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Comment by dfabulich | Hacker News Reader

No, you're forgetting about Certificate Transparency, which protects against this attack.

It doesn't. Pretty much no one monitors CT logs and for those who do there is no way to prove misissuance of domain-validated certificate and revoke it, they don't have private keys.

If you believe you have been successfully attacked this way you should report it, the logs would be part of your evidence. I spent some time looking for this sort of thing, and it does look like it happens sometimes, mostly to military or political targets, but it's rare. That work is owned by a previous employer, but let's say dozens of times across several years.

You are entitled to revocation of any unexpired certificates for names over which you can demonstrate control. For Let's Encrypt for example you can automate this, simply make the API calls to demonstrate control (as you would for issuance) and then present the certificate that is to be revoked (it's in the logs) and ask their API to revoke it.

But if an attacker can intercept domain validation to issue a certificate, there is little reason not to protect his own certificate from revocation by preventing subsequent validations until it is used on a target, if he can't hide this fact in some way of course. A report of that will look like someone is trying to revoke a certificate for a domain they don't control and won't actually solve the problem even if a human can be convinced by other method that you do control the domain.

Maybe DNSSEC could be used here to help if ACME added a way to force DNSSEC-only domain validation.

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