Security Warning for unsafe files must be disallowed (Restricted Sites zone).

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-223139	SRG-APP-000516	DTBI870-IE11	SV-223139r879887_rule	2023-12-01	2

Description
This policy setting controls whether or not the 'Open File - Security Warning' message appears when the user tries to open executable files or other potentially unsafe files (from an intranet file shared by using Windows Explorer, for example). If you enable this policy setting and set the drop-down box to "Enable", these files open without a security warning. If you set the drop-down box to "Prompt", a security warning appears before the files open. If you disable this policy these files do not open. If you do not configure this policy setting, the user can configure how the computer handles these files.

Description

This policy setting controls whether or not the 'Open File - Security Warning' message appears when the user tries to open executable files or other potentially unsafe files (from an intranet file shared by using Windows Explorer, for example). If you enable this policy setting and set the drop-down box to "Enable", these files open without a security warning. If you set the drop-down box to "Prompt", a security warning appears before the files open. If you disable this policy these files do not open. If you do not configure this policy setting, the user can configure how the computer handles these files.

ℹ️ Check
The policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Internet Explorer -> Internet Control Panel -> Security Page -> Restricted Sites Zone -> 'Show security warning for potentially unsafe files' must be 'Enabled', and 'Disable' selected from the drop-down box. Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4 Criteria: If the value "1806" is REG_DWORD = 3, this is not a finding.

ℹ️ Check

The policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Internet Explorer -> Internet Control Panel -> Security Page -> Restricted Sites Zone -> 'Show security warning for potentially unsafe files' must be 'Enabled', and 'Disable' selected from the drop-down box. Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4 Criteria: If the value "1806" is REG_DWORD = 3, this is not a finding.

✔️ Fix
Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Internet Explorer -> Internet Control Panel -> Security Page -> Restricted Sites Zone -> 'Show security warning for potentially unsafe files' to 'Enabled', and select 'Disable' from the drop-down box.