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← Back to Microsoft Office 365 ProPlus Security Technical Implementation Guide

V-223371

CAT II (Medium)

When an untrusted program attempts to send e-mail programmatically using the Outlook object model, Outlook must automatically deny it.

Rule ID

SV-223371r961779_rule

STIG

Microsoft Office 365 ProPlus Security Technical Implementation Guide

Version

V3R5

CCIs

CCI-002460

Discussion

This policy setting controls what happens when an untrusted program attempts to send e-mail programmatically using the Outlook object model. If you enable this policy setting, you can choose from four different options when an untrusted program attempts to send e-mail programmatically using the Outlook object model: - Prompt user - The user will be prompted to approve every access attempt. - Automatically approve - Outlook will automatically grant programmatic access requests from any program. This option can create a significant vulnerability, and is not recommended. - Automatically deny - Outlook will automatically deny programmatic access requests from any program. - Prompt user based on computer security. Outlook will only prompt users when antivirus software is out of date or not running. Important: This policy setting only applies if the "Outlook Security Mode" policy setting under "Microsoft Outlook 2016\Security\Security Form Settings" is configured to "Use Outlook Security Group Policy". If you disable or do not configure this policy setting, when an untrusted application attempts to send mail programmatically, Outlook relies on the setting configured in the ''Programmatic Access'' section of the Trust Center.

Check Content

Verify the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Security >> Security Form Settings >> Programmatic Security >> Configure Outlook object model prompt when sending mail is set to "Enabled (Automatically Deny)".

Use the Windows Registry to navigate to the following key:

HKCU\software\policies\microsoft\office\16.0\outlook\security

If the value for promptoomsend is set to REG_DWORD = 0, this is not a finding.

Fix Text

Set the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Security >> Security Form Settings >> Programmatic Security >> Configure Outlook object model prompt when sending mail to "Enabled (Automatically Deny)".