Mkos ransomware: what it is and how to remove it
Mkos ransomware - cryptovirus that locks data and ensures that you cannot find a solution by modifying hosts file to block cybersecurity sites. This is the threat that can make many setting changes and alterations on the machine to ensure persistence.
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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Mkos ransomware: summary
| Distribution | This STOP virus strain is known to use pirated software packages for spreading the ransomware script mainly. Cheatcodes of videogames, licensed versions of legitimate software and other files include the direct payload of the virus and during the installation of the said applications ransomware ends up on the system |
|---|---|
| Name | Mkos ransomware |
| Danger | This is a highly dangerous threat because it involves money extortion and permanent data or even device damage. Cybercriminals that distribute the malware focus on getting money and don't care about victims or their belongings, so any contact with these people can lead to privacy issues or damaged machine |
| File marker | .mkos is the appendix that appears on every encrypted file as an indication of locking |
| Ransom note | _readme.txt – a file that contains the ransom-demanding message and victims' ID needed for the file decryption and contact information |
| Ransom amount | $980/$490 |
| 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
| Contact emails | datarestorehelp@firemail.cc, datahelp@iran.ir |
|---|---|
| Detection names | No Microsoft detection name is known |
| Encrypted file extension | .mkos |
| 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 | 4 write-ups by security sites; no sample analysed yet |
| Encrypted files | .mkos |
| Attacker contacts | datarestorehelp@firemail.cc |
| Free decryptor | No free decryptor is known (checked 6 October 2026) |
| First seen | 30 December 2019 |
| Facts checked | 6 October 2026 |
- File extension:
.mkos - Note file:
_readme.txt - Contact:
datarestorehelp@firemail.cc
From our report of Dec 2019 · not reviewed since
Mkos ransomware is the threat that is designed to show a fake Windows update window to mask the encryption process
Mkos ransomware - cryptovirus that locks data and ensures that you cannot find a solution by modifying hosts file to block cybersecurity sites.
This is the threat that can make many setting changes and alterations on the machine to ensure persistence. Even though the most intrusive and noticeable symptoms are file encryption and system slowness, malware masks this procedure by showing a fake Windows update window that notifies the progress of such a process.
Djvu ransomware is the family that this Mkos ransomware belongs to, unfortunately. The strain is known for a while as one of the most active and dangerous in the field of crypto-extortion based malware.
For a while, some of the versions were decryptable, and people were able to get their files recovered due to the use of offline keys and flaws in coding and STOPDecrypter. However, developers updated their methods and started using the proper AES encryption algorithm to ensure that every version that goes out is persistent.
Due to all the updates and changes, victims of the notorious Mkos ransomware virus have much fewer options when it comes to the data recovery or malware removal and system cleaning. The online keys that mainly get used right now are unique for each user, and people that get a ransom note in the text file named _readme.txt also receive their victim IDs needed for identification.
Unfortunately, decryption can only happen when those keys are known. The particular Djvu decryption tool only works with files affected using offline keys - variants released before August 25th of 2019. People affected by the .mkos version are less lucky, but it is possible to store encrypted data and wait for the decryption tool updates or coding changes.
When you get a ransom message in the _readme.txt file, and Mkos ransomware developers deliver you the demanding text, you should note if the victims' ID provided for you has t1 at the end or not.
This is an indication that the offline key got used to encrypt your device and allows the decryption to happen. If so, you might be lucky and get your files restored with the help of the Emsisoft decryption tool. (you can found it here)
The Mkos virus ransom message states the following:
Those altered versions that came out early 2019 and Mkos ransomware or .merl, .piny, .redl, .nbes variants are pretty much identical because only a few features of the code and file markers are unique for each virus. Such details like a ransom note name, text in the file, or ransom amount, contact emails, and all the claims remain the same for a while.
These facts that Mkos ransomware virus developers are not changing much about each version shows how dangerous and complex the threat already can get in the future. Unfortunately, this also means that victims of the threat can't fight the virus easily. It was a period when malware researchers could recover files using a particular decryption tool, but not anymore.
Other options for Mkos ransomware decryption can be:
Since there is little to no possibility of decrypting these files affected by the malware, you need to focus on Mkos ransomware removal and system recovery. You cannot use the machine properly and safely if the virus is not eliminated completely from the system.
However, this is not that easy because of the additional Mkos ransomware features that allow the threat to interfere with particular system settings and modify or even disable functions of the machine, add or remove programs and keep the computer running as it is needed for the virus developers.
You need to remove Mkos ransomware as soon as possible because such alterations can lead to permanent damage on the device and loss of money or crucial system and personal data. The malware adds various entries to the Windows hosts file with URLs of sites like this that provide you tips for virus removal and other news on the topic of cybersecurity.
This is done to prevent victims from finding decryption options and accessing websites where malware researchers offer help. You can try to remove such entries, clean Windows registry entries, and other damage that Mkos ransomware leaves behind, but experts recommend relying on PC repair tools instead. Programs like might find and fix corrupted system files and repair the damage.
However, nor anti-malware tools needed for Mkos ransomware termination, nor system cleaning utilities can restore encoded data for you. Nevertheless, you need to repair the crucial files, remove all the malicious data and the virus itself before you even try to recover affected photos, videos, or documents.
The best and safest option is to replace encrypted files with safe copies from external devices or cloud storage, but we have a few alternate methods listed below the article with a few AV software suggestions too.
