Internet calendar integration in Outlook must be disabled.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-228470	DTOO285	SV-228470r822351_rule		Medium

Description
This policy setting allows the user to determine whether or not to include Internet Calendar integration in Outlook. The Internet Calendar feature in Outlook enables users to publish calendars online (using the webcal:// protocol) and subscribe to calendars that others have published. When users subscribe to an internet calendar, Outlook queries the calendar at regular intervals and downloads any changes as they are posted. If this policy setting is enabled, all internet calendar functionality in Outlook is disabled. If this policy setting is disabled or not configured, Outlook allows users to subscribe to trusted and untrusted internet calendars. The webcal protocol also has a history of loading web sites vulnerable to cross site scripting.

Description

This policy setting allows the user to determine whether or not to include Internet Calendar integration in Outlook. The Internet Calendar feature in Outlook enables users to publish calendars online (using the webcal:// protocol) and subscribe to calendars that others have published. When users subscribe to an internet calendar, Outlook queries the calendar at regular intervals and downloads any changes as they are posted. If this policy setting is enabled, all internet calendar functionality in Outlook is disabled. If this policy setting is disabled or not configured, Outlook allows users to subscribe to trusted and untrusted internet calendars. The webcal protocol also has a history of loading web sites vulnerable to cross site scripting.

STIG	Date
Microsoft Outlook 2016 Security Technical Implementation Guide	2022-03-11

Details

Check Text ( C-30703r822349_chk )
Verify the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Account Settings >> Internet Calendars "Do not include Internet Calendar integration in Outlook" is set to "Enabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\16.0\outlook\options\webcal Criteria: If the value Disable is REG_DWORD = 1, this is not a finding.

Check Text ( C-30703r822349_chk )

Verify the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Account Settings >> Internet Calendars "Do not include Internet Calendar integration in Outlook" is set to "Enabled".

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

HKCU\Software\Policies\Microsoft\Office\16.0\outlook\options\webcal

Criteria: If the value Disable is REG_DWORD = 1, this is not a finding.

Fix Text (F-30688r822350_fix)
Set the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Account Settings >> Internet Calendars "Do not include Internet Calendar integration in Outlook" to "Enabled".