Worm Heffer: what it is and how to remove it
Worm Heffer spreads on the Internet by e-mail messages with infected executable attachments, although users might also infect their PCs after inserting a removable drive containing the malicious payload. Once installed, the worm spreads all over the computer, infecting many core system and application 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.
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Worm Heffer: summary
| Name | Worm Heffer |
|---|---|
| Type | Worm, malware |
| Function | Infects multiple Windows system and application files, terminates processes of some security programs |
| Dangers | Installation of other malicious programs, information leak, other computer infections |
| Detection names | No Microsoft detection name is known |
| 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 5 more facts
| Damage | Not recorded in the old report |
|---|---|
| Symptoms | An unknown program in Installed apps |
| Evidence | One write-up by a security site; details still limited |
| First seen | 29 April 2021 |
| Facts checked | 6 October 2026 |
What Worm Heffer does
From our report of Apr 2021 · not reviewed since
More from our earlier report on Worm Heffer
- Use anti-malware software (access Safe Mode if required)
- can help you fix virus damage effectively
How Worm Heffer spreads and got on your PC
From our report of Apr 2021 · not reviewed since
Worm Heffer spreads on the Internet by e-mail messages with infected executable attachments, although users might also infect their PCs after inserting a removable drive containing the malicious payload.
Once installed, the worm spreads all over the computer, infecting many core system and application files.
Since removable drives are the main distribution vector of the worm, disabling the autorun function could stop the worm from accessing your computer. However, users never know if the drive is infected in the first place, allowing it spread freely. A robust anti-malware program can stop the malicious payload from being delivered to the computer. We strongly recommend using or for the Worm Heffer removal process.
On the infected computer, it modifies popular chat programs mIRC and KaZaA peer-to-peer application and spreads through them also. Once per month, it displays several message windows.
The worm can infect some text documents and terminate most processes of antivirus and security-related programs, which can make the elimination process rather difficult. This tactic is often used by malicious programs in order to increase threat persistence.
However, the most up-to-date security software should not be affected by this malware trait. If it is, simply reload your computer in Safe Mode. If you are not sure how to reach it, follow the instructions we provide below.
Also, if you notice that your Windows is malfunctioning after you delete the worm, system files were likely compromised. To revert this damage, we strongly recommend using .
How to remove Worm Heffer
Clean the USB drives as well as the PC, or the worm comes back the next time a stick is plugged in.
Step 1: Clean the USB drives
Worm Heffer spreads through USB sticks, so every drive used in this PC is suspect.
In File Explorer, switch on hidden items, delete the shortcuts that look like your folders, and run
attrib -h -r -s /s /d E:\*.*in Command Prompt (with your drive's letter) to restore the hidden ones.Right-click the drive and choose Scan with Microsoft Defender. Turn off AutoPlay for removable drives in Settings > Bluetooth & devices > AutoPlay (Windows 11) or Devices > AutoPlay (Windows 10).
Full procedure with screenshots: Run a Microsoft Defender Offline scan
Step 2: Remove it from startup
Whatever Worm Heffer installed usually starts with Windows. Open Task Manager with Ctrl + Shift + Esc, go to Startup apps in Windows 11 or the Startup tab in Windows 10, and disable what you do not know, starting with entries that have an empty Publisher column.
Open file location on the right-click menu shows the file, which helps you decide and tells you what to delete later. Disabling is safe: if something you need stops working, switch it back on.
Full procedure with screenshots: Stop apps from opening at startup On uGetFix
Step 3: Delete scheduled tasks that bring it back
Open Task Scheduler from the Start menu and click Task Scheduler Library. Select each task you do not recognise and read the Actions tab:
- a task that starts a file in
%AppData%or%Temp% - runs
powershellwith a long encoded line - opens a web address belongs to Worm Heffer or a similar program
Right-click such a task and choose Delete, and check the subfolders too. Leave tasks from Microsoft, your PC's maker and programs you use. Task Scheduler is the same in Windows 11 and Windows 10.
Windows 11: Task Scheduler Library, the task selected, the Actions tab shows the file it runs. Full procedure with screenshots: Remove what malware leaves behind in Windows
- a task that starts a file in
Step 4: Scan the PC, then run the offline scan
Open Windows Security > Virus & threat protection > Scan options, run a Full scan and remove everything it finds. Then select Microsoft Defender Antivirus (offline scan) and click Scan now: the PC restarts and scans before Windows loads, which finds files that hide while Windows runs.
Save your work first, because the offline scan takes about 15 minutes. Both scans are built into Windows 11 and Windows 10, and a second scanner from another vendor is a useful extra opinion.
Windows 11: Windows Security > Virus & threat protection > Scan options. Full procedure with screenshots: Run a Microsoft Defender Offline scan
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 Apr 2021 · not reviewed since
Delete the worm and stop the Autorun for better protection
Removable drives are rarely used for malware distribution nowadays, but that does not mean that it does not happen.
