TMA-OFFICE-2.3.27.5

Ensure 'Allow Basic Authentication prompts from network proxies' is set to 'Disabled'

HighLevel 1Automatedoffice

Description

Apps such as Word and Excel allow users to use Basic authentication to connect to resources on web servers by sending usernames and passwords with each request. These credentials are often stored on the servers, making it easier for attackers to capture them and reuse them against other endpoints or services. The recommended state for this setting is: Disabled. Rationale: Basic authentication is an outdated industry standard and doesn't support more robust security features, such as multifactor authentication. The threats posed by it have only increased and there are better and more effective user authentication alternatives. User setting: the audit checks HKEY_USERS\<SID>\SOFTWARE\Policies\Microsoft\office\16.0\common\identity:basicauthproxybehavior (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\' + $s + '\SOFTWARE\Policies\Microsoft\office\16.0\common\identity') -Name 'basicauthproxybehavior' -ErrorAction SilentlyContinue).'basicauthproxybehavior'; if (-not ($null -ne $v -and @(0) -contains [int64]$v)) { $bad += $s + ':basicauthproxybehavior=' + $v } }; if ($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\Security Settings\Allow Basic Authentication prompts from network proxies = Disabled

Properties

Operating systems: Any
Tags: officeproductivitycis-l1
Reference: CIS Microsoft Office Enterprise Benchmark v2.0.0 - 2.3.27.5 Ensure 'Allow Basic Authentication prompts from network proxies' 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