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There is no WhatsApp 'backdoor'

whispersystems.org

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Re: There is no WhatsApp 'backdoor'

#311

Post by xg15 »

moxie wrote: post #237
rndgermandude wrote: post #220

Earlier quoted context omitted.

> The notification that you see in WhatsApp, Signal, SSH, PGP, or whatever is the defense. That defense, which happens to be the only defense, is turned off by default in WhatsApp. You seem to argue they do so because it's bad UX to present such notification by default. That's - in my humble opinion - like suggesting browsers should turn off TLS chain errors by default because it's bad UX and just proceed with the co…

> That defense, which happens to be the only defense, is turned off by default in WhatsApp. > You seem to argue they do so because it's bad UX to present such notification by default. That's - in my humble opinion - like suggesting browsers should turn off TLS chain errors by default because it's bad UX and just proceed with the connection as if nothing happened... One thing we've learned over the years is that secur…

Why not phase the message differently, e.g. "It looks like (user) is chatting from a new device. Is this correct?"

Warning about unusual account activity seem to be very common these days, so why not using them here.

The way the warnings are presented as part of the chat history (a very good idea) also means they could be used after-the-fact to figure out when an account was overtaken, even if the warning was initially ignore. I figure even non-technical users would like to know that, after one of their contacts tells them their account was hacked.

Additionally, why is an ignored warning worse than a warning that is suppressed to begin with? That seems to me like a landlord that decides not to install smoke alarms because "the tenants could get used to the sound" - when most of the tenants are not even aware of the concept of "fire".

Finally, I don't find the "it's important the server doesn't know" argument not convincing. If you conclude that the vast majority of people doesn't have the warnings enabled and the costs of hitting someone with warnings is low, that would make snooping still a very low-risk activity.

Summing up, I think the very least consequence Facebook should take from this is to make the warnings in-by-default instead of off-by-default.

Re: There is no WhatsApp 'backdoor'

#312

Post by dbrgn »

giovannibajo1 wrote: post #305
moxie wrote: post #237

Earlier quoted context omitted.

> That defense, which happens to be the only defense, is turned off by default in WhatsApp. > You seem to argue they do so because it's bad UX to present such notification by default. That's - in my humble opinion - like suggesting browsers should turn off TLS chain errors by default because it's bad UX and just proceed with the connection as if nothing happened... One thing we've learned over the years is that secur…

Moxie, what about showing a positive UI for users you have verified keys with? Something like the verified checkmark on twitter. I'm ok with this being client side of course, and possibly even lost if you reinstall the app (better than nothing). I like to verify keys of my main professional contacts on WhatsApp, but it's hard to remember who you verified keys with, and then whether the key was changed since last time…

Threema offers that. You do a QR code scan, after which a contact is marked as verified (3 green dots). Since Threema has a fixed key per user, these verifications are persistent and most people transfer their keys when switching to a new phone.

Re: There is no WhatsApp 'backdoor'

#313

Post by sambe »

hsivonen wrote: post #288
meowface wrote: post #285

Earlier quoted context omitted.

Assuming this is a laptop they assigned to you, what's wrong with any of that?

If you are in Europe (or at least some countries in Europe), it's illegal to read in-transit messages even if the recipient is at work and the interceptor is their employer.

Reference? I've worked at several companies claiming they are allowed to do this (which I don't necessarily believe, of course). Has it been tested in court?

Re: There is no WhatsApp 'backdoor'

#314

Post by dx034 »

rebuilder wrote: post #184
sebleon wrote: post #18

At the end of the day, it comes down to trusting WhatsApp. Even without a backdoor in their protocol, they can easily do all kinds of things. For instance, it could instruct specific clients to encrypt and send each message twice: one for the recipient, and one for the WhatsApp server. As long as this was off for 99.9% of users, it's unlikely that security researchers would ever detect this.

And anyone with sufficient access could push an update from the app store to a selected target that bypasses the normal security protocols of any given messaging app. Who checks their app store downloads against source code?

We're mostly talking about government agencies here that would force Facebook to act in that way. And even though they could force them to try to intercept messages of a user with an ESL, they can't force them to introduce a vulnerability for all users.

Especially as ESL are usually kept secret within the company, this would be too risky, developers would ultimately find such a backdoor (especially since it generates a lot of server traffic).

Re: There is no WhatsApp 'backdoor'

#315

Post by fauigerzigerk »

tyfon wrote: post #309
oconnor663 wrote: post #123

Earlier quoted context omitted.

> catastrophic sacrifices to make security applications popular and viable for the "lay person" This isn't wrong, but it's unfair to bring it up without the most obvious counter-argument. PGP provides absolutely zero security to the average person, because average people don't use it. HTTPS provides lots of security to the average person, whether or not they know what the green lock means, because lots of people use…

No security is better than false security imho.

The problem is that most security technologies only provide protection against specific attack vectors and attackers under specific conditions.

Without understanding these technologies very deeply, they are all creating a false sense of security to some degree.

That doesn't make your statement false, just very difficult to apply. That's not to say it can never be applied. There are clearly cases in which people are deliberately mislead.

