Files from Internet zone must be opened in Excel in Protected View mode.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-223340	O365-EX-000031	SV-223340r879628_rule		Medium

Description
This policy setting allows you to determine if files downloaded from the Internet zone open in Protected View. If you enable this policy setting, files downloaded from the Internet zone do not open in Protected View. If you disable or do not configure this policy setting, files downloaded from the Internet zone open in Protected View.

STIG	Date
Microsoft Office 365 ProPlus Security Technical Implementation Guide	2023-03-17

Details

Check Text ( C-25013r442239_chk )
Verify the policy value for User Configuration >> Administrative Templates >> Microsoft Excel 2016 >> Excel Options >> Security >> Trust Center >> Protected View >> Do not open files from the Internet zone in Protected View is set to "Disabled". Use the Windows Registry Editor to navigate to the following key: HKCU\software\policies\microsoft\office\16.0\excel\security\protectedview If the value DisableInternetFilesInPV is REG_DWORD = 0, this is not a finding. If the value does not exist, this is not a finding. If the value is REG_DWORD = 1, this is a finding.

Check Text ( C-25013r442239_chk )

Verify the policy value for User Configuration >> Administrative Templates >> Microsoft Excel 2016 >> Excel Options >> Security >> Trust Center >> Protected View >> Do not open files from the Internet zone in Protected View is set to "Disabled".

Use the Windows Registry Editor to navigate to the following key:

HKCU\software\policies\microsoft\office\16.0\excel\security\protectedview

If the value DisableInternetFilesInPV is REG_DWORD = 0, this is not a finding.

If the value does not exist, this is not a finding.

If the value is REG_DWORD = 1, this is a finding.

Fix Text (F-25001r442240_fix)
Set policy value for User Configuration >> Administrative Templates >> Microsoft Excel 2016 >> Excel Options >> Security >> Trust Center >> Protected View >> Do not open files from the Internet zone in Protected View to "Disabled".