Telegram Vulnerabilities Could Let Attackers Send Malicious Animated Stickers, Research Finds

A security researcher has discovered a series of vulnerabilities within Telegram that could let attackers send modified animated stickers, which could have exposed the victims’ data. Instant messaging apps seem to have one thing in common: Security researchers always find some kind of image or cleverly crafted message that can interfere with the functionality, either freezing the app or the phone or allowing attackers to take control.

In either case, the problem is not limited to a single app.

A security researcher from Shielder investigated how the Android, iOS and macOS versions of the Telegram app handled animated stickers. They eventually discovered a way that would grant them access to media files that people share in chats, encrypted or not.

“During my research I have identified 13 vulnerabilities in total: 1 heap out-of-bounds write, 1 stack out-of-bounds write, 1 stack out-of-bounds read, 2 heap out-of-bound read, 1 integer overflow leading to heap out-of-bounds read, 2 type confusions, 5 denial-of-service (null-ptr dereferences),” said the researcher.

“All the issues I have found have been responsibly reported to and fixed by Telegram with updates released in September and October 2020,” he explained. This means that, if you’ve only used Telegram in the last four months, you have nothing to worry about.

It’s worth noting that it’s not a single vulnerability responsible for this security issue, which means it’s unlikely to be deployed in the wild. It also requires a high degree of technical expertise, making it available only to sophisticated criminal gangs.

The research also shows why it’s worth keeping all of your devices and software up to date — developers often fix the problems long before the vulnerabilities become public knowledge.