This policy setting configures scanning for all downloaded files and attachments. The recommended state for this setting is: Enabled. Rationale: When running an antivirus solution such as Microsoft Defender Antivirus, it is important to ensure that it is configured to heuristically monitor in real-time for suspicious and known malicious activity. Impact: None - this is the default behavior.
Solution
To establish the recommended configuration via GP, set the following UI path to Enabled: Computer Configuration\Policies\Administrative Templates\Windows Components\Microsoft Defender Antivirus\Real-Time Protection\Scan all downloaded files and attachments Note: This Group Policy path may not exist by default. It is provided by the Group Policy template WindowsDefender.admx/adml that is included with the Microsoft Windows 8.1 & Server 2012 R2 Administrative Templates (or newer). Default Value: Enabled. (All downloaded files and attachments will be scanned.)