Title

Custom Outlook Object Model (OOM) action execution prompts must be configured. (Cat II impact)

Discussion

Custom actions add functionality to Outlook that can be triggered as part of a rule. Among other possible features, custom actions can be created that reply to messages in ways that circumvent the Outlook model's programmatic send protections. By default, when Outlook or another program initiates a custom action using the Outlook object model, users are prompted to allow or reject the action. If this configuration is changed, malicious code can use the Outlook object model to compromise sensitive information or otherwise cause data and computing resources to be at risk.

Check Content

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Security Form Settings -> Custom Form Security "Set Outlook object model Custom Actions execution prompt" is "Enabled (Automatically Deny)". 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 PromptOOMCustomAction 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 -> Custom Form Security "Set Outlook object model Custom Actions execution prompt" to "Enabled (Automatically Deny)".

Additional Identifiers

Rule ID: SV-53994r1_rule

Vulnerability ID: V-17802

Group Title: DTOO247 - Custom OOM Action Exe. Prompt

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.