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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

#81

Post by kccqzy »

exitb wrote: post #67
shantara wrote: post #4

Earlier quoted context omitted.

iOS stores the previously displayed notifications in an internal database, which was used to access the data. It’s outside of Signal’s control, they recommend disabling showing notification content in their settings to prevent this attack vector

They do control the content on the notification. It's a bit odd to put the sensitive text in the notification only to recommend disabling it at the system level.

No. They recommended disabling it at the app level. Only the Signal app can control whether the message contents are included in the notifications.

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

#82

Post by throawayonthe »

frizlab wrote: post #2

Aren’t notifications supposed to be encrypted for Signal?

They are;

“Messages were recovered from Sharp’s phone through Apple’s internal notification storage—Signal had been removed, but incoming notifications were preserved in internal memory. Only incoming messages were captured (no outgoing).”

ie the messages recovered were 1. incoming 2. stored by the OS after decryption

i also was spooked by the headline :p

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

#83

Post by schrodinger »

gruez wrote: post #71
nickburns wrote: post #53

Earlier quoted context omitted.

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.

>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. Source? I don't think either OS implements notification syncing between devices, it's only one way, and as others have mentioned, the actually push notification doesn't contain any message cont…

This sounds correct. When I implemented push notifications for an iPhone application, I remainder needing to obtain a store a separate token for each device a user has, and subscribing to a feed of revoked delivery tokens. Seemed like an interesting design intended to facilitate E2E encryption for push notifications.

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

#84

Post by throawayonthe »

frizlab wrote: post #78
exitb wrote: post #67

Earlier quoted context omitted.

They do control the content on the notification. It's a bit odd to put the sensitive text in the notification only to recommend disabling it at the system level.

They do not. They send encrypted notifications. It’s the OS that stores them unencrypted. It’s the OS at fault here IMHO.

i think they're replying to the "recommendation" part -- if it was recommended, why isn't it the safe default?

i haven't actually seen signal or anyone adjacent recommend that previously though, idk where that claim came from

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

#85

Post by kmbfjr »

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.

With notifications disabled APNS push notifications fail for the sending app backend. The device id is rendered invalid if push notifications are disabled at any point. Backends are supposed to handle this and quit sending messages.

Signal has this setting to tell the backend how much information to put into the push message. It can tell the backend to send a simple notification saying “new message” and not send information through APNS or enable it.

I am willing to bet Signal has a notification extension to handle edge cases where there is lag in settings to scrub the message metadata before it dings a screen alert.

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

#86

Post by aftbit »

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.

Wait... why does Signal need to send notification content to Firebase to trigger a push notification on device? I would instead expect that Signal would send a push to my Android saying nothing more than "wake up, you've got a message in convo XYZ", then the app would take over and handle the rest of it locally.

I also didn't realize that Android stores message history even after I've replied or swiped them away. That's nuts - why!?

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

#88

Post by arvid-lind »

jhalstead wrote: post #22
chasil wrote: post #7

First, a critical setting for Signal users: "Signal’s settings include an option that prevents the actual message content from being previewed in notifications. However, it appears the defendant did not have that setting enabled, which, in turn, seemingly allowed the system to store the content in the database." Second, how can I see this notification history?

On a Pixel, I can see some history by going to Android > Settings > Notifications > Manage > Notification History

Wasn't sure if it was the Pixel or GrapheneOS, but what a relief to actually be covered in one of these weird 0day issues.

Unrelated to the OP, but I bet the thousands of "exploits" that Claude Mythos has identified already are a lot of these kind of things that regular people would never think about.

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

#89

Post by satvikpendem »

aftbit wrote: post #86
nickburns wrote: post #53

Earlier quoted context omitted.

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.

Wait... why does Signal need to send notification content to Firebase to trigger a push notification on device? I would instead expect that Signal would send a push to my Android saying nothing more than "wake up, you've got a message in convo XYZ", then the app would take over and handle the rest of it locally. I also didn't realize that Android stores message history even after I've replied or swiped them away. Tha…

If your app needs to send a notification while it's not currently a running process, it must go through Firebase on Google's side and APNS on Apple's side. There is no way for a non running app to send a notification entirely locally, this is by design of both companies.

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

#90

Post by nashashmi »

tsimionescu wrote: post #61
nashashmi wrote: post #50

Earlier quoted context omitted.

On android its quite easy. There is a page of a protocol address that has all notifications show. I used to have a shortcut to it. It has been years since I was on android. But it was really useful each time I did not see a notification in time. Edit: typo

> I used to have a seizure to it. Hopefully, you meant to write "shortcut"...

Yes! Thanks.
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