CTB-Locker, also known as Critoni Ransomware, is a Trojan that encrypts the files on the infected computer and blocks the user’s access to his data. Critoni Ransomware displays a ransom message demanding a high price for the decryption of the files. As researchers have established, the crypto-malware has been for sale on the black market for around 3000 US dollars. Experts warn that the threat is still actively infecting computers worldwide and recommend installing a trustworthy anti-malware tool no your machine and performing regular backups of your important files.
| Name | CTB-Locker |
| Type | Ransomware |
| Short Description | The cyber-threat encrypts user files leaving a ransom note and asking for 0.2 BTC to decrypt the files. |
| Symptoms | The user may witness his files to become encrypted with the .ctb, .ctbl and .ctb2 as well as random file extensions. |
| Distribution Method | Via exploit kits or Trojans. |
| Detection Tool | Download Malware Removal Tool, to See If Your System Has Been Affected by malware |
| User Experience | Join our forum to discuss CTB-Locker. |
CTB Locker – How Did I Get Infected
CTB Locker has been reported by Microsoft Malware Protection Center to be spread via exploit kits or a Trojan.Downloader. Exploit kits may be created for plugins such as Java or Flash Player and it is easy to insert malicious code that creates weaknesses in Windows. Furthermore, the Trojan.Downloader that may be used might collect different information about the computer that will be infected so that the infection process is undetected. Such information may be details about the Windows version, type of Antivirus software used, etc. The Trojan may spread via malicious links that may contain drive-by-downloads or malicious attachments sent online.
CTB Locker Ransomware – What Does It Do?
Once it has been downloaded and activated, the ransomware may insert malicious code into the critical Windows process, called svchost.exe. Furthermore it may create randomly named files, such as sz0s8g2h.exe for example, in the following folders:
- %Temp%
- %AppData%
According to Microsoft researchers, after it has created its payload files, the ransomware begins to scan for and encrypt files with these file extensions:
→3fr 7z abu accdb ai arp arw bas bay bdcr bdcu bdd bdp bds blend bpdr bpdu bsdr bsdu c cdr cer config cpp cr2 crt crw cs dbf dbx dcr dd dds der dng doc docm docx dwg dxf dxg eps erf fdb gdb groups gsd gsf ims indd iss jpe jpeg jpg js kdc kwm md mdb mdf mef mrw nef nrw odb odm odp ods odt orf p12 p7b p7c pas pdd pdf pef pem pfx php pl ppt pptm pptx psd pst ptx pwm py r3d raf rar raw rgx rik rtf rw2 rwl safe sql srf srw txt vsd wb2 wpd wps xlk xls xlsb xlsm xlsx zip
After encrypting the files of users, it may add a suspicious file extension after the files. The following file extensions are reported by researchers from Microsoft and BleepingComputer to be used by CTB Locker:
- .ctb
- .ctb2
- .ctbl
- Random file extensions(newer versions)
The ransomware then may drop the following files that contain the demands of the cyber-criminals:
- %MyDocuments%\AllFilesAreLocked{randomuserid}.bmp
- %MyDocuments%\{randomname}.html
- %MyDocuments%\DecryptAllFiles{randomuserid}.txt
These files contain the ransom instructions. One of them is the wallpaper that is changed to the following:
The encrypted files contain a decryption key held by the cyber criminals. As other ransomware Trojans, CTB-Locker uses Onion routing (Tor) in order to remain anonymous and protect the cyber-crooks’ identity. The good news is that compared to other crypto-viruses, CTB-Locker does not demand a ransom this high. The ransom amount demanded is 0.2 Bitcoins which is around 120 US dollars.
What is new about this ransomware is that the new variants may use random file extensions to encrypt the files such as .zz2dqj or .9jsaxsf. Upon opening, Windows claims that the questionable files are corrupt, and they cannot be fixed by simply removing the extension for the file. Here is an example of an encrypted file names by CTB-Locker:
- New Document.docx.ctbl
- New Picture.jpg.ctb
- New Presentation.pptx.ctb2
- New Text Document.vdi.adid2k
Even though paying the ransom money may bring back your files, we strongly advise you NOT to do it, even though the newer variant of CTB decrypts 5 files for free. This funds the cyber-criminals to develop further their virus plus it may be no guarantee that the decryption keys for your files will be sent back to you so you can restore them.
Here is the decryption screen users see when they are following the decryption instructions:
Source: Bleeping Computer
Removing CTB-Locker Ransomware Completely
To remove this nasty ransomware virus, you should boot your PC into safe mode and install an anti-malware scanner that will locate its registry entries and restore any scheduled tasks for the malware to run on system start. For maximum effectiveness, it is advisable to download the anti-malware software from a safe PC and install it via offline installer to the infected one while you are offline.
