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Telegram publishes users' locations online

blog.ahmed.nyc

21–30 of 241 posts

Re: Telegram publishes users' locations online

#21
post #20
post #6

>[Line] fixed it by adding a random number to the user's destination This is a imperfect solution. There's two possibilities: the offset (aka "random number") is dynamic, or it's fixed. If it's the former all you have to do is sample enough times to get through the noise. If it's the latter, it's not vulnerable to the previous attack, but if you have a known point of reference (so you can deduce what the offset is),…

> If it's the latter, it's not vulnerable to the previous attack, but if you have a known point of reference (so you can deduce what the offset is) It sounds like this approach could be prevented by having a random fixed offset for each user, so that you have no point of reference unless you already know where that specific user is. [Removed bit about regenerating this offset infrequently.] EDIT: You could even do th…

With enough data points you'd easily figure out that offset. Just overlay each data point with map data and decide whether the location makes sense.

(i.e. you're unlikely to most of the time be in the middle of a lake, farm field etc)

Re: Telegram publishes users' locations online

#22
post #11

It's a shame that people still use Telegram when Signal is so much better, and has better credentials all around.

signal the protocol is (maybe) better, but the app is inferior. People like Telegram for their usability and security is just a bonus.

I definitely agree with this. Getting people to use Telegram instead of SMS or other random chat apps can be difficult but getting them to switch to Signal is basically a "not going to happen" until Signal ups their usability. Even people I've gotten to try out Signal all abandoned it. At least with Telegram, they stuck with it and still use it to this day. It'd honestly probably be easier to get Telegram to adopt Signal's protocol than it would be to get users to adopt [current] Signal.

Re: Telegram publishes users' locations online

#23
post #6

>[Line] fixed it by adding a random number to the user's destination This is a imperfect solution. There's two possibilities: the offset (aka "random number") is dynamic, or it's fixed. If it's the former all you have to do is sample enough times to get through the noise. If it's the latter, it's not vulnerable to the previous attack, but if you have a known point of reference (so you can deduce what the offset is),…

If it's a fixed offset for a particular person, then isn't that just another variable in a simultaneous equation? You'd just need one more sample to solve for it.

Re: Telegram publishes users' locations online

#24
post #20
post #6

>[Line] fixed it by adding a random number to the user's destination This is a imperfect solution. There's two possibilities: the offset (aka "random number") is dynamic, or it's fixed. If it's the former all you have to do is sample enough times to get through the noise. If it's the latter, it's not vulnerable to the previous attack, but if you have a known point of reference (so you can deduce what the offset is),…

> If it's the latter, it's not vulnerable to the previous attack, but if you have a known point of reference (so you can deduce what the offset is) It sounds like this approach could be prevented by having a random fixed offset for each user, so that you have no point of reference unless you already know where that specific user is. [Removed bit about regenerating this offset infrequently.] EDIT: You could even do th…

[deleted]

Re: Telegram publishes users' locations online

#25
post #18

so i know some people around me who are using telegram and very likely most of them did not change anything about their privacy settings as usual. However, i do not see any of them in the list and it even shows me users some 10km away. When viewing this list on the top it has a button to make yourself visible so i assume if you don't do it voluntarily its not broadcasted at all which appears to be a non issue then, l…

Yeah its very much opt in so Im not sure what the real issue is apart from being somewhat granular. How granular telegram makes it is the question. From the article the way they asked didn't sound like it was "do you live at 123 something st" but instead are you by, which even if you were a few blocks off someone might say yes.

For all we know Telegram is doing some rounding. Gonna need to test some more to see I guess.

Re: Telegram publishes users' locations online

#26
post #20

Earlier quoted context omitted.

> If it's the latter, it's not vulnerable to the previous attack, but if you have a known point of reference (so you can deduce what the offset is) It sounds like this approach could be prevented by having a random fixed offset for each user, so that you have no point of reference unless you already know where that specific user is. [Removed bit about regenerating this offset infrequently.] EDIT: You could even do th…

With enough data points you'd easily figure out that offset. Just overlay each data point with map data and decide whether the location makes sense. (i.e. you're unlikely to most of the time be in the middle of a lake, farm field etc)

[deleted]

Re: Telegram publishes users' locations online

#27
post #15

Earlier quoted context omitted.

I have Telegram on iOS and I can't find any People Nearby feature. It doesn't request the location permission according to Settings either.

It took me a while to find it on iOS, it’s under the contacts tab called “find people near by”. It doesn’t seem to work without location enabled so hopefully that would keep you safe.

Also doesn't work unless you share contacts - which .... why would you anyways?

Re: Telegram publishes users' locations online

#28
post #23
post #6

>[Line] fixed it by adding a random number to the user's destination This is a imperfect solution. There's two possibilities: the offset (aka "random number") is dynamic, or it's fixed. If it's the former all you have to do is sample enough times to get through the noise. If it's the latter, it's not vulnerable to the previous attack, but if you have a known point of reference (so you can deduce what the offset is),…

If it's a fixed offset for a particular person, then isn't that just another variable in a simultaneous equation? You'd just need one more sample to solve for it.

No, because your solution will be off by that offset. eg. if the offset is 1KM to the north, and you tried the method mentioned in the blog post then your final solution will also be 1KM to the north. You can still use the information for limited stalking purposes (eg. has the person moved or not), but it's not nearly as useful as knowing their exact location.

Re: Telegram publishes users' locations online

#29
post #20
post #6

>[Line] fixed it by adding a random number to the user's destination This is a imperfect solution. There's two possibilities: the offset (aka "random number") is dynamic, or it's fixed. If it's the former all you have to do is sample enough times to get through the noise. If it's the latter, it's not vulnerable to the previous attack, but if you have a known point of reference (so you can deduce what the offset is),…

> If it's the latter, it's not vulnerable to the previous attack, but if you have a known point of reference (so you can deduce what the offset is) It sounds like this approach could be prevented by having a random fixed offset for each user, so that you have no point of reference unless you already know where that specific user is. [Removed bit about regenerating this offset infrequently.] EDIT: You could even do th…

[deleted]

Re: Telegram publishes users' locations online

#30
On the "People Nearby" page in the Telegram app it specifically says

Quickly add people nearby who are also viewing this section ...

If a user is not specifically on that page, they are not listed in the section. The user most likely wants the world (or strangers) to know his position.

This case shows precise localization can be a double-edge sword. But instead of fuzzing the returned location, we should educate the people on privacy implications of showing their position to the public.

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