MOSK ransomware is the 180th version of STOP, decryptable if offline key was used
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MOSK ransomware is the newest addition to STOP/DJVU ransomware family. It is a malicious file-encrypting computer virus designed for Windows operating systems. Once installed, it disables firewalls and starts encrypting personal files on each folder, adding .mosk file extensions to them. To finalize the malicious operation, the virus creates a ransom note called _readme.txt, installs Azorult password-stealing Trojan and deletes Volume Shadow Copies from the PC.
MOSK ransomware is developed with the intention to infect computers and take victim’s personal files hostage. To learn how to recover lost data, the victim has to read a ransom note left in each folder with corrupted data. As usual, the note suggests contacting criminals via one of the provided emails and paying a sum of money in Bitcoin cryptocurrency.
The price of the ransom varies depending on how fast the victim manages to pay. If he does it within 72 hours, the ransom cost is $490. Otherwise, it increases to $980. As explained in the ransom note _readme.txt, the victim has to contact criminals via salesrestoresoftware@firemail.cc or salesrestoresoftware@gmail.com to receive instructions and Bitcoin wallet to pay.
It is generally recommended NOT to pay the ransom. However, it is your decision based on how important data was to you. You must remember that there is still a chance to never see your files even after paying up, so keep that in mind.
Threat Summary
Name | MOSK virus |
Type | Ransomware |
Malware Family | STOP ransomware (DJVU) |
Encryption Method | RSA |
File Extension | .mosk |
Ransom Note | _readme.txt |
Ransom Amount | $490-$980 |
Contact Emails (Cyber criminals) | salesrestoresoftware@firemail.cc, reserve email: salesrestoresoftware@gmail.com |
Additional details | Installs Azorult Trojan |
Decryption available? | You can decrypt .mosk extension files if your personal ID ends with t1. See a guide on how to use STOP Decrypter |
Removal | Remove using antivirus of your choice in Safe Mode with Networking (see a guide below) |
Is it possible to decrypt your files?
To address the issue of how to decrypt files with .mosk extension, we must explain how the ransomware operates first. When it scans your computer for target files, it attempts to establish a connection with its remote server, which generates and sends an online key to encrypt data. If the connection is not available or gets lost, an offline key is used then. In the future, the offline key might appear and you will be able to recover your files.
STOP Decrypter already supports .MOSK extension, so if your personal ID or one of them ends with t1, you can recover all or part of your data for free. See instructions how to use the decryption tool here.
You can determine if your files were encrypted with the offline key if your personal ID ends with t1. Otherwise, it means that an online key was used, and there are no chances to decrypt your data. Also, STOP Decrypter won’t work for you.
The first thing you need to do after a ransomware attack is to remove MOSK file virus as soon as you can. Please use the guidelines provided at the end of this article to do it properly. Make sure you update your security software so that it could wipe this STOP DJVU version along with Azorult trojan out from your PC.
Distribution means and ways to avoid file-encrypting viruses
Ransomware can be distributed in various ways. To be precise, STOP/DJVU ransomware versions such as MOSK, DERP, TOEC, and COOT tend to infect target systems in a way that requires user interaction. To be specific, you can easily fall victim to this malware strain if you tend to download illegal software activation tools to get licensed products for free.
In other words, software cracks, keygens and other means of stealing is a no-no and can likely carry a malicious payload. Although many victims suggest they didn’t do anything and ransomware corrupted their files out of thin air, it isn’t true.
Besides, you should know that ransom-demanding viruses are also actively distributed via malicious spam and vulnerabilities in outdated software. For instance, if you’re using an old Windows version with Flash Player technology on it, you can easily be attacked if you visit an infected website online (exploit kit attack type).
Remove MOSK virus and recover your files
Remove MOSK ransomware using virus removal guidelines provided below. These explain how to prepare a safe and clean environment for malware removal. Of course, we recommend doing it automatically using a trustworthy antivirus tool rather than attempting to trace malicious remains manually.
Again, we’d like to remind you that there are no ways to restore .mosk files without having data backups. If you’re lucky and your files were locked with an offline key, don’t hesitate and follow the instructions on how to use STOP Decrypter. Now, concentrate on MOSK removal, which is described below.
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MOSK Ransomware Removal Guidelines
Method 1. Enter Safe Mode with Networking
Step 1. Start Windows in Safe Mode with Networking
Before you try to remove the virus, you must start your computer in Safe Mode with Networking. Below, we provide the easiest ways to boot PC in the said mode, but you can find additional ones in this in-depth tutorial on our website – How to Start Windows in Safe Mode. Also, see a video tutorial on how to do it:
Instructions for Windows XP/Vista/7 users
- First of all, turn off your PC. Then press the Power button to start it again and instantly start pressing F8 button on your keyboard repeatedly in 1-second intervals. This launches the Advanced Boot Options menu.
- Use arrow keys on the keyboard to navigate down to Safe Mode with Networking option and press Enter.
Instructions for Windows 8/8.1/10 users
- Open Windows Start menu, then press down the Power button. On your keyboard, press down and hold the Shift key, and then select Restart option.
- This will take you to Windows Troubleshoot screen. Choose Troubleshoot > Advanced Options > Startup Settings > Restart. Tip: If you can't find Startup Settings, click See more recovery options.
- In Startup Settings, press the right key between F1-F9 to enter Safe Mode with Networking. In this case, it is the F5 key.
Step 2. Remove files associated with the virus
Now, you can search for and remove MOSK Ransomware files. It is very hard to identify files and registry keys that belong to the ransomware virus, Besides, malware creators tend to rename and change them repeatedly. Therefore, the easiest way to uninstall such type of a computer virus is to use a reliable malware removal program. In addition, we suggest trying a combination of INTEGO Antivirus (removes malware and protects your PC in real-time) and RESTORO (repairs virus damage to Windows OS files).
Method 2. Use System Restore
In order to use System Restore, you must have a system restore point, created either manually or automatically.
Step 1. Boot Windows in Safe Mode with Command Prompt
Instructions for Windows XP/Vista/7 users
- Shut down your PC. Start it again by pressing the Power button and instantly start pressing F8 button on your keyboard repeatedly in 1-second intervals. You will see Advanced Boot Options menu.
- Using arrow keys on the keyboard, navigate down to Safe Mode with Command Prompt option and press Enter.
Instructions for Windows 8/8.1/10 users
- Launch Windows Start menu, then click the Power button. On your keyboard, press down and hold the Shift key, and then choose Restart option with the mouse cursor.
- This will take you to Windows Troubleshoot screen. Choose Troubleshoot > Advanced Options > Startup Settings > Restart. Tip: If you can't find Startup Settings, click See more recovery options.
- In Startup Settings, press the right key between F1-F9 to enter Safe Mode with Command Prompt. In this case, press F6 key.
Step 2. Start System Restore process
- Wait until system loads and command prompt shows up.
- Type cd restore and press Enter, then type rstrui.exe and press Enter. Or you can just type %systemroot%system32restorerstrui.exe in command prompt and hit Enter.
- This launches System Restore window. Click Next and then choose a System Restore point created in the past. Choose one that was created before ransomware infection.
- Click Yes to begin the system restoration process.
After restoring the system, we recommend scanning the system with antivirus or anti-malware software. In most cases, there won't be any malware remains, but it never hurts to double-check. In addition, we highly recommend checking ransomware prevention guidelines provided by our experts in order to protect your PC against similar viruses in the future.
Alternative software recommendations
Malwarebytes Anti-Malware
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PD says
This will work for C drive, System Drive … Not for unrestored drive like D,E,F