New DMA Locker ransomware is ramping up for widespread attacks

New version fixes known flaws and adopts new exploit kit-based distribution model

The TeslaCrypt creators called it quits recently, but unfortunately for users, there's a new ransomware program that's ready to take its place.

Called DMA Locker, this threat first appeared in January, but its encryption implementation was so flawed that it was hard to take it seriously. Researchers had no problem developing a file recovery tool for the first two versions.

However, its authors have recently fixed all issues and malware researchers believe that with the newly released version 4, DMA Locker has reached maturity and might be the next thing to hit users in widespread attacks.

"The recently observed changes suggest that the product is preparing to be distributed on a massive scale," researchers from Malwarebytes said in a blog post.

Previous versions reached infected computers through weak or stolen remote desktop credentials. The new version, however, is distributed via Web-based drive-by download attacks that rely on exploit kits, meaning that a much bigger number of computers can potentially be affected.

Another big change is that the encryption routine now relies on a command-and-control server to generate unique public and private RSA keys for each infection.

The malware first generates a unique AES (Advanced Encryption Standard) key for every file that it encrypts. That key is then encrypted with a public RSA key and gets appended to the beginning of the file.

In order to decrypt the affected files, users need the corresponding private RSA key that is in the attacker's possession in order to recover the AES keys for each of their files and then use those keys to decrypt their content.

Previous DMA Locker versions did not use a command-and-control server so the RSA private key was either stored locally on the computer and could be recovered by reverse-engineering, or the same public-private key pair was used for an entire campaign. This meant that if someone paid for the private RSA key, that same key would work on multiple computers and could be shared with other victims.

All of these issues have been fixed by adopting a server-based model, which is typical for how most other ransomware programs work. Once it infects a computer, DMA Locker will now wait for a connection with the server to be established so it can send a unique computer ID and have a unique RSA public key generated for it.

The good news it that, for now, the server is not hosted on the Tor anonymity network, so it should be fairly easy to block by security products, preventing the malware from ever initiating its encryption routine.

DMA Locker also stands out by how it chooses the files to encrypt. Almost all file-encryption ransomware programs have a list of file extensions that they will target. Instead, DMA Locker has a list of extensions that it will not touch, encrypting everything else and potentially causing more damage.

It will also encrypt files on network shares where the computer has write access, even if those shares have not been mapped locally to a drive letter.

As always, with ransomware programs prevention is key. Performing regular backups to locations that are only temporarily accessible from the computer, such as an USB hard disk drive that's only connected during backup operations, is very important.

Join the PC World newsletter!

Error: Please check your email address.

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

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

Essentials

Microsoft L5V-00027 Sculpt Ergonomic Keyboard Desktop

Learn more >

Lexar® JumpDrive® S57 USB 3.0 flash drive

Learn more >

Mobile

Lexar® JumpDrive® S45 USB 3.0 flash drive 

Learn more >

Exec

Lexar® JumpDrive® C20c USB Type-C flash drive 

Learn more >

HD Pan/Tilt Wi-Fi Camera with Night Vision NC450

Learn more >

Lexar® Professional 1800x microSDHC™/microSDXC™ UHS-II cards 

Learn more >

Audio-Technica ATH-ANC70 Noise Cancelling Headphones

Learn more >

Budget

Back To Business Guide

Click for more ›

Most Popular Reviews

Latest News Articles

Resources

PCW Evaluation Team

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.

Ed Dawson

HP OfficeJet Pro 8730

As a freelance writer who is always on the go, I like my technology to be both efficient and effective so I can do my job well. The HP OfficeJet Pro 8730 Inkjet Printer ticks all the boxes in terms of form factor, performance and user interface.

Michael Hargreaves

Windows 10 for Business / Dell XPS 13

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Aysha Strobbe

Windows 10 / HP Spectre x360

Ultimately, I think the Windows 10 environment is excellent for me as it caters for so many different uses. The inclusion of the Xbox app is also great for when you need some downtime too!

Mark Escubio

Windows 10 / Lenovo Yoga 910

For me, the Xbox Play Anywhere is a great new feature as it allows you to play your current Xbox games with higher resolutions and better graphics without forking out extra cash for another copy. Although available titles are still scarce, but I’m sure it will grow in time.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?