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5.1.16 Set 'Load Controls in Forms3:' to 'Disabled'

Information

This policy setting allows you to control how ActiveX controls in UserForms should be
initialized based upon whether they are Safe For Initialization (SFI) or Unsafe for
Initialization (UFI).
ActiveX controls are Component Object Model (COM) objects and have unrestricted access
to users' computers. ActiveX controls can access the local file system and change the
registry settings of the operating system. If a malicious user repurposes an ActiveX control
to take over a user's computer, the effect could be significant. To help improve security,
ActiveX developers can mark controls as Safe For Initialization (SFI), which means that the
developer states that the controls are safe to open and run and not capable of causing harm
to any computers. If a control is not marked SFI, the control could adversely affect a
computer or it's possible the developers did not test the control in all situations and are
not sure whether their control might be compromised at some future date.SFI controls run
in safe mode, which limits their access to the computer. For example, a worksheet control
can both read and write files when it is in unsafe mode, but perhaps only read from files
when it is in safe mode. This functionality allows the control to be used in very powerful
ways when safety wasn't important, but the control would still be safe for use in a Web
page. If a control is not marked as SFI, it is marked Unsafe For Initialization (UFI), which
means that it is capable of affecting a user's computer. If UFI ActiveX controls are loaded,
they are always loaded in unsafe mode.
If you enable this policy setting, you can choose from four options for loading controls in
UserForms-

1. For a UFI or SFI signed control that supports safe and unsafe mode, load the control
in unsafe mode. For an SFI signed control that only supports a safe mode
configuration, load the control in safe mode. This option enforces the default
configuration.
2. Users are prompted to determine how UserForm forms will load. The prompt only
displays once per session within an application. When users respond to the prompt,
loading continues based on whether the control is UFI or SFI-

o For a UFI signed control, if users respond Yes to the prompt, load the control
in unsafe mode. If users respond No, load the control using the default
properties.

o For an SFI signed control that supports both safe and unsafe modes, if users
respond Yes to the prompt, load the control in unsafe mode. If users respond
No, load the control using safe mode. If the SFI control can only support safe
mode, load the control in safe mode. This option is the default configuration
in the Microsoft Office 2010 release.3. Users are prompted to determine how UserForm forms will load. The prompt only
displays once per session within an application. When users respond to the prompt,
loading continues based on whether the control is UFI or SFI-

o For a UFI signed control, if users respond Yes to the prompt, load the control
in unsafe mode. If users respond No, load the control with its default
properties.

o For an SFI signed control, load in safe mode.4. For a UFI signed control, load with the default properties of the control. For an SFI
signed control, load in safe mode (considered to be the safest mode).If you disable or do not configure this policy setting, the behavior is as if you enable this
policy setting and then select option 1.
For more information about this policy setting, see Plan security settings for ActiveX
controls, add-ins, and macros in the 2007 Office system
http-//officeredir.microsoft.com/r/rlidGPSecSettingsActXCtrlO14?clid=1033 The
recommended state for this setting is- Disabled.

*Rationale*

ActiveX controls are Component Object Model (COM) objects and have unrestricted access
to users' computers. ActiveX controls can access the local file system and change the
registry settings of the operating system. If a malicious user repurposes an ActiveX control
to take over a user's computer, the effect could be significant.To help improve security, ActiveX developers can mark controls as Safe For Initialization
(SFI), which means that the developer states that the controls are safe to open and run and
not capable of causing harm to any computers. If a control is not marked SFI, the control
could adversely affect a computer or it's possible the developers did not test the control
in all situations and are not sure whether their control might be compromised at some
future date.SFI controls run in safe mode, which limits their access to the computer. For example, a
worksheet control can both read and write files when it is in unsafe mode, but perhaps only
read from files when it is in safe mode. This functionality allows the control to be used in
very powerful ways when safety wasn't important, but the control would still be safe for
use in a Web page.
If a control is not marked as SFI, it is marked Unsafe For Initialization (UFI), which means
that it is capable of affecting a user's computer. If UFI ActiveX controls are loaded, they are
always loaded in unsafe mode.This setting allows administrators to control how ActiveX controls in UserForms should be
initialized based upon whether they are SFI or UFI.

Solution

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

User Configuration\Administrative Templates\Microsoft Office 2010\Security
Settings\Load Controls in Forms3\- Load Controls in Forms3-

Impact-Enabling this setting and selecting '2' enforces the default configuration and is therefore
unlikely to cause usability issues for most users.

See Also

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

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-18b.

Plugin: Windows

Control ID: 112de1fcbb352c4d7e7b6def07bf30d0dd7d485d34bc4c7bf4e727a9c61534fd