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WhatsApp backdoor allows snooping on encrypted messages

theguardian.com

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Re: WhatsApp backdoor allows snooping on encrypted messages

#311

Post by ycmbntrthrwaway »

kordless wrote: post #228
MrsPeaches wrote: post #128

Earlier quoted context omitted.

Simple explanation would be that activists use Signal. [1] They don't trust WhatsApp and rely on Signal for secure messaging. Blocking Signal means they are able to target activists without impacting much of the rest of the population. [1] Many of the people I know who are activists in countries where they need to protect their identities use Signal

There is no logical way to verify that all activists (or even a majority of them) use Signal over WhatsApp. The perception that activists use Signal may have been enough to block them, but having a huge backdoor in WhatsApp is reason enough to not take action.

Signal actively promotes as activist messenger by using names of revolutionaries and anarchists (Makhno, Proudhon, Masha Kolenkina) all over their website. Just for example: https://whispersystems.org/blog/images/signal-faces.png

Re: WhatsApp backdoor allows snooping on encrypted messages

#312

Post by jish »

jaymzcampbell wrote: post #2

The key part is this, and it was apparently reported back in April 2016 with Facebook replying it's "expected behavior", it's not something a general attacker can do but it would enable WhatsApp/Facebook to read conversations: > WhatsApp has the ability to force the generation of new encryption keys for offline users, unbeknown to the sender and recipient of the messages, and to make the sender re-encrypt messages wi…

> "it's not something a general attacker can do but it would enable WhatsApp/Facebook to read conversations"

So it downgrades "end-to-end encryption" to "transport layer security".

Re: WhatsApp backdoor allows snooping on encrypted messages

#313

Post by d33 »

frabbit wrote: post #227

Nothing to worry about according to Gizmodo: > The supposed “backdoor” the Guardian is describing is > actually a feature working as intended, and it would > require significant collaboration with Facebook to be > able to snoop on and intercept someone’s encrypted > messages, something the company is extremely unlikely > to do. http://gizmodo.com/theres-no-security-backdoor-in-whatsapp-d... I, for one, certainly cann…

Moxie says there's no backdoor as well:

https://whispersystems.org/blog/there-is-no-whatsapp-backdoo...

Re: WhatsApp backdoor allows snooping on encrypted messages

#314

Post by xorcist »

jononor wrote: post #170
JJJollyjim wrote: post #92

Earlier quoted context omitted.

AFAIK, Play Services is controlled by Google and has system-level permissions, so it could easily access Signal messages post-decryption if Google wanted it to.

The JVM is also under Googles control, so they could similarly access it there? Or is that open and audited? How to verify which JVM my device runs? EDIT: of course the fewer attack vectors the better

That part of Android is open source, so you could in theory audit it and build it yourself. I would be surprised if any big deliberate backdoors hid there. There are large downstream projects that use this source and builds on it which potentially would notice.

The Play Services however pretty much amounts to a remote root shell open at all times. Google can remove or modify code at will, and they have been known to do it in practice for spyware removal. I can understand how an activist finds that problematic.

Re: WhatsApp backdoor allows snooping on encrypted messages

#316

Post by MichaelGG »

jgaa wrote: post #292
MichaelGG wrote: post #264

Earlier quoted context omitted.

So just look at the actual code executing. Should be fairly easy to tell if there's some huge secret function in the binary.

Well - you know, when you strip the symbols from the optimized binaries, the "huge_exploit_nsa_hook()" function kind of morphs into 0x66666666 or some other seemingly random number. Besides, I knew only one programmer who could read binary dumps of a program and instantly tell what id did. That was 30 years ago, when executables were measured in kilobytes.

Fortunately there are useful tools that'll help navigate binaries, like IDA Pro. They'll produce control flow graphs in addition to letting you annotate things. I've done this in a professional capacity a few times, though I'm not remotely an expert and barely know what I'm doing.

In Java, it's even easier due to JVM restrictions. I wrote an obfuscator for .Net, but Java offers less capabilities in it's bytecode. I even used a commercial product that had been obfuscated. The obfuscator broke something on Mono. It took about an hour to write a small script to go through the binary and fixup the broken bits so other tools would work on it.

Re: WhatsApp backdoor allows snooping on encrypted messages

#317

Post by drdaeman »

detaro wrote: post #299
drdaeman wrote: post #298

Earlier quoted context omitted.

Thanks. Seems that they either somehow don't have contact info (but then - how contact discovery's working?) or they had failed to comply with court order. Or I'm really not getting something, which is also well possible (and quite probable) explanation. Upd: Hmm... or maybe the user had no contacts.

I think they just don't keep the contact list. It is uploaded, but only matched against the list of subscribed users at the time of the upload and then deleted. Only downside is that if a contact joins later and does not have you in its contact list you don't get notified, or only when you recheck your contact list. Your link above says at the end: For TextSecure, however, we've grown beyond the size where that remai…

Oh. I've completely missed/forgot this. Thanks for pointing out.

Yes, now it's all clear - they have contacts, but only ephemerally. Good.

Re: WhatsApp backdoor allows snooping on encrypted messages

#319

Post by FabHK »

andyjohnson0 wrote: post #206
FabHK wrote: post #91

Earlier quoted context omitted.

This should be the top post - exactly this vulnerability was announced last year April; it's just that the Guardian picked it up now (with a somewhat clickbait-y headline, to boot).

I'm going to have to come to the Guardian's defence here. We may take issue with the term "backdoor" but, for a general readership, their headline is a good summary of the issue using appropriate language.

Doesn't backdoor imply malicious intent? (Of course you could argue that a good backdoor looks like a innocuous bug or even a feature...)

Also, if I have notification of key changes enabled and verify key fingerprints, at most one exchange could be snooped without me noticing. (If notification of key changes is not enabled and key fingerprints not verified, all bets are off anyways.)

Re: WhatsApp backdoor allows snooping on encrypted messages

#320

Post by dr_zoidberg »

MichaelGG wrote: post #316
jgaa wrote: post #292

Earlier quoted context omitted.

Well - you know, when you strip the symbols from the optimized binaries, the "huge_exploit_nsa_hook()" function kind of morphs into 0x66666666 or some other seemingly random number. Besides, I knew only one programmer who could read binary dumps of a program and instantly tell what id did. That was 30 years ago, when executables were measured in kilobytes.

Fortunately there are useful tools that'll help navigate binaries, like IDA Pro. They'll produce control flow graphs in addition to letting you annotate things. I've done this in a professional capacity a few times, though I'm not remotely an expert and barely know what I'm doing. In Java, it's even easier due to JVM restrictions. I wrote an obfuscator for .Net, but Java offers less capabilities in it's bytecode. I e…

Good call on reversing, I'd written about it in a first draft but then scratched everything and started over again. Indeed, there are some good reversing tools. Still, his call on packet analysis being incomplete (unless you happen to see an interesting event) is right. I was thinking of a more simple test to see if things are effectively encrypted, and how resistant to cryptoanalysis is the protocol.
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