Windows Defender got stuck!

Screenshot of Microsoft Defender
All is quiet on the Windows front

For the last few weeks, I’ve been getting a daily email from Microsoft Defender telling me about a threat it had found on my desktop PC.

Only, I’d already deleted the offending files manually, but Defender got stuck—thinking they were still there, but unable to find them to remove them.

Here’s how I eventually fixed it.

Problem

For the last month or so, each morning, I received an email from Microsoft Defender <mydefender@microsoft.com> informing me that a threat had been found on my desktop PC (aka STUDY-DESKTOP).

The email looked like this:

Microsoft Defender found a threat on "STUDY-DESKTOP" A threat was found on the Windows device "STUDY-DESKTOP" on 22/05/2023. open Microsoft Defender to take action right away.
Email message from Microsoft Defender <mydefender@microsoft.com>

Only… there wasn’t a threat. I mean, had been. So, I got rid of it manually, but Microsoft Defender hadn’t got the message.

I probably should have left it to Microsoft Defender to safely dispose of the offending threat, but as it was only CCleaner that it had reported, I thought I’d save everyone a little time and I quickly deleted them from my external hard drive.

I had assumed that Microsoft Defender would notice that they’d gone and update its records accordingly. I was wrong.

And what’s more, within Windows Security the details about the current threat (the information in the red box) was completely missing. It simply showed… nothing!

Dialog from Windows Virus & threat protection screen. There is a red box showing the information that was missing.
Microsoft Security had turned into a threat to itself!

Fix

Anyway, long story short, I found a forum online where someone kindly pointed another user with the same issue to this folder in Windows:

C:\ProgramData\Microsoft\Windows Defender\Scans\History

Within this directory, I found a file called Detections.log and when I opened it, there was the information about the files that I had deleted:

277517|file|D:\Install\System\System Tools\CCleaner\ccsetup547.exe
277517|file|D:\Install\System\System Tools\CCleaner\ccsetup551.exe
277517|file|G:\D-Install\System\System Tools\CCleaner\ccsetup547.exe
277517|file|G:\D-Install\System\System Tools\CCleaner\ccsetup551.exe

I deleted the contents of the History folder; this contained three files and a directory:

\DetectionHistory
Detections.log
History.Log
Unknown.Log

I then rebooted my PC and… it worked!

Published by

Gareth Saunders

I’m Gareth J M Saunders, 52 years old, 6′ 4″, father of 3 boys (including twins). Enneagram type FOUR and introvert (INFP), I am a non-stipendiary priest in the Scottish Episcopal Church, I sing with the NYCGB alumni choir, play guitar, play mahjong, write, draw and laugh… Scrum master at Safeguard Global; latterly at Sky and Vision/Cegedim. Former web architect and agile project manager at the University of St Andrews and previously warden at Agnes Blackadder Hall.

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