Ensure 'Excel 4 macrosheets and add-in files' is set to 'Enabled: Open/Save blocked, use open policy'

HighLevel 1Automatedoffice

Description

This policy setting determines whether users can open, view, edit, or save Excel files with Excel 4 macrosheets and add-in file format. Open/Save blocked, use open policy: Both opening and saving of the file type will be blocked. The file will open based on the policy setting configured in the "default file block behavior" key. The recommended state for this setting is: Enabled: Open/Save blocked, use open policy. Rationale: Using legacy file formats could allow malicious code to become active on a user's computer or the network. User setting: the audit checks HKEY_USERS\<SID>\SOFTWARE\Policies\Microsoft\office\16.0\excel\security\fileblock:xl4macros (REG_DWORD) in every loaded user hive (S-1-5-21-*) and is compliant when each holds 2. It prints 'no-user-hive-loaded' (FAIL) when no user profile is loaded, so scan while users are logged on.

How it is checked

Audit method: Windows registry

registry

$sids = @(Get-ChildItem -Path 'Registry::HKEY_USERS' -ErrorAction SilentlyContinue | Where-Object { $_.PSChildName -match '^S-1-5-21-\d+-\d+-\d+-\d+$' } | ForEach-Object { $_.PSChildName }); if ($sids.Count -eq 0) { 'no-user-hive-loaded' } else { $bad = @(); foreach ($s in $sids) { $v = (Get-ItemProperty -Path ('Registry::HKEY_USERS\' + $s + '\SOFTWARE\Policies\Microsoft\office\16.0\excel\security\fileblock') -Name 'xl4macros' -ErrorAction SilentlyContinue).'xl4macros'; if (-not ($null -ne $v -and @(2) -contains [int64]$v)) { $bad += $s + ':xl4macros=' + $v } }; if ($bad.Count -eq 0) { 'compliant' } else { 'non-compliant: ' + ($bad -join ', ') } }

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Configure through Group Policy (User Configuration): User Configuration\Administrative Templates\Microsoft Excel 2016\Excel Options\Security\Trust Center\File Block Settings\Excel 4 macrosheets and add-in Files = Enabled: Open/Save blocked, use open policy

Properties

Operating systems: Any
Tags: officeproductivitycis-l1
Reference: CIS Microsoft Office Enterprise Benchmark v2.0.0 - 2.2.4.7.2.2.7 Ensure 'Excel 4 macrosheets and add-in files' is set to 'Enabled: Open/Save blocked, use open policy'

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target office