Remove Corpseworm ransomware from the operating system

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

Corpseworm ransomware removal instructions

What is Corpseworm?

Discovered by Alex Svirid, Corpseworm is malicious software and a variant of Cryakl ransomware. It is designed to encrypt data and demand ransom payments for decryption. During the encryption process, all affected files are appended with "[CS]", the developer's email address, and an extension comprising a random string of characters ("[CS][].[random_string]"). For example, "1.jpg" might appear as something similar to "1.jpg[CS][].zyk", and so on for all compromised files. After this process is complete, a text file ("README.txt") is stored on the victim's desktop.

The text file informs users that, if they wish to decrypt their data, they must send an email to the address provided or establish contact through the Telegram messaging application. You are strongly advised against communicating with cyber criminals and/or meeting their demands. In most cases of ransomware infections, despite paying, victims receive none of the promised decryption tools/keys (thereby leaving their files encrypted and useless). After studying a sample, the encryption tool used for Corpseworm infection was found to be manual (i.e., the encryption process was not automated and needed to be performed manually). There is, then, a high probability that criminals behind Corpseworm hijack computers and encrypt data manually. This method is very time-consuming and ineffective when attacking regular home users. Therefore, this technique is more prevalent in infections targeting large servers of companies. The encryption tool itself does not have a decryption function. If the cyber criminals do not possess software capable of breaking the encryption, they cannot restore encrypted files. Removing Corpseworm will not revert the affected data to its original state, however, it will prevent further encryption. The only solution is to restore compromised files from a backup, if one was made prior to the infection and stored separately.

Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data:

Corpseworm decrypt instructions

GodLockToec, and CYBORG are just some examples of ransomware infections similar to Corpseworm. Most malicious software of this type encrypts data and keeps it locked, until a ransom is paid. Key differences include cryptographic algorithm used (symmetric or asymmetric) and ransom size. These payments usually range between three-digit and four-digit sums. Cyber criminals tend to prefer digital currencies (e.g. cryptocurrencies, pre-paid vouchers, etc.), since these transactions are difficult/impossible to trace. Unless ransomware is still in development and/or has certain weaknesses/flaws, file decryption with third party software is impossible. To ensure data safety, keep backups on remote servers and/or unplugged storage devices. Ideally, several backup copies should be stored on different locations.

How did ransomware infect my computer?

Ransomware and other malware is commonly proliferated via trojans, spam campaigns, untrustworthy download channels, fake software updaters and "cracking" (activation) tools. Trojans are a type of malware, primarily designed to cause chain infections (i.e., download/install other malicious programs). Massive scale spam campaigns are used to send out deceptive emails with infectious attachments (or web-links leading to them). These emails are usually highlighted as "official", "important", "urgent" or otherwise marked as priority mail. The attached files come in various formats (e.g. archive and executable files, PDF and Microsoft Office documents, JavaScript, etc.). Once opened, they begin downloading/installing malware. Untrustworthy download sources include unofficial and free file-hosting sites, P2P sharing networks (BitTorrent, eMule, Gnutella, etc.) and other third party downloaders. Untrusted channels are far more likely to offer deceptive and/or bundled content for downloading. Fake updaters abuse weaknesses in outdated software and/or simply install malware, rather than the updates. Program "cracking" tools infect systems similarly, by downloading/installing malware rather than activating licensed products.

Threat Summary:
Name Corpseworm virus
Threat Type Ransomware, Crypto Virus, Files locker.
Encrypted Files Extension [CS][].[random_string]
Ransom Demanding Message README.txt
Cyber Criminal Contact and @helprestore (Telegram messaging app)
Detection Names AVG (FileRepMetagen [Malware]), BitDefender (Gen:Variant.Graftor.615132), Kaspersky (HEUR:Trojan-Ransom.Win32.Cryakl.gen), DrWeb (Trojan.Encoder.30019), Full List Of Detections (VirusTotal)
Symptoms Cannot open files stored on your computer, previously functional files now have a different extension (for example, my.docx.locked). A ransom demand message is displayed on your desktop. Cyber criminals demand payment of a ransom (usually in bitcoins) to unlock your files.
Distribution methods Infected email attachments (macros), torrent websites, malicious ads.
Damage All files are encrypted and cannot be opened without paying a ransom. Additional password-stealing trojans and malware infections can be installed together with a ransomware infection.

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How to protect yourself from ransomware infections

Do not open suspicious and/or irrelevant emails, especially those received from unknown senders (addresses). Any attachments (or web-links) found in suspect mail should never be opened, as they are the origin of a potential system infection. Use official and verified download channels. Programs should be activated and updated only with tools/functions provided by legitimate developers. Illegal activation ("cracking") tools and third party downloaders are untrusted and high-risk. You are strongly advised to have a reputable anti-virus/anti-spyware suite installed and kept up-to-date. This software should be used for regular system scans and elimination of detected threats. If your computer is already infected with Corpseworm, we recommend running a scan with Spyhunter for Windows to automatically eliminate this ransomware.

Text presented in Corpseworm ransomware text file ("README.txt"):

decrypt files? write here:
or telegram @helprestore 

Screenshot of files encrypted by Corpseworm ("[CS][].[random_string]" extension):

Files encrypted by Corpseworm

Screenshot of Corpseworm ransomware process ("vis.exe") in Task Manager:

corpseworm process

Screenshot of Corpseworm ransomware encryptor:

corpseworm encryptor

Corpseworm ransomware encryptor appearance (GIF):

corpseworm encryptor appearance (GIF)

Corpseworm ransomware removal:

Instant automatic malware removal: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Spyhunter 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":

Windows 10 users: Click the Windows logo and select the Power icon. In the opened menu click "Restart" while holding "Shift" button on your keyboard. In the "choose an option" window click on the "Troubleshoot", next select "Advanced options". In the advanced options menu select "Startup Settings" and click on the "Restart" button. In the following window you should click the "F5" button on your keyboard. This will restart your operating system in safe mode with networking.

windows 10 safe mode with networking

Video showing how to start Windows 10 in "Safe Mode with Networking":

Step 2

Log in to the account infected with the Corpseworm 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 Corpseworm 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 Corpseworm 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 Corpseworm 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 Corpseworm, 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 encryption ransomware such as this, use reputable antivirus and anti-spyware programs. As an extra protection method, you can use programs called HitmanPro.Alert and EasySync CryptoMonitor, which artificially implant group policy objects into the registry to block rogue programs such as Corpseworm ransomware.

Note that Windows 10 Fall Creators Update includes a "Controlled Folder Access" feature that blocks ransomware attempts to encrypt your files. By default, this feature automatically protects files stored in the Documents, Pictures, Videos, Music, Favorites, and Desktop folders.

Controll Folder Access

Windows 10 users should install this update to protect their data from ransomware attacks. Here is more information on how to get this update and add an additional protection layer from ransomware infections.

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 Corpseworm 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
Corpseworm 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 Corpseworm virus on your mobile device.
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