GANDCRAB V4 Ransomware – Remove + Restore .KRAB Encrypted Files

GANDCRAB V4 Ransomware – Remove and Restore .KRAB Encrypted Files

This article has been written with the main goal of helping you understand what is the GANDCRAB V4 ransomware virus and how to effectively remove it from your PC plus how you can attempt to recover .KRAB files, encrypted by this iteration.

GANDCRAB has successfully come out in a new version, using the .KRAB file extension. With this new version, the ransomware virus, demanding victims to pay the ransom in the DASH cryptocurrency, has become one of the biggest ransomware viruses alongside big ransomware families like WannaCry, Dharma, CryptoWall and CryptoLocker. The main purpose of .KRAB this version of GANDCRAB is to encrypt your data. Typically, the ransomware drops a ransom note file, called KRAB-DECRYPT.txt, which aims to extort victims to pay a ransom “fee” to get the files to work again. If your computer has been infected by the GANDCRAB V4 ransomware virus, we strongly suggest that you read this article and learn how you can remove this malware effectively and how you can try and recover as many .KRAB encrypted files as possible, without paying the ransom.

Threat Summary

TypeRansomware, Cryptovirus
Short DescriptionNew version of GandCrab ransomware. Encrypts the files, making them unable to be opened and asks victims to pay ransom in the DASH cryptocurrency to get the files to work again.
SymptomsThe GANDCRAB V4 virus leaves the files with the .KRAB file extension and drops a ransom note, called KRAB-DECRYPT.txt.
Distribution MethodSpam Emails, Email Attachments, Executable files
Detection Tool See If Your System Has Been Affected by GANDCRAB V4


Malware Removal Tool

User ExperienceJoin Our Forum to Discuss GANDCRAB V4.
Data Recovery ToolWindows 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.

GandCrab Ransomware – Update December 2018

GandCrab ransomware has continued to evolve into a 5.0.9 version, which was discovered in the beginning of December 2018. More information about it can be found on the following related story:

Related: Remove GANDCRAB v5.0.9 Cryptovirus

GANDCRAB V4 Virus – Update November 2018

The v4 release of the Gandcrab ransomware family has been found very effective against IoT devices. The exploit kit and attack configuration parameters used to infect the devices appear to target machines using weak or default account login credentials. Unfortunately many smart device owners do not adhere to the security practice of changing the passwords once they configure their devices. This is the reason why ransomware and malware attacks are very successful against this subset of victim devices.

Web servers and running services can be defaced — user data and content will be deleted and a ransomware note will be displayed. Furthermore through the compromised devices more attacks can be made, especially if they are recruited to a botnet.

GANDCRAB V4 Virus – Update August 2018

The GANDCRAB V4 Virus continues to spread in August, 2018. Malware researchers suspect that more countries might be getting affected as more languages have been added to the payment page of the ransomware. You can clearly see that from the below screenshot:

If more languages are being added, either the cybercriminals are going to spread their malware in more countries (by using malvertising campaigns, for example) or they know that those countries are already affected by the GANDCRAB V4 Virus.

GANDCRAB V4 Virus – How Does It Infect Victims

The infection process of the .KRAB iteration of this ransomware is rather similar to the infection procedure that was used in its older versions. The ransomware authors aim to use a malicious attachment, often a Microsoft Office document or a .PDF file, whose main goal is to trick users to enable Macros. Such documents often deceive users that, unless editing is not enabled, they cannot read what is in the documents. One such file was detected by researcher Marcelo Rivero to be a receipt in a PDF file which then leads to infecting the user with GANDCRAB V4. The infection chain occurs as it follows:

The e-mails carrying the ransomware are spreading the attachment in a .7z archive file with the same name as the PDF document inside, as researcher from malware-traffic-analysis Brad has discovered. The messages in the e-mails themselves aim to convince the user that the attachment is of utmost importance and should be opened immediately. Below, you can see one of the e-mails carrying a malicious GANDCRAB attachment:

