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Comment by omarforgotpwd | Hacker News Reader

Wow. Just wow. These BGP vulnerabilities are ridculous. Imagine, someone taking over DNS for even a small subset of people and being able to basically just rewrite the internet as they see fit, completely taking control of anything. Even without being able to get a valid SSL certificate you could do a lot of damage. For example, let's say I rewrote requests for SomeNationalBank.com to my proxy server. I make a request to the real SomeNationalBank.com with the weakest set of ciphers allowed, and then pass those bytes along to the client. Then I can try and decrypt it and log into your bank account as soon as I do.

OR better yet I wait for you to log into an unsecured site like neopets.com or something and then pair that unencrypted password wait the fact that I saw you request the domain for a certain bank and if your password is the same (which it is for most people) then that can also get me in.

We need a new more secure system to replace DNS.

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>For example, let's say I rewrote requests for SomeNationalBank.com to my proxy server. I make a request to the real SomeNationalBank.com with the weakest set of ciphers allowed, and then pass those bytes along to the client. Then I can try and decrypt it and log into your bank account as soon as I do.

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.

How similar was this to the BGP attack by Russia in late 2017?

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

Ostensibly they were the exact same thing?

>by Russia

Sounds like xenophobic bullshit.

More correct to say "Russian Government"

The correct thing to say is “ISP in Russia”, could be Norwegian hackers using their routers for all you know.

Check out IPFS' DNS alternative -- IPNS. No blockchain needed, it's pretty solid.

The issue with IPNS is it's based off of public private key crypto which means the "domain" is a hash and has no name recognition. While still useful, it's not going to make its way into the mainstream anytime soon.

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...

The first one took 61 seconds to load, while the second one took 121 seconds. It doesn't seem very practical.

I did. It's not very useful or performant, unfortunately.

SomeNationalBank.com in my experience uses 1 or 2 ciphers which are not the most modern, but are secure enough. For a few reasons there are almost no banks which would allow you to drop lower than aes-128-cbc.

Certain configurations of aes-128-cbc using certain software stacks have been found to have vulnerabilities. But if you really couldn't decrypt it, you could at least save anything you think might have the password in it, and then wait until you can decrypt it at some point in the future.

DNSSEC adoption would prevent a hijacker from manipulating responses.

Buuuuut.... not if you hijack the destination route. It helps if the DNS servers are hijacked, but if you also snag the destination route's IP then you can still get the certificate and serve traffic. Sneaky sneaky.

No, it wouldn't. It comically wouldn't: in a BGP hijacking attack, the attackers control IP. It doesn't matter what your signed DNS record points to; attackers will just make that address theirs.

I think in this instance DNSSEC would have prevented the entire attack. If I understand the sequence of events correctly, the route hijack was done to the auth DNS servers hosting myetherwallet.com. Then these rogue DNS servers redirected users to a fake myetherwallet.com.

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.

In a BGP hijacking attack against a DNSSEC-signed zone, the attacker just looks at which IP address is in the signed A record, and then injects that prefix.

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.

If I understand the discussion correctly, I think tptacek is right but he's not explaining his position well, which might be why he's been downvoted.

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.

DNSSEC plus CAA today would let you tell Let's Encrypt "No thanks, automation is too dangerous for my high-value names". If the hijacker fakes the answer, DNSSEC fails, Let's Encrypt says "DNSSEC failed, no issuance". If the hijacker allows the real answer, Let's Encrypt says "CAA says forbidden, no issuance".

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.

Wouldn't https://tools.ietf.org/html/rfc4025 and https://tools.ietf.org/html/rfc4398 cover those cases?

I don't know what IPSEC has to do with this.

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 an alternate universe in which DANE helps this problem. In that universe, there are no CAs anymore

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 TLS WG is currently haggling about, effectively, DANE's future. The thing up in the air was, should this technology for saying "Hi, I can do DANE" be pinned? e.g. a client sees "I can do DANE" and it says to itself "OK, I will now expect DANE certificates from this TLS service for... 24 hours? 10 minutes? 10 years? An amount of time defined in some new parameter?" Or maybe it never does this. Last I looked at the thread, it seemed like "Never do this, make yet another TLS extension to specify if you want pinning" is the choice of the working group.

(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 TLS WG can haggle about DANE all it wants, but DANE is a dead letter: it was tried in two of the four major browsers and failed, and a third (Safari) briefly had nascent framework support for it and jettisoned it. Without support from the browser vendors, DANE is irrelevant.

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.

So, you should not be surprised (but perhaps you are anyway) that how to work around not having DNSSEC on end systems is exactly what this work was about. Specifically, the idea is you shove DNSSEC RRs into TLS. Now the client doesn't need working DNSSEC, because the DNSSEC records were delivered with the connection. Hence the pinning question.

There's also https://tools.ietf.org/html/rfc4956 , which allows a domain to sign that a range of DNS entries does not exist; under this system, a client resolver could demand cryptographic proof that a domain was missing certain records, which stops the MitM RR-stripping attack.

You're describing authenticated denial, which has been a characteristic of DNSSEC since 1994.

Yes, exactly. The RFC I linked to specifically refers to Authenticated Denial in the Security Considerations section.

I'd expect there are limits to BGP hijacking. Certainly not every BGP router can hijack any IP. Moreover, the more specific the hijack, the clearer the target.

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.

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