AnteFrigus ransomware: what it is and how to remove it
AnteFrigus ransomware is the virus that gets distributed via a malvertising campaign that redirects users to the RIG exploit kit. This strange ransomware has some unique and uncommon features in comparison with other ransom-based malware strains.
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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AnteFrigus ransomware: summary
| Distribution | HookAds[1] malvertising redirects users to RIG exploit kit that uses malicious scripts hosted on compromised sites and tries to exploit Internet Explorer vulnerabilities. If that happens, ransomware payload can be added on the machine without users' knowledge |
|---|---|
| Name | AnteFrigus ransomware |
| Unique feature | Ransomware encrypts files in D, E, F, G, H, and I drives, when common cryptovirus targets only C drive. This intruder affects data connected to network storage, removable devices |
| File marker | Encrypted files get the random extension that is also included in the names of other files |
| Ransom note | appendix-readme.txt; the text is quoted in full below |
| Ransom amount | The amount demanded from researchers during the sample tests started at $1,995 and in a few days, got up to $3,990 in Bitcoin. This particular amount of ransom can differ from victim to victim |
| 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 12 more facts
| Contact email | antefrigus@cock.li |
|---|---|
| Possible damage | Encrypted files cannot be opened without paying the ransom, other files loaded on the system and processes running in the background affects the data recovery and virus termination functions. The exploited vulnerability can lead to the installation of other threats like trojans or info-stealing malware |
| Detection names | No Microsoft detection name is known |
| 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 |
| Type | File-encrypting ransomware |
| Symptoms | A ransom note left in folders |
| Evidence | 4 write-ups by security sites; details still limited |
| Attacker contacts | antefrigus@cock.li |
| Free decryptor | No free decryptor is known (checked 7 October 2026) |
| First seen | 15 November 2019 |
| Facts checked | 7 October 2026 |
- Note file:
appendix-readme.txt - Contact:
antefrigus@cock.li
From our report of Nov 2019 · not reviewed since
More from our earlier report on AnteFrigus ransomware
- The text file that includes a demanding message gets placed in various folders like C:\Instraction folder, and on the desktop gets named in a pattern: file appendix-readme.txt
- The best tool that you can use for AnteFrigus ransomware removal is the anti-malware tools because such software is capable of detecting malicious activity
- Since the virus runs through various drives on the machine, it loads files and programs on the device to affect the performance significantly.
- You should try to fix virus alterations using repair tools like that might fix corrupted registry entries and restore files in the system folders that get damaged
The AnteFrigus ransomware note
[+] Whats Happen ? [+]
Your files are encrypted, and currently unavailable.You can check it : all files on you computer has expansion mewqsm.
By the way, everything is possible to recover(restore), but you need to follow our instructions.Otherwise, you cant return your data(NEVER).
[+] What guarantees ? [+]
Its just a business.We absolutely do not care about youand your deals, except getting benefits.If we do not do our workand liabilities - nobody will not cooperate with us.Its not in our interests.
To check the ability of returning files, You should go to our website.There you can decrypt one file for free.That is our guarantee.
If you will not cooperate with our service - for us, its does not matter.But you will lose your timeand data, cause just we have the private key.In practise - time is much more valuable than money.
[+] How to get access on website ? [+]
You have two ways :
1) Using a TOR browser!
a) Download and install TOR browser from this site: hxxps://torproject.org/
b) Open our website : hxxp://yboa7nidpv5jdtumgfm4fmmvju3ccxlleut2xvzgn5uqlbjd5n7p3kid.onion/?mewqsm
(If you canít follow the link or other difficulty write to the technical support email : antefrigus@cock.li)
2) If TOR blocked in your country, try to use VPN! For this:
a) Open any browser (Chrome, Firefox, Opera, IE, Edge) and download and install free VPN programm and download TOR browser from this site hxxps://torproject.org/
b) If you are having difficulty purchase bitcoins, or you doubt in buying decryptor, contact to any data recovery company in your country, they will give you more guarantees and take purchase and decryption procedure on themselves. Almost all such companies heared about us and know that our decryption program work, so they can help you.
When you open our website, put the following data in the input form:
Key:
Extension name :
--------- -
!!!DANGER !!!
DONT try to change files by yourself, DONT use any third party software for restoring your data or antivirus solutions - its may entail damge of the private keyand, as result, The Loss all data.
!!!!!!!!!
ONE MORE TIME : Its in your interests to get your files back.From our side, we(the best specialists) make everything for restoring, but please should not interfere.
!!!!!!!!!
