Defender FullScanRequired = False

Question

When I check the defender setting on my system using the powershell command Get-MpComputerStatus I see that the following settings for full scan. I haven't been able to find much info on why it shows my FullScanRequired = False and how to change it.

I even tried "Set-MpPreference -ScanParameters FullScan" but nothing changed.

Please advise,

FullScanAge                      : 4294967295
FullScanEndTime                  : 
FullScanOverdue                  : False
FullScanRequired                 : False
FullScanSignatureVersion         : 
FullScanStartTime                :

Answer 1

When I try to go to that URL it indicates that my Microsoft Personal account can't be used to access it, so I assume your systems must be part of a Work or School account operating on the Azure platform?

If so, you're in the wrong forums, since these Community forums are for the support of individual consumer users of Microsoft Personal accounts.

Regardless, I wouldn't be worried about this as long as whatever console you're accessing doesn't indicate a specific problem, since it's possible that status only relates to the tracking of manual scans and not the background scan that's performed automatically. I'd look more closely at whatever documentation is available for that portal, since what I found online is relatively light on details and only appears to be an overview of the XDR Portal.

Microsoft Defender portal | Microsoft Learn

Looking at the top of that page, the second menu line contains a 'Resources' selection at the right-hand end, under which is a selection titled 'Microsoft 365 tech Community', which if your Microsoft Defender product is part of that Microsoft 365 product, would likely be a better place to post your question to other users of that specific set of products used by organizations.

Rob

Answer 2

Thank you for replying to my post. The reason I was asking the question was when I look at https://security.microsoft.com/ devices, my system shows "Last Full Scan" status is "No Scan Performed", I am seeing this on most of my systems. Why are no Full Scans being performed automatically? I show that "Last quick Scan" was "completed" just no full scans.

Answer 3

Leave that setting alone, it's likely not what you think it is.

When a new Windows device is first set up, Windows Defender is set to initially perform a background Full scan when the system is on, but otherwise idle, in order to initialize the Defender scan cache database that is used to determine whether an individual file has already been scanned or not. Once this initial Full scan completes. this scan cache database should have every single file currently attached to the system marked as previously scanned, making future scans operate more quickly when definitions updates change how portions of this process are performed.

The Defender FullScanRequired = False flag that you've found is most likely related to this process and as such, only means that the initial Full scan or another later one has already occurred, so there's no need for Defender to perform another one when it starts up fresh after a system reboot. There are also other situations under which this flag might be reset to True by the system itself, in effect requiring that Defender perform another background Full scan again in order to reset the scan cache state for every single file, but Defender and/or the operating system makes the determination that this is necessary, not the user.

This flag has nothing to do with whether a manual Full scan can be performed or not, since you can do one of these any time you wish by simply going into the scanning menu and selecting it.

You don't state exactly why you feel this needs to be changed, but under normal circumstances there's simply no need for you to change it, as I've just described.

Rob