Action to demote an EMail Level 1 attachment to Level 2 must be configured.

From Microsoft Outlook 2013 STIG

Part of DTOO241 - Demote Attachments to Level 2

Associated with: CCI-001662

SV-53954r1_rule Action to demote an EMail Level 1 attachment to Level 2 must be configured.

Vulnerability discussion

Outlook uses two levels of security to restrict access to files attached to email 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 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 affect their computers or compromise the security of sensitive information.

Check content

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Security Form Settings -> Attachment Security "Allow users to demote attachments to Level 2" is set to "Disabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\outlook\security Criteria: If the value AllowUsersToLowerAttachments is REG_DWORD = 0, this is not a finding.

Fix text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Security Form Settings -> Attachment Security "Allow users to demote attachments to Level 2" to "Disabled".

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