Re: There is no WhatsApp 'backdoor'

#316

Post by dx034 »

I don't get the complains here. Whatsapp is used by over a billion people and offers end2end encryption for them. A system that mainly targets people with little tech experience can never be kept 100% secure. If they make it harder to switch phones, people would stop using whatsapp.

The only vulnerability seems to be that they could prevent delivery messages. I'm sure that most people would notice if they suddenly son't see the 2 ticks, even if the other person answered. And if you want your conversation to be secret, that's a major red flag, now that this is known.

And if I get a phone change notification even though the other person didn't change their phones I'd also be confused at least. When I last changed my phone, a lot of people noticed because of the notification and asked me. And those were not tech savvy people, they were just wondering why I got a new phone.

Spying on conversations (especially by govt agencies) is only effective if the target doesn't know about it. It seems that Whatsapp has no way of enforcing that without the user noticing.

Re: There is no WhatsApp 'backdoor'

#317

Post by ajb »

moxie wrote: post #237
rndgermandude wrote: post #220

Earlier quoted context omitted.

> The notification that you see in WhatsApp, Signal, SSH, PGP, or whatever is the defense. That defense, which happens to be the only defense, is turned off by default in WhatsApp. You seem to argue they do so because it's bad UX to present such notification by default. That's - in my humble opinion - like suggesting browsers should turn off TLS chain errors by default because it's bad UX and just proceed with the co…

> That defense, which happens to be the only defense, is turned off by default in WhatsApp. > You seem to argue they do so because it's bad UX to present such notification by default. That's - in my humble opinion - like suggesting browsers should turn off TLS chain errors by default because it's bad UX and just proceed with the connection as if nothing happened... One thing we've learned over the years is that secur…

It would be good to be able to check how long the present safety number has been in place for. That would allow people who have become concerned about snooping to detect snooping back until that point (hey, when did you last change your phone?).

Re: There is no WhatsApp 'backdoor'

#318

Post by danenania »

xg15 wrote: post #311
moxie wrote: post #237

Earlier quoted context omitted.

> That defense, which happens to be the only defense, is turned off by default in WhatsApp. > You seem to argue they do so because it's bad UX to present such notification by default. That's - in my humble opinion - like suggesting browsers should turn off TLS chain errors by default because it's bad UX and just proceed with the connection as if nothing happened... One thing we've learned over the years is that secur…

Why not phase the message differently, e.g. "It looks like (user) is chatting from a new device. Is this correct?" Warning about unusual account activity seem to be very common these days, so why not using them here. The way the warnings are presented as part of the chat history (a very good idea) also means they could be used after-the-fact to figure out when an account was overtaken, even if the warning was initial…

The people who are most likely to be snooped on are also more likely to have the notifications turned on, so I don't think it's such an easy choice for an attacker.

The entities this is designed to thwart are not going to want to risk leaving behind a trail of evidence, even if the risk is small.

It also prevents fishing expeditions, since the risk would quickly add up as more targets were added.

All that said, a one-time prompt to turn on the notifications for users that care about extra-strong security seems like a good idea to me.

Re: There is no WhatsApp 'backdoor'

#319

Post by tyfon »

fauigerzigerk wrote: post #315
tyfon wrote: post #309

Earlier quoted context omitted.

No security is better than false security imho.

The problem is that most security technologies only provide protection against specific attack vectors and attackers under specific conditions. Without understanding these technologies very deeply, they are all creating a false sense of security to some degree. That doesn't make your statement false, just very difficult to apply. That's not to say it can never be applied. There are clearly cases in which people are d…

Yes, security is very hard.

But whatsapp markets itself as a secure system when the client just blindly accepts re-keying from the server without notifying the user by default,

It could easily have the notification on by default, and when a user turns it off actually explain that you are no longer secure.

The very best would of course be to require the users to physically exchange keys whenever they get a new phone etc, but we all know this will never happen.

Re: There is no WhatsApp 'backdoor'

#320

Post by artefacts »

yellowapple wrote: post #281
kentonv wrote: post #266

I love this post for the in-depth explanation of the UX challenges around e2e encryption and why they made the decisions they did. It's educational. I think Moxie highlights a very good point that is commonly underrated among "security Dunning-Krugers": Opening yourself to the possibility of an attack is often OK if the attack is easily detectable, and if the identity of the attacker would be obvious upon detection.…

In most cases, I'd much rather disallow Facebook from MITMing my messages than try to "ruin their reputation" (hint: I won't, because Facebook already does far worse things on a regular basis without so much as an eye-bat from the world). In other words: I care about the confidentiality of my messages far more than the promise of some sort of dubious ability to shame Facebook for simply fulfilling its business model.…

> Transparency is a dependency of trust. WhatsApp is not transparent; therefore, it is not trustworthy. Simple as that.

+1.

The CEO calls its users "Dumb Fucks"; the sister of the CEO, formerly a director of Facebook, claimed "Privacy needs to go away".

There's no transparency with WhatsApp in terms of its implementation, so the fact that Moxie may have helped them get initially set up is moot. Moxie's reputation doesn't provide any provable assurances of confidentiality from Facebook.

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