.Kook Virus (+ .Kook File Decryption) – How To Remove

kook ransomware

What is Kook?

.Kook is the name of a Ransomware virus, created specifically for making money for its criminal developers by encrypting files of unsuspecting web users. The most noticeable symptom of .Kook inside a computer is the ransom note it displays on the screen.

The Kook Virus ransom note

Security experts warn of the spread of this new threat through spam messages, malicious ads, eye- catching promotional messages, misleading links and compromised web pages, as well as various virus-injected email attachments. As soon as the unsuspecting web user interacts with the transmitter, the malicious software sneaks into the device and starts searching its drives for personal files, such as video, audio, images, documents, databases and other commonly used files that can be of great value to the victim. When .Kook detects them, it applies encryption to each and every one of them and, in this way, makes them inaccessible without a decryption key.

In most cases, the kook can also change the file extension to the affected files to a new one that no program can read. At the end of the attack, .Kook creates a ransom message that serves to inform the victim that they must pay a ransom in order to receive the decryption key for their data. The cyber criminals behind the infection give a limited time to pay and promise to those who agree to meet all of their demands to receive a unique decryption key that can help them to decrypt their information.

Ransomware Based Viruses

The .Kook virus is a ransomware-based infection that is hard to detect before it manages to complete its agenda. The .Kook virus is used for money extortion purposes and encrypts user data with the intentions to demand a ransom for its recovery.

kook virus
The Kook Virus encrypted files

Sadly, there typically are no noticeable signs that can rise the users’ attention during the file-encryption process. Only in rare cases, and mostly in less powerful computers that contain a lot of data, some observant users may detect a process in the background that eats up a significant amount of system resources. But that is very rare and is not a sure symptom that can help you catch and remove the ransomware like kook on time.

This is why a reliable anti-malware program (check out the one on this page) is recommended for the efficient removal of the infection. Moreover, such a program can help users correctly remove the hidden files related to the ransomware and also provides protection against similar viruses.

Of course manual deletion is also an option, and that’s why below we have published a free removal guide with step-by-step instructions on how to remove .Kook. However, this method can be difficult for novice computer users and always comes with the risk of deleting something else by mistake.

The .Kook file extension

The .Kook file extension is a combination of symbols that appear at the end of every file that gets encrypted. The .Kook file extension does not look like any known file extension and is not readable by any software.

If you are looking for options to eliminate the virus and avoid the ransom payment, however, you might want to test the instructions below and, perhaps, try some of the suggestions for kook file recovery that we have listed in the second part of the guide.


Danger Level High (.Kook Ransomware encrypts all types of files)
Symptoms.Kook Ransomware is hard to detect and aside from increased use of RAM and CPU, there would barely be any other visible red flags.
Distribution Method Most of the time, Trojans get distributed through spam e-mails and social network messages, malicious ads, shady and pirated downloads, questionable torrents and other similar methods.

Remove .Kook Ransomware Guide

1: Preparations

Note: Before you go any further, we advise you to bookmark this page or have it open on a separate device such as your smartphone or another PC. Some of the steps might require you to exit your browser on this PC.

2: Task Manager

Press Ctrl + Shift + Esc to enter the Task Manager. Go to the Tab labeled Processes (Details for Win 8/10). Carefully look through the list of processes that are currently active on you PC.

If any of them seems shady, consumes too much RAM/CPU or has some strange description or no description at all, right-click on it, select Open File Location and delete everything there.

Also, even if you do not delete the files, be sure to stop the process by right-clicking on it and selecting End Process.

3: IP related to .Kook

Go to c:\windows\system32\drivers\etc\hosts. Open the hosts file with notepad.

Find where it says Localhost and take a look below that. 

hosts_opt (1)

If you see any IP addresses there (below Localhost) send them to us here, in the comments since they might be coming from the .Kook.


4: Disable Startup programs

Re-open the Start Menu and type msconfig.

Click on the first search result. In the next window, go to the Startup tab. If you are on Win 10,  it will send you to the Startup part of the task manager instead, as in the picture:

If you see any sketchy/shady looking entries in the list with an unknown manufacturer or a manufacturer name that looks suspicious as there could be a link between them and .Kook , disable those programs and select OK.

5: Registry Editor

Press Windows key + R and in the resulting window type regedit.

Now, press Ctrl + F and type the name of the virus.

Delete everything that gets found. If you are not sure about whether to delete something, do not hesitate to ask us in the comments. Keep in mind that if you delete the wrong thing, you might cause all sorts of issues to your PC.

6: Deleting potentially malicious data – .Kook

Type each of the following locations in the Windows search box and hit enter to open the locations:






Delete everything you see in Temp linked to .Kook RansomwareAbout the other folders, sort their contents by date and delete only the most recent entries. As always, if you are not sure about something, write to us in the comment section.

7: .Kook Decryption

The previous steps were all aimed at removing the .Kook Ransomware from your PC. However, in order to regain access to your files, you will also need to decrypt them or restore them. For that, we have a separate article with detailed instructions on what you have to do in order to unlock your data. Here is a link to that guide.

Daniel Sadakov has a degree in Information Technology and specializes in web and mobile cyber security. He harbors a strong detestation for anything and everything malicious and has committed his resources and time to battling all manners of web and mobile threats. He has founded MobileSecurityZone.com, a website dedicated to covering the top tech stories and providing useful tips for the everyday user, in an effort to reach and help more people.
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