Mount Locker ransomware: what it is and how to remove it
Mount Locker ransomware is a newly detected threat that locks all files in the device and is designed to demand money to be paid for the return. Once a malicious program manages to perform its doings on a targeted device, it will block your access to stored files on the computer and enforce you to contact cybercriminals and pay a specified ransom fee to get those data decrypted.
Facts checked October 6, 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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Mount Locker ransomware: summary
| Distribution | This malware comes from infected email attachments, torrent websites, pirated software, game cheats, cracks |
|---|---|
| Name | Mount Locker ransomware |
| Type | File locking virus, cryptovirus, malware |
| Issues | This virus is using an encryption algorithm to lock all personal files on the infected device. The victim can't open any encrypted file and gets encouraged to pay the ransom for such an opportunity |
| File extension | Each of the files gets random extension (f. e. .C77BFF8C). These files are encrypted and cannot be opened or used without decryption |
| Ransom note | A file named RecoveryManual.html is dropped for victims to inform people about virus behavior and possible steps to this problem. Hackers state that the only solution is to pay the ransom |
| 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 13 more facts
| File recovery | Data recovery might be impossible if you don't have backups. However, in some cases, official decryption tools or third-party programs recovery software can be useful |
|---|---|
| Malware removal | Remove Mount Locker ransomware by scanning your device with a powerful anti-malware application. |
| Detection names | No Microsoft detection name is known |
| Contact | Not recorded in our earlier report |
| Encrypted file extension | .readmanual |
| Decryptor | No free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates |
| Damage | Not recorded in the old report |
| Symptoms | Files renamed with a new extension and a ransom note left in folders |
| Evidence | 4 write-ups by security sites; no sample analysed yet |
| Encrypted files | .readmanual |
| Free decryptor | No free decryptor is known (checked 6 October 2026) |
| First seen | 29 September 2020 |
| Facts checked | 6 October 2026 |
Names and addresses to look for
- File extension:
.readmanual - Note file:
RecoveryManual.html
How Mount Locker ransomware behaves
From our report of Sep 2020 · not reviewed since
Mount Locker ransomware - a malicious infection that encrypts all files and tries to demand money from its victim
Mount Locker ransomware is a newly detected threat that locks all files in the device and is designed to demand money to be paid for the return.
Once a malicious program manages to perform its doings on a targeted device, it will block your access to stored files on the computer and enforce you to contact cybercriminals and pay a specified ransom fee to get those data decrypted. The infection primarily targets business entities trying to get a huge amount of money from them.
Moreover, the cybercriminals behind the Mount Locker virus are using a whole range of sly tactics and a series of transmitters that often appear harmless and intriguing and can confuse even cybersecurity experts. Such a threat is a really serious problem and can cause a lot of damage to the victim because it can prevent access to very valuable digital information in the infected device.
Mount Locker virus mostly gets installed on a device through email attachments received from hackers. Cybercriminals disguise the email and attachment with hidden malicious codes and create the email letter in such a manner that it all seems received from the organization with a good reputation.
But once such attachments are opened, the ransomware codes secretly start to run in the background and scans the system to find some required settings, details of stored files inside, active security programs on the device, and etc. After that, the malware starts the encryption process for all stored files on the computer and appends files with a random extension like .ReadManual.C77BFF8C that got used with analyzed samples.
If your device is infected, it is important to get rid of the Mount Locker virus before you try to do anything else to fix the damage. If you don't do that, the virus may keep encrypting new files that you create or data that you managed to recover from encryption. Also, it may prevent you from using your device normally.
Hackers are using a strong encryption algorithm, and the decryption key typically is different for all users. Therefore, only criminals behind the Mount Locker ransomware have the right decryption key/software. Unfortunately, if you don't have backups, it may be impossible to recover your files. But it is still not recommended to pay criminals.
Moreover, your backup sources or other devices will be unsafe too if they are connected to the infected computer. The virus may encrypt them, and you won't be able to use these devices to restore your information.
It is clear that losing the backup access to your personal data can lead to a serious loss because the Mount Locker virus encrypts personal videos, images, documents, projects, audio recordings, and all other essential files.
If you want to prevent installed infection from encrypting more files, you should uninstall the virus. Although already encrypted files will remain encrypted even after Mount Locker ransomware removal, your new files will be safe and untouched by this threat.
After the Mount Locker virus termination, you may recover your data from backups. If you have them, you will avoid data loss. This is why it is recommended to always have your files backed up. You should store data on a remote server or unplugged storage device in the future.
In the future, you should be really careful with emails you are opening and websites you are visiting and use reliable anti-malware software.
The Mount Locker ransomware note
Your ClientId:
-
/!\ YOUR COMPANY' NETWORK HAS BEEN HACKED /!\
All your important files have been encrypted and copied to our private servers!