How to remove AnteFrigus 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 AnteFrigus 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 AnteFrigus 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 AnteFrigus 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 AnteFrigus 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 AnteFrigus 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 Nov 2019 · not reviewed since
AnteFrigus ransomware – the cryptovirus that targets only drives associated with removable devices that might be a bug in functionality
AnteFrigus ransomware is the virus that gets distributed via a malvertising campaign that redirects users to the RIG exploit kit.
This strange ransomware has some unique and uncommon features in comparison with other ransom-based malware strains. However, some researchers speculate that malware is still in development, and different functionalities may only be a flaw in coding, not made un purpose.
This virus does not target the C: drive that is commonly affected by the file-locking malware, it only focuses on D:, E:, F:, G:, H:, and I: drives commonly associated with removable devices or network drives.
Since AnteFrigus ransomware doesn't look sophisticated and fully running, it might be released at a later date with more proper coding and encryption functionalities. At the time, what we know is the distribution technique that involves malvertising, RIG EK that tries to take advantage of Internet Explorer vulnerabilities, and install the payload.
When this is successful, the malware encrypts data and marks those files using random appendix, which is also included in the name of the ransom note that delivers instructions for the cryptovirus victim.
Tor payment site link is displayed in the note, so victims can know the price of the alleged decryption key and send the Bitcoin payment to criminals' addresses. However, that is not recommended because paying doesn't guarantee the file recovery.
The best and the safest option is to terminate AnteFrigus ransomware, stay away from contacting the developers, and rely on your data backups to restore files on the already safe machine.
AnteFrigus ransomware is the encryption malware, but it acts apart with its unique features. The threat is not encrypting C: drive and focusing on files with the following strings:
dll, adv, ani, big, bat, bin, cab, cmd, com, cpl, cur, deskthemepack, diagcab, diagcfg, diagpkg, drv, exe, hlp, icl, icns, ico, ics, idx, ldf, lnk, mod, mpa, msc, msp, msstyles, msu, nls, nomedia, ocx, prf, rom, rtp, scr, shs, spl, sys, theme, themepack, wpx, lock, key, hta, msi, pck.
There are many speculations why these files are the focus of the encryptionAnteFrigus ransomware. Some users from the business environment save their data in such network shares, so this is possibly the thought-out method of affecting devices.
However, samples found in the wild got analyzed and reveled other flaws that indicate this ransomware is still in the test mode, and the strange encryption is not sophisticated enough so it can be called a bug.
When AnteFrigus ransomware gets on the system, it starts encrypting files and marks then using a randomized extension that also appears on the ransom note file name that gets placed in the C:\Instraction folder and on the desktop. C:\qweasd\test.txt file also gets created, which may be used as either debug or lock file.
This AnteFrigus ransomware virus is developed by cybercriminals, so when you have some knowledge about such malware, you should know that there is no reason to trust financially motivated people with your files. In most cases, people who pay the ransom don't get their files back. You shouldn't risk getting your files and money permanently lost by paying or contacting the hackers.
AnteFrigus ransomware shows a long ransom-demanding message in the file placed on the desktop and in other folders that gets named after the particular file extension. Although the note seems convincing enough, all the claims about the test decryption and cooperation are there to trick people into believing there is a possible way to get your files back after the encryption.
The ransom note displays:
You can also encounter additional content appearing on the screen when the computer gets affected. AnteFrigus ransomware delivers a warning pop-up with the statement that your machine got encrypted. The virus can also cause freezes or crashes on the device because during the encryption, many processes get launched in the background. You cannot notice the infiltration itself, but ransomware becomes noticeable when the system gets altered and interfered with.
Then you need to focus on AnteFrigus ransomware removal and do that as soon as possible because once the virus is done encrypting data it starts deleting them from places like Windows registry, system folders or disables security functions, programs needed for file restoring purposes.
When you remove AnteFrigus ransomware, you should also focus on that additional damage and repair affected files. Once registry entries get repaired and Windows files replaced with safe ones, you can recover that data encrypted by the malware using file backups or third-party software.
From our report of Nov 2019 · not reviewed since
Exploit kits and other deceptive technique
Exploit kit activity linked with the ransomware distribution gets detected less often, but this particular RIG exploit kit is known for delivering trojans, ransomware, and other malware for a while.
It works via infected sites when the user is browsing compromised pages that causes redirects or malvertising campaigns. Once the redirect is shown RIG landing page triggers the exploitation of some flaws and the direct malware payload download.
Other vectors used by ransomware developers can include malicious files injected on emails as attachments, hiding behind pirated software packages, and so on. Experts always note about malware delivering methods that lure on deceptive sites, misleading emails, and services like torrents, but people remain to pay less attention than needed to these details.
From our report of Nov 2019 · not reviewed since
Terminate AnteFrigus ransomware virus by employing anti-malware tools
The process of AnteFrigus ransomware removal requires your attention and additional help from professional anti-malware tools.
