SV-221562r960879: Extensions installation must be blocklisted by default. | Google Chrome Current Windows STIG SCAP Benchmark

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Assessment Title

Rule Text

Extensions installation must be blocklisted by default.

Description

Discussion Text

Extensions are developed by third party sources and are designed to extend Google Chrome's functionality. An extension can be made by anyone, to do and access almost anything on a system; this means they pose a high risk to any system that would allow all extensions to be installed by default. Allows you to specify which extensions the users can NOT install. Extensions already installed will be removed if blocklisted. A blocklist value of '*' means all extensions are blocklisted unless they are explicitly listed in the allowlist. If this policy is left not set the user can install any extension in Google Chrome.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000169SV-57561V-44727

References

DPMS Target Google Chrome Current Windows DISA DPMS Target Google Chrome Current Windows 4081

Checks

DISA STIG (Manual Reference)

Universal method: 
 1. In the omnibox (address bar) type chrome://policy 
 2. If ExtensionInstallBlocklist is not displayed under the Policy Name column or it is not set to * under the Policy Value column, then this is a finding.

Windows method:
 1. Start regedit
 2. Navigate to HKLM\Software\Policies\Google\Chrome\ExtensionInstallBlocklist
 3. If the a registry value name of 1 does not exist under that key or its value is not set to *, then this is a finding.

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

# Windows PowerShell
# Reconstructed from oval:mil.disa.stig.chrome:def:240005
# Extensions installation must be blocklisted by default.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# Extensions installation are blocklisted by default
# registry_object (registry_test)
function test_1 {
  return (((@{String='reg_sz';ExpandString='reg_expand_sz';Binary='reg_binary';DWord='reg_dword';MultiString='reg_multi_sz';QWord='reg_qword';None='reg_none'}[(Get-Item -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Google\Chrome\ExtensionInstallBlocklist').GetValueKind('1').ToString()]) -eq 'reg_sz') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Google\Chrome\ExtensionInstallBlocklist' -Name '1' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty '1') -eq '*'))
}

if (test_1) {
  Write-Output "PASS"
} else {
  Write-Output "FAIL"
}

Assessment Script Powered by AISyntax-verified

A standalone PowerShell script to assess this control automatically. Review before running it in your environment.

Syntax-checked as valid PowerShell. Not executed here — running it for real needs the actual google_chrome target this check assesses.

# OVAL Definition: oval:mil.disa.stig.chrome:def:240005
if (-not (Test-Path -Path "HKLM:\Software\Policies\Google\Chrome\ExtensionInstallBlocklist")) {exit 1} else {if ((Get-ItemProperty -Path "HKLM:\Software\Policies\Google\Chrome\ExtensionInstallBlocklist" -ErrorAction SilentlyContinue).Value -eq "*") {exit 0} else {exit 1}}

Remediation

Windows group policy:
 1. Open the group policy editor tool with gpedit.msc 
 2. Navigate to Policy Path: Computer Configuration\Administrative Templates\Google\Google Chrome\Extensions\
 Policy Name: Configure extension installation blocklist
 Policy State: Enabled
 Policy Value: *