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FBI used iPhone notification data to retrieve deleted Signal messages

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Re: FBI used iPhone notification data to retrieve deleted Signal messages

#261

Post by AlBugdy »

svpk wrote: post #238
AlBugdy wrote: post #234

So Signal is sending the notifications through Apple's ecosystem somehow, presumably to save battery life by not having a persistent connection to Signal's servers? That's what I think happens on Android, too. When I had Lineage years ago, I had a persistent connection to Signal as the notifications didn't come through Google. Unfortunately there was a persistent notification for the persistent connection with no way…

In my recollection, which may be imperfect: 1. On android if Google Play isn't available (or you install the no Google apk version) it'll use a websocket for notifications. Apple doesn't allow a persistent connection except through their own notification framework. 2. In either case Signal doesn't send message contents through the notification framework (not even encrypted). Once Signal receives a notification the ap…

> Apple doesn't allow a persistent connection except through their own notification framework.

How can iOS not allow persistent connections at all? How would a long download work or a call in the background work at all?

> Regardless when signal shows the contents of your message in the notification menu of your device your device keeps a record on your device of that message content.

How is that not treated as a backdoor unless it's explicitly mentioned when someone installs iOS?

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#262

Post by dwb »

ryandrake wrote: post #139
greysonp wrote: post #124

Earlier quoted context omitted.

We build Signal for everyone, and that includes a lot of people who are not as technologically literate as the average tech worker. For a lot of people, they don't even know they dismissed the notification permission prompt, they were just closing boxes. For them, the reminder is helpful and prevents them from experiencing missing notifications. Striking a balance between helping these people and annoying more techno…

Thanks for the reply. I know it feels noble to do it that way, and I admit I get dogmatic over this one principle: a computer should first and foremost obey the user. It shouldn't have its own agenda. It shouldn't second guess. It shouldn't "did you mean?" I command the computer, and the computer executes that command and then waits for the next command. If I command it to not display a particular output (notificatio…

I broadly sympathise, being a nerd myself also, but this just isn’t a way to build software for a general audience.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#263

Post by david_shaw »

OutOfHere wrote: post #241
jacquesm wrote: post #212

Earlier quoted context omitted.

People keep pushing signal because it is supposedly secure. But it runs on platforms that are so complex with so much eco system garbage that there is no way know even within a low percentage of confidence if you've done everything required to ensure you are communicating just with the person you think you are. There could be listeners at just about every layer and that is still without looking at the meta-data angle…

There is nothing secure about sending encrypted content to notifications. If it were secure, it would only notify that there is a message, with no details included.

> If it were secure, it would only notify that there is a message, with no details included.

You're right. This is configurable via settings, but is not the default state.

That said: if I can get friends and family to use Signal instead of iMessage, that gives me the opportunity to disable those notifications and experience more security benefits.

But I agree with your point: most people think that Signal is bulletproof out of the box, and it's clearly not.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#264

Post by Zak »

satvikpendem wrote: post #258
Zak wrote: post #255

Earlier quoted context omitted.

It doesn't. The API for displaying a notification is purely local. Receiving a ping from Firebase Cloud Messaging triggers the app to whatever it does in order to display its notification. In the case of Signal, that probably means something like fetching the user's latest messages from the server, then deciding what to show in the notification based on the user's settings, metadata, and message content. Here's examp…

Sorry I should clarify, by "it" I meant any sort of ping must go through Firebase Cloud Messaging, not that the message content itself goes through Firebase. Looks like there is a way to bypass Firebase by using something like UnifiedPush which runs a perpetual background process that acts similar to Google Play Services to pick up notifications from the server and calls the local notification API.

It's theoretically possible to just keep an app running in the background all the time and periodically poll a server.

That's unreliable though since some OEM Android builds will kill it for that even if the user disables battery optimizations. Those OEMs sort of have a point; if lots of apps did that it would drain the battery fast.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#265

Post by GeekyBear »

upofadown wrote: post #180

Putting on my user hat... "OK. Signal has forward secrecy. So messages are gone after I receive them. Great!" Oh, you didn't turn on disappearing messages? Oh, right, then forensic tools like Cellebrite can get them. You have to turn on disappearing messages. The default is off. Oh, you did turn on disappearing messages? We send the messages in notifications. So the OS can keep them. Turns out Apple was doing that. T…

> Oh, you did turn on disappearing messages? We send the messages in notifications. So the OS can keep them.

