TMA-GKE-5.9.2

Use CMEK protected boot disks for GKE node pools

MediumLevel 2Automatedgke

Description

Use CMEK protected boot disks for GKE node pools so node boot disks are encrypted with approved Cloud KMS keys managed by the organization. This applies when creating a new cluster or creating a new node pool with the --boot-disk-kms-key setting. Requires gcloud with container.clusters.get; the cluster comes from GKE_CLUSTER and GKE_LOCATION (optional GKE_PROJECT, else the gcloud default project). Every node pool is checked.

How it is checked

Audit method: Shell command

shell

out=$(gcloud container node-pools list --cluster "${GKE_CLUSTER:?set GKE_CLUSTER}" --location "${GKE_LOCATION:?set GKE_LOCATION}" ${GKE_PROJECT:+--project=$GKE_PROJECT} --format='value(name,config.bootDiskKmsKey)') || exit 1
bad=$(printf '%s\n' "$out" | awk -F '\t' 'NF && !($2!="") {print $1 ": " $2}')
if [ -z "$bad" ]; then echo compliant; else printf '%s\n' "$bad"; fi

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

CMEK for node boot disks cannot be enabled, changed, or disabled in place for an existing node pool. To remediate a noncompliant node pool, create a replacement node pool with the approved Cloud KMS key, migrate workloads to the new node pool, validate workload health, and delete the old node pool after migration. Before creating the replacement node pool, grant the required Cloud KMS key access to the Compute Engine service agent for the cluster project. Create the replacement node pool with the approved boot disk type and Cloud KMS key. Current GKE CMEK boot disk guidance uses pd-standard or pd-ssd for this configuration.

Properties

Operating systems: Any
Tags: gkemanaged-servicessecrets
Reference: CIS Google Kubernetes Engine (GKE) Benchmark v2.0.0 - 5.9.2 Use CMEK protected boot disks for GKE node pools

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target gke --level 2