5 ms·

Telegram Trilateration: Abusing “People Near Me” and tracking people's location

94 points by gaius_baltar 5y ago

new_guy 5y ago
Man, I read that as 'People of Color' before 'Proof of Concept' and was very confused.
- IceMetalPunk 5y ago
  Oh, my gods, I was so confused until I read your comment. I thought "people of color" as well, and looked through the entire readme trying to understand the relevance. This might be one of those times where writing out the full phrase is worthwhile
- smegsicle 5y ago
  that's horrible- people just go around calling other people 'POCs'? how dehumanizing!
trompetenaccoun 5y ago
This is messed up. Why would they ever make it so accurate?
- na85 5y ago
  Same reason they made their crypto trivial for the server to MITM. Whether malice or ineptitude it's hard to say but it's one of those.
  - 0xy 5y ago
    Secret Chats cannot be MITM'ed and MTProto2 has never had serious security problems despite multiple audits. That's in contrast to WhatsApp, which backs up your private key to the cloud by default. And in contrast to Signal, which has inexcusable software bugs such as sending private photos to random contacts in your list (is it really E2E encrypted if you can't be sure who the recipient was?).
    - infofarmer 5y ago
      MTProto2 has no published audits nor even overviews that any trusted security researcher has found serious. https://news.ycombinator.com/item?id=24832256 https://news.ycombinator.com/item?id=24832256 WhatsApp stores credentials in iCloud Keychain on iOS which is properly e2ee’d. Signal recipient bug was serious, very rare, and hard to catch due to lack of log collection.
      - upofadown 5y ago
        The link is to a discussion: >Sigh. That Stack Exchange answer is incredibly old and points to the flaws everyone knew in MTProto 1, which has been superseded by MTProto 2 for years. Telegram's 1 on 1 secret chats are quite simple and straightforward in design. It is unlikely that there are any security issues in there. Telegram has the same usability issue that the rest of these end to end encrypted instant messengers have. They base all the security on having the users compare some ridiculously long numbers and then downplay the whole thing.
      - 0xy 5y ago
        I do not consider a messenger "E2E" encrypted if one of those ends is a random person you did not intend to message. The fact that bug was even possible suggests poor engineering standards.
- naoqj 5y ago
  https://9to5mac.com/wp-content/uploads/sites/6/2020/08/how-to-toggle-precise-location.jpg https://9to5mac.com/wp-content/uploads/sites/6/2020/08/how-t...
kadoban 5y ago
The linked page says Telegram fixed this, but they only say they're now rounding the results. Hasn't this come up previously in other services and rounding is _not_ enough? It seems like it just makes it very slightly less obviously possible but doesn't prevent exploitation.
- Scaevolus 5y ago
  It depends on when they do the rounding. If they round the final distance number, all you've done is reduced the accuracy to concentric circles like a dartboard, and you simply need more samples to regain the precision. If they round the input location to the centroid of some larger region-- a square several kilometers on a side or a map shape for a region-- there's no precise information to be leaked.
  - diebeforei485 5y ago
    On an iPhone, that's what disabling "Precise Location" does.
    - throw872291 5y ago
      Android 12 has it too.
  - throw872291 5y ago
    Is there a go-to library for this thing? So many apps mess this up.
- throw872291 5y ago
  Telegram fixed it one or two weeks ago, problably because of the war.
- batch12 5y ago
  From what I recall, some services that rounded locations could still be abused by brute forcing the current location of the attacker to identify the threshold of rounding. This has been mitigated in some cases by changing the rounding threshold or truncating the value.
tejado 5y ago
Here is a full implementation of it: https://github.com/tejado/telegram-nearby-map https://github.com/tejado/telegram-nearby-map
Aachen 5y ago
I tried this Telegram feature out some years ago but have it turned off since then. Spammers still find me, overly sexy profiles starting a conversation with a "xyz is 3km away" banner above the chat. One legit person also started a conversation once, they said I appeared as within a few km in a nearby city, so it doesn't seem to be my home address that I'm sharing. Is there a way to find out which location I've been sharing? (I'd be happy to PM someone my phone number if you've already set up this trilateration script.) And secondarily (damage is done now anyway) how to remove this last seen location?
celticninja 5y ago
Don't use telegram. It's not encrypted, it's not safe.
- RF_Savage 5y ago
  Telegram is fine for public and semi-public use. We mostly use it as a an IRC replacement with better multimedia capabilities. We also bridge some channels to IRC. It's fine as long as people understand that it offers privacy only a notch above email. Now the security is on the level of a post card in an envelope instead of a bare postcard levels of security offered by email.
- username190 5y ago
  This (admittedly terrible, but now rectified) location flaw aside, what safety disadvantages does Telegram have over other communication platforms without end-to-end encryption like Discord, Teams, Slack, or Messenger?
  - older 5y ago
    Here's explanation from Moxie: https://threadreaderapp.com/thread/1474067549574688768.html https://threadreaderapp.com/thread/1474067549574688768.html
    - username190 5y ago
      Thanks, that explanation is useful. The only thing I’m curious about is: > Telegram stores all your contacts, groups, media, and every message you've ever sent or received *in plaintext* on their servers. [emphasis mine] This implies they don’t use encryption “at rest” - unless I’ve missed something in their FAQ[0] (entirely possible, I’m far from an expert on cryptography), they seem to imply they do. If it is indeed the case that they don’t encrypt data at rest, I can definitely see how that would be a problem. If data is encrypted at rest though, I don’t see how any of that is fundamentally different from the other messengers I listed in the parent - the server still holds the keys, and thus must be a trusted party - but it’s nothing new. [0] https://core.telegram.org/techfaq#q-how-does-server-client-encryption-work-in-mtproto https://core.telegram.org/techfaq#q-how-does-server-client-e...
aWRr 5y ago
This is extra interesting given the recent (un?)importance of Telegram in the Ukraine conflict. EFF wrote about it recently here: https://www.eff.org/deeplinks/2022/03/telegram-harm-reduction-users-russia-and-ukraine https://www.eff.org/deeplinks/2022/03/telegram-harm-reductio...
axegon_ 5y ago
WTF!?!?!?!? Why would anyone put a feature like that!?!?!?!?!?!?!?!?!?!?!?

