Telegram dimisses claim of a flaw in its secure messaging application

Zimperium says Telegram doesn't protect content in memory, but Telegram says it's hard to defend against

Telegram, a messaging application that markets itself as a secure communication tool, doesn't handle encrypted conversations securely, according to the founder of a mobile security company.

Zuk Avraham of Zimperium wrote in a blog post Monday that he found several weak points that allowed him to recover plain text messages.

Avraham didn't try to directly crack messages encrypted by Telegram, which is backed by Pavel Durov, founder of the popular Russian social networking site Vkontakte. Instead, Avraham focused on an alternative attack using a kernel exploit to gain root access on an Android device and then looking at how Telegram handled messages in memory.

Telegram spokesman Markus Ra contends that Avraham's attack is one that no application can defend against.

"If you assume that the attacker has root access -- no app can be secure," Ra said via email. "For example, in order to show anything on the screen, you need to put it [in] the device's memory. An attacker with root access can simply read your device's memory."

System-level vulnerabilities such as the one used by Avraham for his research can only be fixed by an OS manufacturer, Ra said.

Attackers are more likely to try and find an OS-level flaw, which would then allow them to probe apps on the phone, Avraham argued in his post.

For his research, Avraham used a device running an older version of Android, 4.2.2. His attack used an application vulnerability that allows an attacker to gain higher level privilege through the Android kernel exploit, CVE-2014-3153, the so-called TowelRoot exploit.

He then looked at how Telegram stores its "secret chat" communications. Telegram doesn't implement end-to-end encryption on all messages by default. Users must initiate a secret chat to ensure messages are encrypted from the point of creation until they're decrypted on a recipient's device.

Avraham dumped Telegram's process memory and looked for traces of messages he created. He found the words he'd written in Telegram stored in clear text.

"Any attacker that gains access to the device can read the messages without too much effort," Avraham wrote.

Further investigation showed secret chats stored in a file called "cache4.db" in Telegram's "files" folder, he wrote. The supposedly secret messages were also there in clear text.

Avraham then set out to see if he could recover messages that had been deleted. He wrote he was still able to find a deleted conversation in memory.

Telegram was notified by Zimperium of the problems on Jan. 18. Avraham wrote that his company contacted Telegram three times over the next three weeks but received no response.

Zimperium has a policy whereby it will publicize some information related to a vulnerability after 30 days if the affected vendor has not responded.

Send news tips and comments to Follow me on Twitter: @jeremy_kirk

Join the CSO newsletter!

Error: Please check your email address.

Tags TelegramsecurityencryptionExploits / vulnerabilities

More about

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Jeremy Kirk

Latest Videos

  • 150x50

    CSO Webinar: Will your data protection strategy be enough when disaster strikes?

    Speakers: - Paul O’Connor, Engagement leader - Performance Audit Group, Victorian Auditor-General’s Office (VAGO) - Nigel Phair, Managing Director, Centre for Internet Safety - Joshua Stenhouse, Technical Evangelist, Zerto - Anthony Caruana, CSO MC & Moderator

    Play Video

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

More videos

Blog Posts

Market Place