Ransomware virus that encrypts the files on the infected computer, dubbed the KK virus because of the file extension it uses (KK_) has been reported to infect users on a massive scale. The virus uses a powerful encryption algorithm, which it claims to be RSA-1024 bit cipher. After encryption, the KK_ virus leaves a ransom note, named “KK_ IN YOUR DOCUMENTS.txt” in which the virus asks users to pay the insane payoff amount of 4 BitCoins to get decryption software for their files. Everyone who has become a victim of the KK_ ransomware is strongly advisable to be extremely careful and not pay any ransom to the cyber-criminals. Instead, we advise reading this article to learn more about KK_ ransomware, learn how to remove it and learn alternative methods to restore your files until a decryptor has been released.
Threat Summary
Name | KK_ |
Type | Remote Access Trojan with file encryption capability. |
Short Description | The ransomware encrypts files with a powerful encryption cipher, demanding users to pay the sum of 4 BTC to get the ransom ammount back. |
Symptoms | The files encoded by the KK_ virus are reported to have the KK_ prefix in front of their name, for example “KK_Picture.jpg” |
Distribution Method | Spam Emails, Email Attachments, File Sharing Networks. |
Detection Tool |
See If Your System Has Been Affected by malware
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Malware Removal Tool
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User Experience | Join our forum to Discuss KK_ Ransomware. |
Data Recovery Tool | Windows Data Recovery by Stellar Phoenix Notice! This product scans your drive sectors to recover lost files and it may not recover 100% of the encrypted files, but only few of them, depending on the situation and whether or not you have reformatted your drive. |
KK_ (Estonian) Virus – Distribution Methods
To successfully be spread, the KK_ ransomware virus may use several different methods, the most widely employed of which is the spam e-mail distribution campaigns. Such campaign may include the wide spreading of spam messages that include malicious e-mail attachments. Such e-mail attachments may contain various topics, like:
- “Your PayPal Receipt.”
- “Your Bank Account has been disclosed.”
- “Your order has been confirmed.”
In addition to these, a malicious e-mail attachment may be added which could resemble a document, like a Microsoft Office or Adobe file.
KK_ (Estonian) Ransomware In Details
When it has been dropped on your computer, via an Exploit Kit, JavaScript or another type of attack, the virus may drop it’s malicious files on several key Windows locations.
- %AppData%
- %Roaming%
- %Local%
- %LocalRow%
- %Startup%
- %SystemDrive%
After dropping it’s malicious files on the computer, the KK_ ransomware may also begin to employ modules that may perform different activities like modify the Run and RunOnce registry keys and delete any system backups, using the vssadmin delete shadows command. Not only this, but the KK_ ransomware may also cause a system restart so that it starts encrypting files on system boot, even before the antivirus software on the compromised machine runs.
Regarding file encryption, the KK_ ransomware uses a strong enough cipher to render the files impossible to directly decrypt in case you do not have the decryption key. The KK_ virus may begin to scan for the following types of files to encrypt them:
- Videos.
- Audio Files.
- Images.
- Files associated with Microsoft Office.
- Files that are associated with Adobe Reader.
- Database files.
- Files belonging to widely used programs such as Adobe Photoshop, etc.
After it has successfully encrypted the files, the KK_ virus drops the following text file on the victim’s computer:
files, and documents on the computer. Your important files encryption produced on this computer: videos, photos, documents, etc.
Encryption was produced using unique public key RSA-1024 generated for this computer. To decrypt files, you need to obtain the private key.
All encrypted files contain KK_
Your number: ***
To obtain the program for this computer, which will decrypt all files, you need to pay 4 bitcoins on our bitcoin address {unique identifier}*** (today 1 bitcoin was 250 $). Only you and we know about this bitcoin address.
You can check bitcoin balance here – https://www.blockchain.info/address/{unique identifier}***
After payment sends us your number on our mail nown@ruggedinbox.com and we will send you decryption tool (you need only run it, and all files will be decrypted during 1…3 hours)
Before payment, you can send us one small file (100.500 kilobytes), and we will decrypt it – it’s your guarantee that we have decryption tool. And send us your number with attached file.
We don’t know who are you. All that we need – it’s some money.
