Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

New NSA Leak Shows MITM Attacks Against Major Internet Services

schneier.com

Post reply on HN
Print view View original

91–100 of 149 posts

Re: New NSA Leak Shows MITM Attacks Against Major Internet Services

#91

Post by ck2 »

JshWright wrote: post #77
ck2 wrote: post #74

Earlier quoted context omitted.

Does OCSP stapling help or hurt? How similar to TACK?

It doesn't really impact the MiTM attacks described in the article. An attacker who is able to sit in the middle with their own trusted cert is simply going to not bother passing the stapled OCSP response along. The victims browser will do an OCSP lookup (or not...) for the trusted cert the attacker provided, and that will succeed. I'm not sure how OCSP caching is implemented in the browsers that implement OCSP in th…

I am not sure what it uses to validate but I have a ocsp stapling file I made

openssl test reports

     OCSP Response Status: successful (0x0)
     Cert Status: good
     This Update: Sep  8 xx:xx:xx 2013 GMT
     Next Update: Sep 10 xx:xx:xx 2013 GMT

        Validity
            Not Before: Aug 22 xx:xx:xx 2013 GMT
            Not After : Oct  2 xx:xx:xx 2013 GMT
So that's quite a long cache. I thought it would fail after the 10th but apparently it is using the CA valid date range?

Re: New NSA Leak Shows MITM Attacks Against Major Internet Services

#93

Post by jackowayed »

MichaelSalib wrote: post #68
moxie wrote: post #65

Trevor Perrin and I have been working on a dynamic certificate pinning proposal called TACK to help mitigate these types of attacks: http://tack.io In the current state of the world, we're all dependent on CA signatures for each connection we make to a website. TACK is a layer of indirection away from CA certificates, such that we'd only be dependent on CA signatures the very first time we contacted a website. It doe…

Your tack.io proposal looks great. Do you have any sense as to whether or when it will be adopted?

Faster the more help we get!

As part of my Matasano internship, I've been working on a patch to NSS (Mozilla's crypto library, used by both Firefox and Chrome for TLS) that will give the necessary hooks needed for browsers that use NSS to implement TACK. I'll hopefully be submitting that for review soon (you can see it on bugzilla[1] and fresher in-progress GitHub[2]).

At this point, it mostly makes sense for me to finish that (though I'll have a lot less time when I go back to school, so there might be some work that needs to get done when the review comments come back that I can't get to for awhile, so someone to power that to the finish might be helpful).

But once that's in, we'll need to work on getting patches into the Firefox and Chrome that actually integrate TACK. There's also some other work to do, especially for some other longterm ideas we have (eg. securing communication between mail servers with TACK).

If you're interested in helping, either email Trevor (email is on his website[3]), or email me (danielj@matasano for the next week, personal email in my profile).

1: https://bugzilla.mozilla.org/show_bug.cgi?id=905848

2: https://github.com/jackowayed/mozilla-nss/pull/1

3: http://trevp.net

Re: New NSA Leak Shows MITM Attacks Against Major Internet Services

#94

Post by devx »

moxie wrote: post #65

Trevor Perrin and I have been working on a dynamic certificate pinning proposal called TACK to help mitigate these types of attacks: http://tack.io In the current state of the world, we're all dependent on CA signatures for each connection we make to a website. TACK is a layer of indirection away from CA certificates, such that we'd only be dependent on CA signatures the very first time we contacted a website. It doe…

Will you be able to make Convergence for Chrome, too (especially now with "packaged apps" and whatnot)?

Re: New NSA Leak Shows MITM Attacks Against Major Internet Services

#95

Post by [deleted] »

jlgaddis wrote: post #53
anologwintermut wrote: post #45

Earlier quoted context omitted.

I think it pin's google's certificates. The article claims The goal of the attack was to "impersonate Google security certificates." I'm not saying NSA doesn't have the ability, just the implication that it was used against Brazil is likely wrong.

> I think it pin's google's certificates. That's what I understand as well but I don't think they pin much more than that -- and certainly not every SSL certificate on every site one might connect to.

[deleted]

Re: New NSA Leak Shows MITM Attacks Against Major Internet Services

#96

Post by stordoff »

txutxu wrote: post #87

Wait. They access google directly... without depend on routing your traffic and tramp your SSL to get a lot of compressed js and ajax traffic. So... maybe this was only needed or relevant before have direct access ?

MITMing a Google server doesn't _necessarily_ mean that they want the info Google has. Google host a number of libraries such as Analytics and jQuery which are widely used on other sites. The attack could have been to send a modified version of those so that websites (other that Google) transmit information that is normally kept on the client (e.g. sending the key to the NSA in an app that normally does client-side encryption).

Re: New NSA Leak Shows MITM Attacks Against Major Internet Services

#97

Post by biot »

leef wrote: post #27

The ephemeral session keys should protect against the MITM attacker getting anything but another encrypted stream of data, right?

Only if you can prove that your ephemeral session keys were negotiated with the intended destination. With a MITM, here's what you think is happening:

  Encrypt Outbound ==> Decrypt Inbound
     at Source         at Destination

  Decrypt Inbound
The ==> and 
  Encrypt Outbound ==> Decrypt/Intercept --> Re-Encrypt  ==> Decrypt Inbound
   at Source              at Attacker        at Attacker     at Destination

  Decrypt Inbound
The --> and <-- indicate nonsecure steps. This happens through all phases from SSL handshake to streaming of data and, if the Attacker is able to use a certificate that you trust, the interception will generally go unnoticed.

Re: New NSA Leak Shows MITM Attacks Against Major Internet Services

#98

Post by juhanima »

anon1385 wrote: post #69
andrewcooke wrote: post #58

Earlier quoted context omitted.

if that's the case, how did they get the private key from verisign? was it stolen? did verisign simply give them it? or was it obtained under some kind of legal process? if it was under a legal process, doesn't this raise additional questions about the judicial overview - did they realise how broad this was?

Sounds like it could be any of those things: they use all those tactics. http://www.nytimes.com/2013/09/06/us/nsa-foils-much-internet... Because strong encryption can be so effective, classified N.S.A. documents make clear, the agency’s success depends on working with Internet companies — by getting their voluntary collaboration, forcing their cooperation with court orders or surreptitiously stealing their encryption…

> they used legal process

They used a secret legal process. There, fixed that one for you!

Re: New NSA Leak Shows MITM Attacks Against Major Internet Services

#100

Post by marcosdumay »

frank_boyd wrote: post #18
joekrill wrote: post #14

Earlier quoted context omitted.

And what makes any smaller providers any more safe?

I don't understand your question. Bigger targets are always more interesting for mass surveillance, because, by definition, they have more users. And that's what the recent revelations are all about: Mass surveillance. Obviously, bitter targets are also more interesting for private/non-NSA/non-state hackers.

That one piece of news is about corporate spyonage, not mass surveilance.

The size of the email provider wouldn't make any difference.

Post reply on HN