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Another flaw in Signal desktop app leaks chats in plaintext

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Re: Another flaw in Signal desktop app leaks chats in plaintext

#141

Post by confounded »

fjsolwmv wrote: post #138
_emacsomancer_ wrote: post #119

Earlier quoted context omitted.

> What are the mechanisms that assure safety for users? What are the mechanisms that assure safety for users of iOS? I understand that it's had a good track record so far, but the proprietary closed nature doesn't inherently inspire trust. Surely a decentralised FOSS model done right could be secure for lawyers &c.

As the old saying goes, "if you could have invented a secure open source desktop chat app, you would have developed a secure open source desktop chat app." In practice, empirict results win over theoretically optimal designs.

I think that’s unfair; the Ghost.io post from a day or so ago is a good reminder of just how much harder it is to do things when you have to make them work in a decentralized fashion. Decentralization makes everything harder.

Doesn’t mean it’s the wrong thing to do! :)

Re: Another flaw in Signal desktop app leaks chats in plaintext

#142

Post by bigiain »

tptacek wrote: post #99
bigiain wrote: post #96

Earlier quoted context omitted.

FWIW, the sort of people with access/leverage to be able to compromise a device through the baseband probably don't leave behind traces revealing it happened. They just drop hints to the local cops that they ought to find a reason to pull you over for a traffic stop and coincidentally smell pot smoke to give them probably cause to search your car... (waves at the NSA guys...) I _hope_ that sort of capability is still…

They probably don't leave traces because compromising a modern Apple device through the baseband would be quite a trick, given that it's an independent peripheral connected to the AP over on-chip USB.

That's good to know (and for almost anybody else I'd add "citation needed"...)

Didn't the iPhone baseband processor at some time in the past have dma? I vaguely recall a perhaps Usenix paper that seemed to claim any phone that had a software unlock where you could disable the carrier locking, was almost certainly using dma connections between the baseband and AP. Any hints or links or search terms which would show me how modern an iPhone needs to be to be "safe" from that?

Re: Another flaw in Signal desktop app leaks chats in plaintext

#143

Post by bigiain »

pvg wrote: post #100
bigiain wrote: post #96

Earlier quoted context omitted.

FWIW, the sort of people with access/leverage to be able to compromise a device through the baseband probably don't leave behind traces revealing it happened. They just drop hints to the local cops that they ought to find a reason to pull you over for a traffic stop and coincidentally smell pot smoke to give them probably cause to search your car... (waves at the NSA guys...) I _hope_ that sort of capability is still…

No, it's cheaper for them to just replace the person you're talking to with a Cylon.

Some may argue this has already happened - to at least half their social circle. (Not me though, I consider myself "recreationally paranoid" rather than "raving looney paranoid" - other people's opinions on that probably differ...)

Re: Another flaw in Signal desktop app leaks chats in plaintext

#144

Post by [deleted] »

ddtaylor wrote: post #104
seba_dos1 wrote: post #69

Earlier quoted context omitted.

>The Signal devs thought $.html() does some kind of escaping: Uhm... that's a really rookie mistake to make. Like, one of the very basics of jQuery usage. I'm not exactly sure what to think about it after seeing this commit you linked...

The worst part is that someone assumed something then removed the code that did the escaping without even doing the most basic of tests, like even in the browser just doing a quick foo.html(' alert("oh snap this is bad") ')

[deleted]

Re: Another flaw in Signal desktop app leaks chats in plaintext

#145

Post by KKKKkkkk1 »

tptacek wrote: post #24

Honestly, and none of you are going to like hearing this, and the Signal people aren't going to appreciate me saying it: if you're serious about messaging securely, don't use Signal Desktop; don't use desktop secure messengers at all. Desktop applications are incredibly risky, far more so than iOS mobile apps are.

I vaguely remember someone on HN (or maybe some other forum) making loud endorsements of Signal over any other encrypted chat app. Even a statement like "9 out of 10 cryptographers would recommend Signal". What's the difference between Signal Desktop and Signal?

