How to update Windows Defender definitions using Windows PowerShell

For basic security protection against viruses and malware, Microsoft has built-in Windows Defender in your Windows 11/10 operating systems. This means that you don’t need to install any antivirus programs and Windows Defender will take care of security issues. With Windows 11/10, this security suite has the ability to update antimalware definitions automatically along with Windows Updates.

We have seen how to manually install the latest definitions for Windows Defender. Today, in this article, we’ll see how you can update Windows Defender virus definitions using Windows PowerShell.

Update Windows Defender Definitions Using Windows PowerShell

1. Press Windows Key + Q, type Windows PowerShell in the search box. From the results, right-click on Windows PowerShell and select Run as administrator. If you’re prompted for the user account password, provide that.

2. Next, in the Windows PowerShell window so open type cd.. and hit Enter key. Again type cd.. and then press Enter key. In this way, you should be arrived at PS C:\> directory.

3. Now you can type this cmdlet, after making choice about parameters, and hit Enter key. The general cmdlet (simplified) goes like this:

Update-MpSignature [-UpdateSource <UpdateSource> {InternalDefinitionUpdateServer | MicrosoftUpdateServer | MMPC | FileShares} ]

For example, the command you’ll use to simply update definitions is:

PS C:\> Update-MpSignature

This automatically determines which is the best update source for and begins downloading definitions.

In case, if you want to specify the update definitions source, you need to alter the general cmdlet. For example, if you want to update from Microsoft Update Server, you can use the following cmdlet:

PS C:\> Update-MpSignature -UpdateSource MicrosoftUpdateServer

Other updated sources you can use are InternalDefinitionUpdateServer, Microsoft Malware Protection Center (MMPC) and FileShares.

When you use InternalDefinitionUpdateServer source, the service checks for updates on the Windows Software Update Services (WSUS) server.

Hope you find the article informative and helpful!