From: Deanna Bennett <>
Subject: Payment Invoice #93611
Attachment: DOC402942349491-PDF.7Z

Dear Customer,
To read your document please open the attachment and reply as soon as possible.
Kind regards,
TCR Customer Support

Naturally, there are other subjects and other e-mails as well, since the cyber-criminals who are behind GANDCRAB V4 have likely created a lot of e-mail templates in order to avoid having their e-mail addresses flagged by the e-mail providers’ detection software. Here are some of the topics (subjects) you are likely to encounter in an e-mail, carrying GANDCRAB V4 ransomware virus:

Document #72170
Invoice #21613
Order #87884
Payment #72985
Payment Invoice #58058
Payment Invoice #93611
Ticket #07009
Your Document #78391
Your Order #16323
Your Ticket #23428

In addition to documents with malicious Macros, the GANDCRAB V4 ransomware may also infect you by simply clicking on the .7z file, since researchers have reported that the malware may self-extract a .JS (JavaScript) file with the same name which automatically starts the infection process:

GANDCRAB V4 Ransomware – Analysis

Once the malicious .JS file or the malicious macros that cause the infection with GANDCRAB V4 ransomware are executed, the ransomware virus begins its malicious activities. The .JS file drops an executable type of fil, which is often named randomly or resembles a legitimate Windows program. The location in which this file is dropped may be the the following:

→ C:\Users\{Your Username}\AppData\{malicious file name}.exe
HASH of the file: 97a910c50171124f2cd8cfc7a4f2fa4f

Then, the virus uses the “RunOnce” registry sub-key in which it adds the REG_SZ type of registry value. This is done with the purpose of getting the malicious file to run automatically on Windows boot. This procedure may result in the ransomware .exe running automatically on Windows login. The RunOnce subkeys in which you can find the value string have the following locations:

→ HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce

The GANDCRAB V4 ransomware also makes sure that the victim reads its ransom note file, which contains instructions how to download and install Tor browser to anonymously pay the ransom in the DASH cryptocurrency by going on the ransomware’s web page. The note is called by two names – CRAB-DECRYPT.txt or KRAB-DECRYPT.txt and has the following message for the victims to see:

All your files, documents, photos, databases and other important files are encrypted and have the extension: .KRAB
The only method of recovering files is to purchase an unique private key. Only we can give you this key and only we can recover your files.
The server with your key is in a closed network TOR. You can get there by the following ways:
| 0. Download Tor browser –
| 1. Install Tor browser
| 2. Open Tor Browser
| 3. Open link in TOR browser:
| 4. Follow the instructions on this page
On our page you will see instructions on payment and get the opportunity to decrypt 1 file for free.

When the victim opens the web page in Tor browser, a similar web page to the other GANDCRAB variants is also seen with this version:

The web page also features a live chat and detailed instructions on how to pay the ransom to get the so-called GandCrab Decryptor:

GANDCRAB V4 Ransomware – Encryption Process

GANDCRAB ransomware uses a very sophisticated and well-developed encryption procedure which utilizes the combination of the following encryption algorithms:

  • AES-256 (Advanced Encryption Standard)
  • RSA-2048 (Rivest-Shamir-Adleman)

Both of the ciphers are respectively in the 256 bit and 2048 bit of strength, making them impossible to be decoded if you do not know the decryption keys. And to further complicate the situation, GANDCRAB V4 ransomware also encrypts the files in something known as CBC mode, or Cipher-Block Chaining mode. This mode chains up the encrypted files in a way that is tamper-proof. To best explain this, GANDCRAB V4 encrypts the files as it follows:

