New CTB-Locker Variant Targets Vulnerable Web Servers - How to, Technology and PC Security Forum |

New CTB-Locker Variant Targets Vulnerable Web Servers

Ransomware, just like any other cyber threat, is constantly evolving and adding new features to its set of capabilities. Ransomware affiliate programs are also a big factor, as any wannabe cyber criminal with basic skills can now join and make some (ransom) money.

Short DescriptionCTB-Locker’s most recent variant targets web servers.
SymptomsPart of the attack is website defacement. The website’s interface is replaced by what appears to be a ransom message with instructions.
Distribution MethodQuite likely – exploiting WordPress vulnerabilities; third-party WordPress plugins; spam emails.
Detection ToolDownload Malware Removal Tool, to See If Your System Has Been Affected by CTB-Locker
User Experience Join our forum to discuss CTB-Locker.
Data Recovery ToolWindows Data Recovery by Stellar Phoenix Notice! This product scans your drive sectors to recover lost files and it may not recover 100% of the encrypted files, but only few of them, depending on the situation and whether or not you have reformatted your drive.

Sometimes, it’s quite obvious for cyber researchers that the particular ransomware was made by ‘beginners’ or ‘amateurs’. And such cases usually end up with decryption software released and available for victims to restore their files. However, in other instances, the ransomware endures.

CTB-Locker, or Onion, is a perfect example of malicious coders that never give up and seek new ways to reinvent their ransomware. Considering its high infection rates and overall destructiveness, CTB-Locker was even named one of the top ransomware families of 2015. In 2016, CTB-Locker continues to be a player, with a new variant just released in the wild.

What’s New in CTB-Locker’s New Variant?

Essentially, the latest variant of the infamous ransomware targets exclusively web servers. According to researchers at Kaspersky Lab, more than 70 servers (possibly even more) in 10 countries have already been attacked successfully. Fortunately, Kaspersky researchers were able to conduct a detailed technical analysis as several victims contacted them and sent them the ‘cryptors’ that compromised their web servers.

CTB-Locker Server Edition: Technical Resume

The ransom demanded by the new variant is approximately $150, or less than a half bitcoin. However, if the ransom payment is not transferred on time, the sum is doubled to $300. Once the payment is finalized, the decryption key is generated and can be used to restore the server’s files.

Researchers were able to discover that the infection process took place because of security holes in the victims’ web servers. Once the vulnerabilities in question are exploited, the website is defaced.

What is website defacement?

Shortly, website defacement is a type of attack that changes the website’s interface. Attackers usually break into a web server and replace the hosted website with their own website (via Wikipedia). Researchers have concluded that most of the recent defacement attacks are not random but may have political or cultural motives.

As for the ransom message dropped by the server variant of CTB-Locker a.k.a. the website version of CTB-Locker, it is a detailed one that provides some interesting facts:


As visible, the website defacement is the ransom note itself. The original code is not deleted and is stored in an encrypted state on the web root. Its name is changed as well.

The exact security hole that initiates the attack on the victims’ web servers is not yet discovered. However, many of the attacks on the servers have one thing in common – WordPress.

It’s not a secret to anyone that WordPress websites that run outdated versions of the platform are full of vulnerabilities. In addition, WordPress has another weak spot – plugins. Using third-party, suspicious plugins put web servers at risk of various attacks and intrusions.

More on the Topic: TeslaCrypt Spreading via Compromised WordPress Websites

Once the vulnerability is located and exploited, and the ransomware operator is inside WordPress, the main website file is replaced and the encryption process is initiated. Then, the main file is renamed, encrypted and saved. Researchers were able to identify that two different AES-256 keys are used in the attacks.

1. create_aes_cipher($keytest) – encrypts the two files which can be decrypted free.
2. create_aes_cipher($keypass) – encrypts the rest of the files hosted on the server web root.

Another peculiar feature present in the server edition of CTB-Locker is that the ransomware operators will decrypt two files for free. However, the victim doesn’t have the option to choose the files for decryption. A chat room for communication with the malicious operators is also available.

Ransomware Removal Manual and Data Backup Tips

For more technical details about the attack, visit Kaspersky Lab.

As with all ransomware cases, security experts’ advice is backing up all important data, not opening suspicious, unexpected emails, and not using third-party software. Or in the case of WordPress – plugins.

If you have been attacked by this particular variant of CTB-Locker, or another currently active ransomware, you can follow the steps below the article.

1. Boot Your PC In Safe Mode to isolate and remove CTB-Locker

Boot Your PC Into Safe Mode

1. For Windows 7,XP and Vista. 2. For Windows 8, 8.1 and 10.

For Windows XP, Vista, 7 systems:

1. Remove all CDs and DVDs, and then Restart your PC from the “Start” menu.
2. Select one of the two options provided below:

For PCs with a single operating system: Press “F8” repeatedly after the first boot screen shows up during the restart of your computer. In case the Windows logo appears on the screen, you have to repeat the same task again.


For PCs with multiple operating systems: Тhe arrow keys will help you select the operating system you prefer to start in Safe Mode. Press “F8” just as described for a single operating system.


3. As the “Advanced Boot Options” screen appears, select the Safe Mode option you want using the arrow keys. As you make your selection, press “Enter“.

4. Log on to your computer using your administrator account


While your computer is in Safe Mode, the words “Safe Mode” will appear in all four corners of your screen.

Step 1: Open the Start Menu


Step 2: Whilst holding down Shift button, click on Power and then click on Restart.
Step 3: After reboot, the aftermentioned menu will appear. From there you should choose Troubleshoot.


Step 4: You will see the Troubleshoot menu. From this menu you can choose Advanced Options.


