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Tell HN: Domain fronting to be blocked on Azure

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Re: Tell HN: Domain fronting to be blocked on Azure

#111

How does domain fronting negatively affect microsoft? Why do they care? Is this all just about making peoples lifes worse?

I know alot of people cite "Security Concerns", but I suspect the problem might be simply a technical reason. I personally have been using nginx's ssl_preread module to reverse proxy my connections without SSL termination, domain fronting would break things in my situation. Having the possibility of domain fronting is just too much to consider in your software stack.

Re: Tell HN: Domain fronting to be blocked on Azure

#112
post #90

Earlier quoted context omitted.

Same. What's your point? VPNs also bypass government blocks. It's a cat and mouse game, they block vpns and guards as they see fit when they have a good reason to. Look at tor, if a country tls decrypts everything and blocks connections that can't be decrypted can it still bypass their blocks? Just because not every government is doing it does not mean Tor can't be blocked. Hell, countries allow-list connections to a…

> many in other countries consider it a form of neo-colonialism where you undermine their sovreignity and self-determination. Only if by "their" you mean the ruling class, and by "self-determination" you mean their ability to control others. You can't really say their opinions represent the will of the people, especially when it's the people themselves ultimately choosing to engage in "illegal" activities. And sure,…

The will of the people is relevant only in a democracy. The neocolonialism part is when you force it in a foreign country. There is absolutley nothing superior or special about democracy. If the people of a country through whatever self-determined means acheive democracy then so be it. The thing people like you don't seem to understand is that individualism is a very western thing, this idea that the individual's will is where a government derives its power from is a very new and western experiment(relatively speaking).

Take a look at Iran, they are religious as a nation. Their religion supersedes any individual's will. Or china, the will if the party supersedes individuals' needs. You in your post-colonialist luxury worry about your own will but historically people worry about the well being of their children and society which means not getting killed/raped, having economic and academic opportunities,etc... and beyonf that also, the will of their god being implemented. Which people? The people with weapons just like in a democracy (else the US would still be under a monarchy). They self determined through violence and politics the state they are in. In China the economy is good so the CCP is actually popular, so they self-determined communism (at least by name).

There many countries where the US exported a revolution or a democracy and they are in shambles now (who cares so long as they are under western influence?) name one nation in europe that was did not prosper under a monarch before self-determining democracy? Yet your arrogant presumption robbed many nations of that opportunity. Because the people are unprepared and uninformed, the loudest asshole takes power by deceiving people and saying the right things the he gets super rich until they protest and he flies off with his money until the next asshole. This keeps happening and is your direct responsibility since it is because of your will your politicians are exporting chaos and installing puppet leaders in other countries. Civil war after civil war, genocide after genocide because humans are tribal by nature and there is no peaceful way a ruling tribe (see iraq) would peacefully let go of power.

Keep in mind that if it wasn't for the threat of violence by your own country's military you also would be part taker in the voiolence and chaos you are exporting.

Democracies cannot thrive when people are starving, destitute and uneducated and lack basic infrastructure by which they can be informed enough to critically analyze what their politicians are saying. "Your life sucks because of $tribe" does that sound familiar?

So you organize a revolt over Tor, I guess the other side will also use Tor to organize the civil war or genocide?

Re: Tell HN: Domain fronting to be blocked on Azure

#113

Lack of SNI encryption is the Achilles heel of modern web when it comes to oppressive regimes blocking access. Between encrypted SNI (Or domain name fronting), encrypted DNS and of course HTTPS. The biggest legitimate use case of Tor would vanish.

Is it 'illegitimate' that I read all of my preferred news content and chat on the internet using Tor?

Re: Tell HN: Domain fronting to be blocked on Azure

#114
post #78

Earlier quoted context omitted.

How would this work? How is the name encrypted before the pubkey is known? I've seen that it uses DNS to fetch another pubkey, but there is no encrypted DNS (DNSSEC is signed DNS). DNS-over-HTTPS is only used in the last-mile --- recursive resolver to client, not NS to NS, so the request is still sent in plain. Besides, DNS-over-HTTPS still requires ... TLS ...

As I understand, the public key that is used for authenticity is not the same as the one being used for encryption — at least since TLS 1.3, before it depends. The scheme is known as forward secrecy. For the encryption, an ephemeral key pair is used on both sides. These pairs are only used for the Diffie-Helman (or similar) key exchange. Therefore an encrypted connection can be established, then SNI can be exchanged…

So the encrypted connection used to exchange SNI isn't authenticated? This hides the SNI from passive eavesdroppers but not from an active MITM, no?

