Crypt0 Ransomware

Also Known As: Crypt0 virus
Distribution: Low
Damage level: Severe

Crypt0 ransomware removal instructions

What is Crypt0?

Crypt0 is a ransomware-type virus that infiltrates computers and encrypts various types of files (e.g., doc, .ppt, .jpg, etc.) During encryption, Crypt0 modifies the names of encrypted files by inserting "_crypt0" before the extension (e.g., encrypted "sample.jpg" is renamed to "sample_crypt0.jpg"). Crypt0 then generates a text file ("HELP_DECRYPT.txt") containing a ransom-demand message and places it on the desktop.

The ransom-demand message states that files have been encrypted supposedly using asymmetric cryptography. Be aware that public (encryption) and private (decryption) keys are generated when encrypting files with asymmetric algorithms. The private key is stored on remote servers controlled by cyber criminals. Since decryption without this key is impossible, Crypt0's developers attempt to sell it. To receive the key, victims must contact cyber criminals via an email address provided ( Detailed payment instructions are then provided. The size of ransom is currently unknown, however, research shows that cyber criminals often demand .5-1.5 Bitcoin (1 Bitcoin is currently equivalent to ~$609). Cyber criminals choose the Bitcoin currency since it allows them to remain anonymous and significantly diminishes the chance of being apprehended by authorities. Research also shows that criminals often ignore victims, despite payments made. Therefore, you are strongly advised to ignore all requests to contact these people and/or pay any ransom. There is a high probability that paying will not deliver any positive results - you will simply be scammed. Fortunately, Michael Gillespie (demonslay335) has developed a tool capable of restoring files encrypted by Crypt0 (download link). Therefore, there is no need to pay any ransom.

Screenshot of a message encouraging users to contact the developers of Crypt0 ransomware to decrypt their compromised data:

Crypt0 decrypt instructions

Crypt0 shares many similarities with other ransomware-type viruses such as Zepto, RansomCuck, Cry, and Cerber3. All encrypt files and make ransom demands. Research shows that ransomware-type viruses often use asymmetric cryptography. Therefore, the only noticeable difference is the size of ransom. Furthermore, ransomware-type viruses are often distributed via peer-to-peer (P2P) networks (for example, Torrent), spam emails (infectious attachments), trojans, and fake software update tools. Use a legitimate anti-virus/anti-spyware suite and keep your installed software up-to-date (cyber criminals can exploit software bugs to infiltrate the system). If possible, download your files/applications from trusted sources (e.g., official download websites) without using any third party downloaders. It is also very important to be cautious when opening files received from unrecognized/suspicious email addresses. Poor knowledge of these threats and rushing steps is often the reason for infections. The key to computer safety is caution.

Crypt0 ransom-demand message ("HELP_DECRYPT.txt"):

What happened to your files ?
They are being held for ransom - All of your files were protected by a strong encryption with RSA-2048 using CryptoWall 3.0.
More information about the encryption keys using RSA-2048 can be found here: hxxp://
What does this mean ?
This means that the structure and data within your files have been irrevocably changed, you will not be able to work with them, read them or see them,
it is the same thing as losing them forever, but with our help, you can restore them.
How did this happen ?
Especially for you, on our server was generated the secret key pair RSA-2048 - public and private.
All your files were encrypted with the public key, which has been transferred to your computer via the Internet.
Decrypting of your files is only possible with the help of the private key and decryption program, which is on our secret server.
What do I do ?
(DO NOT DELETE THIS FILE FROM THIS FOLDER - It is needed to decrypt your files)
Alas, if you do not take the necessary measures within a week then the conditions for obtaining the private key will be changed.
If you really value your data, then we suggest you do not waste valuable time searching for other solutions because they do not exist.
YOU HAVE TO CONTACT: for further instructions on how to get the decryption program to recover your files.

Screenshot of files encrypted by Crypt0 ransomware ("_crypt0" before file extension):

Crypt0 ransomware encrypting victim's files

Screenshot of Crypt0 decrypter:

Decrypter for Crypt0 ransomware

Crypt0 ransomware removal:

Instant automatic malware removal: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Malwarebytes is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:
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Quick menu:

Step 1

Windows XP and Windows 7 users: Start your computer in Safe Mode. Click Start, click Shut Down, click Restart, click OK. During your computer start process, press the F8 key on your keyboard multiple times until you see the Windows Advanced Option menu, and then select Safe Mode with Networking from the list.