Don’t panic if we don’t answer you during 24 hours. It means that we didn’t receive your letter (for example if you use hotmail.com or outlook.com
it can block letter, SO DON’T USE HOTMAIL.COM AND OUTLOOK.COM. You need to register your mail account in www.ruggedinbox.com (it will take 1.2 minutes) and write us again)
You can use one of that bitcoin exchangers for transferring bitcoin.
decrypto.ee
https://localbitcoins.com/country/EE
https://www.clevercoin.com
coinera.eu
https://bitx.co
https://www.kraken.com
You don’t need install bitcoin programs – you need only use one of this exchanger or another exchanger that you can find in www.google.com for your country.
Please use the English language in your letters. If you don’t speak English, then use https://translate.google.com to translate your letter into the English language.”
KK_ (Estonian) Ransomware – Remove It and Restore Encrypted Files
To remove KK_ ransomware fully from your computer, it is strongly advisable to follow the step-by-step instructions posted in this article below. They are methodologically arranged so that you can remove this virus manually as well as automatically in case you are unsure that you have fully deleted it. Malware researchers and security analysts strongly advise that you focus on removing KK_ ransomware using a malware removal tool. Such anti-malware software will not only swiftly delete KK_ virus from your PC but protect you in the future as well.
Files encrypted by KK_ ransomware may be difficult for decryption. This is because the virus has also been reported to send the decryption key to the cyber-criminals’ servers, making them the only holder of your files. However, malware analysts are constantly on the lookout for decryption opportunities, and we are going to notify you if there is a free decryptor released, by updating this article. Meanwhile, you may want to try using the alternative solutions in step “3.Restore files encrypted by KK_ Ransomware” below. They may help you restore some of your files, but they are not 100% guaranteed success.
Attention! SensorsTechForum strongly recommends that all malware victims should look for assistance only by reputable sources. Many guides out there claim to offer free recovery and decryption for files encrypted by ransomware viruses. Be advised that some of them may only be after your money.
As a site that has been dedicated to providing free removal instructions for ransomware and malware since 2014, SensorsTechForum’s recommendation is to only pay attention to trustworthy sources.
How to recognize trustworthy sources:
- Always check "About Us" web page.
- Profile of the content creator.
- Make sure that real people are behind the site and not fake names and profiles.
- Verify Facebook, LinkedIn and Twitter personal profiles.
How to Remove KK_ from Windows.
Step 1: Boot Your PC In Safe Mode to isolate and remove KK_





Step 2: Uninstall KK_ and related software from Windows
Here is a method in few easy steps that should be able to uninstall most programs. No matter if you are using Windows 10, 8, 7, Vista or XP, those steps will get the job done. Dragging the program or its folder to the recycle bin can be a very bad decision. If you do that, bits and pieces of the program are left behind, and that can lead to unstable work of your PC, errors with the file type associations and other unpleasant activities. The proper way to get a program off your computer is to Uninstall it. To do that:



Step 3: Clean any registries, created by KK_ on your computer.
The usually targeted registries of Windows machines are the following:
- HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
- HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
- HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
You can access them by opening the Windows registry editor and deleting any values, created by KK_ there. This can happen by following the steps underneath:



Before starting "Step 4", please boot back into Normal mode, in case you are currently in Safe Mode.
This will enable you to install and use SpyHunter 5 successfully.
Step 4: Scan for KK_ with SpyHunter Anti-Malware Tool
Step 5 (Optional): Try to Restore Files Encrypted by KK_.
Ransomware infections and KK_ aim to encrypt your files using an encryption algorithm which may be very difficult to decrypt. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.
Simply click on the link and on the website menus on top, choose Data Recovery - Data Recovery Wizard for Windows or Mac (depending on your OS), and then download and run the tool.
Get rid of KK_ from Mac OS X.
Step 1: Uninstall KK_ and remove related files and objects
1. Hit the ⇧+⌘+U keys to open Utilities. Another way is to click on “Go” and then click “Utilities”, like the image below shows:
- Go to Finder.
- In the search bar type the name of the app that you want to remove.
- Above the search bar change the two drop down menus to “System Files” and “Are Included” so that you can see all of the files associated with the application you want to remove. Bear in mind that some of the files may not be related to the app so be very careful which files you delete.
- If all of the files are related, hold the ⌘+A buttons to select them and then drive them to “Trash”.
In case you cannot remove KK_ via Step 1 above:
In case you cannot find the virus files and objects in your Applications or other places we have shown above, you can manually look for them in the Libraries of your Mac. But before doing this, please read the disclaimer below:
You can repeat the same procedure with the following other Library directories:
→ ~/Library/LaunchAgents
/Library/LaunchDaemons
Tip: ~ is there on purpose, because it leads to more LaunchAgents.
