Microsoft Defender AV: Update Signatures from PowerShell

 

Here's how to update your Microsoft Defender Antivirus signatures using PowerShell:

• Open a PowerShell (or Terminal) as Administrator
• Run the following command: Update-MpSignature -UpdateSource MicrosoftUpdateServer
  
  

Now just wait for the process to finish and you're done! :)

Microsoft Defender AV: Update Signatures from Command-Line

 

If you need to update your Microsoft Windows Defender Antivirus signatures, here's how:

• Open a CMD as Administrator
• Run the following command: "%ProgramFiles%\Windows Defender\MpCmdRun.exe" -SignatureUpdate
  
  

Now just wait the process to finish and you're done!

Microsoft Defender AV: Client Logs

 

For everyone implementing Microsoft Windows Defender Antivirus, here's a quick note where to find the client logs and how to use them:

• C:\ProgramData\Microsoft\Windows Defender\Support
• MPLog-######-#####.log
• MPDetection-######-#####.log
• MPCacheStats.log (Defender Only)
  
  

You should use the MPLog to:

• Search Threat Name to locate a record of malware detection.
• Search Scan Source to locate a record of a scheduled scan running or record a running scan that is on demand.
• Search Expensive file to locate an instance of an expensive file detection during a scan.
• Seach on update process

Issues - Windows April Updates vs McAfee

Slow boot times, sometimes freezes, this are some of the symptoms described by some users after installing Microsoft’s April 2019 Patch Tuesday.

As it seems this happens in machines with McAfee Endpoint Security (ENS) installed.

Both McAfee and Microsoft have identified the issue and are currently investigating the issue:
McAfee Knowledge Center - KB91465
BleepingComputer - Windows April Updates Also Have Problems with McAfee Software