CryptoJoker 2021 ransomware: what it is and how to remove it
Upon accessing a Windows computer without giving prior warning, CryptoJoker 2021 ransomware locks all personal files and then demands a ransom to be paid for their recovery. This variant of malware showed up in late October and seems to be infecting home users around the world.
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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CryptoJoker 2021 ransomware: summary
| Name | CryptoJoker 2021 ransomware |
|---|---|
| Type | Cryptovirus, ransomware, data-locking malware |
| Malware family | CryptoJoker |
| Encryption method | A combination of AES and RSA encryption algorithms used to lock files |
| File extension | Each of the affected files is appended with the .partially.[encrypter@tuta.io].encrypted extension |
| Ransom note | how to decrypt my files.txt; the text is quoted in full below |
| 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 | encrypter@tuta.io |
|---|---|
| File Recovery | If no backups are available, recovering data is almost impossible. Nonetheless, we suggest you try the alternative methods that could help you in some cases – we list them below |
| Detection names | No Microsoft detection name is known |
| Encrypted file extension | .partially |
| Decryptor | No free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates |
| Distribution | Not recorded in the old report |
| 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 | .partially |
| Free decryptor | No free decryptor is known (checked 7 October 2026) |
| First seen | 26 October 2021 |
| Facts checked | 7 October 2026 |
- File extension:
.partially - Note file:
the ransom note
From our report of Oct 2021 · not reviewed since
More from our earlier report on CryptoJoker 2021 ransomware
- To remove malware automatically, use security software
- Malware can seriously tamper with Windows systems, causing errors, crashes, lag, and other stability issues after it is terminated.
- Free Ransomware Decryptors by Kaspersky
How CryptoJoker 2021 ransomware behaves
From our report of Oct 2021 · not reviewed since
CryptoJoker 2021 ransomware is a type of malware that could result in loss of files and money
Upon accessing a Windows computer without giving prior warning, CryptoJoker 2021 ransomware locks all personal files and then demands a ransom to be paid for their recovery.
This variant of malware showed up in late October and seems to be infecting home users around the world.
As evident, ransomware does not provide any warning before it breaches the PC, and by the time users notice changes it is already too late. Upon entry, the virus performs a variety of changes to the system before it proceeds with its main goal, as otherwise, the built-in Windows defenses would not let the infection spread.
Using a combination of sophisticated algorithms AES and RSA, ransomware encrypts documents, pictures, videos, and all other data on the computer (note that the virus excludes several locations and file types on the system in order to allow it to run). During this time, each of the files receives an extension ".partially.[encrypter@tuta.io].encrypted" and also loses the original icon.
Suchlike data can no longer be accessed or modified and requires a decryption key to be operatable once again. Of course, the attackers are not willing to provide a decryption tool for free, but they are willing to sell it for an unspecified amount of money to be paid in Bitcoin cryptocurrency. The attackers ask victims to send an email to encrypter@tuta.io to negotiate the precise sum to be paid.
We don't recommend contacting malware authors and paying the ransom, as they could simply never send you the needed decryption tool. In fact, there is a free decryptor that worked for some victims of the CryptoJoker 2021 virus. Likewise, there are several alternative methods you could try - we list them all below.
Malware has been created at a more rapid pace the further the technologies evolve. The illegal business of ransomware, in particular, has been on the rise for the past few years, even though we did see the shut down of very prominent malware families such as Clop.
Likewise, the attacks against home users are also rising. With ransomware strains such as Djvu, which infects hundreds of users daily, it became more and more lucrative for the attackers to evolve their attacks and infect more users with every malware version. Luckily, security experts create more advanced solutions for users and try to spread awareness of ransomware infections.
The original version of CryptoJoker was released back in December 2015, when ransomware began to be a more widespread phenomenon, as crooks saw its potential in making easy money. The ransom note used to be written in English and Russian, although more recent versions of malware use the former only. In this case, the message reads as follows:
As per usual, the attackers give several warnings about not removing malware or trying to decrypt files - which is in their best interest, as they are trying to sell victims the keys. Security experts recommend ignoring these requests (we provide alternative methods for data recovery below).
Seeing how the threat evolved over the years, it does not seem that its operators will stop any time soon. If you have been a victim of ransomware, proceed with the steps in order to delete it from your system, attempt to recover files, and remediate your system effectively.