Step 5: After the Advanced Options menu appears, click on Startup Settings.


Step 6: Click on Restart.

Step 7: A menu will appear upon reboot. You should choose Safe Mode by pressing its corresponding number and the machine will restart.

2. Remove CTB-Locker with SpyHunter Anti-Malware Tool

Remove CTB-Locker with SpyHunter Anti-Malware Tool

1. Install SpyHunter to scan for and remove CTB-Locker.2. Scan with SpyHunter to Detect and Remove CTB-Locker.
Step 1:Click on the “Download” button to proceed to SpyHunter’s download page.

It is highly recommended to run a scan before purchasing the full version of the software to make sure that the current version of the malware can be detected by SpyHunter.

Step 2: Guide yourself by the download instructions provided for each browser.
Step 3: After you have installed SpyHunter, wait for it to automatically update.


Step1: After the update process has finished, click on the ‘Scan Computer Now’ button.
Step2: After SpyHunter has finished scanning your PC for any CTB-Locker files, click on the ‘Fix Threats’ button to remove them automatically and permanently.
Step3: Once the intrusions on your PC have been removed, it is highly recommended to restart it.

3. Back up your data to secure it against infections and file encryption by CTB-Locker in the future

Back up your data to secure it against attacks in the future

IMPORTANT! Before reading the Windows backup instructions, we highly recommend to back up your data automatically with cloud backup and insure it against any type of data loss on your device, even the most severe. We recommend reading more about and downloading SOS Online Backup .

To back up your files via Windows and prevent any future intrusions, follow these instructions:

1. For Windows 7 and earlier 1. For Windows 8, 8.1 and 10 1. Enabling the Windows Defense Feature (Previous Versions)

1-Click on Windows Start Menu
2-Type Backup And Restore
3-Open it and click on Set Up Backup
4-A window will appear asking you where to set up backup. You should have a flash drive or an external hard drive. Mark it by clicking on it with your mouse then click on Next.
5-On the next window, the system will ask you what do you want to backup. Choose the ‘Let Me Choose’ option and then click on Next.
6-Click on ‘Save settings and run backup’ on the next window in order to protect your files from possible attacks by CTB-Locker.

1-Press Windows button + R
2-In the window type ‘filehistory’ and press Enter
3-A File History window will appear. Click on ‘Configure file history settings’
4-The configuration menu for File History will appear. Click on ‘Turn On’. After its on, click on Select Drive in order to select the backup drive. It is recommended to choose an external HDD, SSD or a USB stick whose memory capacity is corresponding to the size of the files you want to backup.
5-Select the drive then click on ‘Ok’ in order to set up file backup and protect yourself from CTB-Locker.

1- Press Windows button + R keys.
2- A run windows should appear. In it type ‘sysdm.cpl’ and then click on Run.
3- A System Properties windows should appear. In it choose System Protection.
5- Click on Turn on system protection and select the size on the hard disk you want to utilize for system protection.
6- Click on Ok and you should see an indication in Protection settings that the protection from CTB-Locker is on.
Restoring a file via Windows Defense feature:
1-Right-click on the encrypted file, then choose Properties.
2-Click on the Previous Versions tab and then mark the last version of the file.
3-Click on Apply and Ok and the file encrypted by CTB-Locker should be restored.

4. Restore files encrypted by CTB-Locker

Restore Files Encrypted by CTB-Locker

Since PadCrypt 2.0 deletes Shadow Copies in Windows, security engineers strongly advise users NOT to pay the ransom money and attempt restoring the files using other methods. Here are several suggestions:

Kaspersky have provided a decryptors for files encrypted with the this and other encryption algorithms:

Kaspersky Decryptors

A decent method of restoring your files is by trying to bring back your files via data recovery software. Here are some examples of data recovery programs:

There is also the technical option to use a network sniffer:

Another way to decrypt the files is by using a Network Sniffer to get the encryption key, while files are encrypted on your system. A Network Sniffer is a program and/or device monitoring data traveling over a network, such as its internet traffic and internet packets. If you have a sniffer set before the attack happened you might get information about the decryption key.

Optional: Using Alternative Anti-Malware Tools

Remove CTB-Locker Using Other Alternative Tools

STOPZilla Anti Malware
1. Download and Install STOPZilla Anti-malware to Scan for And Remove CTB-Locker.
Step 1: Download STOPZilla by clicking here.
Step 2: A pop-up window will appear. Click on the ‘Save File’ button. If it does not, click on the Download button and save it afterwards.
Step 3: After you have downloaded the setup, simply open it.
Step 4: The installer should appear. Click on the ‘Next’ button.
Step 5: Check the ‘I accept the agreement’ check circle if not checked if you accept it and click the ‘Next’ button once again.
Step 6: Review and click on the ‘Install’ button.
Step 7: After the installation process has completed click on the ‘Finish’ button.

2. Scan your PC with STOPZilla Anti Malware to remove all CTB-Locker associated files completely.
Step 1: Launch STOPZilla if you haven’t launched it after install.
Step 2: Wait for the software to automatically scan and then click on the ‘Repair Now’ button. If it does not scan automatically, click on the ‘Scan Now’ button.
Step 3: After the removal of all threats and associated objects, you should Restart your PC.


Milena Dimitrova

An inspired writer and content manager who has been with SensorsTechForum for 4 years. Enjoys ‘Mr. Robot’ and fears ‘1984’. Focused on user privacy and malware development, she strongly believes in a world where cybersecurity plays a central role. If common sense makes no sense, she will be there to take notes. Those notes may later turn into articles! Follow Milena @Milenyim

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