Users customizing attachment security settings must be prevented.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-228438	SRG-APP-000210	DTOO238	SV-228438r508021_rule	2022-03-11	2

Description
This policy setting prevents users from overriding the set of attachments blocked by Outlook. If you enable this policy setting users will be prevented from overriding the set of attachments blocked by Outlook. Outlook also checks the "Level1Remove" registry key when this setting is specified. If you disable or do not configure this policy setting, users will be allowed to override the set of attachments blocked by Outlook.

Description

This policy setting prevents users from overriding the set of attachments blocked by Outlook. If you enable this policy setting users will be prevented from overriding the set of attachments blocked by Outlook. Outlook also checks the "Level1Remove" registry key when this setting is specified. If you disable or do not configure this policy setting, users will be allowed to override the set of attachments blocked by Outlook.

ℹ️ Check
Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2016 -> Security "Prevent users from customizing attachment security settings" is set to "Enabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\16.0\outlook Criteria: If the value DisallowAttachmentCustomization is REG_DWORD = 1, this is not a finding.

ℹ️ Check

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2016 -> Security "Prevent users from customizing attachment security settings" is set to "Enabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\16.0\outlook Criteria: If the value DisallowAttachmentCustomization is REG_DWORD = 1, this is not a finding.

✔️ Fix
Set the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2016 -> Security "Prevent users from customizing attachment security settings" to "Enabled".