Frequently Asked Question

How to manually update Windows Defender Virus Definitions?

Last Updated 5 months ago

Open Elevated Command prompt
a) Change directory to location of PS Tools
b) Run “PSEXEC \\Computername CMD” and hit enter
c) Also open an elevated PowerShell Window.

Note: You can do this all locally from the computer too. You will not need PSexec to do it locally. Still need elevated command prompt and Elevated PowerShell Windows.
You will need to get the latest definitions from Microsoft. The mpam-fe.exe file Download the latest Security Signatures from here:64 bit version for Windows 11.It’s at the bottom of the page: Latest security intelligence updates for Microsoft Defender Antivirus and other Microsoft antimalware - Microsoft Security Intelligence
Copy the mpam-fe.exe to the computer you need to update the signatures/definitions on.
Go back to your command prompt from earlier and type the following command to remove bad definitions.
“cd %ProgramFiles%\Windows Defender”
“MpCmdRun.exe -removedefinitions -dynamicsignatures”
In your PowerShell Windows you can run the following command to verify signature dates. Replace computername with the computer you are working on.
“Get-Mpcomputerstatus -CimSession Computername”
From Command prompt change to the directory, you have the mpam-fe.exe and then run it from the command prompt. That Exe will install the latest signatures.
Run the MP Status again from PowerShell window and you should see that your signatures are now up to date.