CILLA ransomware: what it is and how to remove it
CILLA ransomware is a type of malware that focuses on money extortion and comes from a well-known malware family - GlobeImposter 2.0. Soon after infiltration, the virus encrypts all pictures, videos, documents, and other data by using a strong encryption algorithm AES-256 and appends .CILLA extension to each of the files.
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.
Automatic
Get a free scan and check if your PC is infected.
Fortect finds malware, unwanted programs and the Windows damage they leave behind, and repairs it in one pass.
Before you restore backups, a full scan can confirm the program that added .cilla is gone.
Do it yourself · free Remove CILLA ransomware yourself 6 steps, about 18 minutes, no software needed.
Start the steps
CILLA ransomware: summary
| Name | CILLA ransomware |
|---|---|
| Type | File locking virus, crypto-malware |
| Family | CILLA is a variant of GlobeImposter 2.0 ransomware |
| Encryption algorithm | AES-256 is used to encode pictures, music, videos, documents, databases and other files located on local and networked drives |
| File extension | Each of the locked files is marked with .CILLA extension, for example, schedule.xlsx is turned into schedule.xlsx.CILLA |
| Ransom note | The malware drops a how_to_back_files.html ransom note into most of the folders on the affected machine (where the encrypted files are located) |
| 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 17 more facts
| Contact | Crooks ask to contact them via blackcilla@qq.com or blackcilla@cock.li to negotiate the payment process |
|---|---|
| Ransom size | The ransom amount is not provided in the ransom note, although previous variants of malware are known to ask for as much as 10 Bitcoin for the decryption tool |
| Known incidents | The malware locked all files on Food Bank's computers in June 2019 |
| File decryption | Unfortunately, there is no CILLA ransomware decryption tool available. There are only three other ways to recover data: Use third-party recovery software Recover files from a backup Pay cybercriminals (not recommended) |
| Detection names | No Microsoft detection name is known |
| Encrypted file extension | .cilla |
| 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, a ransom note left in folders and a Windows Security "Threats found" notification |
| Evidence | 5 write-ups by security sites; no sample analysed yet |
| Encrypted files | .cilla |
| Attacker contacts | blackcilla@qq.com |
| Free decryptor | No free decryptor is known (checked 6 October 2026) |
| First seen | 4 December 2019 |
| Microsoft Defender name | Ransom:Win32/Filecoder.RB!MSR |
| Facts checked | 6 October 2026 |
What antivirus programs call CILLA ransomware
Microsoft Defender reports CILLA ransomware as Ransom:Win32/Filecoder.RB!MSR.
In a Defender name, the part before the colon is the category, the part after it is the platform, and the part after the slash is the family Microsoft assigned. A suffix after ! is an internal Microsoft marker, not a different threat.
Generic labels such as Agent, GenericKD or Malware.AI only say that a file looks malicious, not what it does; our guide to antivirus detection names shows how to read them.
- File extension:
.cilla - Note file:
how_to_back_files.html - Contact:
blackcilla@qq.com
From our report of Dec 2019 · not reviewed since
More from our earlier report on CILLA ransomware
- Employ reputable anti-malware software and perform a full system scan (entering Safe Mode might be necessary sometimes)
- After the malware is eliminated, users might experience system crashes and errors due to virus damage.
How CILLA ransomware behaves
From our report of Dec 2019 · not reviewed since
CILLA ransomware is a file locking threat that tries to imitate Maoloa virus
CILLA ransomware is a type of malware that focuses on money extortion and comes from a well-known malware family - GlobeImposter 2.0.
Soon after infiltration, the virus encrypts all pictures, videos, documents, and other data by using a strong encryption algorithm AES-256 and appends .CILLA extension to each of the files. To retrieve the access to data, users are asked to email hackers via blackcilla@qq.com or blackcilla@cock.li and pay a ransom in Bitcoin, the amount of which is not stated in the ransom note how_to_back_files.html.
Unlike most file locking viruses, CILLA ransomware tries to imitate another crypto-locking malware Maola - it is done deliberately to prevent security experts from identifying the infection correctly.
