Mischa Ransomware - How To Remove?

Type: Ransomware

Mischa ransomware is a file encryptor related to Petya ransomware. In fact, these two ransomwares come from the same installer. In a sense, Mischa is an improved version of Petya ransomware. If Petya fails to gain administrative privileges to modify the MBR (master boot record) because the user declines it at UAC (user control account) or because of other reasons, Mischa ransomware will be installed (it does not require such privileges).

About Mischa Ransomware

Once Mischa ransomware is installed, it immediately creates a random named executable on the %AppData% or %LocalApp Data% folder and starts scanning for data to be encrypted. This ransomware aims at all versions of Windows including Windows Vista, Windows XP, Windows 10, etc. The virus targets all types of data: documents, images, videos and even archives. When the files have been chosen, Mischa ransomware applies asymmetric encryption by using RSA-2048 key (AES CBC 256-bit encryption algorithm), appending the 4-digit extensions (.cRh8, .3P7m, .aRpt, .eQTz, or .3RNu) to the encrypted files. Then, in each folder containing the encrypted data, it places two ransom notes – YOUR_FILES_ARE_ENCRYPTED.HTML and YOUR_FILES_ARE_ENCRYPTED.TXT. These files are located in the Startup as well so that they are displayed when a user logs in. They enclose information about the fact of encryption, the payment which is 1.93 Bitcoins (approximately 875 USD) at the moment and the payment details (links to TOR network websites).

How does Mischa Ransomware Infect Your Computer?

Mischa cryptomalware spreads via spam e-mails and their attachments. There are two kinds of such fake e-mails: fake job applications and fake notifications of delivery and dispatch by such companies as DHL or FedEx. These e-mails enclose links to a cloud storage service like MagentaCloud which contain infected files. The other way Mischa ransomware infiltrates your computer is by exploiting security vulnerabilities. Insecure software or security software being un-updated may lead to such ransomware attacks.

How to Decrypt files Encrypted by Mischa Ransomware

Unfortunately, there is no decryption tools for Mischa ransomware at the moment of writing this article. Thus, we highly suggest keeping a backup of your data in some external storage drive and update it regularly. Try to plug that drive in only when it is needed as Mischa can sneak in when it is plugged in. Additionally, install a professional security software like Reimage, SpyHunter and update it regularly to prevent your computer from such viral infections.

However, if you have already been attacked by Mischa ransomware, you can try restoring files with special data recovery tools such as Photorec, Kaspersky virus-fighting utilities or R-Studio. However, they do not guarantee the restoration of the encrypted data. The restoration of the encrypted files with the use of Shadow Explorer will not work because Mischa deletes all of the Shadow Volume Copies.

How to recover Mischa Ransomware encrypted files and remove the virus

Step 1. Restore system into last known good state using system restore

1. Reboot your computer to Safe Mode with Command Prompt:

for Windows 7 / Vista/ XP
  • Start Shutdown RestartOK.
  • Press F8 key repeatedly until Advanced Boot Options window appears.
  • Choose Safe Mode with Command Prompt. Windows 7 enter safe mode

for Windows 8 / 10
  • Press Power at Windows login screen. Then press and hold Shift key and click Restart. Windows 8-10 restart to safe mode
  • Choose TroubleshootAdvanced OptionsStartup Settings and click Restart.
  • When it loads, select Enable Safe Mode with Command Prompt from the list of Startup Settings. Windows 8-10 enter safe mode

2.Restore System files and settings.

  • When Command Prompt mode loads, enter cd restore and press Enter.
  • Then enter rstrui.exe and press Enter again. CMD commands
  • Click “Next” in the windows that appeared. Restore point img1
  • Select one of the Restore Points that are available before Mischa Ransomware has infiltrated to your system and then click “Next”. Restore point img2
  • To start System restore click “Yes”. Restore point img3

Step 2. Complete removal of Mischa Ransomware

After restoring your system, it is recommended to scan your computer with an anti-malware program, like Reimage and remove all malicious files related to Mischa Ransomware. You can check other tools here.

Step 3. Restore Mischa Ransomware affected files using Shadow Volume Copies

If you do not use System Restore option on your operating system, there is a chance to use shadow copy snapshots. They store copies of your files that point of time when the system restore snapshot was created. Usually Mischa Ransomware tries to delete all possible Shadow Volume Copies, so this methods may not work on all computers. However, it may fail to do so.

Shadow Volume Copies are only available with Windows XP Service Pack 2, Windows Vista, Windows 7, and Windows 8. There are two ways to retrieve your files via Shadow Volume Copy. You can do it using native Windows Previous Versions or via Shadow Explorer.

a) Native Windows Previous Versions

Right-click on an encrypted file and select PropertiesPrevious versions tab. Now you will see all available copies of that particular file and the time when it was stored in a Shadow Volume Copy. Choose the version of the file you want to retrieve and click Copy if you want to save it to some directory of your own, or Restore if you want to replace existing, encrypted file. If you want to see the content of file first, just click Open.

Previous version
b) Shadow Explorer

It is a program that can be found online for free. You can download either a full or a portable version of Shadow Explorer. Open the program. On the left top corner select the drive where the file you are looking for is a stored. You will see all folders on that drive. To retrieve a whole folder, right-click on it and select “Export”. Then choose where you want it to be stored.
Shadow explorer

Step 4. Use Data Recovery programs to recover Mischa Ransomware encrypted files

There are several data recovery programs that might recover encrypted files as well. This does not work in all cases but you can try this:

  • We suggest using another PC and connect the infected hard drive as slave. It is still possible to do this on infected PC though.
  • Download Data Recovery Pro (commercial)
  • Install and scan for recently deleted files. Data Recovery Pro

Note: In many cases it is impossible to restore data files affected by modern ransomware. Thus I recommend using decent cloud backup software as precaution. We recommend checking out Carbonite, BackBlaze, CrashPlan or Mozy Home.


About the author

 - Main Editor

I have started 2-viruses.com in 2007 after wanting to be more or less independent from single security program maker. Since then, we kept working on this site to make internet better and safer place to use.

May 16, 2016 08:46, January 4, 2017 07:32

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