ANY ATTEMPT TO RESTORE YOUR FILES WITH THIRD-PARTY SOFTWARE WILL PERMANENTLY CORRUPT IT.
DO NOT MODIFY ENCRYPTED FILES.
DO NOT RENAME ENCRYPTED FILES.
But keep calm! There is a solution for your problem!
For some money reward we can decrypt all your encrypted files.
Also we will delete all your private data from our servers.
To prove that we are able to decrypt your files we give you the ability to decrypt 2-3 files for free.
So what is you next step ? Contact Us! Contact us for price and get decryption software.
hxxp://6mlzahkc7vejytppbqhqjou4ipftgs3gizof2x4zklblliayhsqb3wad.onion/?cid= a7fb00164f192687eda014cd1bde83252ad9ac2fdc89a26b1294b11918d6fe33
* Note that you need installed Tor Browser to open this kind of links.
Follow the instructions to install/run Tor Browser:
1. Go to Tor Project using your default browser.
2. Click "Download Tor Browser", choose version depends on you operation system, usually it is Windows. Download and install it
3. After installation you will see new folder on your desktop: "Tor Browser". Open this folder and run "Start Tor Browser" link.
4. Using Tor Browser go to hxxp://6mlzahkc7vejytppbqhqjou4ipftgs3gizof2x4zklblliayhsqb3wad.onion/?cid= a7fb00164f192687eda014cd1bde83252ad9ac2fdc89a26b1294b11918d6fe33
5. Carefully copy your client id from this document and paste it into Authorization window in opened page. Click 'OK'.
6. After that you will see a special chat web application to comminicate with us.
7. NB! Please be patient - sometimes our support team can be away from the keyboard but they will answear you as soon as possible! Time is Money! Contact us as soon as possible.
We won't store you decryption key forever!
How to remove Mount Locker 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 Mount Locker 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
Unplug the network cable or turn off Wi-Fi, and disconnect USB drives, external disks and network shares, so Mount Locker ransomware cannot reach more files. Pause OneDrive, Google Drive or Dropbox sync, because synced folders upload the encrypted copies over the good ones.
Leave the PC on but offline while you read the next steps, since a restart can let the ransomware run again. This applies to Windows 11 and Windows 10 alike.
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
Your files now end in
.readmanualand the instructions are inRecoveryManual.html. Save both to a USB stick, a copy of the note and two small encrypted files, before anything else.On another device, check them with ID Ransomware or Crypto Sheriff: the family name decides which decryptor, if any, can help. Keep the note's ID and contact line for your report.
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
Our last check found that for Mount Locker ransomware, no free decryptor is known (checked 6 October 2026). Look again yourself in the No More Ransom list and the free decryptor pages of Emsisoft, Avast and Kaspersky, which add new families every year.
A decryptor needs the ransomware gone first, or it encrypts the files again. Keep at least one copy of the encrypted files on an external drive, even if no tool works yet.
Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files
Step 4: Remove the ransomware before you restore or decrypt
Removing Mount Locker ransomware does not bring the files back, but it has to come first. Start with Defender's Full scan, then the offline scan from the same Scan options page, which checks the disk before Windows loads.
If the scan cannot start, use Safe Mode with Networking. Delete the ransom notes only after you have saved a copy, because removal tools sometimes leave them behind on Windows 11 and 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
Windows keeps shadow copies for restore points and backups, and some ransomware fails to delete them.
vssadmin list shadowsin an administrator Command Prompt tells you at once whether any exist.If they do, right-click the folder that held your files, open Properties > Previous Versions, select a version from before the attack, and click Open to check it before you Restore or copy the files out. Windows 11 and Windows 10 both have the tab.
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
A backup made before the attack is the surest way back. Connect it only once the PC is clean, then restore from File History, Windows Backup, OneDrive's Restore your OneDrive or your own external copies.
Without a backup, try file recovery: the originals that Mount Locker ransomware deleted may still be on the disk until something overwrites them. Install nothing new on the drive you want to recover from on the Windows 11 or Windows 10 PC.
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 Sep 2020 · not reviewed since
Paying the criminals is not the option to recover encrypted files
The Mount Locker ransomware virus encrypts a wide variety of digital files.
It is important to understand that encryption is usually not reversible unless a special decryption key is applied. Hackers always give victims a ransom note to inform about the ransomware and decryption method.
Sadly, the ransom note tells you only one possible step to take your files back. Mount Locker virus creators state that the only solution is to pay money. But security experts say that it is unwise to give money for the criminals because most likely they won't decrypt files even after the ransom money is in their pocket.
If you are curious about how a ransom note named as "RecoveryManual.html" looks, there is the example (the URL can be different):
Typically, all ransom notes are similar. Criminals try to scare their victims by putting tight deadlines, asking for money, and promising that they send a secret decryption key as long as the victims do everything according to the plan. Mount Locker virus creators shouldn't be trusted, remember that.