Since this threat is distributed involving exploit kits and deceptive online content, you should take the possibility of additional threats already installed on the machine into consideration.
To remove AnteFrigus ransomware alongside all the trojans, malware, and virus-related files, you should employ an anti-malware tool that can run a full system check and detect all the malicious files. If you leave any core files belonging to the virus, your machine can get more affected.
Remember that the AnteFrigus ransomware virus is a serious threat, so you should think about the damage, additional files, and programs added on the machine. Cleaning the system is not only focusing on terminating the threat. Scan the machine using , , or and try to clean the computer as much as possible before you recover your files.
[GI=method-1]You need to remove AnteFrigus ransomware completely, so to achieve that reboot computer in the Safe Mode with Networking
[GI=method-2]You can benefit from the System Restore feature that allows recovering the machine to a previous state before malware infection
Windows Previous Versions is helpful for individual files
You can rely on Windows Previous Versions when System Restore gets enabled
Try ShadowExplorer for files encrypted by AnteFrigus ransomware
When Shadow Volume Copies remain untouched, you can recover files using them
AnteFrigus ransomware has no decryption options yet
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
AnteFrigus ransomware could only hurt the files that had no second copy, and the signs (ransom notes called appendix-readme.txt in every folder) 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.
Protect your privacy - employ a VPN
There are several ways how to make your online time more private - you can access an incognito tab.
However, there is no secret that even in this mode, you are tracked for advertising purposes. There is a way to add an extra layer of protection and create a completely anonymous web browsing practice with the help of VPN. This software reroutes traffic through different servers, thus leaving your IP address and geolocation in disguise.
Besides, it is based on a strict no-log policy, meaning that no data will be recorded, leaked, and available for both first and third parties. The combination of a secure web browser and VPN will let you browse the Internet without a feeling of being spied or targeted by criminals.
No backups? No problem. Use a data recovery tool
If you wonder how data loss can occur, you should not look any further for answers - human errors, malware attacks, hardware failures, power cuts, natural disasters, or even simple negligence.
In some cases, lost files are extremely important, and many straight out panic when such an unfortunate course of events happen. Due to this, you should always ensure that you prepare proper data backups on a regular basis.
If you were caught by surprise and did not have any backups to restore your files from, not everything is lost. is one of the leading file recovery solutions you can find on the market - it is likely to restore even lost emails or data located on an external device.
Questions about AnteFrigus ransomware
Is there a free AnteFrigus ransomware decryptor?
We last checked on 7 October 2026, and for AnteFrigus 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 "AnteFrigus 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 AnteFrigus ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by AnteFrigus ransomware, but the only confirmed sign is ransom notes called appendix-readme.txt in every folder, 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.
Are ransomware recovery services legitimate?
Some are, but read the offer carefully. Genuine data-recovery firms recover deleted originals from disks or rebuild damaged files, and they say so. Others promise to "decrypt any ransomware" for a fixed price, which is impossible without the key; they quietly pay the attackers and keep a margin, sometimes without telling the victim.
Be especially careful with services that contact you after you post about the attack online. Ask for references, a written method and a no-result-no-fee clause, and check the free tools on No More Ransom first.
Should I pay the ransom?
We advise against it, and so do the FBI, Europol and national cyber agencies. Payment does not guarantee a working tool: some attackers never reply, some tools damage files, and some variants have no decryptor at all. Paying also funds further attacks and can make you a target again.
Before considering payment, try every recovery option in this guide and report the attack. Companies must involve their legal adviser and insurer, because payments to sanctioned groups can be illegal. If files are truly irreplaceable, store the encrypted copies and wait; decryptors sometimes appear later.
How did AnteFrigus ransomware get on my computer?
The way AnteFrigus 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 ransom notes called appendix-readme.txt in every folder, and check the Downloads folder and Installed apps sorted by date. Keep anything suspicious for your report, but do not run it again.
Is AnteFrigus 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 appendix-readme.txt?
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. appendix-readme.txt 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 appendix-readme.txt from real ransomware or a bluff?
Look at your files rather than the note. If documents and photos have a new extension and will not open, the encryption is real. If files open normally, or only a few were renamed, the note may come from fake ransomware or extortion-only malware that claims more than it did.
Some wipers also leave notes like appendix-readme.txt while destroying data with no way back. Identification services help here too: they recognise the note and tell you whether the family is known to encrypt, to bluff, or to wipe.
How do I open my .docx, .jpg and other files locked by AnteFrigus?
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 AnteFrigus 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 AnteFrigus 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 AnteFrigus 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
- VirusTital: Ransomware detection rate (read October 7, 2026)
- Virusai: Virusai (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)