Disable Trust access for VBA into Excel, Word, and PowerPoint.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-17522	DTOO146 - Excel	SV-18610r1_rule	ECSC-1	Medium

Description
VSTO projects require access to the Visual Basic for Applications project system in Excel 2007, PowerPoint 2007, and Word 2007, even though the projects do not use Visual Basic for Applications. Design-time support of controls in both Visual Basic and C# projects depends on the Visual Basic for Applications project system in Word and Excel. By default, Excel, Word, and PowerPoint do not allow automation clients to have programmatic access to VBA projects. Users can enable this by selecting the Trust access to the VBA project object model in the Macro Settings section of the Trust Center. However, doing so allows macros in any documents the user opens to access the core Visual Basic objects, methods, and properties, which represents a potential security hazard.

Description

VSTO projects require access to the Visual Basic for Applications project system in Excel 2007, PowerPoint 2007, and Word 2007, even though the projects do not use Visual Basic for Applications. Design-time support of controls in both Visual Basic and C# projects depends on the Visual Basic for Applications project system in Word and Excel. By default, Excel, Word, and PowerPoint do not allow automation clients to have programmatic access to VBA projects. Users can enable this by selecting the Trust access to the VBA project object model in the Macro Settings section of the Trust Center. However, doing so allows macros in any documents the user opens to access the core Visual Basic objects, methods, and properties, which represents a potential security hazard.

STIG	Date
Microsoft Excel 2007	2014-01-07

Details

Check Text ( C-18850r1_chk )
The policy value for User Configuration -> Administrative Templates -> Microsoft Office Excel 2007 -> Excel Options -> Security -> Trust Center “Trust access to Visual Basic Project” will be set to “Disabled”. Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\12.0\Excel\Security Criteria: If the value AccessVBOM is REG_DWORD = 0, this is not a finding.

Check Text ( C-18850r1_chk )

The policy value for User Configuration -> Administrative Templates -> Microsoft Office Excel 2007 -> Excel Options -> Security -> Trust Center “Trust access to Visual Basic Project” will be set to “Disabled”.

Procedure: Use the Windows Registry Editor to navigate to the following key:

HKCU\Software\Policies\Microsoft\Office\12.0\Excel\Security

Criteria: If the value AccessVBOM is REG_DWORD = 0, this is not a finding.

Fix Text (F-17450r1_fix)
The policy value for User Configuration -> Administrative Templates -> Microsoft Office Excel 2007 -> Excel Options -> Security -> Trust Center “Trust access to Visual Basic Project” will be set to “Disabled”.