cis-gcp-foundations-1-8

name	cis-gcp-foundations-1.8
description	Ensure That Separation of Duties Is Enforced While Assigning Service Account Related Roles to Users
category	cis-gcp-foundations
version	4.0.0
author	cyberstrike-official
tags	["cis","gcp","iam","service-accounts","mfa","kms","api-keys"]
cis_id	1.8
cis_benchmark	CIS Google Cloud Platform Foundation Benchmark v4.0.0
tech_stack	["gcp"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

1.8 Ensure That Separation of Duties Is Enforced While Assigning Service Account Related Roles to Users (Automated)

Profile Applicability

• Level 2

Description

It is recommended that the principle of 'Separation of Duties' is enforced while assigning service-account related roles to users.

Rationale

The built-in/predefined IAM role Service Account admin allows the user/identity to create, delete, and manage service account(s). The built-in/predefined IAM role Service Account User allows the user/identity (with adequate privileges on Compute and App Engine) to assign service account(s) to Apps/Compute Instances.

Separation of duties is the concept of ensuring that one individual does not have all necessary permissions to be able to complete a malicious action. In Cloud IAM - service accounts, this could be an action such as using a service account to access resources that user should not normally have access to.

Separation of duties is a business control typically used in larger organizations, meant to help avoid security or privacy incidents and errors. It is considered best practice.

No user should have Service Account Admin and Service Account User roles assigned at the same time.

Impact

The removed role should be assigned to a different user based on business needs.

Audit Procedure

From Google Cloud Console

1. Go to IAM & Admin/IAM using https://console.cloud.google.com/iam-admin/iam.
2. Ensure no member has the roles Service Account Admin and Service account User assigned together.

From Google Cloud CLI

1. List all users and role assignments:

gcloud projects get-iam-policy [Project_ID] --format json | \
  jq -r '[
    (["Service_Account_Admin_and_User"] | (., map(length*"-"))),
      (
        [
          .bindings[] |
          select(.role == "roles/iam.serviceAccountAdmin" or .role == "roles/iam.serviceAccountUser").members[]
        ] |
        group_by(.) |
        map({User: ., Count: length}) |
        .[] |
        select(.Count == 2).User |
        unique
      )
  ] |
  .[] |
  @tsv'

2. All common users listed under Service_Account_Admin_and_User are assigned both the roles/iam.serviceAccountAdmin and roles/iam.serviceAccountUser roles.