Comment by cyberax

6 hours ago

The vast majority of Let's Encrypt installations don't use CAA records or anything in DNS. Or they host the DNS along with the HTTPS servers.

So if the router between the web server and the Internet is compromised, it can just get trusted certs for all the HTTPS traffic going through it, enabling transparent MITM to inject its payload.

7 comments

cyberax

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gzread  4 hours ago

This happened: https://notes.valdikss.org.ru/jabber.ru-mitm/

  • akerl_  4 hours ago

    I touched on this in the parallel comment where you linked this, but worth noting that DNSSEC does not solve this threat model, because re-routing the destination of legitimate IP addresses does not rely on modifying DNS responses.

    • cyberax  2 hours ago

      It does solve it. Unless you know my private key, you can't fake the DNSSEC signatures. The linking DS records in the TLD are presumably out of your control and in future can be audited through something like Certificate Transparency logs.

      So even if you fully control the network path, you will somehow have to get access to my private key material.

      2 replies →

tptacek  5 hours ago

"The web server"? Which web server? Are the HTTP flows with executable content going to the web server or coming from it? I'm sorry, you haven't really cleared this up.

  • cyberax  2 hours ago

    Any web server. Just imagine a worm getting onto a company's router and starting to transparently MITM traffic. Jabber.ru experienced such an attack, apparently.