I'm not sure how CAs deal with situations when a domain has several authoritative DNS servers, but not all of them respond with expected reply. Would it would be a good idea for CAs to ask *all* authoritative DNS servers and require a coherent answer from them?
For the case of the dns-01 challenge type, sure. But if you're using http-01 (or the attacker asks for it), then all those DNS servers will answer back with the same IP address for the A(AAA) query and you're back to the hijacking scenario.
Good point, I forgot about that! But then CAA record might help, I guess, if you specify your accounturi?
* https://datatracker.ietf.org/doc/html/draft-ietf-acme-dns-ac...
I meant to say that CAA record can also specify account, or at least Let’s Encrypt docs mention it[1]. So unless attacker has access to victim's account - they can't get a cert (unless they can hijack dns, too).
[1]: https://letsencrypt.org/docs/caa/#the-accounturi-parameter
Moreover, with dns-01, DNS provider can issue fake certificates - unless you self-host DNS - in which case, only your DNS registrar can... and a government.
Which is what DNSSEC is supposed to help with: the registrar/government would have to replace your DS/KSK with their own. Without DNSSEC queries/replies could potentially be altered over the wire (or you're in a race condition as to whether the real or attacker's reply get back first).
But that's not controlling "the domain" in my book. You control the domain if you control the nameserver.