Safe Mode with Networking

Video showing how to start Windows 7 in "Safe Mode with Networking":

Windows 8 users: Start Windows 8 is Safe Mode with Networking - Go to Windows 8 Start Screen, type Advanced, in the search results select Settings. Click Advanced startup options, in the opened "General PC Settings" window, select Advanced startup. Click the "Restart now" button. Your computer will now restart into the "Advanced Startup options menu". Click the "Troubleshoot" button, and then click the "Advanced options" button. In the advanced option screen, click "Startup settings". Click the "Restart" button. Your PC will restart into the Startup Settings screen. Press F5 to boot in Safe Mode with Networking.

Windows 8 Safe Mode with networking

Video showing how to start Windows 8 in "Safe Mode with Networking":

Step 2

Log in to the account infected with the Crypt0 virus. Start your Internet browser and download a legitimate anti-spyware program. Update the anti-spyware software and start a full system scan. Remove all entries detected.

If you cannot start your computer in Safe Mode with Networking, try performing a System Restore.

Video showing how to remove ransomware virus using "Safe Mode with Command Prompt" and "System Restore":

1. During your computer start process, press the F8 key on your keyboard multiple times until the Windows Advanced Options menu appears, and then select Safe Mode with Command Prompt from the list and press ENTER.

Boot your computer in Safe Mode with Command Prompt

2. When Command Prompt mode loads, enter the following line: cd restore and press ENTER.

system restore using command prompt type cd restore

3. Next, type this line: rstrui.exe and press ENTER.

system restore using command prompt rstrui.exe

4. In the opened window, click "Next".

restore system files and settings

5. Select one of the available Restore Points and click "Next" (this will restore your computer system to an earlier time and date, prior to the Crypt0 ransomware virus infiltrating your PC).

select a restore point

6. In the opened window, click "Yes".

run system restore

7. After restoring your computer to a previous date, download and scan your PC with recommended malware removal software to eliminate any remaining Crypt0 ransomware files.

To restore individual files encrypted by this ransomware, try using Windows Previous Versions feature. This method is only effective if the System Restore function was enabled on an infected operating system. Note that some variants of Crypt0 are known to remove Shadow Volume Copies of the files, so this method may not work on all computers.

To restore a file, right-click over it, go into Properties, and select the Previous Versions tab. If the relevant file has a Restore Point, select it and click the "Restore" button.

Restoring files encrypted by CryptoDefense

If you cannot start your computer in Safe Mode with Networking (or with Command Prompt), boot your computer using a rescue disk. Some variants of ransomware disable Safe Mode making its removal complicated. For this step, you require access to another computer.

To regain control of the files encrypted by Crypt0, you can also try using a program called Shadow Explorer. More information on how to use this program is available here.

shadow explorer screenshot

To protect your computer from file encrypting ransomware such as this, use reputable antivirus and anti-spyware programs. As an extra protection method, you can use programs called HitmanPro.Alert and Malwarebytes Anti-Ransomware, which artificially implant group policy objects into the registry to block rogue programs such as Crypt0 ransomware.)

HitmanPro.Alert CryptoGuard - detects encryption of files and neutralises any attempts without need for user intervention:

hitmanproalert ransomware prevention application

Malwarebytes Anti-Ransomware Beta uses advanced proactive technology that monitors ransomware activity and terminates it immediately - before reaching users' files:

malwarebytes anti-ransomware

  • The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups. More information on online backup solutions and data recovery software Here.

Other tools known to remove Crypt0 ransomware:

About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Malware activity

Global malware activity level today:

Medium threat activity

Increased attack rate of infections detected within the last 24 hours.

QR Code
Crypt0 virus QR code
A QR code (Quick Response Code) is a machine-readable code which stores URLs and other information. This code can be read using a camera on a smartphone or a tablet. Scan this QR code to have an easy access removal guide of Crypt0 virus on your mobile device.
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