cis-gke-v190-5-6-7

name	cis-gke-v190-5.6.7
description	Ensure use of Google-managed SSL Certificates (Automated)
category	cis-gke
version	1.9.0
author	cyberstrike-official
tags	["cis","gke","kubernetes","gcp","networking","ssl-certificates","tls","ingress","load-balancer"]
cis_id	5.6.7
cis_benchmark	CIS Google Kubernetes Engine (GKE) Benchmark v1.9.0
tech_stack	["kubernetes","gcp","gke"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

5.6.7 Ensure use of Google-managed SSL Certificates (Automated)

Profile Applicability

• Level 2

Description

Encrypt traffic to HTTPS load balancers using Google-managed SSL certificates.

Rationale

Encrypting traffic between users and the Kubernetes workload is fundamental to protecting data sent over the web.

Google-managed SSL Certificates are provisioned, renewed, and managed for domain names. This is only available for HTTPS load balancers created using Ingress Resources, and not TCP/UDP load balancers created using Service of type:LoadBalancer.

Impact

Google-managed SSL Certificates are less flexible than certificates that are self obtained and managed. Managed certificates support a single, non-wildcard domain. Self-managed certificates can support wildcards and multiple subject alternative names (SANs).

Audit

Using Command Line:

Identify if there are any workloads exposed publicly using Services of type:LoadBalancer:

kubectl get svc -A -o json | jq '.items[] | select(.spec.type=="LoadBalancer")'

Consider using ingresses instead of these services in order to use Google managed SSL certificates.

For the ingresses within the cluster, run the following command:

kubectl get ingress -A -o json | jq .items[] | jq '{name: .metadata.name, annotations: .metadata.annotations, namespace: .metadata.namespace, status: .status}'

The above command should return the name of the ingress, namespace, annotations and status. Check that the following annotation is present to ensure managed certificates are referenced:

"annotations": {
    ...
    "networking.gke.io/managed-certificates": "<example_certificate>"
},

For completeness, run the following command to ensure that the managed certificate resource exists:

kubectl get managedcertificates -A

The above command returns a list of managed certificates for which <example_certificate> should exist within the same namespace as the ingress.

Remediation