: certificate
label: Explicitly Distrust DigiNotar Root CA
trust: distrusted
category: authority