Ensure Tiller (Helm V2) deployment is not accessible from within the cluster

Error: Tiller (Helm V2) deployment is accessible from within the cluster

Bridgecrew Policy ID: BC_K8S_40
Checkov Check ID: CKV_K8S_45
Severity: LOW

Tiller (Helm V2) deployment is accessible from within the cluster

Description

Tiller (Helm v2) is the in-cluster component of Helm. It interacts directly with the Kubernetes API server to install, upgrade, query, and remove Kubernetes resources. It also stores the objects that represent releases. Its permissive configuration could grant the users a broad range of permissions.

Helm v3 removes Tiller, and it is recommended that you upgrade: see Ensure Tiller (Helm V2) Is Not Deployed. However, this is not always feasible.

Restricting access to Tiller from within the cluster limits the abilities of a compromised pod or anonymous user in the cluster.

Fix - Runtime

CLI Commands

kubectl -n kube-system patch deployment tiller-deploy --patch '
spec:
  template:
    spec:
      containers:
        - name: tiller
          ports: []
          args: ["--listen=localhost:44134"]
'

Fix - Buildtime

Kubernetes

  • Resource: Container
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tiller
  labels:
    app: tiller
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: helm
      name: tiller
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: helm
        name: tiller
    spec:
      automountServiceAccountToken: true
      containers:
+     - args:
+       - --listen=localhost:44134
        env:
        - name: TILLER_NAMESPACE
          value: kube-system
        - name: TILLER_HISTORY_MAX
          value: "0"
        image: gcr.io/kubernetes-helm/tiller:v2.16.9
        name: tiller
-       ports:
-       - containerPort: 44134
-         name: tiller
-         protocol: TCP
-       - containerPort: 44135
-         name: http
-         protocol: TCP

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