Ensure 'Encryption mode for Information Rights Management (IRM)' is set to 'Enabled: Cipher Block Chaining (CBC)'

HighLevel 1Automatedintune-office

Description

This setting controls the encryption mode that Office uses to protect content with Information Rights Management. • For Microsoft 365 Apps (Version 2304 or later): Cipher Block Chaining (CBC) mode is used • For earlier Microsoft 365 Apps and Office LTSC 2021, 2019, and 2016: Electronic Codebook (ECB) mode is used The recommended state for this setting is: Enabled: Cipher Block Chaining (CBC). Audit: reads the registry value(s) compatibleencryption that the Intune policy writes for every loaded user profile (HKEY_USERS) and prints compliant only when each satisfies the benchmark value.

How it is checked

Audit method: Windows registry

registry

$bad = @(); $bad += @(Get-ChildItem Registry::HKEY_USERS | Where-Object { $_.PSChildName -match '^S-1-5-21-\d+-\d+-\d+-\d+$' } | ForEach-Object { $v = (Get-ItemProperty -Path ('Registry::HKEY_USERS\' + $_.PSChildName + '\SOFTWARE\Policies\Microsoft\office\16.0\common\drm') -Name 'compatibleencryption' -ErrorAction SilentlyContinue).'compatibleencryption'; if (-not ($null -ne $v -and @(1) -contains [int64]$v)) { $_.PSChildName + ':compatibleencryption=' + $v } }); if ($bad.Count -eq 0) { 'compliant' } else { 'non-compliant: ' + ($bad -join ', ') }

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

To establish the recommended state via configuration profiles, set the following Settings Catalog path to Enabled: Cipher Block Chaining (CBC): Microsoft Office 2016\Security Settings\Encryption mode for Information Rights Management (IRM)

Properties

Operating systems: Any
Tags: intune-officeintuneregistry
Reference: CIS Microsoft Intune for Office Benchmark v1.1.0 - 2.3.27.12 Ensure 'Encryption mode for Information Rights Management (IRM)' is set to 'Enabled: Cipher Block Chaining (CBC)'

Check this host

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

shell

tmaegis scan --target intune-office