GandCrab v4.1 ransomware: what it is and how to remove it
GandCrab v4.1 ransomware is a crypto-virus and a continuation of the infamous GandCrab v4 ransomware. It encrypts files using a complicated encryption algorithm and adds a .krab appendix to each of the affected files.
Facts checked October 7, 2026. Removal steps tested on Windows 11 (26H2) and checked against Microsoft's and the browser makers' current documentation. Sections marked as our earlier report are the original text: they describe the threat as it was then and have not been reviewed since. The 2026 status, the removal steps and the questions are current.
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GandCrab v4.1 ransomware: summary
| Detection names | No Microsoft detection name is known |
|---|---|
| Ransom note | krab-decrypt.txt; the text of the note is not in our records |
| Contact | Not recorded in our earlier report |
| Encrypted file extension | .krab |
| Decryptor | No free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates |
| Distribution | Not recorded in the old report |
| Removal | Scan the PC with security software to find and remove the malware and anything installed with it. Fortect scans Windows for malware and repairs the system files and settings it damaged. Remove it nowTo use the full-featured product, you have to purchase a license for Fortect. The scan is free. |
Show 9 more facts
| Damage | Not recorded in the old report |
|---|---|
| Name | GandCrab v4.1 ransomware |
| Type | File-encrypting ransomware |
| Symptoms | Files renamed with a new extension and a ransom note left in folders |
| Evidence | 3 write-ups by security sites; no sample analysed yet |
| Encrypted files | .krab |
| Free decryptor | No free decryptor is known (checked 7 October 2026) |
| First seen | 25 July 2018 |
| Facts checked | 7 October 2026 |
- File extension:
.krab - Note file:
krab-decrypt.txt
From our report of Jul 2018 · not reviewed since
More from our earlier report on GandCrab v4.1 ransomware
- $1200 in DASH, might double
- Ransom note present in each of the affected folders and files appear to have .krab appendix
- Use Gandcrab 4.1 decryptor to recover your files
How GandCrab v4.1 ransomware behaves
From our report of Jul 2018 · not reviewed since
GandCrab v4.1 - ransomware that showed up quickly after its predecessor
GandCrab v4.1 ransomware is a crypto-virus and a continuation of the infamous GandCrab v4 ransomware.
It encrypts files using a complicated encryption algorithm and adds a .krab appendix to each of the affected files. The data locker does not modify wallpaper but drops a ransom note in the text format in each of the affected folders - krab-decrypt.txt.
Hackers demand to pay the ransom of $1200 in DASH cryptocurrency for data release. The main difference from its previous variant is that the virus added network communication feature. Additionally, the GandCrab v4.1 ransomware does not use the Command and Control server anymore, allowing it to spread without the internet connection.
According to security experts, GandCrab v4.1 virus is mostly distributed through fake websites that look identical to those that host cracked software, keygens, and similar. Nevertheless, as it is typical of data encrypting viruses, they can also spread via spam emails, break through the RDP, and similar methods.
There have been speculations that GandCrab v4.1 crypto-malware spreads via SMB exploit, which was used by WannaCry and Petya cyber attacks, although security experts did not find any evidence for that. However, they did not reject the possibility that the feature could be introduced in the next malware version. Therefore, users should make sure that the MS17-010 patch is implemented on their machines.
To ensure encryption of files, GandCrab v4.1 kills several .exe processes, allowing malware to execute its purpose successfully. The virus targets a variety of files, such as:
As soon as the .krab extension is added to each of personal files, they become unusable. Note that they are not damaged, but encoded. To get them back, users need to obtain decryption key that is stored on a remote server which is only accessible to cybercriminals.
GandCrab v4.1 ransomware as a long list of hard-coded websites it communicates with to send out the information about victims. The malware generates an URL address for each host in the following format: http://{host}/{word1}/{word2}/{fname}.{extension}, for example: www.{host}.com/uploads/pics/potekim.gif.
This functionality does not seem logical, as sending data of the victim to each of the hosts seems useless, considering one send-off would be enough to fulfill the purpose.
Additionally, the hard-coded websites were not designed to act as GandCrab servers or the virus carriers. Therefore, security experts think that this functionality is experimental or is only there to divert researchers from the correct analysis.
