Apple's response to the WoSign incidents

Seems like a sensible response. I do wonder how they will know what certificates are currently signed by WoSign, as they stated that individual certificates will still be trusted somehow.

Couple notes for people less familiar with the Internet PKI/CA industry:

1. WoSign (who also owns StartCom) violated all sorts of industry standards. The worst of them was circumventing the SHA-1 deprecation by backdating an SSL certificate.

2. Now all the root programs (Mozilla, Apple, Microsoft, and Google) need to decide how they will react to this.

3. Mozilla proposed dis-trusting all new WoSign/StartCom certificates and giving them a chance to re-apply as a trusted CA in a year. This is only their proposed action, and they have not totally committed to it.

4. Apple has now said they will take similar action to Mozilla. Apple will block a specific intermediate certificate: "WoSign CA Free SSL Certificate G2"

But they will continue to "trust individual existing certificates" if they had been published to Certificate Transparency logs by September 19th.

While I have not personally confirmed this, my understanding is that there are other Wosign certificates that are trusted on Apple via cross-signing. So this seems like an incomplete solution - in the sense that some WoSign certificates (mainly the commercial certificates they sell, vs the ones they give away for free) will remain unaffected in anyway.

(Someone more familiar with the specifics of the Apple root store may be able to provide more clarity here)

5. Google and Microsoft have not yet committed to any action yet. Google will certainly make a detailed public announcement when they are ready.

6. Mozilla is meeting with QiHoo (a chinese tech company which owns a majority stake in WoSign). It is expected that Mozilla will make a final decision following this meeting.

Apple will continue to trust existing certs from WoSign (provided they are CT logged). New certs will not be trusted.

mac OS will make this decision by first looking at signatures. It will receive the "end-entity" certificate (a cert for a specific site, like example.com) and while checking the chain, will see that there is a signature from the "WoSign CA Free SSL Certificate G2 intermediate CA" certificate.

It will then look at the "notBefore" date listed in the certificate, which tells you when the certificate was issued. If it is a new certificate, it will not be trusted.

If the certificate is preexisting (presumably issued before 9/19/16) it will be trusted ONLY if the certificate is CT logged. It will know if this is the case by looking for an SCT belonging to that certificate. The SCT will either be embedded directly in the certificate, or provided with the certificate during the SSL handshake (this is known as "stapling").

> But they will continue to "trust individual existing certificates" if they had been published to Certificate Transparency logs by September 19th.

This seems even more sensible than Mozilla's existing proposal to trust the certificate notBefore date until proof of further backdated certificates.

>> But they will continue to "trust individual existing certificates" if they had been published to Certificate Transparency logs by September 19th. > This seems even more sensible than Mozilla's existing proposal to trust the certificate notBefore date until proof of further backdated certificates.

The question is how they'll actually do that. This was discussed in the moz-sec-policy-thread and people came to the rough conclusion that there are just too many wosign/startcom certificates to whitelist them in any reasonable way.