Re: Another flaw in Signal desktop app leaks chats in plaintext

#146

Post by tptacek »

KKKKkkkk1 wrote: post #145
tptacek wrote: post #24

Honestly, and none of you are going to like hearing this, and the Signal people aren't going to appreciate me saying it: if you're serious about messaging securely, don't use Signal Desktop; don't use desktop secure messengers at all. Desktop applications are incredibly risky, far more so than iOS mobile apps are.

I vaguely remember someone on HN (or maybe some other forum) making loud endorsements of Signal over any other encrypted chat app. Even a statement like "9 out of 10 cryptographers would recommend Signal". What's the difference between Signal Desktop and Signal?

Signal Desktop is one of several clients for Signal Protocol; the most common client is --- I believe, but am not sure, but have good reason to believe --- either the Android or iOS mobile client, neither of which is a Javascript application.

We've recommended the mobile versions of Signal for a long time (see, for instance, the Tech Solidarity security resources, which haven't changed in a year), and everyone still recommends Signal Protocol. I think we all should have been noisier about the security limitations of the desktop app environment. And about Electron.

Re: Another flaw in Signal desktop app leaks chats in plaintext

#148

Post by tptacek »

bigiain wrote: post #142
tptacek wrote: post #99

Earlier quoted context omitted.

They probably don't leave traces because compromising a modern Apple device through the baseband would be quite a trick, given that it's an independent peripheral connected to the AP over on-chip USB.

That's good to know (and for almost anybody else I'd add "citation needed"...) Didn't the iPhone baseband processor at some time in the past have dma? I vaguely recall a perhaps Usenix paper that seemed to claim any phone that had a software unlock where you could disable the carrier locking, was almost certainly using dma connections between the baseband and AP. Any hints or links or search terms which would show me…

I don't know what the first iPhone to have an HSIC baseband was, but it has been awhile. I assume every iPhone anyone is really using today fits the description I gave. The iPhone 4 does. This is a really basic security design concern for mobile devices; you can assume that neither Apple nor Google (for their own Google-branded phones) ships products where a corrupted baseband can simply DMA its way into the AP. It is a little weird to me that people on message boards assume they've outguessed the hardware security teams at both Apple and Google on one of the most obvious attack vectors for their phone designs; both companies spend huge amounts of money on this stuff.

Re: Another flaw in Signal desktop app leaks chats in plaintext

#149

Post by girvo »

4ad wrote: post #22
tptacek wrote: post #21

Earlier quoted context omitted.

By "almost nobody", you mean everyone who used Apple Mail/GPGTools and Thunderbird/Enigma, meaning, the vast majority of everybody who used PGP?

Thunderbird does not download remote content by default. I don't know anybody who is using Apple Mail with GPG, but if there are such people, they have been doing it very wrong regardless of this vulnerability. It's an unsafe combination. I have no statistics on what people use PGP with, but asserting that most people use it with Apple Mail and Thunderbird is baseless and without proof.

Why would Apple Mail and PGP be a unsafe combination by default?

Re: Another flaw in Signal desktop app leaks chats in plaintext

#150

Post by RVuRnvbM2e »

tptacek wrote: post #140
jancsika wrote: post #136

Earlier quoted context omitted.

> Desktop applications are incredibly risky, far more so than iOS mobile apps are. Ok, I'll play. I get to choose 10 arbitrary apps from the Apple App store for you to install on an Iphone model of your choice. You get to choose 10 arbitrary apps for me to install from the default Debian repos (which I believe excludes nonfree). Let's say Sid to make it interesting. Who is going to be in worse shape after installing…

You will be in worse shape than I will be. It's possible, in that insane proposition, that your Debian machine will be conceding remote code execution to the whole Internet, while my phone will just have some crappy apps on the home screen.

Doesn't that answer assume some or all of the following?

a) Apple does a better job reviewing apps than Debian maintainers do.

b) iPhone app code is better quality than Debian packages.

c) iOS sandboxing is better than Linux.

Default configuration may mean c) is true. However not if you use wayland, apparmor, seccomp, namespaces etc. What do you think about a) and b)?

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