A ransomware-type virus is hazardous and can lead to permanent loss of personal data. Nevertheless, to ensure normal operation of the PC, users should hurry and remove the GandCrab v4.1 virus from their computers by using reputable security software.
- MS Office/OpenOffice documents
- Archives
- Databases
- Photos
- Video
- Image
- Music, etc.
From our report of Jul 2018 · not reviewed since
Be careful online and avoid nasty ransomware infections
When it comes to internet safety, users are not careful.
At least not careful enough. Even though ransomware has been one of the most elaborated topics when it comes to cybersecurity (we saw massive attacks last year - WannaCry and NotPetya, which brought several high-profile organizations to the knees), users still refuse to believe that they can be victims, and so do companies. They fail to patch their computer systems on time or fall for a cleverly presented phishing email.
Do not forget that, ransomware targets both, organizations and private users. Therefore, do not exclude yourself as a potential victim. Always use strong passwords, install powerful security software, update the software and the OS as soon as new patches are out, and learn to recognize malicious spam emails.
The GandCrab v4.1 ransomware note
The note is called krab-decrypt.txt.
We did not record the full text of the ransom note in our report.
How to remove GandCrab v4.1 ransomware
Tools you'll need
All of these are free except where noted. Download them on a clean device if the infected PC is offline.
- A USB stick: to keep the ransom note, two or three encrypted files and screenshots off the infected PC.
- Microsoft Defender Offline: built into Windows 11 and Windows 10; scans before Windows starts, so running malware cannot hide.
- Microsoft Safety Scanner: a second, portable scanner with current signatures; each download works for 10 days.
- ID Ransomware: identifies the family from the note and one encrypted file and says whether a decryptor exists.
- No More Ransom: the free decryptors from police and security companies; check it again every few months.
- Fortect (optional): scans Windows for malware and repairs the system files and settings it damaged. The free scan is in the box above.
How to remove GandCrab v4.1 ransomware and get your files back
Work in this order.
Disconnecting comes first, removal comes before any restore, and nothing here asks you to contact the attackers.
Step 1: Disconnect the PC and unplug backup drives
GandCrab v4.1 ransomware encrypts everything it can reach, including drives and shares you connect later. Cut the network first: cable out, or Wi-Fi off from the taskbar.
Then unplug every USB stick and backup disk and pause cloud sync, so the encrypted versions do not replace your online copies. Do not reconnect any of them until the ransomware is removed from the Windows 11 or Windows 10 PC.
Windows 11: turn off Wi-Fi to take the PC offline. Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files
Step 2: Save the ransom note and confirm the family
Copy
krab-decrypt.txtand one or two files ending in.krabto a USB stick, and leave the originals where they are.From another device, upload the note and a sample file to ID Ransomware or No More Ransom's Crypto Sheriff, which name the family from the note, the extension and the file structure.
Write down the contact address and your personal ID from the note, because a decryptor or the police may ask for them.
Warning: Never contact the attackers from the infected Windows 11 or Windows 10 PC.
Windows 11: the ransom note and encrypted files to copy for identification. Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files
Step 3: Check for a free decryptor
For GandCrab v4.1 ransomware, no free decryptor is known (checked 7 October 2026). Search the family name in the No More Ransom decryption tools list and in the free decryptors of Emsisoft, Avast and Kaspersky, because new tools appear years after an attack.
Important: Keep the encrypted files even if nothing works today, and do not pay before every free option is ruled out: payment does not guarantee a working key.
Decryptors run on Windows 11 and Windows 10, but only after the ransomware itself is removed.
Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files
Step 4: Remove the ransomware before you restore or decrypt
Restoring or decrypting files while GandCrab v4.1 ransomware still runs lets it encrypt them again. Run a Full scan in Windows Security > Virus & threat protection > Scan options, then the Microsoft Defender Antivirus (offline scan).
If the ransomware blocks Windows Security, start Safe Mode with Networking and scan from there. Some families install a password stealer as well, so let both scans finish on Windows 11 or Windows 10.
