TMA-CHROME-2.22

Ensure 'Enable TLS Encrypted ClientHello' Is Enabled

HighLevel 1Automatedchrome

Description

This setting controls the defaults for using Encrypted ClientHello (ECH). ECH is an extension to TLS and encrypts the initial handshake with a website that can only be decrypted by that website. Google Chrome may, or may not, use ECH based on 3 factors: sever support, HTTPS DNS record availability, or rollout status. Rationale: Previously all handshakes were in the open and could expose sensitive information like the name of the website that you are connecting to. 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:EncryptedClientHelloEnabled (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

registry

$v = (Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome' -Name 'EncryptedClientHelloEnabled' -ErrorAction SilentlyContinue).'EncryptedClientHelloEnabled'; if ($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

shell

$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 'EncryptedClientHelloEnabled' -Value 1 -PropertyType DWord -Force | Out-Null

Properties

Operating systems: Any
Tags: chromebrowsercis-l1
Reference: CIS Google Chrome Benchmark v3.0.0 - 2.22 Ensure 'Enable TLS Encrypted ClientHello' Is Enabled

Check this host

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

shell

tmaegis scan --target chrome