Title

Automatic download of Internet Calendar appointment attachments must be disallowed. (Cat II impact)

Discussion

Files attached to Internet Calendar appointments could contain malicious code that could be used to compromise a computer. By default, Outlook does not download attachments when retrieving Internet Calendar appointments.

Check Content

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Account Settings -> Internet Calendars "Automatically download attachments" is set to "Disabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\outlook\options\webcal Criteria: If the value EnableAttachments is REG_DWORD = 0, this is not a finding.

Fix Text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Account Settings -> Internet Calendars "Automatically download attachments" to "Disabled".

Additional Identifiers

Rule ID: SV-54057r1_rule

Vulnerability ID: V-17738

Group Title: DTOO284 - Auto download attachments Internet Cal

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.