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Unless I'm mis-reading the domain history, this domain was (and is) DNSSEC signed and that did not prevent the takeover. The attackers move is to hi-jack the HTTP endpoints instead of DNS servers, get the cert through HTTP upload verification, and then MiTM.

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Michal Špaček

@spazef0rze

Feb 15

Replying to @danielcormier and @campuscodi

Good question. With BGP hijack in progress, seems the hackers were able to obtain a valid TLS cert for developers.kakao.com, see crt.sh/?q=developers. (now revoked).

Replying to

I don't know whether it was, but currently, if I'm looking at these results right, the domain doesn't seem to be signed: en.internet.nl/site/developer & hardenize.com/report/develop Also, not MitM but modified source on a different server using a fake cert where traffic was redirected to.

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You're seeing them right, and I'm seeing something different and now wonder if they are rolling out DNSSEC and I caught an experiment? It doesn't really change the dynamic ... hi-jack to HTTP works regardless :(

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CAA and datatracker.ietf.org/doc/html/rfc86 is integration of DNSSEC and WebPKI issuance. If they aren't using that, they aren't trying to secure WebPKI issuance with it. DANE is an alternative to WebPKI or a pinning method to use alongside it, which they weren't using. DNSSEC isn't DANE.

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CAA would not have helped: it doesn't specify validation methods

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datatracker.ietf.org/doc/html/rfc86 which was linked in the tweet that you're responding to. There's a standard for specifying validation methods (which can be limited to DNS) and making HTTP validation secure via pinning a key. Not every CA supports HTTP/SMTP validation in the first place.

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If you CAA down to one CA that doesn't support HTTP validation yes. Other fix would have been RPKI

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CAA doesn't really need to permit even one CAA most of the time, only when you're doing renewal. Ideally you have a CA which supports accounturi/validationmethods. I don't understand why Let's Encrypt still has those features in staging. Can have secure HTTP validation with it.

5:54 AM · Feb 17, 2022Twitter Web App

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Let's Encrypt has supported accounturi/validationmethods for something like 2 years on their staging server. It works fine from our testing and we deployed it already ourselves for both their staging/production infrastructure. It doesn't do anything for production yet though...

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Look at the CAA records for our infrastructure for an example: grapheneos.org time.grapheneos.org matrix.grapheneos.org attestation.app etc. Have tested that it properly works for their staging CA infrastructure. Very unfortunate it's limited to that...

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