Nevertheless, this does not make any difference to the affected users, as a result in both cases is the same - locked data. Unfortunately, there is no CILLA ransomware decryptor currently available, although there are other methods that might be able to help you recover your files.
Just as any other large ransomware family member, CILLA ransomware is spread with the help of various methods, including:
In some cases, malicious actors are also known to insert a legitimate program Process hacker or Process Hacker 2 into the infected system in order to monitor it and perform other malicious activities. Nevertheless, this unwanted activity can be detected and stopped by most of the up-to-date security tools, which can also help with CILLA removal.
Once CILLA ransomware gets into the machine, it starts the preparation for the file encryption process. For example, it deletes several files (such as Windows' automatic file backups) and modifies the Windows registry to run without interruptions. After that, the virus targets the most common file types like .doc, .html, .jpg, .mp4, .ppt, and others, all while skipping executables, as well as system files.
The dropped ransom note how_to_back_files.html states the following:
As evident, the crooks are trying to intimidate victims and make them pay the ransom. However, security experts do not recommend contacting cybercriminals, as there is no guarantee that they will send required decryption software after the payment in Bitcoin. Additionally, paying crooks behind the CILLA virus will only fuel their will to produce more advanced viruses and infect more users.
While it is true that, in some cases, the files might get damaged after you remove CILLA ransomware, there is a solution for that.
Before you do anything, you should backup all the encrypted data and then access Safe Mode to get rid of the virus with the help of reputable security software that can recognize the threat. According to Virus Total, most security tools should be able to detect and eliminate the infection. CILLA ransomware is identified as follows:
After that, you can try using third-party recovery tools to retrieve .CILLA encrypted files.
- Spam emails
- Exploit kits
- Software cracks
- Pirated software installers
- Unprotected RDP connections
- Fake updates, etc.
- HEUR/AGEN.1011584
- Win32:Trojan-gen
- Ransom:Win32/Filecoder.RB!MSR
- Ransom_FAKEGLOBE.SMB
- Generic.Ransom.GlobeImposter.4361C1A9
- Heuristic.HEUR/AGEN.1011584, etc.
From our report of Dec 2019 · not reviewed since
There are several ways to protect yourself from ransomware intrusion
Some cybercriminals are implementing various methods when it comes to the illegal ransomware business.
One thing is clear: ransomware is on the rise, and there are multiple hacking groups with highly established networks - these gangs infect thousands of users worldwide, as well as various businesses and organizations, resulting in millions of dollars in repair costs. While it is impossible to avoid ransomware completely, however, there are several ways to diminish that chance to a minimum.
The first step for a more secure computer is automated protection - anti-malware software. There are plenty of security tools available, and most of them even employ a separate feature that enables ransomware protection (so make sure it is always on).
However, defenses provided by anti-malware software are never enough, and you should also be very careful when spending time online, opening emails, and downloading files. Here's what to do to increase your PC security level:
To conclude, a combination of careful web browsing habits and comprehensive security solutions should be enough to keep even the most dangerous malware away.
- Do not open spam email attachments (files that ask you enable macros are most likely viruses) or click on hyperlinks inside;
- Patch your Windows OS along with all the installed software immediately when the updates are available;
- Avoid visiting high-risk websites like torrents, porn, gambling, etc. (if you do, enable ad-block for extra protection);
- Do not download and use software cracks or pirated program installers;
- Use strong passwords for all your accounts and never reuse them. Also, enable two-factor authentication where possible;
- Backup all your files as required;
The CILLA ransomware note
☠ YOUR FILES ARE ENCRYPTED! ☠
ALL YOUR IMPORTANT DATA HAS BEEN ENCRYPTED.
To recover data you need decryptor.
To get the decryptor you should:
Send 1 test image or text file blackcilla@qq.com or blackcilla@cock.li.
In the letter include your personal ID (look at the beginning of this document).
We will give you the decrypted file and assign the price for decryption all files
After we send you instruction how to pay for decrypt and after payment you will receive a decryptor and instructions We can decrypt one file in quality the evidence that we have the decoder.
Attention!
