|A Telegram App logo in QR code|
How the attackers gained access?
In normal procedure, whenever someone logs into Telegram using a different device, a one-time password (OTP), is texted to them and the user can log into their account using this secret code. Now, these hackers managed to access this one-time secret code and snooped on Telegram chats of various users.
Dmitry Rodin, one of the victims of this attack, runs a coding school in Russia. He told the media, he was given a warning by telegram, that someone is trying to access his account. He ignored the notification but another notification came saying some has successfully logged in from Samara, Russia, he immediately terminated all active sessions except for his.
Like Group-IB, he also believes that there was a problem with the telecom operators or his phone was hacked and not the messaging app Telegram. “Perhaps someone logged into my account by intercepting the SMS, which suggests that there might be a problem on the side of the telecom operator,” he said. “This means that other accounts using SMS as an authentication factor are also threatened.” 13 such cases have been reported so far.
“However, this number is likely to increase since we are speaking about a new threat, which has just started spreading,” a company spokesperson said.
Is SS7 being abused?
The most worrying part is that One-time password (OTP) were hacked, if this hypothesis is indeed true then we are looking at a very big security threat as this technology is used in many log-ins and financial transactions. Another hypothesis is that victim’s devices were hacked and the attackers were spying on their messages but Group-IB found no traces of such activity on the victims’ phones. And thus Group-IB is tilting towards a mobile network SS7, that’s being abused.
Forbes reported, “Think of SS7 as the part of telecom infrastructure that deals with shifting users between networks as they travel abroad. It also manages the changes in charges when traversing different nations’ networks. But in recent years, hackers have learned that if they can get leverage on that network they can silently intercept text messages. Previously, such attacks have been used in bank account breaches and by surveillance companies.”
Now, this same network could be used for hacking Telegram accounts.
Selling access to accounts on the dark web
Group-IB also suspects that access to these accounts is being sold on the dark web-based Hydra forum for 3,900$ as well as selling access to WhatsApp messages and user info. Now, they think that these could be linked.
“What made us think that the attacks might have something in common with these advertisements is the fact that the incidents coincided with the time the posts were published,” the company spokesperson added.“But we cannot rule out that there are far more connections between these two events, which is yet to be established in the course of an investigation.”