Ensure 'Blocks external extensions from being installed' is set to 'Enabled'

HighLevel 1Automatedchrome

Description

Enabling this setting blocks external extensions (an extension that is not installed from the Chrome Web Store) from being installed. The recommended state for this setting is: Enabled (1) Rationale: Allowing users to install extensions from other locations (not the Chrome Web Store) can lead to malicious extensions being installed. 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:BlockExternalExtensions (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

$v = (Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome' -Name 'BlockExternalExtensions' -ErrorAction SilentlyContinue).'BlockExternalExtensions'; if ($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 'BlockExternalExtensions' -Value 1 -PropertyType DWord -Force | Out-Null

Properties

Operating systems: Any
Tags: chromebrowsercis-l1
Reference: CIS Google Chrome Benchmark v3.0.0 - 2.3.1 Ensure 'Blocks external extensions from being installed' is set to 'Enabled'

Check this host

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

shell

tmaegis scan --target chrome