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5.1.9 Set 'Configure Outlook object model prompt when responding to meeting...

Information

5.1.9 Set 'Configure Outlook object model prompt when responding to meeting and task requests: Guard behavior:' to 'Enabled:Automatically Deny'

This policy setting controls what happens when an untrusted program attempts to
programmatically send e-mail in Outlook using the Response method of a task or meeting
request.
If you enable this policy setting, you can choose from four different options when an
untrusted program attempts to programmatically send e-mail using the Response method
of a task or meeting request-

. 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 only prompts users when
antivirus software is out of date or not running. This is the default configuration.
If you disable or do not configure this policy setting, when an untrusted application
attempts to respond to tasks or meeting requests programmatically, Outlook relies on the
setting configured in the 'Programmatic Access' section of the Trust Center. This setting
determines whether Outlook will warn users about programmatic access attempts-
- Only when antivirus software is out of date or not running (the default setting)
- Every time
- Not at all. If the 'Not at all' option is selected, Outlook will silently grant programmatic
access to any program that requests it.
Note - This described default functionality assumes that you have not followed the
recommendation to enable the 'Outlook Security Mode' Group Policy setting to ensure that
Outlook security settings are configured by Group Policy. If Group Policy security settings
are used for Outlook, the 'Programmatic Access' section of the Trust Center is not used. In
this situation, the default is to prompt users based on computer security, which is the
equivalent of the 'Only when antivirus software is out of date or not running' option in the
Trust Center, and the user experience is not affected.
Important- This policy setting only applies if the 'Outlook Security Mode' policy setting
under 'Microsoft Outlook 2010\Security\Security Form Settings' is configured to 'Use
Outlook Security Group Policy.'
For more information about the Object Model Guard, see Security Behavior of Outlook
(http-//officeredir.microsoft.com/r/rlidGPSecBehaviorOutlookModelO14?clid=1033) in
the MSDN Outlook 2010 Developer Reference. The recommended state for this setting is-
Enabled-Automatically Deny.

*Rationale*

If an untrusted application programmatically responds to tasks or meeting requests, that
application could impersonate a user response to the tasks or meeting requests with false
information.
By default, when an untrusted application attempts to respond to tasks or meeting
requests programmatically, Outlook 2010 relies on the setting configured in the
'Programmatic Access' section of the Trust Center. This setting determines whether
Outlook will warn users about programmatic access attempts-. Only when antivirus software is out of date or not running (the default setting)
. Every time
. Not at all
If the 'Not at all' option is selected, Outlook will silently grant programmatic access to any
program that requests it, which could allow a malicious program to gain access to sensitive
information.
Note This described default functionality assumes that you have not followed the
recommendation to enable the 'Outlook Security Mode' Group Policy setting to ensure that
Outlook security settings are configured by Group Policy. If Group Policy security settings
are used for Outlook, the 'Programmatic Access' section of the Trust Center is not used. In
this situation, the default is to prompt users based on computer security, which is the
equivalent of the 'Only when antivirus software is out of date or not running' option in the
Trust Center, and the user experience is not affected.

Solution

To implement the recommended configuration state, set the following Group Policy setting
to Enabled.

User Configuration\Administrative Templates\Microsoft Outlook 2010\Security\Security
Form Settings\Programmatic Security\Configure Outlook object model prompt when
responding to meeting and task requests\Configure Outlook object model prompt when
responding to meeting and task requests

Then set the Configure Outlook object model prompt when responding to meeting
and task requests- Guard behavior- option to Automatically Deny.

Impact-Enabling this setting and selecting Prompt user based on computer security enforces the
default configuration in Outlook 2010, and therefore is unlikely to cause usability issues for
most users.Note- For this setting to apply, you must also enable the 'Outlook Security Mode' setting in


User Configuration\Administrative Templates\Classic Administrative Templates
(ADM)\Microsoft Office Outlook 2010\Security\Security Form Settings\Microsoft Office
Outlook 2010 Security and select Use Outlook Security Group Policy from the drop-down
list.For more information about the Object Model Guard, see Security Behavior of the Outlook
Object Model in the MSDN Outlook Developer Reference.

See Also

https://workbench.cisecurity.org/files/530

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b.

Plugin: Windows

Control ID: 8567d9f8e9649e5687e27d802c93469a4ec754dc51004737932e62cab1e13f98