1. 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
1. Install SpyHunter to scan for and remove CTB-Locker.2. Scan with SpyHunter to Detect and Remove CTB-Locker.
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 attacks in the future
Security engineers recommend that you back up your files immediately, preferably on an external memory carrier in order to be able to restore them. In order to protect yourself from CTB-Locker (For Windows Users) please follow these simple steps:
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.
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. Remove CTB-Locker Using Other Alternative Tools
Malwarebytes Anti-Malware
STOPZilla Anti MalwareStep 1: Download Malwarebytes 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 ‘Next’ on the following 4 steps that will appear afterwards and after that click on the ‘Install’ button.
Step 7: After the installation process has completed click on the ‘Finish’ button and check the ‘Launch MalwareBytes AntiMalware’ check box.
2. Scan your PC with MalwareBytes to remove all CTB-Locker associated files automatically.
Step 1: Launch MalwareBytes if you havent launched it after install.
Step 2: Wait for the software to update and then click on the blue ‘Scan Now’ button. If it doesnt start updating automatically, click on the blue ‘Update Now’ highlighted text.
Step 3: At this point, after clicking the ‘Scan Now’ button, the system should start scanning your PC. It may take a while but be patient – it is worth it.
Step 4: After the scan has been complete and all of the threats have been identified, click on the ‘Remove Selected’ button to delete them permanently.
Step 5: Once the scan has completed, MalwareBytes will prompt you to restart your computer. It is recommended to save all your data you are working on before restarting.
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.
Restore Files Encrypted by CTB-Locker Ransomware
Security engineers strongly advise users NOT to pay the ransom money and attempt restoring the files using other methods. Here are several suggestions:
To restore your data, your first bet is to check again for shadow copies in Windows using this software:
If this method does not work, Kaspersky have provided a decryptors for files encrypted with the RSA and other encryption algorithms:
Another 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:
EaseUS Data Recovery
Recuva
R-Studio
Photorec
For further information you may check the following articles:
Remove RSA-2048 Key From Crypto Ransomware
Restore Files Encrypted via RSA Encryption
Attention! SensorsTechForum strongly recommends that all malware victims should look for assistance only by reputable sources. Many guides out there claim to offer free recovery and decryption for files encrypted by ransomware viruses. Be advised that some of them may only be after your money.
As a site that has been dedicated to providing free removal instructions for ransomware and malware since 2014, SensorsTechForum’s recommendation is to only pay attention to trustworthy sources.
How to recognize trustworthy sources:
- Always check "About Us" web page.
- Profile of the content creator.
- Make sure that real people are behind the site and not fake names and profiles.
- Verify Facebook, LinkedIn and Twitter personal profiles.
How to Remove CTB-Locker from Windows.
Step 1: Boot Your PC In Safe Mode to isolate and remove CTB-Locker
Step 2: Uninstall CTB-Locker and related software from Windows
Here is a method in few easy steps that should be able to uninstall most programs. No matter if you are using Windows 10, 8, 7, Vista or XP, those steps will get the job done. Dragging the program or its folder to the recycle bin can be a very bad decision. If you do that, bits and pieces of the program are left behind, and that can lead to unstable work of your PC, errors with the file type associations and other unpleasant activities. The proper way to get a program off your computer is to Uninstall it. To do that:
Follow the instructions above and you will successfully uninstall most programs.Step 3: Clean any registries, created by CTB-Locker on your computer.
The usually targeted registries of Windows machines are the following:
- HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
- HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
- HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
You can access them by opening the Windows registry editor and deleting any values, created by CTB-Locker there. This can happen by following the steps underneath:
Tip: To find a virus-created value, you can right-click on it and click "Modify" to see which file it is set to run. If this is the virus file location, remove the value.Before starting "Step 4", please boot back into Normal mode, in case you are currently in Safe Mode.
This will enable you to install and use SpyHunter 5 successfully.
Step 4: Scan for CTB-Locker with SpyHunter Anti-Malware Tool
Step 5 (Optional): Try to Restore Files Encrypted by CTB-Locker.
Ransomware infections and CTB-Locker aim to encrypt your files using an encryption algorithm which may be very difficult to decrypt. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.
Simply click on the link and on the website menus on top, choose Data Recovery - Data Recovery Wizard for Windows or Mac (depending on your OS), and then download and run the tool.
Get rid of CTB-Locker from Mac OS X.