From our report of Oct 2021 · not reviewed since
Use anti-malware software
The first thing to do is not to panic, as it won't bring anything positive to the situation.
In fact, the incorrect steps could make matters worse. The first step is to make sure that all malware and its traces are eliminated from the infected computer with the help of security software such as or .
Since the CryptoJoker 2021 virus might tamper with your anti-malware software, it might be difficult to get rid of it in the normal mode. In such a case, you should access Safe Mode and perform a full system scan from there:
Windows 7 / Vista / XP
Windows 10 / Windows 8
- Click Start > Shutdown > Restart > OK.
- When your computer becomes active, start pressing the 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.
- Right-click on the Start button and select Settings.
- On the left side of the window, pick Recovery.
- Click Restart now.
- Select Troubleshoot.
- Go to Advanced options.
- Select Startup Settings.
- Click Restart.
- Press 5 or click 5) Enable Safe Mode with Networking.
From our report of Oct 2021 · not reviewed since
Make data backups
There are two situations you might find yourself in - you either have working backups for your files, or you don't.
If you do have copies of the working files, you can skip this and the next step. However, most users don't, and it is a problem.
While it is too late to reverse anything, you should ensure that you copy all the important files onto a separate medium, such as USB flash; otherwise, files might be permanently corrupted during the recovery attempts. Locked data does not carry any malicious code within it, so it is safe to transfer.
If you wish to learn how to back up your files correctly on widely accessible platforms, you should check the instructions at the bottom of this post. Data backups are crucial for repelling any ransomware attack in the future, as it removes the need to hope that there's a working decryptor available or that the files can no longer be recovered at all.
The CryptoJoker 2021 ransomware note
hello !!! all your data is encrypted..
and for decrypt it you need a key..
if you want to return your data :
contact us whit this email :
encrypter@tuta.io
warning : please be careful if you try decrypt it
yourself or change windows or every things
you may damage it and damage the some hidden
necessary decryption files
How to remove CryptoJoker 2021 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 CryptoJoker 2021 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 CryptoJoker 2021 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
.partiallyand the instructions are inthe ransom note. 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 CryptoJoker 2021 ransomware, no free decryptor is known (checked 7 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 CryptoJoker 2021 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 CryptoJoker 2021 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.
Create data backups to avoid file loss in the future
Report the incident to your local authorities
Ransomware is a lucrative, highly illegal business, and authorities are actively targeting ransomware operators. The level of investigation and follow-up depends on the country, the scale of the incident, and whether the attack is linked to known ransomware groups. To increase the likelihood of identifying the culprits, the agencies need information. In many cases, reports are used primarily for intelligence gathering, trend analysis, and victim support rather than immediate identification of attackers.
Therefore, by reporting the crime, you could help stop the cybercriminal activities and catch the threat actors. Reporting does not guarantee investigation or recovery of data, but it contributes to broader efforts to track ransomware campaigns. Make sure you include all the possible details, including how did you notice the attack, when it happened, etc. Relevant details may also include affected systems, ransom demands, cryptocurrency wallet addresses, and any communication with the attackers. Additionally, providing documents such as ransom notes, encrypted files, or malware executables would be beneficial.
Law enforcement agencies typically deal with online fraud and cybercrime, although it depends on where you live. Here is the list of local authority groups that handle incidents like ransomware attacks, sorted by country:
- USA - Internet Crime Complaint Center IC3
- United Kingdom - ActionFraud
- Canada - Canadian Anti-Fraud Centre
- Australia - ScamWatch
- New Zealand - ConsumerProtection
- Germany - Polizei
- France - Ministère de l'Intérieur
If your country is not listed above, you should contact the local police department or communications center.
From our report of Oct 2021 · not reviewed since
File recovery options
Unfortunately, ransomware victims rarely know what this infection actually is and have plenty of misunderstandings about how it works.
Some people believe that they can restore their files by simply scanning with anti-malware software, while others think that their files have been simply corrupted. None of these statements are actually true in this case.
Data encryption is a secure way of using complex passwords that are unique for each individual. The generated key is sent to the attackers as soon as ransomware is finished with the data-locking process. Thus, victims can't share the same decryptor and retrieve data for free. This is precisely why ransomware is so devastating.
