Checking If A Security Exception Has Been Accepted By The Client

We have a few staging environments for internal testing/dev that do not use 'real' SSL certs. Honestly I'm a bit fuzzy on the details, but the bottom line is when accessing a subdo

Solution 1:

Checking the validity of the certificate is solely the responsibility of the client. Only it can know that it has to use HTTPS, and that it has to use it against a certificate that's valid for that host.

If the users don't make these checks and therefore put themselves in a position where a MITM attack could take place, you wouldn't necessarily be able to know about it. An active MITM attacker could answer perform the tasks you use to try to check the users are doing things correctly, but the legitimate users might not even get to know about it. This is quite similar to wanting to use redirections from http:// to https://: it works as long as there is no active MITM attack downgrading the connection.

(There is an exception to this, to make sure the client has seen the same handshake as you: when using client certificates. In this case, you would at least know that the client that ha authenticated with a cert would have seen your server cert and not a MITM cert, because of the signature at the end of the handshake. This is not really what you're looking for, though.)

JavaScript mechanisms generally won't let you check the certificate themselves. This being said, XHR requests to untrusted websites (with such warnings) will fail one way or another (generally via an exception): this could be a way to detect whether other pages than the landing page have are accessible by background requests (although you will certainly run into issues regarding Same Origin Policies).

Rather than using self-signed certificates for testing/development, you would be in a much better position if you deployed a test Certification Authority (CA). There are a number of tools to help you do this (which one to use would depend on the number of certificates you need). You would then have to import your own CA certificate into these browsers (or other clients), but the overall testing would be more realistic.

Solution 2:

No.

That acceptance (or denial) only modifies a behavior in the client's browser (each browser, in a different way). It ACKs nothing to the server and the page is not yet loaded, therefore, there is no chance to catch that event.