Worse than that, they did not take advantage of the ability to send that message data as an encrypted payload inside the notification.

https://blog.davidlibeau.fr/push-notifications-are-a-privacy...

Either do not include sensitive user data inside a notification by default, or encrypt that data before you send it to the notification server.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#266

Post by satvikpendem »

Zak wrote: post #264
satvikpendem wrote: post #258

Earlier quoted context omitted.

Sorry I should clarify, by "it" I meant any sort of ping must go through Firebase Cloud Messaging, not that the message content itself goes through Firebase. Looks like there is a way to bypass Firebase by using something like UnifiedPush which runs a perpetual background process that acts similar to Google Play Services to pick up notifications from the server and calls the local notification API.

It's theoretically possible to just keep an app running in the background all the time and periodically poll a server. That's unreliable though since some OEM Android builds will kill it for that even if the user disables battery optimizations. Those OEMs sort of have a point; if lots of apps did that it would drain the battery fast.

Then that's basically what I said right? That there is in practice no way to opt out of using Firebase if you want consistent notifications.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#267

Post by ransom1538 »

upofadown wrote: post #180

Putting on my user hat... "OK. Signal has forward secrecy. So messages are gone after I receive them. Great!" Oh, you didn't turn on disappearing messages? Oh, right, then forensic tools like Cellebrite can get them. You have to turn on disappearing messages. The default is off. Oh, you did turn on disappearing messages? We send the messages in notifications. So the OS can keep them. Turns out Apple was doing that. T…

0) send a public key. 1) encrypt the file with your private key 2) send file.

WTF. This is super simple stuff.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#268

Post by alfiedotwtf »

microtonal wrote: post #237
upofadown wrote: post #180

Putting on my user hat... "OK. Signal has forward secrecy. So messages are gone after I receive them. Great!" Oh, you didn't turn on disappearing messages? Oh, right, then forensic tools like Cellebrite can get them. You have to turn on disappearing messages. The default is off. Oh, you did turn on disappearing messages? We send the messages in notifications. So the OS can keep them. Turns out Apple was doing that. T…

I think one of the main issues is that end-to-end message encryption is a sham as long as backups are not encrypted. I could have good device security, but if the person I'm talking to does not use ADP, iMessage and WhatsApp messages get backed up with only at-rest encryption (I think Signal opts out of standard iOS backups) and possibly the same for backups of the iPhone notification database (which the article sugg…

This is what I’ve always hated with Apple Time Machine, which I think MUST have been deliberate:

    - create an encrypted disk
    - install Mac OS on the encrypted disk
    - use Time Machine to back it up with encrypt turned on
All good so far. Ok, time to restore:

    - Restore from Time Machine
    - enjoy your PLAIN TEXT install :poo:

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#269

Post by alfiedotwtf »

microtonal wrote: post #253
AJ007 wrote: post #247

Earlier quoted context omitted.

"end-to-end message encryption is a sham as long as" -- I agree with that but would add even more caveats. If someone can't list those caveats off the top of their head they shouldn't be pretending they aren't able to communicate securely. Just look at Salt Typhoon, every single person should be way more paranoid than they are, including government & agency officials. The attach surface and potential damage - financi…

I mean the Hungarian minister of Foreign Affairs briefed Lavrov on internal EU matters and there are recordings of one or more calls. It seems that opsec is bad at pretty much every level.

We’re already forgetting when the Secretary of War invited a journalist to the secret SIGNAL group chat

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#270

Post by alfiedotwtf »

nickburns wrote: post #53
hammock wrote: post #52

Earlier quoted context omitted.

Wait so if I do iOS setting notifications > never show previews it’s still caching them in the background? Unencrypted?

Yes. And technically, from a privacy perspective, it's even worse than that. What's additionally happening is they're still 'syncing' back to Apple servers via APNS (and to Alphabet servers via Firebase on Android)—even with notifications completely disabled , that's correct. If the app generates them, the OS receives them. That's why the Signal app offers this setting.

Sad to think there is a PostIt note somewhere in Virginia and written on it is a box labelled Signal, with an arrow pointing to a box labelled Apple servers, followed by a smirking smiley face pointing between the boxes with the message “encryption added and removed here”
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