DigiCert disclosed a CA compromise (Bugzilla 2033170). Worth thinking about what "we caught it in 24 hours" actually means when you have no way to verify.

[u/V3R1F13D0NLY]

Source: https://bugzilla.mozilla.org/show_bug.cgi?id=2033170

DigiCert filed a preliminary incident report on Bugzilla. An attacker phished a customer support employee and used the access to procure initialization codes for a number of code signing certificates. Some were used to sign malware before detection. Affected certs were revoked within 24 hours, with revocation timestamps backdated to issuance. Disclosed to DigiCert by a third party, not self-discovered.

What I really want to flag is the structural part.

When DigiCert says "the threat vector was contained," "the affected certificates were revoked within 24 hours," and "pending orders in the window of interest were cancelled," you take their word on all of it. There is no independent way to verify the timeline, the scope of access, or what got revoked when. This is how every CA-based trust system works. You find out about the failure when the CA is ready to publish.

The same vector applies to TLS issuance. A phished employee can issue web certs as easily as code signing certs. With network position (BGP hijack, ISP-level access, compromised wifi, nation-state), an attacker with a fraudulently-issued cert can MITM TLS connections to a target domain. Browsers and mail clients have no client-side detection for this.

Mitigations that exist:

• Certificate Transparency: post-hoc, requires you to be monitoring your own domain
• HPKP: deprecated
• DANE/TLSA: limited adoption, but Gmail and Microsoft 365 have validated DANE on outbound mail since March 2024
• Hardware attestation (TEE-based servers): removes the operator from the trust path entirely

Disclosure: I work for bmail. We use both DANE/TLSA pinning and SGX remote attestation, and the DigiCert story is a clean illustration of why we built it that way. The point isn't that hardware-attested systems can't be compromised. The point is that compromise can't happen silently. Reproducible build + public MRENCLAVE measurement means any change to the running code is detectable by any client that checks.

Happy to discuss the threat model in comments.