Re: Tell HN: Domain fronting to be blocked on Azure

#115
post #6

This seems to be a user-hostile move. https://en.m.wikipedia.org/wiki/Domain_fronting ”Many large cloud service providers, including Amazon and Google, now actively prohibit domain fronting, which has limited it as a censorship bypass technique. Pressure from censors in Russia and China is thought to have contributed to these prohibitions”

It is not just used for censorship. When I was working as a pentester and domain fronting was still allowed on AWS, it became our method of choice for establishing C2 because it camouflaged so well with regular organizational outbound that it will bypass any egress filtering and restrictions. If we were using it on a pentest, you'd best believe there are actors using it for far more nefarious purposes.

oh well, you could use a document on google suite to implement the communication. I guess google.com is next.

Re: Tell HN: Domain fronting to be blocked on Azure

#116
post #78

Earlier quoted context omitted.

As I understand, the public key that is used for authenticity is not the same as the one being used for encryption — at least since TLS 1.3, before it depends. The scheme is known as forward secrecy. For the encryption, an ephemeral key pair is used on both sides. These pairs are only used for the Diffie-Helman (or similar) key exchange. Therefore an encrypted connection can be established, then SNI can be exchanged…

So the encrypted connection used to exchange SNI isn't authenticated? This hides the SNI from passive eavesdroppers but not from an active MITM, no?

Good point. So there is more to it, which I didn't consider before. As I understand [1], the client uses the public key of the key pair used by the SNI to encrypt the SNI value, additionally to any TLS encryption. Only the actual SNI has the private key to decrypt the SNI value. The client must look up the public key in the DNS (I guess at least if it doesn't know the key already, which it could have in the cache).

This whole thing is still a draft RFC [2] and currently called encrypted client hello.

What I don't get: The client will have to disclose, which public key it used to encrypt the client hello / SNI value. But don't we know "all" the public keys from the certificate transparency logs? Usually a public key is only valid for a limited set of domains, so it would be easy to associate the public key used for encrypting the SNI value with the relevant service. Just look up the public key, read it's SAN or CN, and you pretty much know the SNI value. Or at least the service, which might be good enough. What am I missing?

[1] https://blog.cloudflare.com/encrypted-sni [2] https://www.ietf.org/archive/id/draft-ietf-tls-esni-15.html

Re: Tell HN: Domain fronting to be blocked on Azure

#117

Earlier quoted context omitted.

I clearly remember it being an explicit decision though, not a bug mitigation To be clear, that's not correct we did do this to mitigate the bug. We were facing the bug that I described (the cross stream thing) showing up when Lantern was used. It was causing disruption to our service and customers were writing in. We were trying to understand what was happening and needed to stop it. One of the things we did to stop…

Maybe domain fronting was initially disabled as an unsuccessful attempt to fix that bug, that's possible and as I said I was not involved in that decision. Still, if that's the case, there was a policy decision afterwards to leave it disabled, because disabling it did not fix the bug, as you seem to agree. (Again, not elaborating on the bug publicly without permission, but I remember it turned out to have nothing to…

No post body was provided.

Re: Tell HN: Domain fronting to be blocked on Azure

#118
post #109

How does domain fronting negatively affect microsoft? Why do they care? Is this all just about making peoples lifes worse?

Unfortunately much like every nice thing on the internet, once it is being abused, it gets axed... Domain fronting (having Host header differ to SNI in TLS) is a powerful way a malware author could send payload into organisations.. imagine seeing seemingly legitimate traffic to azure.com but end up with malwaredomain.com/lulz.exe... Unless organisations are peeking into TLS, check Host header, response with MZ file h…

Security teams should be doing DPI, using a corporate controlled CA to decrypt the traffic and then feed it into a SIEM which should start screaming bloody murder when it detects a mismatch between SNI and the requested host

Re: Tell HN: Domain fronting to be blocked on Azure

#119

Earlier quoted context omitted.

Maybe domain fronting was initially disabled as an unsuccessful attempt to fix that bug, that's possible and as I said I was not involved in that decision. Still, if that's the case, there was a policy decision afterwards to leave it disabled, because disabling it did not fix the bug, as you seem to agree. (Again, not elaborating on the bug publicly without permission, but I remember it turned out to have nothing to…

Quoted post unavailable.

Just for the record, there are very few people on the Internet I would trust more about this kind of stuff than Filippo.

Re: Tell HN: Domain fronting to be blocked on Azure

#120

Earlier quoted context omitted.

Yeah, I believe China doesn't even allow TLSv1.3

Not allowing TLS 1.3 means nothing (no modern web sites) works. Modern browsers and servers both speak TLS 1.3 and if they can't they give up. Some things don't work in China, but China wouldn't have a thriving economy if nothing was working. So no, they did not block TLS 1.3 although it's interesting how this rumour seems to have self-popularised. China blocks certain popular sites, but it does not block whole proto…

> Some things don't work in China, but China wouldn't have a thriving economy if nothing was working.

Any company who does not want to lose a market of ~18% of global population will make sure it complies (example: Apple).

We need to think about real life here and not just technical implementation

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