CTB-Locker ransomware hits over 100 websites

The new threat is written in PHP and encrypts all files in Web server directories

A new malicious program that encrypts files on Web servers has affected at least 100 websites over the past few weeks, signaling a new trend in ransomware development.

The program, which is written in PHP, is called CTB-Locker, a name also used by one of the most widespread ransomware programs for Windows computers. It's not clear though if there's a relationship between this new Web-based ransomware and the Windows version.

Once installed on a Web server, the program replaces the site's index.php and creates a directory called Crypt that contains additional PHP files. It starts to encrypt all the files in the server's Web directory when it receives a specifically crafted request from an attacker.

After the encryption process is complete, the website's home page will display a message asking for a payment to be made in bitcoin.

One of the first attacks with this Web-based version of CTB-Locker was reported on Feb. 12 when the website of the British Association for Counselling and Psychotherapy fell victim to it.

It wasn't immediately clear at the time whether the website was affected by a real ransomware attack or if it was just an attempt to scare the website owners. Some people were understandably skeptical because the CTB-Locker name had previously only been associated with Windows ransomware.

Researchers from Stormshield, a subsidiary of Airbus Defence and Space, have since managed to obtain a full copy of the malicious code from another affected website. In fact they they found 102 websites that have been infected with this Web-based ransomware so far.

It's not yet clear how the attackers gained access to those websites in order to install CTB-Locker. Blaming a specific vulnerability in a popular content management system (CMS) like WordPress is hard, because some of the affected websites did not use a CMS, the Stormshield researchers said in a blog post Friday.

"The infected hosts run both Linux and Windows and the majority of them (73%) host an Exim service (SMTP server)," they said. "Some of them are vulnerable to ShellShock, but without a deep access on victims' servers, it is difficult to understand how this ransomware infected hosts."

Most of the affected websites also had a password-protected Web shell installed. This is a type of backdoor program that attackers install on Web servers once they've gained unauthorized access to them.

CTB-Locker is not the first ransomware to target websites. In November, researchers discovered a similar threat dubbed Linux.Encoder.1, but that program appeared to be experimental and had cryptographic flaws that allowed researchers to create a decryption tool.

It's likely that Linux.Encoder.1 served as inspiration for other ransomware creators, showing that such attacks against Web servers are viable. As such, CTB-Locker will probably not be the last ransomware program to encrypt websites.

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?