FessLeak ransomware: what it is and how to remove it
FessLeak is a dangerous campaign that is used for spreading Cryptolocker, Cryptowall, CTB Locker and other cyber threats that belong to ransomware category. This means the only thing - if you want to avoid these threats, you should stay away from malicious websites that were registered on FessLeak@qip(dot)ru.
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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FessLeak ransomware: summary
| Detection names | No Microsoft detection name is known |
|---|---|
| Ransom note | Not named in our report; the text of the note is not in our records |
| Contact | Not recorded in our earlier report |
| Encrypted file extension | Not recorded in our earlier report |
| 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 8 more facts
| Damage | Not recorded in the old report |
|---|---|
| Name | FessLeak ransomware |
| Type | File-encrypting ransomware |
| Symptoms | An unknown program in Installed apps |
| Evidence | One write-up by a security site; details still limited |
| Free decryptor | No free decryptor is known (checked 7 October 2026) |
| First seen | 26 April 2021 |
| Facts checked | 7 October 2026 |
How FessLeak ransomware behaves
From our report of Apr 2021 · not reviewed since
What is FessLeak?
FessLeak is a dangerous campaign that is used for spreading Cryptolocker, Cryptowall, CTB Locker and other cyber threats that belong to ransomware category.
This means the only thing - if you want to avoid these threats, you should stay away from malicious websites that were registered on FessLeak@qip(dot)ru. Othgerwise, you can end up with the virus that seeks to encrypt important victims' files and then make them pay a required fee for their decryption.
In most of the cases, this payment should be paid in bitcoins via Tor web browser and that's they only way that helps in this situation.. If a ransomware that belongs to FessLeak malvertising campaign infiltrates the system, the first thing that it does is system's scan.
After scanning the system and finding predetermined files, it encrypts them using the RSA 2048 encryption. After that, each of affected files becomes locked. After trying to open any of these files, user sees a huge warning message, which informs him/her about the whole situation.
Warning: Please, do NOT pay this ransom because you can never be sure that this will help you to get an decryption key.
If you have been performing backups and now you have just discovered that your computer is infected with one of FessLeak malwares, then you should try to restore your files from there. Of course, you should also make sure that all malicious files (including the ones that belong to this ransomware) are eliminated before doing so.
The easiest way to do that is to run a full system scan with updated anti-sptyware. For that we highly recommend using . If you have no idea what backup means, then you should try programs that are given at the end of this post.
From our report of Apr 2021 · not reviewed since
How can FessLeak infect my computer?
There are several methods that are used for spreading ransomwares, including FessLeak campaign.
It relies on malicious websites that are promoted thru fake alerts. Such alerts are usually filled with various logos, so they look quite convincing. If you, while browsing on the web, were interrupted by alert that claims that you need to update your Java or Flash Player, you must realize that it might be fake.
Please, ignore such ads and never fall for them because you can be redirected to malicious website that can easily download Cryptolocker or other ransomware onto your computer. In addition, remember that you can also be tricked into downloading this threat to your computer via spam.
According to the latest reports, spammers have been actively working in France and other Europe's countries, but there is no guarantee that there is no group of hackers who are trying to increase the distribution rate of these ransomwares in USA and other world's countries. In this case, the most important thing is to understand that there are lots of malicious emails spreading around.
In most of occasions they look like official notifications about various purchases, fines, prizes and other things that have always been attracting people. If you have just discovered that FessLeak-related ransomware has already attacked your computer and blocked your important files, please follow this guide and get rid of this threat.
The FessLeak ransomware note
We did not record the full text of the ransom note in our report.
How to remove FessLeak 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 FessLeak 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 FessLeak 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 FessLeak 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 FessLeak 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 FessLeak 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
From our report of Apr 2021 · not reviewed since
How to remove FessLeak virus?
If ransomware, using FessLeak campaign, has just affected your system, you will need a key if you want to decrypt your corrupted files.
For that you need to pay a ransom. Nevertheless, you can also try a backup or using file recovery tools. If you have been performing backups, you should be capable of restoring your files. In addition, for that you can also try such programs as R-Studio or Photorec.
For FessLeak removal, we highly recommend using , or .
Finally, we must add that we highly recommend thinking about the prevention of such infections like FessLeak-related ransomware, Cryptowall, Cryptolocker, CTB Locker and similar threats. For that you can use previously mentioned programs.
Besides, don't forget to think about the immunity of your files and make backups as frequently as possible. In addition, you can use USB external hard drives, CDs, DVDs, or simply rely on Google Drive, Dropbox, Flickr and other solutions.
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.
Make the next attack harmless
FessLeak ransomware could only hurt the files that had no second copy, and the signs (fessLeak ransomware in the list of installed apps) showed exactly which ones those were.
The 3-2-1 rule fixes that:
- three copies
- two media
- one disconnected
A practical version for a home PC: OneDrive or another cloud backup with version history, plus an external disk that you plug in once a week for File History and then unplug. Test a restore now and then by opening a few files from the backup on another device.
Details, schedules and what not to back up are in our 3-2-1 backup guide for 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 FessLeak ransomware
Is FessLeak ransomware a virus?
Most programs that appear the way FessLeak ransomware did are not viruses in the strict sense. They are potentially unwanted programs:
- real software that arrives bundled with other downloads and then shows offers
- changes browser settings
- starts with Windows
Some are harmless, some are annoying and a few carry adware. What makes it worth removing is that you did not choose it.
Uninstall it from Installed apps and check the startup list and the browsers for anything added the same day. If it refuses to uninstall or returns after a restart, treat it as more serious and run a Microsoft Defender offline scan.
Is there a free FessLeak ransomware decryptor?
We last checked on 7 October 2026, and for FessLeak 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 "FessLeak 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.
How did FessLeak ransomware get on my computer?
The way FessLeak 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 fessLeak ransomware in the list of installed apps, 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.
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.
Is FessLeak 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.
How do I stop programs like FessLeak ransomware from being installed again?
Most unwanted programs arrive through installers, so the fix is in how you install software. Download programs from their official sites or the Microsoft Store, not from download portals or ads above search results. During setup, choose Custom or Advanced installation and untick every extra offer, including browsers, toolbars and optimizers.
Decline update prompts that appear inside other programs unless you know them. In Windows Security, turn on reputation-based protection and potentially unwanted app blocking. These steps would most likely have stopped FessLeak ransomware before it reached the app list.
Should I reset my PC because of FessLeak ransomware?
Only if the signs point to deeper access. Reset when you see fessLeak ransomware in the list of installed apps again after removal, when Windows Security cannot start or update, when remote access tools you did not install keep appearing, or when you simply cannot trust the PC any more.
Otherwise, the plan in this guide plus an offline scan is enough. If you do reset, choose Remove everything and Cloud download for a fresh copy of Windows, restore only documents and photos, and reinstall programs from their official sites. Change important passwords from the clean system afterwards.
How do I open my .docx, .jpg and other files locked by FessLeak?
You cannot open locked files normally while they stay encrypted, and renaming them will not help. Our earlier report did not record the extension that FessLeak adds, so check one locked file name and the ransom note for it.
No free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates. Do not rename the files, change the extension or edit them, because that can make recovery harder. Copy the locked files to an external drive before you clean the system, so a decryptor released later still has them.
Will Fortect remove FessLeak 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 FessLeak 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
- 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)
- Microsoft Learn: Microsoft Defender Offline (read October 7, 2026)
- Microsoft Learn: How Microsoft names malware (read October 7, 2026)