Windows Defender first appeared as an anti-virus utility for Windows XP. Since Vista, it was built into all Microsoft OSs as a protection against viruses, worms, trojans, and other types of malicious software. In Windows 8 it was merged with another antivirus product—Microsoft Security Essentials, and now it is full-featured antivirus software. Windows Defender is productive enough and has low system requirements. It can be updated online from the Microsoft website or an internal WSUS server. That allows you to use it not only on home computers but also in SMB and enterprise corporate networks. In this article, we will take a closer look at how to manage different settings and enable/disable Windows Defender using PowerShell.
Managing Windows Defender Using PowerShell
The main advantage of the Defender is that it is easy to use, it’s already pre-installed in Windows 10 and 8.1, enabled by default, and practically doesn’t need manual configuration.
Tip. At the moment, Windows Defender is a part of the only desktop Windows OS and not available in the current versions of Windows Server. Although, in the latest Windows Server 2016/2019, Windows Defender can be installed as an additional server feature using the command:Install-WindowsFeature-Name Windows-Server-Antimalware
In most cases, Windows Defender works well with the default settings, but sometimes the user needs to change its behavior. A large number of settings available from the PowerShell console, through a built-in module Defender. It appeared first time in PowerShell 4.0 and was designed specifically for Windows Defender management. This module contains 11 cmdlets, which we are reviewing today.
To display a list of cmdlets contained in the Defender module, run the following command:
Get-Command -Module Defender
- Add-MpPreference—used to change Windows Defender settings;
- Get-MpComputerStatus—allows you to get the status of anti-virus software on your computer;
- Get-MpPreference—used to get Windows Defender scan and update options;
- Get-MpThreat—view the history of detected threats on your computer;
- Get-MpThreatCatalog—allows you to get known threats from the definitions directory;
- Get-MpThreatDetection—displays a list of active and recent threats detected on the computer;
- Remove-MpPreference—allows you to remove Windows Defender settings or exceptions;
- Remove-MpThreat—allows you to remove active threats from your computer;
- Set-MpPreference—used to change scan and update options;
- Start-MpScan—runs a computer scan;
- Update-MpSignature—anti-virus definition database update;
- Start-MpWDOScan—runs a Windows Defender offline scan;
To get full help on a specific cmdlet of the Defender module, use the command:
Get-Help cmdlet name –Full
If you need only examples of PowerShell commands, run:
Get-Help cmdlet name -Examples
How to Check if Windows Defender is Running?
Before using PowerShell cmdlets to control Windows Defender, it is advisable to check that the service is running. You can use the following PowerShell command to check the service state of Windows Defender:
Get-MpComputerStatus allows you to display the current status of Windows Defender: enabled options, virus definition date and version, last scan time, and others.
AMEngineVersion : 1.1.17700.4
AMProductVersion : 4.18.2011.6
AMRunningMode : Normal
AMServiceEnabled : True
AMServiceVersion : 4.18.2011.6
AntispywareEnabled : True
AntispywareSignatureAge : 0
AntispywareSignatureLastUpdated : 10/12/2020 16:53:44
AntispywareSignatureVersion : 1.329.171.0
AntivirusEnabled : True
AntivirusSignatureAge : 0
AntivirusSignatureLastUpdated : 10/12/2020 16:53:46
AntivirusSignatureVersion : 1.329.171.0
BehaviorMonitorEnabled : True
ComputerID : EDE4AA6A-2A4A-4D19-856A-ABD46C360A25
ComputerState : 0
FullScanAge : 4294967295
IoavProtectionEnabled : True
IsTamperProtected : True
IsVirtualMachine : False
LastFullScanSource : 0
LastQuickScanSource : 2
NISEnabled : True
NISEngineVersion : 1.1.17700.4
NISSignatureAge : 0
NISSignatureLastUpdated : 10/12/2020 16:53:46
NISSignatureVersion : 1.329.171.0
OnAccessProtectionEnabled : True
QuickScanAge : 3
QuickScanEndTime : 08/12/2020 00:18:45
QuickScanStartTime : 08/12/2020 00:15:56
RealTimeProtectionEnabled : True
RealTimeScanDirection : 0
To quickly check if Windows Defender is running on your computer and find out the last antivirus definition update date, run the following PowerShell command:
Get-MpComputerStatus | Select-Object -Property Antivirusenabled,AMServiceEnabled,AntispywareEnabled,BehaviorMonitorEnabled,IoavProtectionEnabled,NISEnabled,OnAccessProtectionEnabled,RealTimeProtectionEnabled,AntivirusSignatureLastUpdated
To display current Windows Defender settings you can use cmdlet Get-MpPreference. To change the settings use the Set-MpPreference.
In the Windows Defender settings, the IPS, removable disk check, email, and some other checks are disabled by default. For example, you need to enable the scanning of removable drives. Let’s get the current settings using the command:
Get-MpPreference | fl disable*
As you can see, scan removable drives is disabled (DisableRemovableDriveScanning = True). Turn it on using the following command:
Set-MpPreference -DisableRemovableDriveScanning $false
By default, the Windows Defender doesn’t check the archive files (RAR, ZIP, CAB), which can potentially contain malicious files. You can enable the checking of archive files by running:
Set-MpPreference -DisableArchiveScanning 0
After that, the Windows Defender will start scanning all opened archive files in real-time, as well as when scanning a disk.
