Telegram lets scammers connect directly with potential victims by way of stored contacts

Don’t want to be identified as Telegram user? Yeah, about that…

David Bisson

Telegram lets scammers connect directly with potential victims by way of stored contacts

Scammers can use the Telegram mobile messaging app to connect with a potential victim if they already have their phone number in their contact list.

In a blog post, Fidelis Cybersecurity researcher John Bambenek discusses the ease with which scammers can reach out to Telegram users:

“Here’s the deal: If a scammer signs up for Telegram and already has your phone number in their contact list, it will also notify them that you also have Telegram. So in addition to connecting you to your friends and contacts, the app will also connect scammers directly to you. Likewise, if you have scammers’ numbers in your contact list for some reason, you will get push notifications when they join Telegram…”

What’s going on here? How is this even possible?

Most of us know there are there “Do Not Call” rules that help prevent unwanted (spam) calls. These records reflect the complaints users have filed on phone number reputation sites. Mobile applications that block unwanted calls build their registries off this reputation data.

There’s just one catch. “Do Not Call” rules don’t apply to encrypted messaging apps. Those include Telegram, which has versions for Android and iOS.

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That’s annoying, but surely there’s a way of blocking others from seeing you have Telegram installed, right?


You can block specific users. You can choose who can see when you were last active on Telegram. And you can choose whether everybody or just your existing contacts can join you to group chats. But you cannot block others from seeing if you have Telegram installed if they know your mobile number.

To make matters worse, Bambenek said it would be quite easy for someone to develop a method of determining whether a user has installed Telegram on their mobile device. Criminals could use such a service to target unsuspecting users. But so too could law enforcement and intelligence agencies looking to determine “risk factors” among the general population.

So what is to be done?

Users of encrypted messaging apps like Telegram, which has seen bugs both real and bogus, need to understand that these risks are out there. As such, they should be careful when approving new contacts, even if they’re a friend. Ideally, they should use an out-of-band means of verification.

They should also review the app’s default settings and check to see if they can prevent the app from capturing their address book.

Finally, they should be careful about answering calls from unknown users. A simple “hello” tells a scammer that their number is active. As such, they’ll find no reason to not spend months or even years trying to reconnect with that user. They just need a direct means of communication.

And with apps like Telegram, they’ve got that.

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David Bisson is an infosec news junkie and security journalist. He works as Contributing Editor for Graham Cluley Security News and Associate Editor for Tripwire's "The State of Security" blog.

11 comments on “Telegram lets scammers connect directly with potential victims by way of stored contacts”

  1. Yeh so? I get at least 2 friend requests from scammers on Facebook per day. I don't see how this is worse, or even worth any extra concern beyond the usual level of vigilance. Don't be a fear monger

    1. What he's saying is that Telegram is a bit different.

      If somebody has YOUR phone number in their address book and YOU join Telegram then that person will get an alert saying "Freman has joined Telegram".

      Facebook is a little different to an instant messaging application. Personally I think Telegram should give the end user an option NOT to proactively alert people to the fact that they're using the platform.

      You could argue that WhatsApp is very similar however their method requires you to look through your phonebook to find other WhatsApp users.

      The Telegram privacy options are far superior to those in WhatsApp and they also allow you to use a username so that you can contact people (or they can contact you) without providing your phone number. That's a major benefit.

    2. The difference is in the topology. No matter what you do on Facebook, it's a website and you communicate with their server so as your contacts, that's how they keep control. End-to-end apps talk to each other directly meaning you both know the address of each other. When you pass through a server its like having a friend A making a conference call to let you talk to friend B. You'll both see the the number of friend A. So B cannot use your number to spam you after.

  2. It is true some scammer already use telegram and registered as famous person, like Timothy Sykes, on his Bio, it is exactly like Timothy Sykes, and he will promise you that he can turn $1400 into $5000 within few hours and ask you to sent 0.128 BTC, worth $1500 to his BTC address! never do it! after you sent the BTC to him, he will tell you he already made $7000, now want to release to you, in order to do so, the scammer ask you to sent additional 0.1 BTC, worth $1100 to his different BTC wallet! I hope FBI do the investigation to arrest this scammer! I am one of the victimes!. not sure how many victims on the telegram! watch out!

    1. I didn't join any telegram but a scammer has a code sent to me by telegram. Could it be that my number is registered somewhere else

  3. I just got a scanm on Telegram. This person is using text only phone number from Iowa and using a person's name from New York city for a job with Morgan Stanley. I sent a message to the person in New York on Linledin and asked if this is really the same person. The scammer from Iowa not stop texting me.

  4. I am sorry but telegram should deactivate these accounts when people complain they just continue all the time ??

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