Malicious actors even give the website that can be used to upload a few files for free test decryption. This way cybercriminals try to persuade the victim that all files can be decrypted if they pay the required amount of money. MountLocker ransomware is not decryptable, so you should either wait for the official tool release or rely on other methods.
In reality, there is no guarantee that even if you satisfy all requirements the decryption code will be granted to you. Hackers can always disappear without sending anything in exchange or even ask for more money. That's why the best decision is to remove the Mount locker ransomware from the device and look for possible alternatives instead of doing everything that anonymous blackmailers want you to do.
And if you are still wondering how Mount Locker ransomware did infect your computer, it is important to remember that typically malware gets installed through untrustworthy software or file download sources, trojans, email spam campaigns, unofficial, fake software updating tools, and software "cracking tools.
If you want to avoid any damage to your computer, you should stop installing unofficial software. You must be especially cautious with emails you get because malicious files can be downloaded by the attached file or downloaded via a given website link.
From our report of Sep 2020 · not reviewed since
Removing Mount Locker ransomware from your device is important before you can rely on file-recovery options
Ransomware can be a really serious problem.
As we already recommended, you should make a copy of all your files and use a different place to store them. If you have backups, get rid of the Mount Locker ransomware virus as soon as possible.
This step won't give your encrypted files back, but it protects new files. Only after the Mount Locker ransomware removal, you may try to recover your data from backups.
Moreover, ransomware or other threats sometimes can cause serious damage to your device OS. In some cases, you will even need to reinstall it.
After you remove Mount Locker ransomware, you may try to recover your data. Unfortunately, if none of the methods below help, there is no other way to recover encrypted files at the present time. Nevertheless, keep in mind that paying cybercriminals is always risky, and they don't decrypt files in most cases too.
[GI=method-1]To delete Mount Locker ransomware with Safe Mode, you need to perform this procedure on your device.
[GI=method-2]Sometimes, System Restore can be useful when you are trying to eliminate ransomware.
You can use the built-in Previous Version Feature in Windows.
It is possible to recover files one-by-one if you had System Restore point prepared before the ransomware attack.
Recover your files with ShadowExplorer
If the Mount Locker file virus failed to delete Shadow Volume copies, it is possible to recover data by using ShadowExplorer.
MountLocker ransomware is not decryptable
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.
Protect the files you restore
Restore only after the scans are clean and the PC no longer shows files that end in .readmanual and no longer open; otherwise the restored copies can be damaged again.
Then build a backup that survives the next infection:
- one copy in the cloud with version history
- one on an external drive that is disconnected between backups
- the working copy on the PC
Version history matters because a backup that syncs damaged files overwrites the good ones.
How to do this with the tools built into Windows: the 3-2-1 backup rule on Windows.
Access your website securely from any location
When you work on the domain, site, blog, or different project that requires constant management, content creation, or coding, you may need to connect to the server and content management service more often. The best solution for creating a tighter network could be a dedicated/fixed IP address.
If you make your IP address static and set to your device, you can connect to the CMS from any location and do not create any additional issues for the server or network manager that needs to monitor connections and activities. VPN software providers like can help you with such settings and offer the option to control the online reputation and manage projects easily from any part of the world.
Recover files after data-affecting malware attacks
While much of the data can be accidentally deleted due to various reasons, malware is one of the main culprits that can cause loss of pictures, documents, videos, and other important files.
More serious malware infections lead to significant data loss when your documents, system files, and images get encrypted. In particular, ransomware is is a type of malware that focuses on such functions, so your files become useless without an ability to access them.
Even though there is little to no possibility to recover after file-locking threats, some applications have features for data recovery in the system. In some cases, can also help to recover at least some portion of your data after data-locking virus infection or general cyber infection.
Questions about Mount Locker ransomware
How do I open .readmanual files?
You cannot open them by renaming or by choosing another program. The .readmanual ending shows that Mount Locker 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 Mount Locker ransomware. Store the encrypted files on an external disk until then.
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.
Is there a free Mount Locker ransomware decryptor?
We last checked on 6 October 2026, and for Mount Locker 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 "Mount Locker 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.
How did Mount Locker ransomware get on my computer?
The way Mount Locker 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 .readmanual 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.
Did Mount Locker ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by Mount Locker ransomware, but the only confirmed sign is files that end in .readmanual 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 Mount Locker 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 .readmanual from the file names?
You can try it on a copy, but for real ransomware it will not help. The .readmanual 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 RecoveryManual.html?
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. RecoveryManual.html 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 Mount Locker 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 Mount Locker 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
- Trend Micro: What is Ransomware? (read October 6, 2026)
- Wikipedia: Encryption (read October 6, 2026)
- Odstranit Virus: Odstranit Virus (read October 6, 2026)
- CISA: StopRansomware (read October 6, 2026)
- No More Ransom (read October 6, 2026)