TMA-CHROME-2.31
Ensure 'Enable strict MIME type checking for worker scripts' Is Enabled
Description
This setting controls the ability for Google Chrome to upgrade to HTTPS from HTTP while navigating to certain sites. It can be configured to either: - Disabled (0): Scripts for workers (Web Workers, Service Workers, etc.) use lax MIME type checking. Worker scripts with legacy MIME types, like text/ascii, will work. Rationale: Setting this policy will require worker scripts to use more secure and strict JavaScript MIME types and ones with legacy MIME Types will be rejected. Audit reads the Group Policy registry value and prints 'compliant', 'unset' (policy not configured, reported as FAIL) or the non-compliant value. Registry value: HKLM\SOFTWARE\Policies\Google\Chrome:StrictMimetypeCheckForWorkerScriptsEnabled (REG_DWORD); compliant when it is 1. Remediation writes 1 locally; in a domain set it through the ADMX so Group Policy does not revert it.
How it is checked
Audit method: Windows registry
$v = (Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome' -Name 'StrictMimetypeCheckForWorkerScriptsEnabled' -ErrorAction SilentlyContinue).'StrictMimetypeCheckForWorkerScriptsEnabled'; if ($null -eq $v) { 'unset' } elseif (($null -ne $v -and @(1) -contains [int64]$v)) { 'compliant' } else { "non-compliant: $v" }- Expected output
compliant
How it is fixed
Fix method: Shell command
$p = 'Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome'; if (-not (Test-Path -Path $p)) { New-Item -Path $p -Force | Out-Null }; New-ItemProperty -Path $p -Name 'StrictMimetypeCheckForWorkerScriptsEnabled' -Value 1 -PropertyType DWord -Force | Out-NullProperties
- Operating systems
- Any
- Tags
- chromebrowsercis-l1
- Reference
- CIS Google Chrome Benchmark v3.0.0 - 2.31 Ensure 'Enable strict MIME type checking for worker scripts' Is Enabled
Check this host
Run this on a machine you are allowed to audit. The scan is read-only.
tmaegis scan --target chrome