Windows 11: Windows Security > Virus & threat protection > Scan options. Full procedure with screenshots: Run a Microsoft Defender Offline scan
Step 5: Look for shadow copies of the files
Open Command Prompt as administrator and run
vssadmin list shadows. If it lists copies dated before the attack, right-click a folder with encrypted files in File Explorer, choose Properties > Previous Versions, and open or restore a version from before that date.ShadowExplorer, a free tool, shows the same copies when the tab is empty or hidden. Most current families delete shadow copies, so an empty list is normal, but the check takes two minutes on Windows 11 or Windows 10.
Windows 11: vssadmin list shadows shows whether shadow copies exist. Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files
Step 6: Restore the files from a backup or recover deleted originals
Restore from an external backup, File History or OneDrive's version history, choosing a date before the attack. Connect the backup drive only after the scans are clean, or the ransomware encrypts it too.
If there is no backup, file recovery software can sometimes find the deleted originals, because some ransomware writes an encrypted copy and deletes the original file.
Stop writing to the drive and try recovery on Windows 11 or Windows 10 before new files overwrite the space.
Full procedure with screenshots: Recover deleted files (Recycle Bin, backups, OneDrive) On uGetFix
Instructions for each browser and system
The detailed steps for every browser and system this guide covers. Open the one you use.
Manual removal using Safe Mode
Important! →
Manual removal guide might be too complicated for regular computer users. It requires advanced IT knowledge to be performed correctly (if vital system files are removed or damaged, it might result in full Windows compromise), and it also might take hours to complete. Therefore, we highly advise using the automatic method provided above instead.
Step 1. Access Safe Mode with Networking
Manual malware removal should be best performed in the Safe Mode environment.
Windows 7 / Vista / XP
- Click Start > Shutdown > Restart > OK.
- When your computer becomes active, start pressing F8 button (if that does not work, try F2, F12, Del, etc. - it all depends on your motherboard model) multiple times until you see the Advanced Boot Options window.
- Select Safe Mode with Networking from the list.
Windows 10 / Windows 8
- Right-click on Start button and select Settings.
- Scroll down to pick Update & Security.
- On the left side of the window, pick Recovery.
- Now scroll down to find Advanced Startup section.
- Click Restart now.
- Select Troubleshoot.
- Go to Advanced options.
- Select Startup Settings.
- Press Restart.
- Now press 5 or click 5) Enable Safe Mode with Networking.
Step 2. Shut down suspicious processes
Windows Task Manager is a useful tool that shows all the processes running in the background. If malware is running a process, you need to shut it down:
- Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
- Click on More details.
- Scroll down to Background processes section, and look for anything suspicious.
- Right-click and select Open file location.
- Go back to the process, right-click and pick End Task.
- Delete the contents of the malicious folder.
Step 3. Check program Startup
- Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
- Go to Startup tab.
- Right-click on the suspicious program and pick Disable.
Step 4. Delete virus files
Malware-related files can be found in various places within your computer. Here are instructions that could help you find them:
- Type in Disk Cleanup in Windows search and press Enter.
- Select the drive you want to clean (C: is your main drive by default and is likely to be the one that has malicious files in).
- Scroll through the Files to delete list and select the following:
Temporary Internet Files
Downloads
Recycle Bin
Temporary files - Pick Clean up system files.
- You can also look for other malicious files hidden in the following folders (type these entries in Windows Search and press Enter):
%AppData%
%LocalAppData%
%ProgramData%
%WinDir%
After you are finished, reboot the PC in normal mode.
From our report of Jul 2018 · not reviewed since
Remove GandCrab v4.1 ransomware using security software and recover your locked files
Ransomware-type viruses use a complicated code that might lead to permanent data loss.
You need to realize, that manual GandCrab v4.1 removal should not be performed by regular users, as it will end up in a failure. Only trained and highly skilled IT professionals would be able to execute such a task. Therefore, leave it for security software - or will work, although you can use any anti-malware program of your liking.
GandCrab v4.1 virus stops certain executable files, so it might prevent security software from starting and operating correctly. In such a case, enter Safe Mode with Networking, as explained below. You can also use a video guide that explains how to create a safe environment before you start performing the removal procedure.
Note that you should start recovering your encrypted files only after you remove GandCrab v4.1 from the infected machine. Otherwise, your files will get encrypted again. To recover data, use backups or the official decryption tool.
