Im still suspecting that there's a virus on my windows 11 system. What should I do?

Question

Im still suspecting that there's a virus on my windows 11 system. What should I do?

Aaron Naser 81

Hi

I had a nasty Trojan that seemed to be undetectable by most antiviruses so I re-installed windows 11 using a bootable usb stick on my machine and deleted all my partitions during the setup. I noticed some abnormal behaviours on my computer like my cpu increasing when I close task manager. I’m unsure if that’s a problem to be concerned of though. Is there anyway that I can be completely sure that there’s no viruses on my computer?

Adrian Tadeo 0 Reputation points

2023-12-30T14:38:10.83+00:00

Same here. I tried full scan multiple times. I tried updating everything that needs/can be updated. 😭
l d 0 Reputation points

2025-05-21T00:07:47.0233333+00:00

I never had a problem with Security Suites

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Adrian Tadeo 0 Reputation points

2023-12-30T14:38:10.83+00:00

Same here. I tried full scan multiple times. I tried updating everything that needs/can be updated. 😭
l d 0 Reputation points

2025-05-21T00:07:47.0233333+00:00

I never had a problem with Security Suites

Answer 1

Hello @Aaron Naser

First of all you can run a antivirus full scan on your computer using the Microsoft Defender Antivirus on your computer.

Steps:
Open Start on Windows 11.

1.Search for Windows Security and click the top result to open the app.
2.Click on Virus & threat protection.
3.Under the “Current threats” section, click on Scan options.\
4.Select the Full scan option to check the entire system for viruses and any other type of malware.
5.Click the Scan now button.

Additionally, my comment in case it appears clean, is because most of malicious software on your computer will be removed once partitions are deleted and system is installed over the old data. My suggestion to explain the abnormal behavior would be:
A) Windows 11 is still installing some updates in the background after the 1st time boot.
-The best option is to leave it on for some time, but you can always expedite the process by going to the Update section of your Windows Settings.

B) Some drivers may be automatically installed by Windows installation but may not be the most efficient version of the drivers. I would recomment 2 options:
1.From the Update section of your Windows Settings, select View Optional Updates and select Drivers and Firmware to install updates
2.Check on the computer or devices manufacturer for updated BIOS, Firmware or Drivers for the devices of your computer (Motherboard, Chipset, GPU, CPU, etc...).

Hope this helps with your query,

--If the reply is helpful, please Upvote and Accept as answer--

Aaron Naser 81 Reputation points

2022-05-10T07:24:19.047+00:00

I ran a scan with Microsoft defender although it detected 0 threats. I also updated all my drivers and firmware although I’m still experiencing the same abnormal behaviours. Let’s say my computer had no viruses and there was maybe a safe program eating all the cpu. Why is it when I open task manger my cpu decreases immediately as if a a virus is trying to hide its self?

Answer 2

Nic Bennett 5

I’ve had the same issue my self since I upgraded back in February. I still believe there is a big security hole somewhere and it’s rewriting dism and sfc. Because every time I use them, my system goes catastrophic on me. It’s undetectable by everything I’ve tried, including defender. Also it modified the registry entries for safe boot so any time I’d try to safe boot it would basically lock up the system. OP have you seen any of these same issues? Even after a clean install? I’m curious if I’m still alone in this or someone else is having the same exact problems.

W Watson 0 Reputation points

2023-11-30T18:47:03.31+00:00

I have been investigating a virus that has all of the same behaviors, unfortunately it remains persistent through reinstalls by staying in the X: virtual directory. I have been looking at ways to get rid of it, but none so far since it effectively takes admin rights from you, and gives itself supervisor. It isn't just 1 virus, it is a ransomware, keylogger among other things. It is also very well written. It gives Windows 11 users a false Bitlocker screen to take full control of secure boot (it is the one thing it can't take when a system is in S Mode. There is much more to it than this, but until I have a way of removing it from the virtual environment, there isn't much more to mention. In regards to should of bought a Mac/used Linux? Well surprise, it has code for that as well.

Answer 3

Reza-Ameri 17,341 Volunteer Moderator

CPU and Performance issue might or might not be related to the malware.
Normally, when you completely format and reinstall Windows, all traces of malwares are being removed.
You may try run Windows Update and download and install all updates and restart your PC.
Try use your PC for a while and see if there is improvement in performance.
When Windows freshly installed, it will run multiple services like Search Index, Anti-Malware Engine, Windows Update in the background and that might affect performance.
Do you know how you get infected?
Do you have a sample of the infected file?
If yes, NEVER post it here, I will guide you to submit sample of possible infected sources (if any) to Microsoft Anti-Malware team for more analysis.

Aaron Naser 81 Reputation points

2022-05-10T07:29:02.237+00:00

Sadly I don’t have the infected files but before when I did a factory reset on my computer I did.

I got the Trojan by attempting to download pirated software.
Reza-Ameri 17,341 Reputation points Volunteer Moderator

2022-05-10T15:50:33.023+00:00

Do you have the address of the website with the pirate software?
If yes, submit the URL on:
https://www.microsoft.com/en-us/wdsi/support/report-unsafe-site

Answer 4

Kapil Arya 8,461 MVP Volunteer Moderator

Make a full scan with Windows Defender/Security app to ensure there are no security threats on your system,

Answer 5

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Im still suspecting that there's a virus on my windows 11 system. What should I do?

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