Security software is designed to remove all the malicious files and modules from the system and ensure that the infection is no longer active on the device. It is simply not designed for the file decryption process, although there are other automatic solutions that could be useful in this case.
From our report of Oct 2021 · not reviewed since
1. Try recovery software
Data recovery software might be able to help you in some situations (it highly depends on the encryption algorithm used, whether ransomware managed to complete the programmed tasks, etc.).
Since there are thousands of different ransomware strains, it is immediately impossible to tell whether third-party software will work for you.
Therefore, we suggest trying regardless of which ransomware attacked your computer. Before you begin, several pointers are important while dealing with this situation:
Install data recovery software
- Since the encrypted data on your computer might permanently be damaged by security or data recovery software, you should first make backups of it - use a USB flash drive or another storage.
- Only attempt to recover your files using this method after you perform a scan with anti-malware software.
- Download .
- Double-click the installer to launch it.
- Follow on-screen instructions to install the software.
- As soon as you press Finish, you can use the app.
- Select Everything or pick individual folders where you want the files to be recovered from.
- Press Next.
- At the bottom, enable Deep scan and pick which Disks you want to be scanned.
- Press Scan and wait till it is complete.
- You can now pick which folders/files to recover - don't forget you also have the option to search by the file name!
- Press Recover to retrieve your files.
From our report of Oct 2021 · not reviewed since
2. Search for a free decryptor
A decryption tool for CryptoJoker exists, although its effects on the newest versions of malware are not fully clear yet.
In order words, the decryption might or might not be successful when used on the encrypted files. You can download the decryptor and try running it on your machine.
Likewise, there are plenty of websites that could be useful when looking for a decryption tool. Security researchers from various IT companies are working hard to battle ransomware and sometimes manage to create working decryption tools, letting victims recover files for free. Thus, use the following places to check for new tools that could be available in the future:
- No More Ransom Project
- Free Ransomware Decryption Tools from Emsisoft
From our report of Oct 2021 · not reviewed since
3. Pay cybercriminals
This option is very controversial and is discouraged by security researchers and agencies.
We also advise you to avoid this option unless absolutely necessary. Keep in mind that crooks might ask for further payments, send you a fake or broken decryptor, or never contact you after you transfer money. Remember, they are not your friends - even if they might try acting friendly - and you can never trust them.
From our report of Oct 2021 · not reviewed since
Remediate Windows
Malware can cause tremendous damage to Windows systems to the point where a full reinstallation could be required.
For example, an infection can alter the Windows registry database, damage vital bootup, and other sections, delete or corrupt DLL files, etc. Antivirus software can't repair damaged files, and a specialized app should be used instead.
- Download
- Click on the ReimageRepair.exe
- If User Account Control (UAC) shows up, select Yes
- Press Install and wait till the program finishes the installation process
- The analysis of your machine will begin immediately
- Once complete, check the results - they will be listed in the Summary
- You can now click on each of the issues and fix them manually
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 .partially 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 CryptoJoker 2021 ransomware
How do I open .partially files?
You cannot open them by renaming or with another program, because the content of files ending in .partially 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 CryptoJoker 2021 ransomware decryptor?
We last checked on 7 October 2026, and for CryptoJoker 2021 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 "CryptoJoker 2021 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.
Did CryptoJoker 2021 ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by CryptoJoker 2021 ransomware, but the only confirmed sign is files that end in .partially 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.
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 CryptoJoker 2021 ransomware get on my computer?
The way CryptoJoker 2021 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 .partially 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 CryptoJoker 2021 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.
Will .partially spread to my other drives?
It can. Ransomware encrypts every drive and network share it can reach while it runs, so external disks, USB sticks and shared folders connected during the attack may also have files ending in .partially. Disconnect everything now, then check each device from a clean computer.
Do not plug a backup drive into the infected PC until the ransomware has been removed with an offline scan. Cloud folders such as OneDrive sync the encrypted versions, but they keep earlier versions you can usually restore.
Will Fortect remove CryptoJoker 2021 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 CryptoJoker 2021 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
- Precisely: AES vs. RSA Encryption: What Are the Differences? (read October 7, 2026)
- Tech Crunch: Ukranian police arrest multiple Clop ransomware gang suspects (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)