[GI=method-1]If GandCrab 4.1 is blocking the operation of anti-malware software, enter Safe Mode with Networking and start-up the program from there:
[GI=method-2]You can also use System Restore to disable the threat:
Try Data Recover Pro
This tool was originally created to redeem files that were accidentally deleted or otherwise corrupted. Nevertheless, experts observed positive results when it comes to Data Recover Pro dealing with ransomware encrypted files.
Use Windows Previous Versions feature
This option can only be used if System Restore was enabled before ransomware attacked the device.
ShadowExplorer could be the answer
Ransomware usually deletes Shadow Volume Copies automatically. However, in some cases, it may fail to do that. ShadowExplorer would be an excellent tool to recover all encrypted files in such a case.
Gandcrab 4.1 decrypter is already available
To recover files encrypted by this ransomware, download the official decryption tool by clicking this link.
Report it and recover your files
Report it
Report the attack even if you do not expect the files back: insurers and banks ask for the report number, and police use the contacts in the note to link cases.
- United States
- FBI IC3 · FTC ReportFraud
- United Kingdom
- Report Fraud (formerly Action Fraud) · NCSC
- Australia
- ReportCyber (ASD)
- EU countries
- Europol: national reporting sites
Give the victim ID, the note and the date the files were encrypted. A business that holds personal data may also have to notify its data protection authority, in the EU within 72 hours.
Backups: the 3-2-1 rule
Keep three copies of files that matter, on two kinds of storage, with one copy offline or off-site.
A disk that stays plugged in is reached by malware like GandCrab v4.1 ransomware together with the PC; one you connect only for the backup is not.
On Windows 11, File History keeps versions on an external drive, and OneDrive keeps earlier versions of synced files. Before restoring anything, make sure the PC no longer shows files that end in .krab and no longer open.
Setting it up step by step: 3-2-1 backups on Windows 11 and 10.
Choose a proper web browser and improve your safety with a VPN tool
Online spying has got momentum in recent years and people are getting more and more interested in how to protect their privacy online.
One of the basic means to add a layer of security - choose the most private and secure web browser. Although web browsers can't grant full privacy protection and security, some of them are much better at sandboxing, HTTPS upgrading, active content blocking, tracking blocking, phishing protection, and similar privacy-oriented features.
However, if you want true anonymity, we suggest you employ a powerful VPN - it can encrypt all the traffic that comes and goes out of your computer, preventing tracking completely.
Lost your files? Use data recovery software
While some files located on any computer are replaceable or useless, others can be extremely valuable.
Family photos, work documents, school projects - these are types of files that we don't want to lose. Unfortunately, there are many ways how unexpected data loss can occur:
- power cuts
- Blue Screen of Death errors
- hardware failures
- crypto-malware attack
- even accidental deletion
To ensure that all the files remain intact, you should prepare regular data backups. You can choose cloud-based or physical copies you could restore from later in case of a disaster. If your backups were lost as well or you never bothered to prepare any, can be your only hope to retrieve your invaluable files.
Questions about GandCrab v4.1 ransomware
How do I open .krab files?
You cannot open them by renaming or by choosing another program. The .krab ending shows that GandCrab v4.1 ransomware encrypted the content, and only the matching key can reverse it. Renaming a file back to .docx or .jpg changes nothing except the icon, and it can confuse a future decryptor, so leave the names as they are.
To get the content back, use a backup, an unencrypted copy elsewhere, or a decryptor listed on No More Ransom if one exists for GandCrab v4.1 ransomware. Store the encrypted files on an external disk until then.
Did GandCrab v4.1 ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by GandCrab v4.1 ransomware, but the only confirmed sign is files that end in .krab and no longer open, which says nothing about what happened before. Many current ransomware attacks copy files or run a password stealer first, so it is wise to act as if they did.
From a clean device, change the passwords that were saved in the browsers on this PC, starting with e-mail and banking, sign out of all sessions and turn on two-step verification. Watch bank statements and account activity for the next few weeks.
Is there a free GandCrab v4.1 ransomware decryptor?
