AlmaLinux OS 9 must only allow the use of DOD PKI-established certificate authorities for authentication in the establishment of protected sessions to the operating system.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-269427	SRG-OS-000403-GPOS-00182	ALMA-09-041270	SV-269427r1050310_rule	2025-02-20	1

Description
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.

Description

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.

ℹ️ 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

✔️ 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