Windows 10: Windows defender threats found and available actions

I did a full system scan with windows defender and it found threats. My question is with the available actions, i'm not sure what each one does exactly and want to make sure I choose the right one.

My options


Clean threat

quarantine

remove

allow on device


What do the first three do exactly and all i want to do is safely and fully remove these from my system.

:)

 

'windows defender successfully took action on 1 threat'

I get a notification that 'windows defender successfully took action on 1 threat' but I am not able to see what the problem or threat was that it took action on. Advice?

 

Windows Defender keeps taking action on nonexistent threats on nonexistent scans

I have a laptop (Dell Inspiron 3541) running Windows 10 v1803. Recently, I have been getting notifications from Windows Defender saying threats were found and removed on scnas that didn't happen.

Some of the notifications are:

and

When I go to Windows Defender, it doesn't show any threats found - nor does it even show a recent scan. For example, I got one of the above notifications today, and this is what Windows Defender showed.





I tried running a scan, but the ETA was 4 hours, then 20, then 70, and still kept going up.

Is there a way I can find out what the "threats" are? Or make it stop sending these unnecessary notifications?

 

Windows defender false positive - forced to allow threat


Windows defender has started to identify C:\Windows\System32\mshta.exe as a threat [normally reported as a Trojan Powessere.G]. I use mshta.exe to run an hta custom MsgBox - I have been hoping to keep using my current CustomMsgBox tool [batch file calling a vbs-hta file] until later this year when I hope to have had enough time to replace it with a PowerShell alternative.

Windows defender's notification lets me "allow the threat" but that seems to me to be a bigger security hole than is necessary - it will now ignore a potentially real intrusion when all I want to run is a genuine Windows component. My immediate problem is fixed but I would prefer to fix the false positive using the exclusions list.

I cleared the 'Allowed threats history' so I could use the exclusions list instead. I added C:\Windows\System32\mshta.exe to the file exclusions list and I checked that it had taken properly by checking the exclusions list both in the UI & in the Registry. But the exclusion made no difference, it continued to detect and block the exe.

I have repeated the attempt several times [by clearing the allowed threats list & exclusions list beforehand] and the results are the same every time
- allowing the threat works,
- using the exclusions list has no effect.

I studied the relevant tutorial but have not spotted an error in what I have been doing - Add or Remove Windows Defender Exclusions

Does anybody with experience of using the exclusions list to counter false positives have any suggestions for me?

Denis