Trust access for VBA must be disallowed.

From Microsoft Excel 2013 STIG

Part of DTOO146-Disable Trust access to VB Project Macros

Associated with: CCI-000381

SV-53813r1_rule Trust access for VBA must be disallowed.

Vulnerability discussion

VSTO projects require access to the Visual Basic for Applications project system in Excel, PowerPoint, and Word, 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.

Check content

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Excel 2013 -> Excel Options -> Security -> Trust Center "Trust access to Visual Basic Project" is set to "Disabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\excel\security Criteria: If the value AccessVBOM is REG_DWORD = 0, this is not a finding.

Fix text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Excel 2013 -> Excel Options -> Security -> Trust Center "Trust access to Visual Basic Project" to "Disabled".

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