Only blackcilla@qq.com and blackcilla@cock.li can decrypt your files
Do not trust anyone blackcilla@qq.com and blackcilla@cock.li
Do not attempt to remove the program or run the anti-virus tools
Attempts to self-decrypting files will result in the loss of your data
Decoders other users are not compatible with your data, because each user's unique encryption key
How to remove CILLA 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 CILLA 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
CILLA ransomware encrypts everything it can reach, including drives and shares you connect later. Cut the network first: cable out, or Wi-Fi off from the taskbar.
Then unplug every USB stick and backup disk and pause cloud sync, so the encrypted versions do not replace your online copies. Do not reconnect any of them until the ransomware is removed from the Windows 11 or Windows 10 PC.
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
Copy
how_to_back_files.htmland one or two files ending in.cillato a USB stick, and leave the originals where they are.From another device, upload the note and a sample file to ID Ransomware or No More Ransom's Crypto Sheriff, which name the family from the note, the extension and the file structure.
Write down the contact address and your personal ID from the note, because a decryptor or the police may ask for them.
Warning: Never contact the attackers from the infected Windows 11 or Windows 10 PC.
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
For CILLA ransomware, no free decryptor is known (checked 6 October 2026). Search the family name in the No More Ransom decryption tools list and in the free decryptors of Emsisoft, Avast and Kaspersky, because new tools appear years after an attack.
Important: Keep the encrypted files even if nothing works today, and do not pay before every free option is ruled out: payment does not guarantee a working key.
Decryptors run on Windows 11 and Windows 10, but only after the ransomware itself is removed.
Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files
Step 4: Remove the ransomware before you restore or decrypt
Restoring or decrypting files while CILLA ransomware still runs lets it encrypt them again. Run a Full scan in Windows Security > Virus & threat protection > Scan options, then the Microsoft Defender Antivirus (offline scan).
If the ransomware blocks Windows Security, start Safe Mode with Networking and scan from there. Some families install a password stealer as well, so let both scans finish on Windows 11 or 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
Open Command Prompt as administrator and run
vssadmin list shadows. If it lists copies dated before the attack, right-click a folder with encrypted files in File Explorer, choose Properties > Previous Versions, and open or restore a version from before that date.ShadowExplorer, a free tool, shows the same copies when the tab is empty or hidden. Most current families delete shadow copies, so an empty list is normal, but the check takes two minutes on Windows 11 or Windows 10.
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
Restore from an external backup, File History or OneDrive's version history, choosing a date before the attack. Connect the backup drive only after the scans are clean, or the ransomware encrypts it too.
If there is no backup, file recovery software can sometimes find the deleted originals, because some ransomware writes an encrypted copy and deletes the original file.
Stop writing to the drive and try recovery on Windows 11 or Windows 10 before new files overwrite the space.
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
Do not listen to cybercriminals and remove CILLA ransomware immediately
As already mentioned, it is true that CILLA ransomware removal might compromise the encrypted data permanently.
To prevent that, you should immediately copy all the files to an external drive (flash USB or external HDD) or virtual drive (Google Drive, OneDrive, Dropbox, etc.). Once that is done, you need to ensure that you remove CILLA ransomware correctly.
It is not uncommon for crypto-malware to disable anti-virus software like Microsoft Defender. In such a way, hackers might prevent users from getting rid of the malicious payload and attempting alternative data recovery methods. In such a case, you should access Safe Mode with Networking and scan the machine with anti-malware software like or and get rid of CILLA virus infection.
For .CILLA file recovery, you can either refer to the section below for various methods (keep in mind that chances of retrieving locked files with recovery software are relatively low) and risk your money and pay criminals for a decryption key, which is not recommended.
[GI=method-1]If the virus prevents your security software from working correctly, enter Safe Mode with Networking:
[GI=method-2]You can also apply the Safe Mode for CILLA ransomware removal:
Make use of Windows Previous Versions feature
This method can only function if you had System Restore enabled before.
ShadowExplorer method might save your files
CILLA virus is programmed to delete Shadow Volume Copies. If this process fails, you have a high chance of recovering all your files with ShadowExplorer.