Step 3 (Optional): Try to Restore Files Encrypted by KK_.
Ransomware infections and KK_ aim to encrypt your files using an encryption algorithm which may be very difficult to decrypt. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.
Simply click on the link and on the website menus on top, choose Data Recovery - Data Recovery Wizard for Windows or Mac (depending on your OS), and then download and run the tool.
KK_ FAQ
What is KK_ ransomware and how does it work?
KK_ is a ransomware infection - the malicious software that enters your computer silently and blocks either access to the computer itself or encrypt your files.
Many ransomware viruses use sophisticated encryption algorithm how to make your files inaccessible. The goal of ransomware infections is to demand that you pay a ransom payment to get access to your files back.
How does KK_ ransomware infect my computer?
Via several ways.KK_ Ransomware infects computers by being sent via phishing e-mails, containing virus attachment.
This attachment is usually masked as an important document, like an invoice, bank document or even a plane ticket and it looks very convincing to users.
After you download and execute this attachment, a drive-by download occurs and your computer is infected with the ransomware virus.
Another way, you may become a victim of KK_ is if you download a fake installer, crack or patch from a low reputation website or if you click on a virus link. Many users report getting a ransomware infection by downloading torrents.
How to open .KK_ files?
You can't. At this point the .KK_ files are encrypted. You can only open them once they are decrypted.
Decryptor did not decrypt my data. What now?
Do not panic and backup the files. If a decryptor did not decrypt your .KK_ files successfully, then do not despair, because this virus is still new.
One way to restore files, encrypted by KK_ ransomware is to use a decryptor for it. But since it's a new virus, advised that the decryption keys for it may not be out yet and available to the public. We will update this article and keep you posted as soon as this decryptor is released.
How Do I restore ".KK_" files (Other Methods)?
Yes, sometimes files can be restored. We have suggested several file recovery methods that could work if you want to restore .KK_ files.
These methods are in no way 100% guarantee that you will be able to get your files back. But if you have a backup, your chances of success are much greater.
How do I get rid of KK_ ransomware virus?
The safest way and the most efficient one for the removal of this ransomware infection is the use a professional anti malware software. It will scan for and locate KK_ ransomware and then remove it without causing any additional harm to your important .KK_ files.
Also, keep in mind that viruses like KK_ ransomware also install Trojans and keyloggers that can steal your passwords and accounts. Scanning your computer with an anti-malware software will make sure that all of these virus components are removed and your computer is protected in the future.
What to Do If nothing works?
There is still a lot you can do. If none of the above methods seem to work for you, then try these methods:
- Try to find a safe computer from where you can can login on your own line accounts like One Drive, iDrive, Google Drive and so on.
- Try to contact your friends, relatives and other people so that they can check if they have some of your important photos or documents just in case you sent them.
- Also, check if some of the files that were encrypted it can be re-downloaded from the web.
- Another clever way to get back some of your files is to find another old computer, a flash drive or even a CD or a DVD where you may have saved your older documents. You might be surprised what will turn up.
- You can also go to your email account to check if you can send any attachments to other people. Usually what is sent the email is saved on your account and you can re-download it. But most importantly, make sure that this is done from a safe computer and make sure to remove the virus first.
More tips you can find on our forums, where you can also asks any questions about your ransomware problem.
How to Report Ransomware to Authorities?
In case your computer got infected with a ransomware infection, you can report it to the local Police departments. It can help authorities worldwide track and determine the perpetrators behind the virus that has infected your computer. Below, we have prepared a list with government websites, where you can file a report in case you are a victim of a cybercrime:
Cyber-security authorities, responsible for handling ransomware attack reports in different regions all over the world:
- Germany - Offizielles Portal der deutschen Polizei
- United States - IC3 Internet Crime Complaint Centre
- United Kingdom - Action Fraud Police
- France - Ministère de l'Intérieur
- Italy - Polizia Di Stato
- Spain - Policía Nacional
- Netherlands - Politie
- Poland - Policja
- Portugal - Polícia Judiciária
- Greece - Cyber Crime Unit (Hellenic Police)
- India - Mumbai Police - CyberCrime Investigation Cell
- Australia - Australian High Tech Crime Center
Reports may be responded to in different timeframes, depending on your local authorities.