5.1.4 Set 'Allow users to demote attachments to Level 2' to 'Disabled'

Information

This policy setting controls whether Outlook users can demote attachments to Level 2 by
using a registry key, which will allow them to save files to disk and open them from that
location. Outlook uses two levels of security to restrict access to files attached to e-mail
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 you enable this
policy setting, users can create a list of Level 1 file types to demote to Level 2 by adding the
file types to the following registry key-
HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Security\Level1Remove.
If you disable or do not configure this policy setting, users cannot demote level 1
attachments to level 2, and the
HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Security\Level1Remove
registry key has no effect. The recommended state for this setting is- Disabled.

*Rationale*

Outlook 2010 uses two levels of security to restrict access to files attached to e-mail
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. By default, Outlook
does not allow users to demote file types from Level 1 to Level 2. If this setting is Enabled,
users can create a list of Level 1 file types to demote to Level 2 by adding the file types to
the following registry key-
HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\12.0\Security\Level1Remove
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.

Solution

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

User Configuration\Administrative Templates\Microsoft Outlook 2010\Security\Security
Form Settings\Attachment Security\Allow users to demote attachments to Level 2

Impact-Allowing users to demote attachments to Level 2 can pose a significant risk. Unless your
users have a legitimate business need for such functionality, this setting should be disabled.

See Also

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

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b.

Plugin: Windows

Control ID: b96c4927a70fcacd93c0201732aa86b6ddcc3e2d99c72b8c447d53224d6472f7