No decryption tool is currently available
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 CILLA 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 .cilla and no longer open.
Setting it up step by step: 3-2-1 backups on Windows 11 and 10.
Stream videos without limitations, no matter where you are
There are multiple parties that could find out almost anything about you by checking your online activity.
While this is highly unlikely, advertisers and tech companies are constantly tracking you online. The first step to privacy should be a secure browser that focuses on tracker reduction to a minimum.
Even if you employ a secure browser, you will not be able to access websites that are restricted due to local government laws or other reasons. In other words, you may not be able to stream Disney+ or US-based Netflix in some countries. To bypass these restrictions, you can employ a powerful VPN, which provides dedicated servers for torrenting and streaming, not slowing you down in the process.
Data backups are important - recover your lost files
Ransomware is one of the biggest threats to personal data.
Once it is executed on a machine, it launches a sophisticated encryption algorithm that locks all your files, although it does not destroy them. The most common misconception is that anti-malware software can return files to their previous states. This is not true, however, and data remains locked after the malicious payload is deleted.
While regular data backups are the only secure method to recover your files after a ransomware attack, tools such as can also be effective and restore at least some of your lost data.
Questions about CILLA ransomware
Is there a decryptor for .cilla files?
That depends on the family behind the .cilla extension, which this guide cannot confirm yet from the reports alone. Check No More Ransom and ID Ransomware with your ransom note and one encrypted file; they list families with free tools.
If none exists today, keep the encrypted files and a copy of the note on a separate drive, because decryptors are sometimes published months later after flaws are found or servers are seized. Never buy a decryptor from a website that is not the security company that made it.
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 do I open .cilla files?
You cannot open them by renaming or by choosing another program. The .cilla ending shows that CILLA ransomware encrypted the content, and only the matching key can reverse it. Renaming a file back to .docx or .jpg changes nothing except the icon, and it can confuse a future decryptor, so leave the names as they are.
To get the content back, use a backup, an unencrypted copy elsewhere, or a decryptor listed on No More Ransom if one exists for CILLA ransomware. Store the encrypted files on an external disk until then.
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 CILLA ransomware get on my computer?
The way CILLA 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 .cilla 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 CILLA ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by CILLA ransomware, but the only confirmed sign is files that end in .cilla 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 CILLA ransomware the same as other ransomware with a similar name?
Not necessarily. Ransomware names come from the file extension, the note or a word in the code, so unrelated families often end up with similar names, and one family can appear under several names. The difference matters: a decryptor or advice for one family does not fit another and can damage files.
Compare the ending added to your files and the exact name of the note with the summary table at the top of this guide, then upload the note and one encrypted file to ID Ransomware from a clean device. If the result names another family, follow the guide for that family instead.
Can I delete how_to_back_files.html?
Yes, the note itself is harmless text and deleting it does not affect your files. Keep at least one copy first, outside the infected PC. how_to_back_files.html contains your personal ID and the attackers' contact details, which identification services use to tell which family encrypted your files, and which a decryptor may need later.
Police reports also ask for it. Once you have saved a copy, you can remove the notes from every folder after the ransomware program has been removed and your files are restored or backed up.
Is Ransom:Win32/Filecoder.RB!MSR a false positive?
Sometimes. Names ending in !ml or describing behaviour are generated by machine learning and occasionally flag cracked tools, game mods or small unsigned utilities. A false positive is likely only when the file is a program you installed from its official developer, it is signed by that developer and other scanners do not flag it.
Files from cracks, cheats, fake updates or unknown downloads are rarely false positives, whatever the detection name. If you are sure the file is genuine, you can report it to Microsoft as a false positive; never add an exclusion for Ransom:Win32/Filecoder.RB!MSR just to make the alert stop.
Will Fortect remove CILLA 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 CILLA 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)
- PaloAlto: What is an Exploit Kit? (read October 6, 2026)
- Lesvirus: Lesvirus (read October 6, 2026)
- Virus Total: fa76446fed3a950676eb7376ff8f6c345c7e00e728d121f83c62d5f709938970 (read October 6, 2026)
- CISA: StopRansomware (read October 6, 2026)