cis-gworkspace-3-1-3-5-3

name	cis-gworkspace-3.1.3.5.3
description	Ensure per-user outbound gateways is disabled
category	cis-gworkspace
version	1.3.0
author	cyberstrike-official
tags	["cis","gcp","google-workspace","gmail","forwarding"]
cis_id	3.1.3.5.3
cis_benchmark	CIS Google Workspace Foundations Benchmark v1.3.0
tech_stack	["gcp","google-workspace"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

Ensure per-user outbound gateways is disabled (Manual)

Description

A per-user outbound gateway is a mail server, other than the Google Workspace mail servers, that delivers outgoing mail for a user in your domain.

Rationale

Mail sent via external SMTP will circumvent your outbound gateway.

Impact

Care should be taken before implementation to ensure there is no business need for mail sent via external SMTP gateway.

Audit Procedure

Using Google Workspace Admin Console

1. Log in to https://admin.google.com as an administrator
2. Select Apps
3. Select Google Workspace
4. Select Gmail
5. Under End User Access - Allow per-user outbound gateways, ensure Allow users to send mail through an external SMTP server when configuring a "from" address hosted outside your email domain is unchecked

Expected Result

Allow users to send mail through an external SMTP server when configuring a "from" address hosted outside your email domain should be unchecked.

Remediation

Using Google Workspace Admin Console

1. Log in to https://admin.google.com as an administrator
2. Select Apps
3. Select Google Workspace
4. Select Gmail
5. Under End User Access - Allow per-user outbound gateways, set Allow users to send mail through an external SMTP server when configuring a "from" address hosted outside your email domain to unchecked
6. Select Save

Default Value

Allow users to send mail through an external SMTP server when configuring a "from" address hosted outside your email domain is unchecked

CIS Controls

This control does not have explicit CIS Controls mappings in the PDF.

Profile

Level 1