Ensure 'Legacy format signatures' is set to 'Disabled'

HighLevel 1Automatedoffice

Description

This policy setting controls whether users can apply binary format digital signatures to Office 97-2003 documents. The recommended state for this setting is: Disabled. Rationale: By default, Office applications use the XML-based XMLDSIG format to attach digital signatures to documents, including Office 97-2003 binary documents. XMLDSIG signatures are not recognized by Office 2003 applications or previous versions. User setting: the audit checks HKEY_USERS\<SID>\SOFTWARE\Policies\Microsoft\office\16.0\common\signatures:enablecreationofweakxpsignatures (REG_DWORD) in every loaded user hive (S-1-5-21-*) and is compliant when each holds 0. 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\' + $s + '\SOFTWARE\Policies\Microsoft\office\16.0\common\signatures') -Name 'enablecreationofweakxpsignatures' -ErrorAction SilentlyContinue).'enablecreationofweakxpsignatures'; if (-not ($null -ne $v -and @(0) -contains [int64]$v)) { $bad += $s + ':enablecreationofweakxpsignatures=' + $v } }; if ($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 Office 2016\Signing\Legacy format signatures = Disabled

Properties

Operating systems: Any
Tags: officeproductivitycis-l1
Reference: CIS Microsoft Office Enterprise Benchmark v2.0.0 - 2.3.31.1 Ensure 'Legacy format signatures' is set to 'Disabled'

Check this host

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

shell

tmaegis scan --target office