Montserrat ransomware: what it is and how to remove it
Montserrat ransomware, also known as BaCkUp ransomware, is a newly-released cyber threat that uses both an appendix and file marker to sign encrypted files and documents. The main targets are English-speaking users that employ Windows machines for their computing work.
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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Montserrat ransomware: summary
| Distribution | The most common distribution sources of ransomware infections include email spam messages and their infected attachments, software cracks, and malicious software updates |
|---|---|
| Name | Montserrat ransomware |
| Category | Ransomware/malware |
| Danger level | High. Locks files that can result in permanent data loss, can modify various system directories, and infiltrate other malicious strings such as trojans |
| Appendix/file marker | Once all the files are encrypted by using the Advanced Encryption Standard, the components end up with the .encrypted_backup extension and the .BaCkUp file marker |
| Target | Regarding the language in which the ransom note is written, the hackers are targetting people who speak English and live in English-speaking countries |
| 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 14 more facts
| Ransom note | All the demands are provided in the How to the restore data.html ransom message; the text is quoted in full below |
|---|---|
| Emails | The criminals provide montserrat501@protonmail.com or montserrat501@airmail.cc email addresses as a way to contact these people and receive further payment instructions |
| Detection names | No Microsoft detection name is known |
| Contact | montserrat501@protonmail.com, montserrat501@airmail.cc |
| Encrypted file extension | .encrypted |
| Decryptor | No free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates |
| Damage | Not recorded in the old report |
| Type | File-encrypting ransomware |
| Symptoms | Files renamed with a new extension and a ransom note left in folders |
| Evidence | 5 write-ups by security sites; no sample analysed yet |
| Encrypted files | .encrypted |
| Free decryptor | No free decryptor is known (checked 7 October 2026) |
| First seen | 18 December 2019 |
| Facts checked | 7 October 2026 |
- File extension:
.encrypted - Note file:
the ransom note
From our report of Dec 2019 · not reviewed since
More from our earlier report on Montserrat ransomware
- You should opt for the removal process ASAP before the ransomware provides any more damage.
- For this purpose, employ reliable antimalware software
- If you have discovered some system locations that have been touched by the ransomware or additional threats, you can try repairing your machine and its components with software such as
How Montserrat ransomware behaves
From our report of Dec 2019 · not reviewed since
Ransomware often gets delivered via cracked software and email spam
Cybersecurity experts from LosVirus.es claim that ransomware virus ends up on the system by using multiple deceptive techniques.
However, the most commonly used infiltration methods are the following ones:
These are just the most popular techniques that are used for spreading ransomware but there, of course, are many more of them, for example, exploit kits, malvertising, malicious links, PUPs, etc. The best way to protect yourself is to take all security measures seriously. You should be careful with all the emails that you receive and always identify the sender.
If the email message comes with suspicious attachments, links, or a lot of grammar mistakes included, you should delete the message right away. Continuously, do not download software from unreliable sources such as p2p networks. Get all of your products from original developers and avoid installing malware via software cracks.
Continuously, do not download any unknown updates. If you have been randomly provided with an upgrade, you should check the app's official website and look for pending updates there. Last but not least, always have an active antivirus tool that will inform you if something potentially malicious is trying to invade your computer system.
- Email spam. When the malware gets delivered via phishing email messages and their clipped attachments/links included. The criminals pretend to be from reliable shipping organizations such as FedEx or from other well-known firms/institutions that are related to banking, healthcare, education.
- Software cracks. A big variety of illegitimate products and services are distributed on peer-to-peer networks such as The Pirate Bay, eMule, and BitTorrent. These websites have weak protection and crooks can easily misuse them for their malicious purposes.
- Fake software updates. Some ransomware infections are spread via fake JavaScript, Adobe Flash Player, or other types of updates. The updating windows might pop up whenever visiting an unsecured source and start encouraging you to download a particular upgrade for your outdated software.
From our report of Dec 2019 · not reviewed since
Montserrat ransomware - dangerous malware that adds the .encrypted backup appendix to each locked component
Montserrat ransomware, also known as BaCkUp ransomware, is a newly-released cyber threat that uses both an appendix and file marker to sign encrypted files and documents.
The main targets are English-speaking users that employ Windows machines for their computing work. The stealth infiltration begins with a spam message or software crack. After opening such content, Montserrat virus ends up on the machine and starts modifying registries.
