Remove Kook Ransomware (Decrypt .kook Files)

By Chona Esjay | Posted on July 29, 2020 |

If majority of computer files are appended with .kook file extension, it only signifies that computer is infected with a dangerous kind of computer threat called Kook ransomware. It belongs to the notorious STOP or DJVU family of malware where the primary objective is to gain profit by locking targeted files on the computer. To regain access, victims need to pay the ransom demand through designated payment channels that is reflected in the ransom note file named _readme.txt.

Kook ransomware commonly spreads over the internet by making use of the email channels. It is usually attached to spam email messages purporting to be originated from prominent organization or company. Kook executable file is in disguise of correspondence letter as Inquiry, Price Quotation, Business Partnership, and so on. The context of the email body revolves on seducing recipient into opening the attached document.

If computer user was tricked to open the attachment, Kook ransomware initiates the attack scheme and starts to drop several malicious files on the system. It prefers to run on Windows start-up and accomplishing this requires Kook to add registry data. The, it searches local drive for specific files like MS Office data, Adobe files, drawings, images, pictures, databases, archives, and similar. As long as the file is important to user, Kook ransomware will surely encrypt them with a complex algorithm. As stated, all infected data will bear the .kook file extension as a mark that it is rendered inoperable.

The last thing that Kook ransomware would do is to inform computer users about the current attack. It generates a ransom note file under the same folder as infected data and it specifically affirms that there is no other way of decrypting the entire .kook files other than paying the ransom money to avail of the Kook decryption tool and private key.

Is paying the ransom demand guarantees complete recovery of .kook files? There is actually no textbook kind of answer to this. In the first place, dealing with online fraudsters like Kook authors are highly skeptical. Since the payment passes through untraceable channels, attackers can flee away without delivering the decryption tool and private key. In if case victims were able to avail it, the guarantee of recovering all .kook files is quite uncertain.

How to Remove Kook Ransomware

Ransomware files are placed deeply into the system and on various locations, thus, thorough scanning is vital to totally remove Kook virus. Aside from our suggested tool, you may also run your own security program.

Though affected files may be impossible to decrypt due to complexity of the encryption, you can still try recovery method like alternative tool, Shadow Explorer or Previous Version as described below.

Stage 1: Scan the Computer with Anti-Malware Tool

1. Download free anti-malware scanner called MalwareBytes Anti-Malware.
Malwarebytes Anti-Malware Download Link (this will open a new window)

2. After downloading, install the program. It may run automatically or you have to double-click on the downloaded file MBSetup.exe.

3. Carry out the installation with default setup process.

4. After the installation process, click the Get Started button to launch the program.

5. Continue with the prompts until the main program opens.

6. On the main console, click on Scan to run most complete detection method to find hidden objects associated to Kook ransomware.

7. Scanning may take a while. Please wait until the anti-malware tool is done with the checking.

MBAM-threatscan

8. Once the scan has completed, the tool will display the list of detected threats. Remove all identified malicious items and restart the computer if necessary.

Stage 2: Double-check for Kook’s leftover with Microsoft’s Malicious Software Removal Tool

1. Download the free scanner called Malicious Software Removal Tool.
Malicious Software Removal Tool Download Link (this will open a new window)

download-msrt

2. The tool automatically checks the operating system and suggest appropriate download version. Click on Download button to begin. Save the file to a convenient location, preferably on Desktop.

3. After downloading the file, Windows will prompt that download has completed. Click Run to start scanning for Kook ransomware. Another option is to browse the location folder and double click on the file to run.

msrt-icon

4. The tool will display Welcome screen, click Next. Please note the message “This tool is not a replacement for an antivirus product.” You must understand that this program is made specifically to find and remove malware, viruses, Trojans, and other harmful elements on the computer. It was not designed to protect the computer.

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5. Next, you will see Scan Type. Please choose Full Scan to ensure that all Kook ransom virus entities and other harmful files left on the computer will be found and removed. For advanced computer user, you can opt for Customized Scan, if there are other drives or folders you wanted to include in this scan.

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6. Full scan may take a while, please wait for Malicious Software Removal Tool to complete the tasks. However, you may cancel the scan anytime by clicking on the Cancel button.

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7. After scanning, the tool will reveal all identified threats. There may be other threats that our first scan fails to detect. Please remove/delete all detected items.

8. When removal procedure is complete, you may now close Malicious Software Removal Tool. We hope that Kook ransomware have been completely deleted from the computer. Please restart Windows to proceed with the normal operation.

Stage 3 : Unlocking files with Kook Decryption Tool

Emsisoft Decryptor for STOP Djvu will work only if affected files were encrypted using Offline Keys. Kook ransomware uses the alternate Offline Keys during encryption if there is a problem encountered while communicating to a remote command-and-control server. Follow the guide to start recovering .Kook encrypted files.

1. As precautionary measures, we suggest to BACKUP all your .Kook encrypted files first on a separate media (USB Drive, Flash Drive, DVD Discs, etc…).

2. Download Emsisoft Decryptor for STOP Djvu from this archive page.

3. Right-click on decrypt_STOPDjvu.exe and click “Run as Administrator“. Windows may prompt “Do you want to allow this app…” just click Yes to continue.

4. By default, the tool will pre-populate the locations where encrypted files were identified. To include other directories, simply click Add Folder button.

5. To start recovering files infected by Kook ransomware, click on Decrypt button to start the procedure. The interface will display status of the current decryption process.

decrypt_STOPDjvu.exe

We will update this section once the full decryption tool is on hand. In the meantime, please try other options below if the above procedure is not not effective.

Option 1: Windows Previous Version Tool

Windows Vista and Windows 7 have a feature called Previous Versions. However, this tool is only usable if restore point was made prior to Kook ransomware infection. To use this tool and recover files affected by the virus, please follow these steps:

1. Open My Computer or Windows Explorer.

2. Right-click on the affected files or folders. From the drop-down list, please click on Restore previous versions.

3. New window will open display all backup copy of files and folders you wanted to recover. Choose the appropriate file and click on Open, Copy, or Restore. Restoring selected files overwrites the current encrypted files on the computer.

Option 2: Use ShadowExplorer to restore files encrypted by Kook Ransomware

Just like Previous Version tool, ShadowExplorer is taking advantage of shadow copy created by Windows. This tool allows you to retrieve older version of files before it was encrypted by Kook ransomware.

1. Download ShadowExplorer from the official web site.

2. Install the program with the default settings.

3. The program should run automatically after installation. If not, double-click on ShadowExplorer icon.

4. You can see the drop-down list on top of the console. Please select proper drive and the most recent point-in-time shadow copies of files you wish to restore prior to Kook ransomware infection.

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5. Right-click on the Drive, Folder, or File you wish to restore and click Export…

6. Lastly, ShadowExplorer will prompt for location where you want to save the copy of recovered files.

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