94 points by gaius_baltar 5y ago

new_guy 5y ago

Man, I read that as 'People of Color' before 'Proof of Concept' and was very confused.

IceMetalPunk 5y ago
Oh, my gods, I was so confused until I read your comment. I thought "people of color" as well, and looked through the entire readme trying to understand the relevance. This might be one of those times where writing out the full phrase is worthwhile
smegsicle 5y ago
that's horrible- people just go around calling other people 'POCs'? how dehumanizing!

trompetenaccoun 5y ago

This is messed up. Why would they ever make it so accurate?

na85 5y ago
Same reason they made their crypto trivial for the server to MITM. Whether malice or ineptitude it's hard to say but it's one of those.
- 0xy 5y ago
  Secret Chats cannot be MITM'ed and MTProto2 has never had serious security problems despite multiple audits. That's in contrast to WhatsApp, which backs up your private key to the cloud by default. And in contrast to Signal, which has inexcusable software bugs such as sending private photos to random contacts in your list (is it really E2E encrypted if you can't be sure who the recipient was?).
  - infofarmer 5y ago
    MTProto2 has no published audits nor even overviews that any trusted security researcher has found serious. https://news.ycombinator.com/item?id=24832256 https://news.ycombinator.com/item?id=24832256 WhatsApp stores credentials in iCloud Keychain on iOS which is properly e2ee’d. Signal recipient bug was serious, very rare, and hard to catch due to lack of log collection.
    - upofadown 5y ago
      The link is to a discussion: >Sigh. That Stack Exchange answer is incredibly old and points to the flaws everyone knew in MTProto 1, which has been superseded by MTProto 2 for years. Telegram's 1 on 1 secret chats are quite simple and straightforward in design. It is unlikely that there are any security issues in there. Telegram has the same usability issue that the rest of these end to end encrypted instant messengers have. They base all the security on having the users compare some ridiculously long numbers and then downplay the whole thing.
    - 0xy 5y ago
      I do not consider a messenger "E2E" encrypted if one of those ends is a random person you did not intend to message. The fact that bug was even possible suggests poor engineering standards.
naoqj 5y ago
https://9to5mac.com/wp-content/uploads/sites/6/2020/08/how-to-toggle-precise-location.jpg https://9to5mac.com/wp-content/uploads/sites/6/2020/08/how-t...

kadoban 5y ago

The linked page says Telegram fixed this, but they only say they're now rounding the results. Hasn't this come up previously in other services and rounding is _not_ enough? It seems like it just makes it very slightly less obviously possible but doesn't prevent exploitation.

