3

Let's make the following assumptions:

  1. A trusted root certificate was being served with a vulnerable version of OpenSSL.
  2. Prior to public disclosure, a malicious entity was aware of and exploited the heartbleed vulnerability
  3. Said malicious entity attacked and gained the private key for the root certificate
  4. I don't have an affected version of OpenSSL on my server, but I have a certificate signed by the compromised root certificate

Presumably, at this point, the CA would revoke their root certificate, and any certificates signed by it would have to be re-issued, correct? Once the root certificate was revoked, the potential for damage would be limited to clients that didn't update their trusted root bundle, correct?

What about last week? A compromised root certificate would have allowed an attacker to create a certificate for any domain, not just one that had been signed by that certificate, right? There wouldn't be any additional vulnerabilities for my domain because its certificate was signed by the compromised certificate, right?

And, as a bonus made up of complete speculation, how likely do you think it is that this vulnerability has been found and exploited prior to public disclosure?

  • 3
    It would take an astonishing amount of incompetence for a CA to use their root signing key directly to secure TLS connections. – Stephen Touset Apr 10 '14 at 21:10
  • 2
    It would take an astonishing amount of incompetence for a CA to keep their root signing key on a webserver. Although one or two of the 600+ of them do manage to astonish everyone occasionally... – pyramids Apr 10 '14 at 21:29
  • All your "correct?"s and "right?"s are correct and right. – Matt Nordhoff Apr 10 '14 at 21:39
  • Exposing the CA externally does not make any sense to me. I approve of the above comments. – Neophyte Apr 10 '14 at 21:48
  • I was under the apparently mistaken impression that the trust chain was a chain of SSL certificates, served the way typical SSL certificates are served. I should have done some more reading first :) – Jason Apr 11 '14 at 14:51
4

They are two different services, that are not related.

  1. PK Signing service

    • These keys use the CA's crown jewels.
    • They are protected as much as they can.
    • If they are lost, they will be Out of Business
    • So they use network segmentation, firewalling, HSM's, armed guards, whatever it takes to secure them.
  2. Normal SSL website using a signed key (possibly but not necessarily from the service above).

    • Impact of compromise - embarrassing, reputation damage but not critical.

So, they 'could' choose to combine these two services, using the same key on the outside of their website, but as @StephenTouset says above, "It would take an astonishing amount of incompetence"

  • What's the empirical evidence for "if they are lost, they will be Out of Business?" Granted, DigiNotar is no more. Yet Comodo survived and seems to be doing well. Were there any others so far? – pyramids Apr 10 '14 at 21:32
  • 1
    @pyramids I don't think Comodo has ever misplaced a private key. Their systems just rubber-stamped certs for hacked resellers. If we're referring to the 2011 incident. – Matt Nordhoff Apr 10 '14 at 21:37
  • Thanks for keeping me honest @pyramids, At the very least the CA business will be likely closed unless the browser makers can be convinced that 'things have been fixed'. – Andrew Russell Apr 10 '14 at 21:52
  • @MattNordhoff You're right, of course. Thanks for the correction! I suppose in my mind I oversimplified that as "bad enough," but of course it's not quite as big a catastrophe to let someone use the root key maliciously versus giving it away outright. – pyramids Apr 10 '14 at 21:57
  • So, if I understand what you are saying correctly, and I suppose I should have looked up more about how the SSL/CA/Trust system works first, the Root Certificate that is trusted by default, and that essentially resides at the top of the trust chain, is not a typical SSL certificate nor is it served in the way a typical SSL certificate is served? That was where my misunderstanding lay. – Jason Apr 11 '14 at 14:48

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