What you're describing is called a Downgrade attack, and it can be detected. The newer the software at both ends, the better (more capable) the detection.

In TLS 1.3 both sides need to have experienced exactly the same conversation right up until the encryption switches on, or else encryption fails and they abort. If you sneak in say a message saying "No, do crappy old crypto" to the client that was never actually sent by the server, the two conversations won't match and the connect fails. If you snuck in a message to the server saying "I can only do crappy old crypto" that was never really sent by the client, again, no match, no connection.

In earlier versions of TLS, you can't fake the version number or tweak the ciphersuites or again the encryption fails and no connection is made.

Only downgrading to SSL 3.0 or lower gets you somewhere, and no modern client software will allow such a downgrade.

https://arstechnica.com/information-technology/2017/12/suspi...

Sounds like xenophobic bullshit.

For instance, I host my personal site on both IPFS and normal web traffic.

https://fn.lc/ipns/Qmea45XwFtdwaCGAPLRMxFmoUP5YLnknc2WGCGQ3H...

https://gateway.ipfs.io/ipns/Qmea45XwFtdwaCGAPLRMxFmoUP5YLnk...

If myetherwallet.com had been DNSSEC signed then users who validated the signature chain would have not been redirected to the fake site. But it's not DNSSEC signed.

Note that "the auth servers hosting myetherwallet.com" aren't some random IP addresses in Tallinn, Estonia. It's Route53!

I get what you're saying with your counterfactual, that DNSSEC "breaks the exploit", requiring the attackers to use a slightly different exploit. But who cares? The slightly different exploit has the same predicates.

That's what's so funny about the narrative that DNSSEC has some role to play in today's attack. It would almost make sense if the narrative was "we could use DANE to get rid of all CAs and then it wouldn't matter if you could trick a DV validator". But, no, people are talking about how DNSSEC would help LetsEncrypt, in the event of a global BGP hijacking. Admit it! That's funny.

I think he's saying: let's say the correct IP address for example.com is 192.0.2.80. Instead of hijacking the prefix containing example.com's nameservers, an attacker could just hijack 192.0.2.0/24 and immediately get a DV cert. Within seconds they would be up and running and DNSSEC wouldn't have done a thing to prevent it.

I posted in response to pfg's comment above a mechanism that high value targets could choose, which is modelled on how Facebook behave today but (since we're proving a point here) more extreme. Make a deal with a CA, forbid all other CAs from issuing.

The other thing about Let's Encrypt is that they wouldn't be a good target for such an attacker because they are seeing the world from more than one place. You specify particularly a global BGP hijack, but those are hard, which is why this wasn't global. Tricking just, say, the original San Francisco office of Let's Encrypt doesn't get the job done.

Your second link is a reference to what is now called DANE. There is an alternate universe in which DANE helps this problem. In that universe, there are no CAs anymore (otherwise, DANE is effectively just another CA, and attackers will just choose whichever CA allows them to execute their attack).

But DANE is already dead on arrival. Both Mozilla and Chrome flirted with DANE support a few years ago, and then withdrew it. Adam Langley wrote a post on why DANE support turned out to be untenable.

There's another big reason why you shouldn't be excited for DANE deployment, which is that it is essentially a TLS key escrow system. The most important TLDs in the world are controlled by world governments with massive SIGINT infrastructure. DANE turns those TLDs into the new Web PKI roots.

There is another, even less likely, universe where DANE works. Here, every cert needs to be validated by both DANE and a CA. Security wise, this would be an improvement over just CAs. However, the large governments would still be able to MitM TLDs in their control (just patriot act some CA).

This is where I point out that the current CA system is also controlled by those who control the TLD, because domain validation depends on the DNS system. But that is an old argument.

There is some hope for the CA system through the use of certificate transparency logs. Notably, this system moves away from trusting the DNS system. Sadly, it is mostly a detection-after-the-fact system, but there is hope.

(The reason this isn't an application header like HSTS is that DANE advocates want to bake this into TLS itself, so that it works without needing new application features in every single TLS-using application)

The big problem Chrome had with DANE was that they couldn't (and presumably still can't) assume reliable DNSSEC/DANE record lookups. If you can't fail closed with DANE, then all DANE really is is another CA; attackers can "strip" DANE from connections, trivially, and be exactly where they are today. Meanwhile, end-users pay the price in latency and reduced performance for a cosmetic security improvement that most people don't care about.

At this point in this attack, we are not sure of which domains have been hit. With a BGP attack, the specific IPs would've been quite public.