The malware also brings the Backup.exe executable to the system which allows the parasite to fulfill its module. This leads to the secret encryption of various files and all data ends up with the .encrypted_backup appendix and the .BaCkUp file marker.
Afterward, the cyber threat provides the How to the restore data.html message where the crooks' demands are expressed. These people require to write them via montserrat501@protonmail.com or montserrat501@airmail.cc email addresses and offer to send a file that holds no larger of size than 10 MB to receive evidence that the decryption software truly exists.
Montserrat ransomware is detected by 46 AV engines at the time of writing. According to VirusTotal file detection information, some of the detection names include Trojan.GenericKD.42093054, Win32:RansomX-gen , Trojan.Win32.Zudochka.dtd, Ransom.Montserrat, Trojan.Encoder.30337, Trojan.TR/FileCoder.ofeiy, and others.
Montserrat ransomware does not provide any particular ransom demands via the ransom message, however, the criminals are most likely to urge for cryptocurrencies such as Bitcoin (the most popular one), Litecoin, Monero, or Ethereum as these types of transfers ensure the anonymity of the entire process. Take a peek how to the ransom note looks like:
Montserrat ransomware uses an AES encryption cipher to lock up all components that are found on the computer. The malware targets files such as databases, images, audio, video, excel sheets, word documents, powerpoints, and similar data. After the locking, both encryption and decryption keys are safely stored on remote servers.
Montserrat ransomware developers might try to harden the decryption process for you. They might have included a specific module into the ransomware that allows it to execute PowerShell commands and eliminate the Shadow Volume Copies of all encrypted files. This way the chances of decrypting data independently lessen.
Furthermore, Montserrat ransomware might hold other commands and modify locations such as the Windows Registry and Task Manager for carrying out its activities. Sometimes, this type of malware ensures that the system will be scanned for encryptable files and documents once in a while, for example, half an hour.
Continuously, Montserrat ransomware will make sure that it is loaded every time when you boot your Windows computer system, it might end up disabling some antivirus software and modifying the Windows hosts file. The last activity is carried out to prevent you from visiting security-related websites where you might get valuable information on the virus's removal.
In addition, Montserrat ransomware can bring other malicious products to the system, this way you will have to different types of malware operating on your machine at once. The risk of system and software damage will definitely increase if your computer system receives such type of infection as a Trojan virus.
The only way to avoid such risk is to remove Montserrat ransomware from your Windows computer system by employing reliable software. However, if the ransomware virus has already managed to bring other threats into your machine, they will need to be eliminated too. If some damage was caused to your computer, try using to repair it.
If your antimalware is somehow failing to detect the ransomware or you have run into difficulties while performing the Montserrat ransomware removal process, you should boot your machine in Safe Mode with Networking or activate System Restore. We have provided some instructing steps on these two methods, take a look at the end of this article.
One more tip from our side would be not to pay the Montserrat ransomware cybercriminals as you can easily get scammed. These people might urge for a big price between $200 and $2000 in Bitcoin or another type of cryptocurrency that you will not receive back. Instead of risking in your money, go to the end of this page and find some alternative data recovery tips.
The Montserrat ransomware note
Your data has been encrypted!
To restore it, contact us using the following e-mail:
montserrat501@protonmail.com
If you didn't get a response in 24 hours, write to:
montserrat501@airmail.cc
You must include the following ID information in your message:
To prove that we are able to restore your files, you can attach a single encrypted file not larger than 10MB.
It will be decrypted and sent back to you.
Any modification of encrypted files will lead to irrecoverable data loss!
How to remove Montserrat 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 Montserrat 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
Montserrat 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
the ransom noteand one or two files ending in.encryptedto 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 Montserrat 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 Montserrat 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 Dec 2019 · not reviewed since
The removal process of Montserrat ransomware
Montserrat ransomware removal is a process that should be completed with big care and requires a lot of effort.
You should not try to eliminate the malware without using antimalware help. Manual elimination is not a possibility in this case and you might easily fail while trying to get rid of the cyber threat on your own.
Continuously, the automatical system software is more capable to remove Montserrat ransomware from all infected locations on the computer. The program will scan the entire machine and search all potentially affected directories. Afterward, the automatical program will be able to deal with the cyber threat safely and effectively.
When Montserrat ransomware is gone, it is time to search for system damage. You can employ software such as or and perform a full machine checkup process with these programs. When the scan results show which locations have been damaged, you can try fixing them by employing another tool such as .