Also, to change or remove the antivirus settings, you can use Add-MpPreference and Remove-MpPreference cmdlets. For example, let’s add some folder paths to the antivirus exclusions:
Add-MpPreference -ExclusionPath C:\Video, C:\install
Display a list of path exceptions for Windows Defender:
Get-MpPreference | fl excl*
To exclude anti-virus scanning of certain processes, run the following command:
Set-MpPreference -ExclusionProcess "word.exe", "vmwp.exe"
To remove an exception for a specific folder:
Remove-MpPreference -ExclusionPath C:\install
Windows Defender has a hidden function to protect against unwanted programs (Potentially Unwanted Program—PUP, Potentially Unwanted Application—PUA). By default, it is accessible only in Windows 10 Enterprise edition, but with the help of the following command you can enable PUP/PUA protection in any Windows 10 edition:
Set-MpPreference -PUAProtection 1
After you turn on protection, when you try to launch or install potentially unwanted programs on your computer, you will receive the following notification from Defender in Windows 10.
Windows Defender took action
Your settings caused Windows Defender Antivirus to block an app that may potentially perform unwanted actions on your device.
Use PowerShell to Update Windows Defender Signatures
To start the antivirus signature update, you can use the command Update-MpSignature. By default, the Windows Defender updates with standard computer settings, but using the UpdateSource argument lets you specifying where exactly you want to take the virus definition updates.
The following virus definition sources are available:
- MMPC Microsoft Malware Protection Center;
- InternalDefinitionUpdateServer — internal WSUS server.
To update antivirus from a network shared folder on a Windows file server you need to download the necessary definition update files and place them into a shared folder. Then you have to specify that Windows Defender should be updated from a file share source (use UNC path):
Set-MpPreference -SignatureDefinitionUpdateFileSharesSources \\DESKTOP-V20E3PO\Updates
To run virus update and malware definitions manually:
Update-MpSignature -UpdateSource FileShares Update-MpSignature
In some cases, after receiving an incorrect update, Windows Defender may not work correctly. In this case, it is recommended to reset the current thread definition databases and reload them from source:
"%PROGRAMFILES%\Windows Defender\MPCMDRUN.exe" -RemoveDefinitions -All "%PROGRAMFILES%\Windows Defender\MPCMDRUN.exe" –SignatureUpdate
How to Perform Virus Scan with Microsoft Defender?
To perform an antivirus scanning of your computer, use the Start-MpScan cmdlet. With the ScanType argument, you can choose one of three scan modes:
- FullScan — scan is performed for all files on your computer, as well as the system registry and currently running apps;
- QuickScan — analysis of only those areas that are most likely may be infected by malware (registry, active RAM, system folders);
- CustomScan — user selects the folders and drives to scan.
For example, run a custom scan to check the system folder “C:\Program Files”:
Start-MpScan -ScanType CustomScan -ScanPath ”C:\Program Files”
You can perform a full computer scan by Windows Defender using the command:
Start-MpScan -ScanType FullScan
Or quick threats scan:
Start-MpScan -ScanType QuickScan
To remove all active threat on your computer, use the command:
All Defender module cmdlets can be performed both for the local and remote computers. To connect to a remote computer you need to use the CimSession option. For example, to get the date of the last scan from the remote computer with hostname lnd_wks21, run the following commands (WimRM must be enabled):
$session = NewCimSession -ComputerName lnd_wks21 Get-MpComputerStatus -CimSession $session | fl fullscan*
How to Disable and Remove Windows Defender using PowerShell?
If you want to disable Defender real-time protection:
Set-MpPreference -DisableRealtimeMonitoring $true
To completely disable Windows Defender on a computer, use the command:
New-ItemProperty -Path “HKLM:\SOFTWARE\Policies\Microsoft\Windows Defender” -Name DisableAntiSpyware -Value 1 -PropertyType DWORD -Force
On Windows client-based operating system (like Windows 10/Windows 8.1) you cannot completely uninstall the Windows Defender feature. The only available option is to disable it using the registry key DisableAntiSpyware = 1 or using the Local Group Policy Editor.
- Run the gpedit.msc console;
- Go to the following GPO section: Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Antivirus;
- Find the parameter named Turn off Windows Defender Antivirus on the right pane;
- Change its value to Enabled;
- In the same way disable the following Group Policy setting in the Real-time Protection section: Turn off real time protection = Disabled;
- To apply new settings, update local Group Policy settings on a computer using the command:
You can uninstall Windows Defender on Windows Server 2016\2019 using PowerShell. Just run the following command in the elevated PowerShell session:
Uninstall-WindowsFeature -Name Windows-Defender –whatif
Or use the DISM tool:
Dism /online /Disable-Feature /FeatureName:Windows-Defender /Remove /NoRestart /quiet
How to Reset Windows Defender to Default?
You can reset all Windows Defender settings using the Windows Security App.
- Press the Start button and type: Windows Security;
- Select the App settings;
- Scroll down to the Reset button and click on it;
- The following warning will appear: “This will permanently delete the app’s data on this device, including your preferences and sign-in details”. Confirm it by pressing the Reset button.
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