Bart ransomware shows it can be effective without sophisticated encryption

The new malware program locks user files in password-protected ZIP archives

A new ransomware program making the rounds uses a simple, yet effective technique to make user files inaccessible: locking them in password-protected ZIP archives.

The new threat is called Bart and shares some similarities -- in the ransom note in particular -- with Locky, a much more widespread ransomware program. It is distributed through spam emails that masquerade as photos.

The emails have ZIP attachments that contain JavaScript files. These files can be run directly on Windows without the need of additional software and are an increasingly common way to distribute malware.

If the rogue JavaScript file is executed, it downloads and runs a malicious program known as RocketLoader that's designed to download and install additional malware. In this case, RocketLoader installs Bart.

Bart stands out through its simplicity and efficiency, according to researchers from security vendor PhishMe who first came across this new threat.

Most ransomware programs encrypt files with a locally generated AES (Advanced Encryption Standard) key, which is then itself encrypted with a public RSA key that's part of a public-private key pair. The private key, which is needed for decryption, is sent to a command-and-control server operated by attackers and deleted from the local computer.

Bart does not use public key cryptography like RSA. It scans for files with certain extensions -- music, photos, videos, archives, documents, databases and more -- and then locks them in password-protected ZIP archives using the naming format: original_name.extension.bart.zip.

The ZIP format supports AES encryption natively, so its creators didn't need to implement AES themselves, which is prone to errors. This doesn't mean Bart is flawless, but, at least for now, there's no known way to recover the affected files.

Because it doesn't use public-private key pairs, the new ransomware program doesn't need a command-and-control server either, significantly reducing the costs of development for its creators.

The attackers use only a Tor-hosted payment gateway where victims can submit their malware-generated unique ID, pay the ransom in bitcoin and receive a decryptor. The ransom amount is 3 bitcoins, or around US$1,920, which is high, especially if the victim is not a company.

The ransom note is localized for English, Spanish, Italian, French, and German, according to Lawrence Abrams, the founder of computer help forum BleepingComputer.com, where some users have already reported Bart infections. If the computer's language is detected as Russian, Belorussian, or Ukrainian, the ransomware will not encrypt the victim's files.

Unfortunately for users, Bart is proof that attackers don't need advanced crypto knowledge or complex infrastructure to create reliable and effective ransomware programs. That's why this cybercrime model is so successful and why it won't go away anytime soon.

In order to protect themselves against ransomware attacks, users should be wary of email attachments, especially those with unusual file extensions like JS. They should also keep their computer software up to date, especially their browsers and browser plug-ins, and they should implement a file backup routine that involves an offline or offsite backup location.

Join the newsletter!

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

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

George Khoury

Sharp PN-40TC1 Huddle Board

The biggest perks for me would be that it comes with easy to use and comprehensive programs that make the collaboration process a whole lot more intuitive and organic

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.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?