[GI=method-1]To disable malicious processes on your Windows computer system, you should boot your machine in Safe Mode with Networking. Apply this function by completing the following guidelines:
[GI=method-2]To deactivate malware-laden activities on your machine, start the computer in System Restore. Turn this feature on by completing the following steps:
Try this software if the ransomware virus has encrypted your data files and documents. Perform all steps as required to reach the best results possible.
Try using Windows Previous Versions feature for data restoring tasks.
Try using this piece of software if you have enabled the System Restore function in the past, otherwise, you might not receive delighting results.
Shadow Explorer might allow you to recover some individual files.
If the ransomware virus has erased or permanently damaged the Shadow Volume Copies of encrypted data, this software might not be that helpful as expected.
Currently, no official decryptor has been released for this cyber threat.
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 Montserrat 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 .encrypted and no longer open.
Setting it up step by step: 3-2-1 backups on Windows 11 and 10.
Stream videos without limitations, no matter where you are
There are multiple parties that could find out almost anything about you by checking your online activity.
While this is highly unlikely, advertisers and tech companies are constantly tracking you online. The first step to privacy should be a secure browser that focuses on tracker reduction to a minimum.
Even if you employ a secure browser, you will not be able to access websites that are restricted due to local government laws or other reasons. In other words, you may not be able to stream Disney+ or US-based Netflix in some countries. To bypass these restrictions, you can employ a powerful VPN, which provides dedicated servers for torrenting and streaming, not slowing you down in the process.
Data backups are important - recover your lost files
Ransomware is one of the biggest threats to personal data.
Once it is executed on a machine, it launches a sophisticated encryption algorithm that locks all your files, although it does not destroy them. The most common misconception is that anti-malware software can return files to their previous states. This is not true, however, and data remains locked after the malicious payload is deleted.
While regular data backups are the only secure method to recover your files after a ransomware attack, tools such as can also be effective and restore at least some of your lost data.
Questions about Montserrat ransomware
How do I open .encrypted files?
You cannot open them by renaming or with another program, because the content of files ending in .encrypted has been encrypted. The only ways back are a working decryptor for the family, or clean copies from elsewhere:
- OneDrive versions
- File History
- an offline backup drive
- Previous Versions if the ransomware did not delete them
Identify the family first by uploading the ransom note and one encrypted file to ID Ransomware or No More Ransom. Avoid websites and programs that promise to open any encrypted file; they do not work and some are scams.
Should I pay the ransom in the ransom note?
Not before you have tried everything else. Identify the family from the ransom note and one encrypted file, check No More Ransom for a free decryptor, and look for clean copies in OneDrive, backups and Previous Versions.
Paying funds further attacks, may be illegal if the group is sanctioned, and is no promise of a working key: many victims get partial or broken decryption. If you consider paying for business-critical data, involve the police and a professional incident responder first, and never pay through intermediaries who promise their own decryption.
How did Montserrat ransomware get on my computer?
The way Montserrat 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 .encrypted 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 there a free Montserrat ransomware decryptor?
We last checked on 7 October 2026, and for Montserrat 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 "Montserrat 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.
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.
Did Montserrat ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by Montserrat ransomware, but the only confirmed sign is files that end in .encrypted 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 Montserrat 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.
Should I open the ransom note?
Reading it is fine if you open it in Notepad. A plain text the ransom note cannot harm the PC. Be careful with notes in HTA or HTML format: double-clicking those runs them in a window that can contain scripts, so right-click and choose Open with > Notepad instead.
The note tells you the contact addresses, the claimed amount and the deadline. Do not visit links or write to the addresses from this PC. Use the note to identify the family and check for a free decryptor first.
My files got .encrypted overnight. What happened?
Ransomware often runs at night or when the PC is idle, so the encryption finishes before anyone notices. It usually entered earlier through a cracked program, a fake installer, an e-mail attachment or remote desktop with a weak password.
The .encrypted extension marks every file it reached. Start by disconnecting the PC from the network, then identify the family from the ransom note and one encrypted file, check for a decryptor, and look for copies in backups and OneDrive before you consider anything else.
Will Fortect remove Montserrat 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 Montserrat 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
- Virus Total: 46 engines detected this file (read October 7, 2026)
- Wikipedia: Advanced Encryption Standard (read October 7, 2026)
- LosVirus: LosVirus.es (read October 7, 2026)
- CISA: StopRansomware (read October 7, 2026)
- No More Ransom (read October 7, 2026)