Step 1: Uninstall CTB-Locker and remove related files and objects
1. Hit the ⇧+⌘+U keys to open Utilities. Another way is to click on “Go” and then click “Utilities”, like the image below shows:
- Go to Finder.
- In the search bar type the name of the app that you want to remove.
- Above the search bar change the two drop down menus to “System Files” and “Are Included” so that you can see all of the files associated with the application you want to remove. Bear in mind that some of the files may not be related to the app so be very careful which files you delete.
- If all of the files are related, hold the ⌘+A buttons to select them and then drive them to “Trash”.
In case you cannot remove CTB-Locker via Step 1 above:
In case you cannot find the virus files and objects in your Applications or other places we have shown above, you can manually look for them in the Libraries of your Mac. But before doing this, please read the disclaimer below:
You can repeat the same procedure with the following other Library directories:
→ ~/Library/LaunchAgents
/Library/LaunchDaemons
Tip: ~ is there on purpose, because it leads to more LaunchAgents.
Step 2: Scan for and remove malware from your Mac
When you are facing problems on your Mac as a result of unwanted scripts, programs and malware, the recommended way of eliminating the threat is by using an anti-malware program. Combo Cleaner offers advanced security features along with other modules that will improve your Mac’s security and protect it in the future.
Step 3 (Optional): Try to Restore Files Encrypted by CTB-Locker.
Ransomware infections and CTB-Locker aim to encrypt your files using an encryption algorithm which may be very difficult to decrypt. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.
Simply click on the link and on the website menus on top, choose Data Recovery - Data Recovery Wizard for Windows or Mac (depending on your OS), and then download and run the tool.
CTB-Locker FAQ
What is CTB-Locker ransomware and how does it work?
CTB-Locker is a ransomware infection - the malicious software that enters your computer silently and blocks either access to the computer itself or encrypt your files.
Many ransomware viruses use sophisticated encryption algorithm how to make your files inaccessible. The goal of ransomware infections is to demand that you pay a ransom payment to get access to your files back.
How does CTB-Locker ransomware infect my computer?
Via several ways.CTB-Locker Ransomware infects computers by being sent via phishing e-mails, containing virus attachment.
This attachment is usually masked as an important document, like an invoice, bank document or even a plane ticket and it looks very convincing to users.
After you download and execute this attachment, a drive-by download occurs and your computer is infected with the ransomware virus.
Another way, you may become a victim of CTB-Locker is if you download a fake installer, crack or patch from a low reputation website or if you click on a virus link. Many users report getting a ransomware infection by downloading torrents.
How to open .CTB-Locker files?
You can't. At this point the .CTB-Locker files are encrypted. You can only open them once they are decrypted.
Decryptor did not decrypt my data. What now?
Do not panic and backup the files. If a decryptor did not decrypt your .CTB-Locker files successfully, then do not despair, because this virus is still new.
One way to restore files, encrypted by CTB-Locker ransomware is to use a decryptor for it. But since it's a new virus, advised that the decryption keys for it may not be out yet and available to the public. We will update this article and keep you posted as soon as this decryptor is released.
How Do I restore ".CTB-Locker" files (Other Methods)?
Yes, sometimes files can be restored. We have suggested several file recovery methods that could work if you want to restore .CTB-Locker files.
These methods are in no way 100% guarantee that you will be able to get your files back. But if you have a backup, your chances of success are much greater.
How do I get rid of CTB-Locker ransomware virus?
The safest way and the most efficient one for the removal of this ransomware infection is the use a professional anti malware software. It will scan for and locate CTB-Locker ransomware and then remove it without causing any additional harm to your important .CTB-Locker files.
Also, keep in mind that viruses like CTB-Locker ransomware also install Trojans and keyloggers that can steal your passwords and accounts. Scanning your computer with an anti-malware software will make sure that all of these virus components are removed and your computer is protected in the future.
What to Do If nothing works?
There is still a lot you can do. If none of the above methods seem to work for you, then try these methods:
- Try to find a safe computer from where you can can login on your own line accounts like One Drive, iDrive, Google Drive and so on.
- Try to contact your friends, relatives and other people so that they can check if they have some of your important photos or documents just in case you sent them.
- Also, check if some of the files that were encrypted it can be re-downloaded from the web.
- Another clever way to get back some of your files is to find another old computer, a flash drive or even a CD or a DVD where you may have saved your older documents. You might be surprised what will turn up.
- You can also go to your email account to check if you can send any attachments to other people. Usually what is sent the email is saved on your account and you can re-download it. But most importantly, make sure that this is done from a safe computer and make sure to remove the virus first.
More tips you can find on our forums, where you can also asks any questions about your ransomware problem.
