Mosk File Extension Virus - How to remove

Mosk ransomware – a new entry in the Djvu book of viruses. This virus is first noticed by most victims when they see that most of their files fail to open and have “.mosk” as an extension/file type. This is quite a serious infection and might actually result in those files being completely lost, in the worst cases.

How Mosk infects computers

Djvu viruses, like Toec, Nakw, or Coot, are known for spreading in pirate sites. A variety of files might be infected with the Mosk file virus:

• Cracking tools
• Activators and key generators
• Ebooks
• Streaming and video editing software
• Office software
• Creation software

Mosk is active all over the world and files infected with it might be shared in pirating sites and unofficial download sites.

Another feature of these file extension viruses is that they might bundle Azorult – a trojan that steals passwords and installs other malware. That makes the Mosk file virus potentially even more harmful than just encrypting your files – if you don’t change your passwords after cleaning the computer, your online accounts might get hacked. Also, it’s a good idea to turn on 2fa wherever that’s possible – that way, you will be alerted if someone tries to hack your account.

Mosk is a dangerous file extension virus:

Mosk distribution	Hidden in pirated files and software Infects files and installers in unofficial download sites
Effects of the Mosk file virus	Files have “.mosk” appended to their names and won’t open _readme.txt notes present in various folders Some websites are blocked
How to remove the malware	Fix the hosts file Scan with an antivirus tool (SpyHunter) Change passwords Install software updates (OS, browser, antivirus software)
How to recover Mosk files	Restore files from a backup Run the decryptor on the locked files Use shadow volume copies or data recovery software

How to recognize Mosk

Not all Windows systems show file extensions – you can turn this setting on by going to your File Explorer’s View menu and filling the checkbox in “File Name Extensions”. It’s a good setting to keep turned on because it can help you notice things like malicious files with double extensions. In the case of Mosk, files locked by this virus will have names like:

picture.jpg.mosk

You can try to rename the files and get rid of the extension, but most of the files still won’t work.

Mosk also drops _readme.txt files with a message from the people behind this malware. They say that they can fix your files and demand a lot of money:

ATTENTION!

Don’t worry, you can return all your files!
All your files like photos, databases, documents and other important are encrypted with strongest encryption and unique key.
The only method of recovering files is to purchase decrypt tool and unique key for you.
This software will decrypt all your encrypted files.
What guarantees you have?
You can send one of your encrypted file from your PC and we decrypt it for free.
But we can decrypt only 1 file for free. File must not contain valuable information.
You can get and look video overview decrypt tool:
https://we.tl/t-IbdGyCKhdr
Price of private key and decrypt software is $980.
Discount 50% available if you contact us first 72 hours, that’s price for you is $490.
Please note that you’ll never restore your data without payment.
Check your e-mail “Spam” or “Junk” folder if you don’t get answer more than 6 hours.

To get this software you need write on our e-mail:
[email protected]

Reserve e-mail address to contact us:
[email protected]

Your personal ID:
…

While Mosk is corrupting the files, your computer might slow down. During this time, the file virus might display a fake Windows Update pop-up to justify the heavy usage of resources. Unfortunately, it’s not a slow virus and does a lot of damage in a really short time.

To prevent anything interfering with it, the Mosk virus tries to delete important updates of some antivirus programs – though this virus is detected by reliable security programs, they can’t do that without their definitions and updates. And since not all security programs have real-time anti-ransomware protection, they might just allow Mosk to do its thing.

Other effects of Mosk file virus infection include being unable to visit sites like ours on the infected computer. Mosk blocks websites by messing with your hosts file – instructions on how to fix it are below. The file virus does this to stop people from quickly accessing information about it and this can make its victims feel desperate and lonely. In fact, there is some hope to recover some of the files and Mosk’s creators don’t want you to know that.

Recovering Mosk files and removing the virus

How to restore Mosk files

Unless you have backups of your files (congratulations – that’s the best and smartest way to protect yourself against ransomware), there’s no guaranteed 100% way to restore your files after a Mosk infection. Not even by paying the extortionists, as they seem to abandon their victims and take off with the money almost as often as they provide decryptors. Even if they do send a decryptor, it’s so unwieldy and crude that technical difficulties are almost guaranteed.

Researchers at Emsisoft worked really hard and released a decryptor for Djvu. Run this decryptor on your files. It’s free and created by cybersecurity researchers. But here’s the problem: it’s useless without the decryption keys. Each victim of the Mosk file virus has unique decryption keys associated with them and only the extortionists know them. The exception – if Mosk was forced to run without being able to connect over the internet to the server that controls it, it used the offline key, one that’s the same for each victim of Mosk. However, as I’m writing this, this key for Mosk is not known and it’s not certain that it ever will be.

How to get rid of the virus

First, you might want to make sure to back up your encrypted files. They’re not infected with anything and if you hope to decrypt them, you’ll need them. Then, to prevent Mosk from running again and encrypting any new files you create, it and other malware need to be quarantined. Do this by scanning your computer with a reliable antivirus scanner that you trust, for example, SpyHunter. If Mosk is being stubborn, safe mode might help, or malicious process killers.

Important -- edit the hosts file to unblock security websites

TL DR : The hosts file is edited to block security sites Before the virus can be removed, it's necessary to fix the hosts file (the file which controls which addresses connect to which IPs). That is the reason the majority of security websites is inaccessible when infected with this particular parasite. This infection edits this file to stop certain websites, including anti-malware download sites, from being accessed from the infected computer, making browsers return the "This site can't be reached" error. Luckily, it's trivial to fix the file and remove the edits that were made to it.

Find and edit the hosts file

The hosts file can be found on C:/Windows/System32/Drivers/etc/hosts. If you don't see it, change the settings to see hidden files.

1. In the Start Menu, search for Control Panel.
2. In the Control Panel, find Appearance and Personalization.
3. Select Folder Options.
4. Open the View tab.
5. Open Advanced settings.
6. Select "Show hidden files...".
7. Select OK.

Open this file with administrator privileges.

1. Open the Start Menu and enter "notepad".
2. When Notepad shows up in the result, right-click on it.
3. In the menu, choose "Run as administrator"
4. File->Open and browse for the hosts file.

The hosts file should look like this: Delete additional lines that they connect various domain names to the wrong IP address. Save the file.

Download and run the antivirus program

After that, download antivirus programs and use them to remove the ransomware, the trojan, and other malware. Spyhunter (https://www.2-viruses.com/reviews/spyhunter/dwnld/).

Automatic Malware removal tools

How to recover Mosk File Extension Virus 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 → Restart → OK.
• Press F8 key repeatedly until Advanced Boot Options window appears.
• Choose Safe Mode with Command Prompt.

for Windows 8 / 10

• Press Power at Windows login screen. Then press and hold Shift key and click Restart.
• Choose Troubleshoot → Advanced Options → Startup Settings and click Restart.
• When it loads, select Enable Safe Mode with Command Prompt from the list of Startup Settings.

 

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.
• Click “Next” in the windows that appeared.
• Select one of the Restore Points that are available before Mosk File Extension Virus has infiltrated to your system and then click “Next”.
• To start System restore click “Yes”.

 

Step 2. Complete removal of Mosk File Extension Virus

After restoring your system, it is recommended to scan your computer with an anti-malware program, like Spyhunter and remove all malicious files related to Mosk File Extension Virus. You can check other tools here.  

Step 3. Restore Mosk File Extension Virus 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 Mosk File Extension Virus 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 Properties → Previous 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.

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.

Step 4. Use Data Recovery programs to recover Mosk File Extension Virus 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 a data recovery program.
• Install and scan for recently deleted files.

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.