Accidentally downloaded a malicious file and it was a trojan virus, been reoccurring in window security notifications

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Accidentally downloaded a malicious file and it was a trojan virus, been reoccurring in window security notifications

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Hello, I'm wondering how to ensure a permanent removal of a trojan virus after accidentally clicking on a malicious file and downloading it weeks ago. At first it had been reoccurring after a week or two each period where window security will notify me of a threat detected and update after quarantining and then blocking the virus. I've clicked on the action to be performed through window security to remove the virus in the dropdown and performed microsoft offline scans in order to make sure the additional files are removed. However, the threat popped up again recently in a different type of file, still a trojan virus, and at first it said remediation incomplete before updating 5 hrs later to the threat being blocked. I have just pressed the action to remove it and done another offline scan today, to which it removed a couple of files by notifying me.

I'm wondering if there is anything I need to do in order to ensure the virus is gone since it seems to be coming back in a different form. Or if there is nothing to worry about as long as window security and microsoft security defender is working as normal. Here are the screenshots below and the last threat before the most recent one was on oct 8th.

Screenshot 2026-10-14 225340

Screenshot 2026-10-14 225151 Screenshot 2026-10-14 225414

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Answer 1

Since the same PC has shown repeated detections weeks apart, including Remediation incomplete and then later Threat removed/blocked, the safest conclusion is that something on the device may have been reinstalling or re-triggering the malware.

Recommended next steps:

Review Protection history carefully
- Open Windows Security > Virus & threat protection > Protection history.
- Look for the most recent entries and confirm whether they say:
  - Threat blocked: Defender blocked and removed it; no immediate action is required.
  - Threat quarantined: it is contained, and Remove deletes it.
  - Remediation incomplete: Defender could not fully finish cleanup, so open that card and complete any additional action shown.
Check quarantined items and remove them
- Go to Start > Settings > Update & Security > Windows Security > Virus & threat protection.
- Under Current threats, select Threat history.
- Under Quarantined threats, select See full history.
- Remove any remaining quarantined items if they are still present.
Run another Microsoft Defender Offline scan
- This is the right scan when malware appears to come back after restart or over time.
- Go to Start > Settings > Update & Security > Windows Security > Virus & threat protection.
- Under Current threats, select Scan options.
- Select Windows Defender Offline scan > Scan now.
- Save open files first, because the PC will restart.
Run a Full scan after the offline scan
- In Scan options, run Full scan to scan every file and program on the device.
Make sure nothing was accidentally allowed
- In Windows Security, check the Allowed threats page.
- If any detected item was previously allowed by mistake, select it and choose Don’t allow so Defender will act on it again.
Update Defender components
- Run Windows Update to make sure the latest fixes and security components are installed.
- If Defender keeps encountering scan or cleanup errors, install the latest protection updates manually.

What the current alerts mean:

Threat blocked means Defender blocked and removed the threat; no further action is normally needed.
Remediation incomplete means cleanup did not fully finish and needs follow-up.
Repeated detections can happen when the same malicious source is encountered again, or when a hidden component keeps reinstalling the malware.

Important caution:

Do not choose Allow for any of these detections unless the file is fully trusted. Allowing a threat lets it run and suppresses future alerts for that file.

If detections continue after another Offline scan and Full scan, that is not normal background behavior. It indicates the malware may still be recurring, and the key sign to watch is whether new entries continue appearing in Protection history after Defender reports removal.