This page contains description and removal guide for Trojan:Win32/Crilock.A virus infection. Run a complete scan of suggested tool to ensure the removal of this threat.

Trojan:Win32/Crilock.A is a detection for a ransomware called CryptoLocker. This is the type of Trojan that invades a computer through social networking sites, instant messaging program, and spam email messages. Trojan:Win32/Crilock.A comes in a form of link or attached file to emails. It tries to deceive victims by pretending to be an important message from trusted contact.

Trojan Downloader that can explore the target system for known exploit is likely to deliver Trojan:Win32/Crilock.A into the computer. This Trojan will take advantage of browser’s security flaw or system vulnerabilities to gain an access on the PC. Once inside Trojan Downloader will fetch a copy of the Trojan:Win32/Crilock.A or CryptoLocker virus from the main server. Once inside, this threat will search and encrypt targeted files. Registry entries and files are also placed on the system to run the malware each time Windows starts.

While on the computer, Trojan:Win32/Crilock.A regularly connects to a command and control (C&C) server using hard coded IP address or domain generation algorithm. Initially, this malware will send data like malware version, system language, user ID, and group ID to the remote server. Then the server will issue an RSA public key to the infected computer. This key has to pair with a Private Key that was created on the server side. In this case, encrypted files need to have both keys in order to be decrypted.

In order to remove Trojan:Win32/Crilock.A, you need to follow the guide on this page. This instruction covers only the removal procedure. We will update it once we have an effective way of decrypting affected files.


How to Remove Trojan:Win32/Crilock.A

Systematic procedures to get rid of the threat are presented on this section. Make sure to scan the computer with suggested tools and scanners.

Step 1 : Download Microsoft Safety Scanner and Run a Scan

NOTE: We suggest that you PRINT or BOOKMARK this guide. There are steps that we may have to restart the computer in order to successfully remove the threat.

If you have previous version of Microsoft Safety Scanner that is more than 10 days old, please disregard it. Download a new copy from the official web site. Every 10 days, Microsoft will release the latest edition of this tool with updated anti-virus definitions to ensure that it will detect even most recent malware threats.

1. Download Microsoft Safety Scanner by clicking the button below and save it on your desktop. This is a free tool from Microsoft that offers on-demand scanning. It helps remove computer infection such as malware, virus, and Trojan.

Click to Download

2. Restart Windows in Safe Mode.

Boot in Safe Mode on Windows XP, Windows Vista, and Windows 7 system
a) Before Windows begins to load, press F8 on your keyboard.
b) It will display the Advanced Boot Options menu. Select Safe Mode.

Start computer in Safe Mode using Windows 8 and Windows 10
a) Close any running programs on your computer.
b) Get ready to Start Windows. On your keyboard, Press and Hold Shift key and then, click on Restart button.
c) It will prompt you with options, please click on Troubleshoot icon.
d) Under Troubleshoot window, select Advanced Options.
e) On next window, click on Startup Settings icon.
f) Lastly, click on Restart button on subsequent window.
g) When Windows restarts, present startup options with numbers 1 - 9. Select "Enable Safe Mode with Networking" or number 5.

Startup Options

h) Windows will now boot on Safe Mode with Networking. Proceed with virus scan as the next step.

3. Once Windows starts in Safe Mode, locate the file of Microsoft Safety Scanner (msert.exe) that you have downloaded earlier. Double-click to run the file.

Icon of MSS

4. When it shows End user license agreement, please accept and click Next to continue.

5. On Scan Type window, please select Full scan. The tool will scan the entire system. This is ideal to detect and remove all threats that are present on the computer.

Image of MS Safety Scanner in full scan

6. Click Next to begin the scan. This process will take a while to finish. Please be patient and let MSS complete the scan procedure.

MSS while Scanning the computer

7. Once the scan operation ends, it will provide a report for identified threats. Please remove all the threats.

8. Reboot the computer and run another scan after Windows boots normally to make sure that Trojan:Win32/Crilock.A is gone. You may now restart Windows normally.

Step 2 : Double-check for Remnants of Trojan:Win32/Crilock.A using Malwarebytes Anti-Malware

This guide requires a tool called Malwarebytes' Anti-Malware. It is a free tool designed to eradicate various computer infections including Trojan:Win32/Crilock.A. MBAM scanner and malware removal tool is distributed for free.

1. In order to completely remove Trojan:Win32/Crilock.A, it is best to download and run the recommended tool. Please click the button below to begin download.

Download Tool

2. After downloading, double-click on the file to install the application. If you are using Windows Vista or higher version, right-click on the file and select 'Run as administrator' from the list.

3. When User Account Control prompts, please click Yes to proceed with the installation.

4. Follow the prompts and install as 'default' only. There are no changes needed during the installation process.

Launch MBAM

5. Malwarebytes Anti-Malware will launch for the first time. It is necessary to proceed with software update.

6. After downloading updates, please click on Scan on the left sidebar.

7. Choose Threat Scan on scanner's console to ensure that it thoroughly check the PC for any presence of Trojan:Win32/Crilock.A and other forms of threats. Click the Start Scan button to begin.


8. Once the scan has completed, Malwarebytes Anti-Malware will issue a list of identified threats. Mark all threats and click on Quarantine Selected.

MBAM Scan Finish

9. If it prompts to restart the computer, please reboot Windows.

Alternative Removal Procedure for Trojan:Win32/Crilock.A

Use Windows System Restore to return Windows to previous state

During an infection, Trojan:Win32/Crilock.A drops various files and registry entries. The threat intentionally hides system files by setting options in the registry. With these rigid changes, the best solution is to return Windows to previous working state is through System Restore.

To verify if System Restore is active on your computer, please follow the instructions below to access this feature.

How to Access System Restore on Windows XP, Windows Vista, and Windows 7

a) Go to Start Menu, then under 'Run' or 'Search Program and Files' field, type rstrui.
b) Then, press Enter on the keyboard to open System Restore Settings.


How to Open System Restore on Windows 8 and Windows 10

a) Hover your mouse cursor to the lower left corner of the screen and wait for the Start icon to appear.
b) Right-click on the icon and select Run from the list. This will open a Run dialog box.
c) Type rstrui on the 'Open' field and click on OK to initiate the command.


If previous restore point is saved, you may proceed with Windows System Restore. Click here to see the full procedure.


About Marco Mathew

Marco Mathew works as Windows Network administrator before establishing Now, Marco is dedicating full-time to help computer users' fight viruses, malware, trojan, worms, adware, and potentially unwanted programs.

1 Comment

  1. AvatarKyle

    Any way to decrypt the files yet?

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