We last checked on 7 October 2026, and for GandCrab v4.1 ransomware no free decryptor is known. We check No More Ransom, which collects free tools from police and security companies, and the decryptor pages of the major antivirus vendors. A working decryptor exists only when the encryption has a flaw or the keys were leaked or seized.
Ignore sites and videos that offer a "GandCrab v4.1 ransomware decryptor" for download or for a fee: these are usually scams or malware. Real decryptors are free and come from known security companies or law enforcement. Keep the encrypted files in case a tool appears later.
Should I pay the ransom?
We advise against it, and so do the FBI, Europol and national cyber agencies. Payment does not guarantee a working tool: some attackers never reply, some tools damage files, and some variants have no decryptor at all. Paying also funds further attacks and can make you a target again.
Before considering payment, try every recovery option in this guide and report the attack. Companies must involve their legal adviser and insurer, because payments to sanctioned groups can be illegal. If files are truly irreplaceable, store the encrypted copies and wait; decryptors sometimes appear later.
Can a data-recovery company decrypt my files for a fee?
Only if a decryptor already exists or the company pays the attackers for you. Some "ransomware recovery" services advertise that they can decrypt families with no known flaw; in practice they negotiate with the attackers and add their own fee. Others use the same free tools listed on No More Ransom.
Before you hire anyone, ask in writing how they will recover the files, whether they will contact the attackers and what happens if they fail. A legitimate service answers clearly. If a free decryptor exists for your family, you can run it yourself.
How did GandCrab v4.1 ransomware get on my computer?
The way GandCrab v4.1 ransomware spreads has not been documented yet, so look at your own recent activity. On home PCs, ransomware most often comes with cracked programs, game cheats, key generators and fake updates, or with an e-mail attachment that was opened. On business networks, attackers usually log in through Remote Desktop with a stolen or guessed password.
Think back to what was downloaded or installed in the days before files that end in .krab and no longer open, and check the Downloads folder and Installed apps sorted by date. Keep anything suspicious for your report, but do not run it again.
Is GandCrab v4.1 ransomware the same as other ransomware with a similar name?
Not necessarily. Ransomware names come from the file extension, the note or a word in the code, so unrelated families often end up with similar names, and one family can appear under several names. The difference matters: a decryptor or advice for one family does not fit another and can damage files.
Compare the ending added to your files and the exact name of the note with the summary table at the top of this guide, then upload the note and one encrypted file to ID Ransomware from a clean device. If the result names another family, follow the guide for that family instead.
Can I just remove .krab from the file names?
You can try it on a copy, but for real ransomware it will not help. The .krab extension is only a label; the file content has been scrambled with a key the attackers hold.
If a renamed copy opens normally, the malware only renamed files, which happens with some fake ransomware, and you can rename the rest back. If it does not open, leave the files as they are. Renaming encrypted files can confuse a decryptor later, so always work on copies.
Can I delete krab-decrypt.txt?
Yes, the note itself is harmless text and deleting it does not affect your files. Keep at least one copy first, outside the infected PC. krab-decrypt.txt contains your personal ID and the attackers' contact details, which identification services use to tell which family encrypted your files, and which a decryptor may need later.
Police reports also ask for it. Once you have saved a copy, you can remove the notes from every folder after the ransomware program has been removed and your files are restored or backed up.
Will Fortect remove GandCrab v4.1 ransomware?
Fortect scans Windows for malware and unwanted programs and repairs the system files and settings they change, and its free scan shows what it finds on your PC before you decide anything.
For GandCrab v4.1 ransomware, follow the plan above as well: the browser steps take back permissions and settings that no scanner treats as a threat, and uninstalling the program that brought it removes the source.
Run Microsoft Defender's full scan and, if anything was found, its offline scan as a second opinion. If the symptoms are gone after the plan and both scans are clean, there is nothing more to do.
Sources
- 2-spyware: GandCrab V4.1 ransomware is using SMB exploit to spread around (read October 7, 2026)
- Microsoft: Microsoft Security Bulletin MS17-010 - Critical (read October 7, 2026)
- CISA: StopRansomware (read October 7, 2026)
- No More Ransom (read October 7, 2026)
- FTC: How to recognize, remove and avoid malware (read October 7, 2026)