Step 1: The ransomware scans for the files it wants to encrypt (documents, videos, images, audio files, archives, etc.), while excluding files in Windows directories that may damage the functioning of your PC.
Step 2: GANDCRAB V4 encrypts the files by creating copies of the original files, which are with replaced blocks of data within them. The bad news is that the CBC mode links those blocks together and if the files are tampered with, the CBC mode breaks them indefinitely.
Step 3: After encryption, the ransomware generates a unique decryption key for each file; all files are likely linked in a KEY file, which is also encrypted, making it impossible to decrypt the files without the decryption key.
Step 4: GANDCRAB V4 ransomware adds the .KRAB file suffix to the encrypted copies of the files and deletes the original files. This makes the encrypted files to appear like the following:

Step 5: The virus likely triggers the following commands as an administrator in Windows Command Prompt:

→ sc stop VVS
sc stop wscsvc
sc stop WinDefend
sc stop wuauserv
sc stop BITS
sc stop ERSvc
sc stop WerSvc
cmd.exe /C bcdedit /set {default} recoveryenabled No
cmd.exe /C bcdedit /set {default} bootstatuspolicy ignoreallfailures
C:\Windows\System32\cmd.exe” /C vssadmin.exe Delete Shadows /All /Quiet

This is done with the purpose to delete the shadow volume copies of the infected machine, so that the user cannot restore the files, using Windows Recovery.

Remove GANDCRAB V4 Ransomware and Restore .KRAB Encrypted Files

Removing GANDCRAB V4 ransomware may be more complicated than it seems, since this ransomware virus may contain multiple defensive techniques that may damage your files and your computer indefinitely. One way to remove the ransomware manually is if you follow the manual removal instructions underneath this article and use the information to do the removal yourself. Keep in mind you must really know what you are doing, since you risk loosing your files indefinitely.

Another way to do the removal, which is often advised by security analysts, is to download and install an advanced anti-malware software. Such program will automatically scan for and remove all of the GANDCRAB V4-related virus files and make sure that the virus is safely removed from your computer.

If you want to restore your encrypted files, directly trying to decrypt them is not a good idea, unless there is an official decryptor available. Paying the ransom is one way to go with, but it is not advisable, mainly because you may not get your files after paying. By paying, you are also supporting the operation of the cyber-criminals as well. Thus, we suggest that you try out the alternative methods for file recovery underneath this article in step “2. Restore files, encrypted by GANDCRAB V4”. They have been created to help you try and restore the deleted original files by GANDCRAB V4 by using data recovery software to recover some or most of your files, depending on the condition of the deleted file. The methods are not 100% effective to recover your data, but their main goal is to help you to restore as many files as possible, as they have helped some of the users on our forums.


Ventsislav Krastev

Ventsislav has been covering the latest malware, software and newest tech developments at SensorsTechForum for 3 years now. He started out as a network administrator. Having graduated Marketing as well, Ventsislav also has passion for discovery of new shifts and innovations in cybersecurity that become game changers. After studying Value Chain Management and then Network Administration, he found his passion within cybersecrurity and is a strong believer in basic education of every user towards online safety.

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  1. AvatarLynne

    I have a battery symbol in the top right corner of my phone. It is not the life of the battery it has what looks like 3 triangles in it. It appeared about a week ago. Please can you help.

  2. Avataranonimo

    es el ahorro de datos, saludos

  3. AvatarMohammad Yari

    My files are encrypted by gandcrab’s ransomware and there is currently no way to access my data. Dear custodians, I ask you to help in solving this problem. If I can not retrieve my elephants, I might lose my job. That’s why I ask for help from all of you.

  4. Avatarricardo

    meus amigos estou numa sinuca de bico, é isso mesmo, meus arquivos estão tds criptografados .krab e tenho um studio com trabalhos de clientes diversos e não consigo acessar mais nada e estou aqui a ponto de enlouquecer pq já procurei em tds os locais que era possivel na internet e não existe uma forma de resolver isso, se estiver alguém que possa me ajudar ficarei muito agradecido com isso,
    se aguém puder ajudar agradeço desde já…

    [SensorsTechForum: comment has been edited, personal information was removed from it]


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