Kuus File Locker Virus - How to remove

Kuus is malware, file-encrypting ransomware that installs a trojan. It is detected by many anti-malware scanners (Virustotal.com). Kuus encrypts files and renames them by adding “kuus” as a second file type extension, but you can also expect to see excessive ads and hacked online accounts.

About Kuus ransomware:

Type of threat	Ransomware, adware, spyware, trojan.
How Kuus affects the computer	Downloaded from unsafe and disreputable pirating sites, bundled with a trojan, deleted backup files, blocks websites, installs adware, encrypts files and gives them “kuus” as the second extension.
How to get your files back	Check the free decryptor, look for unencrypted files, recover deleted files, repair partially encrypted files.
Remove Kuus and other malware	Unblock blocked sites, find and remove all malware with an antivirus application, such as Spyhunter.

How Kuus infects PCs

Downloaded from unsafe websites

Kuus comes in cracking tools and other pirated material.

Unlike most ransomware that spreads by abusing remote access vulnerabilities, Kuus infects computers by tricking users to download infected files. Pirating and unofficial downloads of programs and media are how Kuus spreads. You might even have unknowingly downloaded a cracked program or an infected key generator. I’ve seen people pirate software without realizing that’s what they’re doing.

If you pirate, you have to be more careful. Scan downloads before opening them and make backups of your files. Be ready for any new download to be malicious. Use a good anti-malware program. Keep all software up-to-date. And try to stick to reputable websites as much as possible.

Makes changes on the infected machine

Then, Kuus changes some settings on the computer:

• Kuus blocks a few websites, especially those that have to do with cybersecurity. Makes it difficult for Kuus’s victims to find information.
• It deletes backups if it finds any.
• Kuus is bundled with the trojan Azorult that can download more malware and steal files, screenshots, and data saved in some online apps (such as your login details). This trojan is dangerous and needs to be removed.
• Azorult very likely installs adware that causes pop-up ads and browser redirects. It’s separate from Kuus so it needs to be deleted separately.

And, finally, Kuus goes through your files and encrypts them. This makes most of them unopenable and unreadable. You can tell which files Kuus encrypted because their names are changed by appending the extension “.kuus”.

Kuus also creates a bunch of files named _readme.txt whose contents are displayed in the illustration for this post. Kuus’ makers are asking victims for up to $980 to decrypt their files. They must be making a lot of money because they’ve been in the ransomware business for a while. Kuus is not new – it’s part of the Djvu family, together with Vawe, Usam, and others.

Can you restore your files?

Decryption

The question on the minds of many Kuus’ victims is whether they can get their encrypted files back. If you didn’t have a recent backup from before the Kuus attack, this might be relevant to you, too.

Kuus’ encryption cannot be undone without the decryption keys. Decryptors for Kuus already exist, however, without the key that is unique to each victim, these decryptors are useless. The only way to get the key is to contact the criminals, pay them, and hope that they actually deliver the key.

An analogy for what Kuus does is password protection for your files. It’s available on Windows and it makes it so only people who have the password can read the protected files. Kuus is like criminals getting on your PC, protecting your files, and then holding the password for ransom.

Exception – Kuus may have run into difficulties and resorted to using the hardcoded offline key to lock your files. If someone else gets the corresponding decryption key, it will probably be available via the Emsisoft decryptor, so check it out and scan your files with it.

But before you try to fix the Kuus’ encrypted files, make a backup. Always have a backup of the files. One way to do that is to connect the infected drive to another computer like you would an external drive so that Kuus and the other malware don’t have a chance to run.

Other methods

First, look inside your folders. Kuus might have skipped some folders and left some files alone, so check everywhere.

If you didn’t do much with your computer after Kuus attacked, you might be able to restore some data with a data recovery tool – a program that scans your drive and brings back deleted files. This is tricky to do because you might need an empty drive.

After you make backups of the Kuus-infected files, you might be able to repair them manually – it’s possible because Kuus only encrypts some files partially. Media files, such as audio recordings and images, as well as archives can possibly be repaired and only some data needs to be thrown out. But because it’s easy for things to go wrong, always have a backup of the file you’re editing.

How to remove Kuus ransomware

Kuus ransomware, adware, the trojan, and other malware can be deleted with an anti-malware program, such as Spyhunter. But it might be tricky to get your antivirus working after a Kuus attack. You need to check that Kuus didn’t delete the updates of your antivirus. At the same time, it is dangerous to connect your computer to the internet.

Follow the guide below to start your computer in safe mode to prevent unnecessary programs (like Kuus) from running. Then, download your antivirus tools and scan your computer.

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 Kuus File Locker 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 Kuus File Locker Virus has infiltrated to your system and then click “Next”.
• To start System restore click “Yes”.

 

Step 2. Complete removal of Kuus File Locker 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 Kuus File Locker Virus. You can check other tools here.  

Step 3. Restore Kuus File Locker 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 Kuus File Locker 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 Kuus File Locker 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.