Microsoft Defender AV must be configured to block the Potentially Unwanted Application (PUA) feature.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
high	V-213426	SRG-APP-000279	WNDF-AV-000001	SV-213426r823024_rule	2022-04-08	2

Description
After enabling this feature, PUA protection blocking takes effect on endpoint clients after the next signature update or computer restart. Signature updates take place daily under typical circumstances. PUA will be blocked and automatically quarantined.

ℹ️ Check
Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> "Configure detection for potentially unwanted applications" is set to "Enabled" and "Block". Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows Defender If the value "PUAProtection" does not exist, this is a finding. If the value "PUAProtection" is REG_DWORD = 1, this is not a finding.

ℹ️ Check

Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> "Configure detection for potentially unwanted applications" is set to "Enabled" and "Block". Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows Defender If the value "PUAProtection" does not exist, this is a finding. If the value "PUAProtection" is REG_DWORD = 1, this is not a finding.

✔️ Fix
Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> "Configure Detection for Potentially Unwanted Applications" to "Enabled" and "Block".