cis-gke-v190-5-9-2

name	cis-gke-v190-5.9.2
description	Enable Customer-Managed Encryption Keys (CMEK) for Boot Disks (Automated)
category	cis-gke
version	1.9.0
author	cyberstrike-official
tags	["cis","gke","kubernetes","gcp","storage","encryption","cmek","boot-disk","kms"]
cis_id	5.9.2
cis_benchmark	CIS Google Kubernetes Engine (GKE) Benchmark v1.9.0
tech_stack	["kubernetes","gcp","gke"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

5.9.2 Enable Customer-Managed Encryption Keys (CMEK) for Boot Disks (Automated)

Profile Applicability

• Level 2

Description

Use Customer-Managed Encryption Keys (CMEK) to encrypt node boot disks using keys managed within Cloud Key Management Service (Cloud KMS).

Rationale

GCE persistent disks are encrypted at rest by default using envelope encryption with keys managed by Google. For additional protection, users can manage the Key Encryption Keys using Cloud KMS.

Impact

Encryption of dynamically-provisioned attached disks requires the use of the self-provisioned Compute Engine Persistent Disk CSI Driver v0.5.1 or higher.

If CMEK is being configured with a regional cluster, the cluster must run GKE 1.14 or higher.

Audit

Using Google Cloud Console:

1. Go to Kubernetes Engine by visiting: https://console.cloud.google.com/kubernetes/list
2. Click on each cluster, and click on any Node pools.
3. On the Node pool Details page, under the Security heading, check that Boot disk encryption type is set to Customer managed with the desired key.

Using Command Line:

Run this command:

gcloud container node-pools describe $NODE_POOL --cluster $CLUSTER_NAME --zone $COMPUTE_ZONE

Verify that the output of the above command includes a diskType of either pd-standard, pd-balanced or pd-ssd, and the bootDiskKmsKey is specified as the desired key.

Remediation

This cannot be remediated by updating an existing cluster. The node pool must either be recreated or a new cluster created.

Using Google Cloud Console:

To create a new node pool:

1. Go to Kubernetes Engine by visiting: https://console.cloud.google.com/kubernetes/list
2. Select Kubernetes clusters for which node boot disk CMEK is disabled.
3. Click ADD NODE POOL.
4. In the Nodes section, under machine configuration, ensure Boot disk type is Standard persistent disk or SSD persistent disk.