2.5.14.3.15 (L1) Ensure 'Display Level 1 attachments' is set to 'Disabled'

Information

This policy setting controls whether Outlook blocks potentially dangerous attachments designated Level 1. To protect users from viruses and other harmful files, Outlook uses two levels of security, designated Level 1 and Level 2, to restrict access to files attached to e-mail messages or other items. Potentially harmful files can be classified into these two levels by file type extension, with all other file types considered safe.

The recommended state for this setting is: Disabled

By default, Outlook completely blocks access to Level 1 files, and requires users to save Level 2 files to disk before opening them. If this configuration is changed, users will be able to open and execute potentially dangerous attachments, which can affect their computers or compromise the confidentiality, integrity, or availability of data.

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 > Display Level 1 attachments

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:

See

attachment file types restricted by Office

for the full list of file types classified Level 1 by default.

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: 28d79eacc72d22c3fee5bd2574bb04a7574cb423a63604f8fa0340f5ab67a55e