In order to protect yourself from such an infection method, you should firstly install a powerful anti-malware software which likely to detect and stop the payload before it is executed.
Also, disabling the Autorun function can stop the parasite from spreading. Here's how:
- Right-click on Start and select Settings
- Go to Devices section
- Select AutoPlay on the left side
- Turn the switch to the left to turn the feature off.
After removal and prevention
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 Worm Heffer 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 worm Heffer in the list of installed apps.
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 Worm Heffer
Can I safely uninstall Worm Heffer?
If you did not install Worm Heffer yourself and it is not part of your hardware or a program you rely on, yes. Uninstalling an unwanted program does not harm Windows. Before you do, search the exact name and publisher to be sure it is not a driver tool, a printer utility or a game launcher with an odd name.
Then remove it from Settings, Apps, Installed apps. Ignore any offers or warnings in its uninstaller about losing protection or performance. Afterwards check Startup apps and your browsers for leftovers, and restart once to confirm that it does not reinstall itself.
Worm Heffer came back after I uninstalled it. Why?
Something else is reinstalling it. Common causes are a second program from the same publisher, a scheduled task that downloads it again, or a browser extension that keeps prompting for it. Sort Installed apps by install date and uninstall each entry from the same day that you did not choose.
Then open Task Scheduler and look in the Task Scheduler Library for tasks with updater-style names that you do not recognise. Check Startup apps in Task Manager too. If Worm Heffer still returns, start Windows in Safe Mode, uninstall it there and run a Microsoft Defender offline scan, which looks for loaders that ordinary scans can miss.
Are my files on the USB drive lost?
Usually not. USB worms hide the real folders and put shortcuts with the same names in their place. After scanning the drive on a cleaned PC, open it in File Explorer, choose View > Show > Hidden items, and your folders appear, faded.
Clear their Hidden attribute in Properties, delete the shortcuts and any unknown script files, then scan once more. Copy important files to a safe place before using the drive again. If anything is missing, a data recovery tool run from the cleaned PC may still find it.
The PC is still slow after removing Worm Heffer. What now?
Restart the PC first; some changes only take effect after a reboot. Then open Task Manager and check the Processes and Startup apps tabs for anything unfamiliar using the processor, disk or network. If something remains, run the Microsoft Defender offline scan once more.
Slowness can also come from a second infection installed alongside Worm Heffer, or from programs that were damaged during the clean-up. If nothing helps, back up your files and reset Windows. Copy only documents and photos before a reset, and scan the copies.
Are my files and accounts safe after Worm Heffer?
Your files are probably intact: nothing in the reports of Worm Heffer mentions encryption or deletion, and the sign people saw is worm Heffer in the list of installed apps. Accounts are the bigger question. Code that runs under your user account can read browser data, and threats like this one are often bundled with a stealer.
Until a scan proves the PC clean, avoid signing in to important accounts on it. Afterwards, change your main passwords from another device and turn on two-step verification. Check your e-mail for forwarding rules you did not set up, a common sign that an account was accessed.
How did Worm Heffer get on my computer?
The route for Worm Heffer is not documented yet. Malware that shows worm Heffer in the list of installed apps usually arrives with something you ran yourself:
- a cracked program or game cheat
- a free tool from a mirror site
- a fake installer found through a search ad
- a file on a USB drive
Some infections are dropped later by a loader that was already on the PC. To find your source, sort Installed apps by install date and look at the Downloads folder for the days before the sign appeared. Remove that item as well; otherwise the same infection may come back after the clean-up.
Should I scan my other computers too?
It is a good idea, even for malware that does not spread by itself. The same download, USB stick or loader may have been used on other PCs in the household, and shared folders can carry files between them.
Run a full scan followed by the Microsoft Defender offline scan on each Windows PC that shared drives or files with the infected one. Do not copy programs or installers from the infected PC until it is clean, and change Wi-Fi and router passwords if they were saved on it.
Should I reset my PC because of Worm Heffer?
Only if the signs point to deeper access. Reset when you see worm Heffer 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.
Can I just delete the file Windows Security found?
Let Windows Security handle it instead. When it finds Worm Heffer, choose Remove or Quarantine; the scanner also removes related startup entries and tasks that a manual delete would miss. Deleting a running file by hand often fails, and many threats restore themselves from a second copy.
After the removal, run the Microsoft Defender offline scan, which works before Windows starts and catches parts that hide while Windows runs. Then check Task Scheduler for leftovers. Restart afterwards and check that the detection does not return.
Will Fortect remove Worm Heffer?
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 Worm Heffer, 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
- FTC: How to recognize, remove and avoid malware (read October 6, 2026)
- Microsoft Learn: Microsoft Defender Offline (read October 6, 2026)
- Microsoft Learn: How Microsoft names malware (read October 6, 2026)