1.20.3 Ensure 'Enable Microsoft Defender SmartScreen DNS requests' is set to 'Disabled'

Information

This policy setting configures DNS requests made by Microsoft Defender SmartScreen.

Note: This policy is available only on Windows instances that are joined to a Microsoft Active Directory domain, Windows 10 Pro or Enterprise instances that enrolled for device management, or macOS instances that are that are managed via MDM or joined to a domain via MCX.

The recommended state for this setting is: Disabled.

Rationale:

Whenever SmartScreen is enabled for Edge browser, SmartScreen tries to check if the website is a phishing/malicious URL and also does a local DNS query. If the DNS server fails to resolve the website, Web Isolation will not be used to isolate those websites.

Impact:

DNS server might not resolve queries sent to external websites or the website may have no information stored on its local server or cache.

Warning: Disabling DNS requests will prevent Microsoft Defender SmartScreen from getting IP addresses, and potentially impact the IP-based protections provided.

Solution

To establish the recommended configuration via GP, set the following UI path to Disabled:

Computer Configuration\Policies\Administrative Templates\Microsoft Edge\SmartScreen settings\Enable Microsoft Defender SmartScreen DNS requests

Note: This Group Policy path may not exist by default. It is provided by the Group Policy template MSEdge.admx/adml that can be downloaded from: Download Microsoft Edge for Business - Microsoft.

Default Value:

Enabled. (Microsoft Defender SmartScreen will make DNS requests.)

See Also

https://workbench.cisecurity.org/files/4094