Scaevolus 5y ago
It depends on when they do the rounding. If they round the final distance number, all you've done is reduced the accuracy to concentric circles like a dartboard, and you simply need more samples to regain the precision. If they round the input location to the centroid of some larger region-- a square several kilometers on a side or a map shape for a region-- there's no precise information to be leaked.
- diebeforei485 5y ago
  On an iPhone, that's what disabling "Precise Location" does.
  - throw872291 5y ago
    Android 12 has it too.
- throw872291 5y ago
  Is there a go-to library for this thing? So many apps mess this up.
throw872291 5y ago
Telegram fixed it one or two weeks ago, problably because of the war.
batch12 5y ago
From what I recall, some services that rounded locations could still be abused by brute forcing the current location of the attacker to identify the threshold of rounding. This has been mitigated in some cases by changing the rounding threshold or truncating the value.

tejado 5y ago

Here is a full implementation of it: https://github.com/tejado/telegram-nearby-map https://github.com/tejado/telegram-nearby-map

Aachen 5y ago

I tried this Telegram feature out some years ago but have it turned off since then. Spammers still find me, overly sexy profiles starting a conversation with a "xyz is 3km away" banner above the chat. One legit person also started a conversation once, they said I appeared as within a few km in a nearby city, so it doesn't seem to be my home address that I'm sharing. Is there a way to find out which location I've been sharing? (I'd be happy to PM someone my phone number if you've already set up this trilateration script.) And secondarily (damage is done now anyway) how to remove this last seen location?

celticninja 5y ago

Don't use telegram. It's not encrypted, it's not safe.

RF_Savage 5y ago
Telegram is fine for public and semi-public use. We mostly use it as a an IRC replacement with better multimedia capabilities. We also bridge some channels to IRC. It's fine as long as people understand that it offers privacy only a notch above email. Now the security is on the level of a post card in an envelope instead of a bare postcard levels of security offered by email.
username190 5y ago
This (admittedly terrible, but now rectified) location flaw aside, what safety disadvantages does Telegram have over other communication platforms without end-to-end encryption like Discord, Teams, Slack, or Messenger?
- older 5y ago
  Here's explanation from Moxie: https://threadreaderapp.com/thread/1474067549574688768.html https://threadreaderapp.com/thread/1474067549574688768.html
  - username190 5y ago
    Thanks, that explanation is useful. The only thing I’m curious about is: > Telegram stores all your contacts, groups, media, and every message you've ever sent or received *in plaintext* on their servers. [emphasis mine] This implies they don’t use encryption “at rest” - unless I’ve missed something in their FAQ[0] (entirely possible, I’m far from an expert on cryptography), they seem to imply they do. If it is indeed the case that they don’t encrypt data at rest, I can definitely see how that would be a problem. If data is encrypted at rest though, I don’t see how any of that is fundamentally different from the other messengers I listed in the parent - the server still holds the keys, and thus must be a trusted party - but it’s nothing new. [0] https://core.telegram.org/techfaq#q-how-does-server-client-encryption-work-in-mtproto https://core.telegram.org/techfaq#q-how-does-server-client-e...

aWRr 5y ago

This is extra interesting given the recent (un?)importance of Telegram in the Ukraine conflict. EFF wrote about it recently here: https://www.eff.org/deeplinks/2022/03/telegram-harm-reduction-users-russia-and-ukraine https://www.eff.org/deeplinks/2022/03/telegram-harm-reductio...

axegon_ 5y ago

WTF!?!?!?!? Why would anyone put a feature like that!?!?!?!?!?!?!?!?!?!?!?