Decryption tool available for TeslaCrypt ransomware that targets games

Security researchers found that decryption keys can be recovered from systems infected with TeslaCrypt

Some users whose computers have been infected with a ransomware program called TeslaCrypt might be in luck: security researchers from Cisco Systems have developed a tool to recover their encrypted files.

TeslaCrypt appeared earlier this year and masquerades as a variant of the notorious CryptoLocker ransomware. However, its authors seemed intent on targeting gamers in particular.

Once installed on a system, the program encrypts files with 185 different extensions, over 50 of which are associated with computer games and related software, including user-generated content like game saves, maps, profiles, replays and mods.

In the ransom note displayed on infected computers, TeslaCrypt claims to be using asymmetric encryption based on the RSA public-key cryptosystem. If true, this would mean that the data is encrypted with a public key stored on the system and can only be decrypted with a private key held by the attackers.

However, after analyzing the malicious program, researchers from Cisco's Talos Group found that it actually uses a symmetric encryption algorithm called AES. This algorithm uses the same key for both encryption and decryption.

Some versions of TeslaCrypt store the encryption key in a file called key.dat on infected systems, but others delete it after they finish encrypting files and store an encrypted version of it in a different file called RECOVERY_KEY.TXT, the Cisco researchers said Monday in a blog post.

The researchers developed a tool that can decrypt files affected by TeslaCrypt if the master encryption key is still found in key.dat. Users should save a copy of this file as soon as they realize that their computers have been infected with TeslaCrypt so they can later use it with the Cisco tool.

The Cisco researchers are still working on reverse-engineering the algorithm used by attackers to restore the master encryption key based on the recovery key. If successful, this will allow them to also decrypt files from versions of TeslaCrypt that delete the master key from the key.dat file when the encryption operation is done.

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection

Tags Cisco Systemssecurityencryptionmalware

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Lucian Constantin

IDG News Service
Show Comments

Father’s Day Gift Guide

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

David Coyle

Brother PocketJet PJ-773 A4 Portable Thermal Printer

I rate the printer as a 5 out of 5 stars as it has been able to fit seamlessly into my busy and mobile lifestyle.

Kurt Hegetschweiler

Brother PocketJet PJ-773 A4 Portable Thermal Printer

It’s perfect for mobile workers. Just take it out — it’s small enough to sit anywhere — turn it on, load a sheet of paper, and start printing.

Matthew Stivala

HP OfficeJet 250 Mobile Printer

The HP OfficeJet 250 Mobile Printer is a great device that fits perfectly into my fast paced and mobile lifestyle. My first impression of the printer itself was how incredibly compact and sleek the device was.

Armand Abogado

HP OfficeJet 250 Mobile Printer

Wireless printing from my iPhone was also a handy feature, the whole experience was quick and seamless with no setup requirements - accessed through the default iOS printing menu options.

Azadeh Williams

HP OfficeJet Pro 8730

A smarter way to print for busy small business owners, combining speedy printing with scanning and copying, making it easier to produce high quality documents and images at a touch of a button.

Andrew Grant

HP OfficeJet Pro 8730

I've had a multifunction printer in the office going on 10 years now. It was a neat bit of kit back in the day -- print, copy, scan, fax -- when printing over WiFi felt a bit like magic. It’s seen better days though and an upgrade’s well overdue. This HP OfficeJet Pro 8730 looks like it ticks all the same boxes: print, copy, scan, and fax. (Really? Does anyone fax anything any more? I guess it's good to know the facility’s there, just in case.) Printing over WiFi is more-or- less standard these days.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?