Short bio

This detection is for potentially unwanted modifications (PUMs) in the Windows registry where specific file types and processes are excluded for scanning by Windows Defender and Microsoft Security Essentials. Such changes may have been set by malware to avoid detection.

System modifications

Suspect registry values are created under the following keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender\

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender\

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Antimalware\

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Antimalware\


Malwarebytes can change the value data to 0 so the exclusions will be inactive, without user interaction.

Also, we advise users to do a full system scan as PUM.Optional.MSExclusion could have been added to the system by malware or a PUP.

Add an exclusion

When PUM is detected on your computer, Malwarebytes for Windows does not know if it was authorized. Optimization software, malware, and Potentially Unwanted Programs (PUPs) are known to make these types of changes, hence they are regarded as potentially unwanted.

To have Malwarebytes for Windows ignore a PUM, you must add the PUM as an exclusion.

  1. Open Malwarebytes for Windows.
  2. Click Settings, then click the Protection tab.
  3. Scroll down to the bottom.
  4. Turn off Automatically quarantine detected malware.Turning this setting off prevents Malwarebytes for Windows from quarantining the PUM automatically.
  5. Go to the Dashboard, then click Scan Now.
  6. When the Threat Scan Results appear, uncheck the box next to the detected PUM you want to keep.
  7. Click Next.
  8. On the Remaining Items window, click Ignore Always to add the exclude the detected PUM(s).
  9. Turn on Automatically quarantine detected malware.To find this setting, click Settings > Protection.

When a PUM is excluded, Malwarebytes for Windows does not detect the PUM during scans or Real-Time Protection.

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