CryptoJoker ransomware: what it is and how to remove it
CryptoJoker is a name of a ransomware virus that damages personal files stored on computers. The virus first emerged in 2016 , but in July 2017, CryptoJoker 2017 ransomware virus emerged.
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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CryptoJoker ransomware: summary
| Detection names | No Microsoft detection name is known |
|---|---|
| Ransom note | Not recorded in our earlier report |
| Contact | file987@sigaint.org, file9876@openmail.cc, file987@tutanota.com |
| Encrypted file extension | .crjoker |
| Decryptor | No free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates |
| Distribution | Not recorded in the old report |
| Removal | Scan the PC with security software to find and remove the malware and anything installed with it. Fortect scans Windows for malware and repairs the system files and settings it damaged. Remove it nowTo use the full-featured product, you have to purchase a license for Fortect. The scan is free. |
Show 9 more facts
| Damage | Not recorded in the old report |
|---|---|
| Name | CryptoJoker ransomware |
| Type | File-encrypting ransomware |
| Symptoms | Files renamed with a new extension |
| Evidence | 4 write-ups by security sites; details still limited |
| Encrypted files | .crjoker |
| Free decryptor | No free decryptor is known (checked 6 October 2026) |
| First seen | 18 July 2017 |
| Facts checked | 6 October 2026 |
- File extension:
.crjoker
From our report of Jul 2017 · not reviewed since
More from our earlier report on CryptoJoker ransomware
- Write to us at mail: file987@sigaint.org Spare mails: file9876@openmail.cc or file987@tutanota.com.
- Instructions for payment will be sent in the opposite letter.
How CryptoJoker ransomware behaves
From our report of Jul 2017 · not reviewed since
CryptoJoker ransomware is a true menace to your computer
CryptoJoker is a name of a ransomware virus that damages personal files stored on computers.
The virus first emerged in 2016 , but in July 2017, CryptoJoker 2017 ransomware virus emerged. Both viruses seek to encrypt files on victim's computer to demand a ransom.
As much as we know, the initial CryptoJoker seeks to infect files with extensions such as .txt, .docx, .doc, .xls, .pdf, .java, .jpeg, .sql, .db, .docm, .odt, .csv, .xlsb, .xlsm, .aspx, .html, .psd, .pptx, .mdb, .sln, .xlsx, and many more. The virus encrypts these files using the AES-256 encryption algorithm. After the file gets encrypted, this ransomware adds a .crjoker extension to the filename.
If you have noticed that your files have changed their names in such way, you should immediately take actions to stop this deadly virus! For that, we STRONGLY recommend using a reputable anti-malware software, for instance, or any other reliable one.
Keep in mind that once CryptoJoker virus encrypts these files, you will not be able to access them anymore. Crypto Joker leaves messages in the folders that hold the encrypted files as .txt or .html documents. The message states that the personal records were encrypted, and to retrieve them, user needs to contact CryptoJoker developers by sending an e-mail letter to them:
As you can see, this terrible computer threat demands to pay a ransom to retrieve the encrypted files back. Surprisingly, this machine threat does not demand a fixed amount of money, and that gives an idea that the cybercriminals are ready for a negotiation.
However, security vendors do not recommend paying the ransom, because there is no guarantee that you will get your files back. Plus, do you wish to support cyber-criminals so that they can continue their knavish activities?
From our report of Jul 2017 · not reviewed since
2017 brings another version of CryptoJoker
In June 2017, malware analysts spotted a CryptoJoker 2017 ransomware virus making rounds on the Internet.
It was dubbed identically as the malware that emerged in 2016, but to distinguish both viruses, a year of the first appearance was added. The ransomware encodes files but experiences problems when trying to corrupt files that are opened by the user.
The ransomware checks .txt and .md files' sizes with FileInfo.Length property, and encrypts large files partially. The virus marks these files with .partially.cryptojoker extensions. For smaller files of the same types, the malware uses a .fully.cryptojoker extension. The rest of files get encrypted partially and get corresponding file extensions.
The developer of the ransomware has published the ransomware code online, stating that it was created "for education purposes only." Such statement is a complete nonsense since script kiddies can quickly take that code and convert the ransomware into a fully working extortion tool. If you accidentally got infected with this ransomware, we strongly suggest using anti-malware software to remove CryptoJoker 2017 as soon as possible.
