Details

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.

If you enable this policy setting, 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_USERSoftwareMicrosoftOffice14.0OutlookSecurityLevel1Remove.

If you disable or do not configure this policy setting, users cannot demote level 1 attachments to level 2, and the HKEY_CURRENT_USERSoftwareMicrosoftOffice14.0OutlookSecurityLevel1Remove registry key has no effect.

Solution

Policy Path: Microsoft Outlook 2016SecuritySecurity Form SettingsAttachment Security
Policy Setting Name: Allow users to demote attachments to Level 2

Supportive Information

The following resource is also helpful.

• https://techcommunity.microsoft.com/t5/microsoft-security-baselines/security-baseline-for-office-365-proplus-v1908-sept-2019-final/ba-p/873084

This security hardening control applies to the following category of controls within NIST 800-53: Configuration Management.This control applies to the following type of system Windows.

References

• 800-53|CM-6b.

Source

• Tenable.com/audits