Encryption goof fixed in TorrentLocker file-locking malware

A new variant of TorrentLocker fixes a problem that allowed encrypted files to be freed

The developers of a type of malicious software that encrypts a computer's files and demands a ransom have fixed an error security experts said allowed files to be recovered without paying.

The malware, called TorrentLocker, popped up last month, targeting users in Australia, according to iSight Partners, a security consultancy. It now appears to be also geo-targeting victims in the U.K.

TorrentLocker's developers ironically made a similar mistake as the creators of another ransomware program, CryptoDefense. Researchers found earlier this year that CryptoDefense left a decryption key on a person's computer, although the error was soon fixed.

Earlier this month, researchers with the consultancy Nixu found that TorrentLocker used the same keystream to encrypt all of a computer's files. That was a mistake, as a keystream should never be used more than once, according to a writeup on the SANS Institute blog.

"As the encryption was done by combining the keystream with the plaintext file using the XOR operation, we were able to recover the keystream used to encrypt those files by simply applying XOR between the encrypted file and the plaintext file," they wrote.

With the error out in the open, it was only a matter of time before it was fixed.

Richard Hummel, a senior technical analyst with iSight, wrote that a variant of TorrentLocker without that bug has now been found, which shows the "extremely high pace of innovation of our collective adversaries."

The latest version also scans profiles in the Thunderbird email client for email addresses and passwords, he wrote. "This will almost certainly be used to further the spam campaign for TorrentLocker," he wrote.

TorrentLocker asks for US$500 to unlock the files, payable in bitcoin. Hummel wrote that although the percentage of people who pay is low, a look at the bitcoin address associated with TorrentLocker showed that the attackers are making "many bitcoins," he wrote.

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

Join the CSO newsletter!

Error: Please check your email address.

Tags NixuSANS InstitutesecurityiSight Partnersmalware

More about SANS Institute

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Jeremy Kirk

Latest Videos

  • 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

  • 150x50

    IDG Live Webinar:The right collaboration strategy will help your business take flight

    Speakers - Mike Harris, Engineering Services Manager, Jetstar - Christopher Johnson, IT Director APAC, 20th Century Fox - Brent Maxwell, Director of Information Systems, THE ICONIC - IDG MC/Moderator Anthony Caruana

    Play Video

More videos

Blog Posts