I noted that Apple says the governments in question are allies of the United States. I wonder if this is a case of American intelligence outsourcing the surveillance of American citizens to foreign intelligence. If that is indeed the case, I’d expect a quid pro quo.
Governments spying on Apple, Google users through push notifications
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Re: Governments spying on Apple, Google users through push notifications
#32Are the contents of push notifications not encrypted? Or are we talking about payloads rather than transport?
They mention metadata in the article. Imagine sending a message to a Signal account at time X, then asking Apple a list of all users that received a Signal notification at that specific time.
Re: Governments spying on Apple, Google users through push notifications
#33Earlier quoted context omitted.
I can’t tell if you’re being sarcastic. How is that acceptable and democratic?
I am being sarcastic ;) the guy is supposed to be a freedom fighter for privacy/security but is trying to ban boycotts, the most basic form of protest, and integral to US democracy.
Well, apparently, that's how a good politician works. Just like a good software engineer would have not one, but two backups, at different locations.
It's similar to what economists say about not pulling all your eggs in the same basket.
Re: Governments spying on Apple, Google users through push notifications
#34What sort of metadata or information can be gathered from a push notification from an app like iMessage? I know a timestamp is there and most likely the sender's phone number.
But is there some sort of sensitive info that these governments are trying to glean? Or is it more so they can build info maps and communication maps on targets?
Re: Governments spying on Apple, Google users through push notifications
#35Do push notifications still get sent and just ignored if they are disabled on the device?
This depends on how the app implements notifications, and which mechanism is used to disable them. I know FCM/Android, not APNS/iOS, so here's a breakdown:
1. The app registers a push token with their backend. This can happen without granting notification permissions, and without notifying the user. So the backend is free to start sending push messages immediately after registration, which is typically done on the first app launch.
2. The controls available in Android's per-app notification settings have nothing to do with push messaging. These allow the user to limit or change how the app displays notifications, regardless of the reason the app is displaying them. Some apps have additional options to disable push messages, but that preference must be communicated to the app's backend to prevent the backend from sending pushes in the first place. Some apps may consider Android's notification settings to determine this preference, but it's extra work to do so.
The concepts of "push messaging" and "notifications" are often used interchangeably, but at least on Android these are separate systems that are tied together with client code. The push messages may also contain notification data, and the official FCM client will display these automatically, so this confusion is understandable.
Re: Governments spying on Apple, Google users through push notifications
#36Metadata in this case apparently means Apple and Google are helping find “this real user connected to that real user at this time”. So governments may or may not be able to decrypt a push message payload, or data delivered because of that payload.
Re: Governments spying on Apple, Google users through push notifications
#37Earlier quoted context omitted.
I can’t tell if you’re being sarcastic. How is that acceptable and democratic?
I am being sarcastic ;) the guy is supposed to be a freedom fighter for privacy/security but is trying to ban boycotts, the most basic form of protest, and integral to US democracy.
He's only banning the 'bad' boycotts. Right? /s
Re: Governments spying on Apple, Google users through push notifications
#38Earlier quoted context omitted.
> I see that there is a lot of signal What signals are you talking about? Someone tends to respond to Tinder's notifications at 6 PM on weekends, and such useless data?
It would indicate that they're lonely and looking for a partner. If you were looking to turn them into an intelligence asset, you could have an officer approach and seduce them. If it's Grindr instead of Tinder, or if they're married, you have a blackmailing angle. In a lot of countries it would be very effective.
There's no need for notification snooping when these apps are spamming requests to unique subdomains on analytics services and their own APIs. DNS snooping is a much easier method of getting that metadata.
Although I suppose one advantage of push notifications compared to DNS is that they're delivered even when the app isn't open, and more generally they can also serve as a liveness check (successful delivery means your device is online).
Push notifications would be most valuable for p2p metadata (e.g. iMessage key exchange handshake between two users) and, to the degree they can snoop on the message content, obviously that would be valuable.
Re: Governments spying on Apple, Google users through push notifications
#39Some issues could be prevented if push messages added end-to-end encryption by default, something that shouldn’t be particularly hard to use if it was built into the dev tooling. Instead, developer recommendations like this one [0] suggest that you should put content into your push messages and optionally use a separate library to encrypt them. Clearly developers aren’t doing this, hence the opportunity for surveilla…
Encryption wouldn’t help as the whole point would be to look for coincident timings. I.e. after activity from one user to a known service you see a push occur going to another user. If this pattern repeats you can build confidence they are in contact.
Re: Governments spying on Apple, Google users through push notifications
#40Some issues could be prevented if push messages added end-to-end encryption by default, something that shouldn’t be particularly hard to use if it was built into the dev tooling. Instead, developer recommendations like this one [0] suggest that you should put content into your push messages and optionally use a separate library to encrypt them. Clearly developers aren’t doing this, hence the opportunity for surveilla…
The timing would still give you away - with a privileged network position you can tell that a user sent a message to an messaging service, and that some set of users got notifications from that messaging service moments later. Observe that enough times and you'll have good confidence in the members of a group.
If you're trying to hide from that type of attack you need to send a fixed rate stream of messages (most of which are dummy messages, except the occasional message containing genuine content -- like number stations). Furthermore, every point in the chain also needs to avoid revealing which messages are genuine (by fetching the encrypted message from the server when it receives a genuine notification, you're giving data away).
The operator of the app could send messages at fixed intervals to make it more difficult to correlate the messages (more samples required to have confidence in the recipient). If they send dummy notifications they'd probably fall foul of Apple/Google's constraints around invisible-to-the-user notifications (I know Apple prohibits them, I assume Google does as well)
I can't see that frustrating this type of attack would be interesting to Apple/Google: it would push up power & radio bandwidth requirements for everybody pretty significantly.