Make Windows Defender protect you against Potentially Unwanted Programs too

Microsoft has now made it possible for you to add protection against Potentially Unwanted Programs (PUPs) or Potentially Unwanted Applications (PUA) to your Windows Defender on Windows 10.

This feature has been announced by Microsoft exclusively for Enterprise users only, but with a little bit of work, you can make it work on your Windows 10/8/7 PCs too.

The Potentially Unwanted Application protection feature is available only for enterprise customers.  If you are already one of Microsoft’s existing enterprise customers, you need to opt-in to enable and use PUA protection. PUA protection updates are included as part of the existing definition updates and cloud protection for Microsoft’s enterprise customers, says Microsoft.

Potential Unwanted Application (PUA) or PUPs is a threat classification based on reputation and research-driven identification. They are typically Crapware or Bundleware, and such software that you really do not want on your system, and which could potentially do more harm than good. You can protect yourself from PUA or PUPs by deploying an antimalware policy. This protection policy setting is disabled by default.

Make Windows Defender block Potentially Unwanted Programs

Make Windows Defender block Potentially Unwanted Programs

To do this you will have to modify the Windows Registry. The registry key varies according to your product version, and is different for System Center Endpoint Protection, Forefront Endpoint Protection, Microsoft Security Essentials or Windows Defender, as shown in the above image.

PUA protection will quarantine the PUP file and prevent them from running if it meets one of the following conditions:

  1. The file is being scanned from the browser
  2. The file has Mark of the Web set
  3. The file is in the %downloads% folder
  4. Or if the file in the %temp% folder

To make Windows Defender protect you against Potentially Unwanted Programs, Run regedit to open the Registry Editor and navigate to the following key:

HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender

Windows Defender

Here, right-click on Windows Defender and select New > Key > Name it MpEngine.

Now right-click on MpEngine and select New > DWORD (32-bit) Value > Name it MpEnablePus and give it a value 1.

  • With a value of 0 which is the default, Potentially Unwanted Application protection is disabled
  • With a value of 1 Potentially Unwanted Application protection is enabled. The applications with unwanted behavior will be blocked at download and install-time.

Restart your Windows computer.

In Windows 10, the following dialog box will be displayed, when a PUP file is blocked:


If you think that a program has been wrongfully identified as PUA, you can submit the file here.

Read: Windows Defender will block Unwanted Software based on these criteria.

You can also configure Windows Defender PUP protection, to exclude specific files or folders. More on this at TechNet.

This post shows how you can harden Windows Defender protection to the highest levels on Windows 10 v1703 by changing a few Group Policy settings.

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Anand Khanse is the Admin of, a 10-year Microsoft MVP Awardee in Windows (2006-16) & a Windows Insider MVP. Please read the entire post & the comments first, create a System Restore Point before making any changes to your system & be careful about any 3rd-party offers while installing freeware.