I think the argument isn’t that it’s okay, but that one bad thing doesn’t mean we should do two bad things. Just because my DNS provider can see my domain requests doesn’t mean I also want arbitrary CAs on the Internet to also see them.
You have to trust the DNS server more than you trust the server you are reaching out to as the DNS server can direct you anywhere as well as see everything you are trying to access anyhow.
Don't think I agree with this. TLS is important against MITM scenarios - integrity, privacy. You don't need DNS for this to be abused but a man in the middle - whether that is some open wifi, ISP or tapped into your network any other way.
Although tbh I think that just moves the problem somewhere else (which is perfectly fine if you don’t like the current PKI).
I’m not sure I understand the logic here. To me TLS PKI and DNS are somewhat orthogonal.
In practice, TLS certificates are given out to domain owners, and domain ownership is usually proven by being able to set a DNS record. This means compromise of the authorative DNS server implies compromise of TLS.
Malicious relaying servers and MitM on the client is already solved by DNSSEC, so it's not adding anything there either.
If we got rid of CAs and stored our TLS public keys in DNS instead, we would lose relatively little security. The main drawback I can think of is the loss of certificate issuance logs.
Yes, except for CT, which can help detect this kind of attack.
> Malicious relaying servers and MitM on the client is already solved by DNSSEC, so it's not adding anything there either.
I'm not sure quite what you have in mind here, but there is more to the issue than correct DNS resolution. In many cases, the attacker controls the network between you and the server, and can intercept your connection regardless of whether DNS resolved correctly.
> If we got rid of CAs and stored our TLS public keys in DNS instead, we would lose relatively little security. The main drawback I can think of is the loss of certificate issuance logs.
This may be true in principle but has a very low chance of happening in practice, because there is no current plausible transition path, so it's really just a theoretical debate.
Well, DANE exists and provides an obvious transition path, as brittle of an approach it is. Ideally you would be able to create your own intermediates (with name constraints) and pin the intermediate rather than the lead certificate, but PKI isn't set up for that.
From my understanding, the biggest issue with DNSSEC is that it's just a return to the single signing authority model that TLS used in the 90s. Isn't it also just Verisign again? (At least for .com.)
You still have the problem where a substantial cohort of Internet users can't resolve DANE records. They're on Internet paths that include middleboxes that freak out when they see anything but simple UDP DNS records. You can't define that problem away.
So now you need to design a fallback for those users. Whatever that fallback is, you have to assume attackers will target it; that's the whole point of the exercise. What you end up with a system that decays to the natural security level of the WebPKI. From a threat model perspective, what you've really done is just add another CA to the system. Not better!
DANE advocates tried for years to work around this problem by factoring out the DNS from DANE, and stapling DANE records to TLS handshakes. Then someone asked, "well, what happens when attackers just strip that out of the handshake". These records are used to authenticate the handshake, so you can't just set "the handshake will be secure" as an axiom. Nobody had a good answer! The DANE advocates were left saying we'd be doing something like HPKP, where browsers would remember DANE-stapled hosts after first contact. The browser vendors said "lol no".
That's where things stand. The stapling thing was so bad that Geoff Huston --- a DNS/DNSSEC éminence grise --- wrote a long blog post asking (and more or less conceding) that it was time to stick a fork in the whole thing.
Just imagine you succeeded in inventing a perfectly secure DNS server. Great, we know this IP address we just got back is the correct one for the server.
Ok, then I go to make a connection to that IP address, but someone on hop 3 of my connection is malicious, and instead of connecting me to the IP, just sends back a response pretending to be from that IP. How would I discover this? TLS would protect me from this, perfectly secure DNS won't.
If you are saying every packet sent is secure, then it would have nothing to do with DNS?
(I'm not necessarily in favour of this, I just don't see the revocation part as being the main issue.)
You can't refresh your certificates every 2 minutes but you can set the DNS TTL to 2 minutes and thus stop compromised certs as soon as you discover them (plus 2 minutes). If you use DANE this is already possible but quite fragile unless you have configured your TLS certificate issuing server to have access to modify your DNS records (which is probably less safe overall).
However I don't believe I've ever seen it used "in the wild".