Internet calendar integration in Outlook must be disabled.

From Microsoft Outlook 2016 Security Technical Implementation Guide

Associated with: CCI-000381

SV-85887r1_rule Internet calendar integration in Outlook must be disabled.

Vulnerability discussion

This policy setting allows you to determine whether or not you want 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 you enable this policy setting, all Internet calendar functionality in Outlook is disabled. If you disable or do not configure this policy setting, Outlook allows users to subscribe to Internet calendars.

Check content

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

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".

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