From our report of Jul 2017 · not reviewed since
Tricks used to spread the ransomware
In most of the cases, this or any other ransomware viruses are distributed via harmful e-mail attachments.
Ransomware is spread like Trojans - mostly, these viruses pretend to be a safe file to convince the user to download and open it. According to VirusActivity research, the described virus is spread as a PDF file. However, you can also infect your computer with this virus by browsing insecure websites or clicking on corrupted links. We have some tips how you should prevent installing CryptoJoker ransomware:
- Do not browse through suspicious web sources - there is a chance you might click on an infected link and download a computer threat without realising that.
- NEVER OPEN e-mails AND attachments from senders that you DO NOT personally know! Also, do not open suspiciously looking e-mails, because some viruses tend to take over victim's e-mail and forward the infected letter to victim's contacts.
- Install software safely. Some programs tend to promote third-party freeware in an indirect way, so you have to be careful when installing new apps. Select either Advanced or Custom installation settings and opt-out any suspicious or unfamiliar attachments.
How to remove CryptoJoker 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 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 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 identify the family
The name of the family decides whether a free decryptor can help. Copy the ransom note and two small encrypted files to a USB stick, and check them on another device with ID Ransomware or Crypto Sheriff.
Note the extension added to the files, the contact address and the victim ID shown in the note. Keep the originals on the Windows 11 or Windows 10 PC untouched.
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 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 CryptoJoker 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 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 Jul 2017 · not reviewed since
Remove CryptoJoker and try existing data recovery tools
You can remove CryptoJoker virus on your own, but you will need to use an anti-malware software to complete this task.
It is highly advisable not to attempt to delete the ransomware manually because you can never know what files and programs it brought into your system. Leave this task for a professional anti-malware tool that can detect potentially dangerous files automatically.
Before you begin CryptoJoker removal procedure, take a look at instructions provided below. They are designed to help you to delete the malware from the system. See, some ransomware viruses are made to block anti-malware programs, and our guide explains how to bypass this obstacle.
[GI=method-1]Use the provided instructions to remove CryptoJoker while in Safe Mode with Networking.
The tool may or may not be capable of restoring them.
Use Volume Shadow Copies
Volume Shadow Copy Service is available on Microsoft Windows. It helps to recover lost, corrupted or damaged files using their previous versions.
Crypto Joker decryption tools are not available yet
Neither CryptoJoker or CryptoJoker2017 have official decryption tools released yet. As soon as they appear on the market, the article will be updated.
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 CryptoJoker 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 .crjoker and no longer open.
Setting it up step by step: 3-2-1 backups on Windows 11 and 10.
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 CryptoJoker ransomware
How do I open .crjoker files?
You cannot open them by renaming or with another program, because the content of files ending in .crjoker 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 ransomware decryptor?
We last checked on 6 October 2026, and for CryptoJoker 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 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.
How did CryptoJoker ransomware get on my computer?
The way CryptoJoker 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 .crjoker 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.
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.
Did CryptoJoker ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by CryptoJoker ransomware, but the only confirmed sign is files that end in .crjoker 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 CryptoJoker 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.
Will .crjoker 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 .crjoker. 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 removing CryptoJoker ransomware unlock my .crjoker files?
No. Removing CryptoJoker ransomware stops it from encrypting more files and from starting again, but it does not decrypt the files that already end in .crjoker. The scanner does not have the attackers' key.
Files come back only from a backup, from copies the ransomware did not reach, such as OneDrive version history, Previous Versions, e-mail attachments or a phone, or with a working decryptor if one exists.
Remove the ransomware first anyway: if you restore files while it is still active, it can encrypt them again. Keep the encrypted files; a decryptor may be published later.
Will Fortect remove CryptoJoker 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 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: Advanced Encryption Standard (read October 6, 2026)
- VirusActivity: The Official Website of VirusActivity (read October 6, 2026)
- CISA: StopRansomware (read October 6, 2026)
- No More Ransom (read October 6, 2026)
- FTC: How to recognize, remove and avoid malware (read October 6, 2026)