2.5.14.3.8 (L1) Ensure 'Allow users to demote attachments to Level 2' is set to 'Disabled'

Information

This policy setting controls whether Outlook users can demote attachments to Level 2 by using a registry key, which will allow them to save files to disk and open them from that location. Outlook uses two levels of security to restrict access to files attached to e-mail messages or other items. Files with specific extensions can be categorized as Level 1 (users cannot view the file) or Level 2 (users can open the file after saving it to disk). Users can freely open files of types that are not categorized as Level 1 or Level 2.

Note: If this policy is enabled, users can create a list of Level 1 file types to demote to Level 2 by adding the file types to the following registry key:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Security\Level1Remove

The recommended state for this setting is: Disabled

If users can demote Level 1 files to Level 2, they will be able to access potentially dangerous files after saving them to disk, which could allow malicious code to infect their system or compromise the security of sensitive information.

Solution

To establish the recommended state via configuration profiles, set the following Settings Catalog path to Disabled :

Microsoft Outlook 2016\Security\Security Form Settings\Outlook Security Mode > Allow users to demote attachments to Level 2

Important: For this setting to apply, the

Outlook Security Mode

setting must be enabled in

Microsoft Outlook 2016\Security\Security Form Settings

with Use Outlook Security Group Policy selected, as set in this benchmark.

Impact:

Users will not be able to demote a Level 1 file to a Level 2 file.

See Also

https://workbench.cisecurity.org/benchmarks/15808

Item Details

Category: SYSTEM AND INFORMATION INTEGRITY

References: 800-53|SI-3, 800-53|SI-8

Plugin: Windows

Control ID: ff17f6b916ac764671ef308065957caf00cb254757bef34d13207c8b6dcc0abd