- waiting for the decryption tool developed by researchers;
- relying on malware experts that can recover files using the offline victims' ID;
- file pair usage when the identical data can be analyzed and a way to recover the particular type of the file is found;
- file backups stored on the external devices where malware cannot reach during the initial encryption.
From our report of Dec 2019 · not reviewed since
More from our earlier report on Mkos ransomware
- You need to remove Mkos ransomware even when you can't recover encrypted files.
- Anti-malware tools can clean all the traces of the malware and detect the malicious activity of the virus.
- Then you can replace affected data using your backups
- Virus files can be eliminated, and the behavior stopped, but the damage is left behind even after the proper AV scan on the PC.
- System repair tools like might find and even fix system files damaged by the malware, so you don't need to worry about the corrupted machine
How Mkos ransomware behaves
From our report of Dec 2019 · not reviewed since
Malicious ransomware heavily promoted via pirated software and shady emails
When software cracks get installed, the main installer file gets loaded in the LocalAppData folder, and the executable file automatically is launched.
Once that is done, ransomware components also get triggered. Once the core payload is loaded and executed, malware can freely run on the system.
PowerShell scripts can get launched automatically, and the victim is not even noticing the infiltration and the encryption until those locked files get marked using a particular appendix. Such malicious payload can also get installed using email attachments and the help of spam email campaigns.
Emails that raise questions should be deleted once received and those file attachments examined before downloaded. The best option would be to clean emails that you are not expecting to get once they end up on the email box. Also, paying attention to sources where you get any programs and software is crucial. Pirated content can easily spread malicious programs like trojans, not only unwanted applications like adware or hijackers.
The Mkos ransomware note
ATTENTION!
Don't worry, you can return all your files!
All your files like photos, databases, documents and other important are encrypted with strongest encryption and unique key.
The only method of recovering files is to purchase decrypt tool and unique key for you.
This software will decrypt all your encrypted files.
What guarantees you have?
You can send one of your encrypted file from your PC and we decrypt it for free.
But we can decrypt only 1 file for free. File must not contain valuable information.
You can get and look video overview decrypt tool:
hxxps://we.tl/t-Be28TGxMAy
Price of private key and decrypt software is $980.
Discount 50% available if you contact us first 72 hours, that's price for you is $490.
Please note that you'll never restore your data without payment.
Check your e-mail "Spam" or "Junk" folder if you don't get answer more than 6 hours.
To get this software you need write on our e-mail:
datarestorehelp@firemail.cc
Reserve e-mail address to contact us:
datarestore@iran.ir
Your personal ID:
How to remove Mkos 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 Mkos 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 Mkos 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
.mkosand the instructions are in_readme.txt. 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 Mkos 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 Mkos 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 Mkos 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 Dec 2019 · not reviewed since
Eliminate Mkos cryptovirus to get the system virus-free before data recovery
Don't forget that Mkos ransomware virus is the version of a notorious threat and can perform more changes than you imagine or notice.
This is the threat that you need to eliminate fully from the system to ensure that there is no risk to damage anything else. If you wait too long, the virus can damage and modify essential settings of the device.
To remove Mkos ransomware and end the malicious behavior, you need to get anti-malware tools that can detect such infection and clean it off of the machine. and should scan the machine fully and indicate anything suspicious, so you then decide what is going to be terminated.
After such Mkos ransomware removal procedure should follow the virus damage elimination and file recovery processes, even though that is not easy too. We can recommend for system data repairing and since such cleaners can indicate any system files requiring damage control. As for data recovery, follow the options below if you don't have reliable backups.
[GI=method-1]Remove Mkos ransomware by entering the Safe Mode which allows running AV tools without interuption
[GI=method-2]You can rely on System Restore feature because this function clears the system to a certain point when the virus was not present
Windows Previous Versions feature offers an alternate version for file recovery
When System Restore gets enabled, you can use Windows Previous Versions for data restoring purposes
ShadowExplorer can restore some files
However, Shadow Volume Copies should be untouched for this method to work
There are some options for decryption
This topic in the forum has all the updates of decryption possibilities
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 .mkos 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.
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 Mkos ransomware
How do I open .mkos files?
You cannot open them by renaming or with another program, because the content of files ending in .mkos 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.
Is there a free Mkos ransomware decryptor?
We last checked on 6 October 2026, and for Mkos 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 "Mkos 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.
Are ransomware recovery services legitimate?
Some are, but read the offer carefully. Genuine data-recovery firms recover deleted originals from disks or rebuild damaged files, and they say so. Others promise to "decrypt any ransomware" for a fixed price, which is impossible without the key; they quietly pay the attackers and keep a margin, sometimes without telling the victim.
Be especially careful with services that contact you after you post about the attack online. Ask for references, a written method and a no-result-no-fee clause, and check the free tools on No More Ransom first.
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.
How did Mkos ransomware get on my computer?
The way Mkos 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 .mkos 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 Mkos ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by Mkos ransomware, but the only confirmed sign is files that end in .mkos 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 Mkos 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 _readme.txt?
Reading it is fine if you open it in Notepad. A plain text _readme.txt 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 .mkos 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 .mkos 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 Mkos 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 Mkos 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
- Wikipedia: AES encryption algorithm (read October 6, 2026)
- Virustotal: Malware detection rate (read October 6, 2026)
- Virusai: Virusai (read October 6, 2026)
- CISA: StopRansomware (read October 6, 2026)
- No More Ransom (read October 6, 2026)