OWASP 쿠버네티스 상위 10

apiVersion: v1
kind: Pod
metadata:
  name: insecure-app
spec:
  containers:
  - name: app
    image: myapp:latest          # Mutable tag!
    securityContext:
      privileged: true            # Full host access!
      runAsUser: 0                # Running as root!
    volumeMounts:
    - mountPath: /host
      name: host-fs
  volumes:
  - name: host-fs
    hostPath:
      path: /                    # Entire host filesystem!

apiVersion: v1
kind: Pod
metadata:
  name: secure-app
spec:
  securityContext:
    runAsNonRoot: true
    seccompProfile:
      type: RuntimeDefault
  containers:
  - name: app
    image: myapp@sha256:abc123...  # Immutable digest
    securityContext:
      allowPrivilegeEscalation: false
      readOnlyRootFilesystem: true
      runAsUser: 1000
      capabilities:
        drop: ["ALL"]
    resources:
      limits:
        cpu: "500m"
        memory: "256Mi"
      requests:
        cpu: "100m"
        memory: "128Mi"

# ClusterRoleBinding granting cluster-admin to a service account
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: app-admin-binding
subjects:
- kind: ServiceAccount
  name: my-app            # App SA with cluster-admin!
  namespace: default
roleRef:
  kind: ClusterRole
  name: cluster-admin      # Full cluster control!
  apiGroup: rbac.authorization.k8s.io

# Scoped Role with minimum required permissions
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: app-role
  namespace: my-app-ns
rules:
- apiGroups: [""]
  resources: ["configmaps"]
  verbs: ["get", "list"]     # Read-only, specific resources
  resourceNames: ["app-config"]  # Named resource only
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: app-role-binding
  namespace: my-app-ns
subjects:
- kind: ServiceAccount
  name: my-app
  namespace: my-app-ns
roleRef:
  kind: Role
  name: app-role
  apiGroup: rbac.authorization.k8s.io

# Secret in plain ConfigMap — visible to anyone
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  DB_PASSWORD: "SuperSecret123!"   # Plaintext password!
  API_KEY: "sk-live-abc123xyz"      # API key in ConfigMap!
---
apiVersion: v1
kind: Pod
metadata:
  name: app
spec:
  containers:
  - name: app
    image: myapp:latest
    envFrom:
    - configMapRef:
        name: app-config    # All values as env vars!

# Use External Secrets Operator with a vault backend
apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: app-secrets
spec:
  refreshInterval: 1h
  secretStoreRef:
    name: vault-backend
    kind: ClusterSecretStore
  target:
    name: app-secrets
  data:
  - secretKey: db-password
    remoteRef:
      key: secret/myapp/db
      property: password
---
apiVersion: v1
kind: Pod
metadata:
  name: app
spec:
  containers:
  - name: app
    image: myapp@sha256:abc123...
    volumeMounts:
    - name: secrets
      mountPath: /etc/secrets
      readOnly: true          # Mount as read-only files
  volumes:
  - name: secrets
    secret:
      secretName: app-secrets

#!/bin/bash
# No admission control — any pod spec is accepted
# No Pod Security Standards configured

# Anyone can deploy a privileged container
kubectl run hacker-pod --image=alpine \
  --overrides='{"spec":{"containers":[{
    "name":"hack",
    "image":"alpine",
    "securityContext":{"privileged":true},
    "command":["nsenter","--target","1","--mount","--uts","--ipc","--net","--pid","--","bash"]
  }]}}'

# No policy blocks this — now has host root access!

# Enforce Pod Security Standards with Kyverno
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: disallow-privileged
spec:
  validationFailureAction: Enforce
  background: true
  rules:
  - name: deny-privileged
    match:
      any:
      - resources:
          kinds: ["Pod"]
    validate:
      message: "Privileged containers are not allowed."
      pattern:
        spec:
          containers:
          - securityContext:
              privileged: "false"
  - name: require-run-as-non-root
    match:
      any:
      - resources:
          kinds: ["Pod"]
    validate:
      message: "Containers must run as non-root."
      pattern:
        spec:
          securityContext:
            runAsNonRoot: true

# No NetworkPolicy — all pods can communicate freely
apiVersion: v1
kind: Namespace
metadata:
  name: production
  # No default deny policy
  # No network policies at all
  # Any pod can reach:
  #   - Other pods in any namespace
  #   - Kubernetes API server
  #   - Cloud metadata API (169.254.169.254)
  #   - External internet

# Default deny all ingress and egress
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: default-deny-all
  namespace: production
spec:
  podSelector: {}
  policyTypes: ["Ingress", "Egress"]
---
# Allow only frontend to backend communication
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-frontend-to-backend
  namespace: production
spec:
  podSelector:
    matchLabels:
      app: backend
  policyTypes: ["Ingress"]
  ingress:
  - from:
    - podSelector:
        matchLabels:
          app: frontend
    ports:
    - port: 8080
      protocol: TCP

# Kubernetes Dashboard exposed via LoadBalancer
apiVersion: v1
kind: Service
metadata:
  name: kubernetes-dashboard
  namespace: kubernetes-dashboard
spec:
  type: LoadBalancer        # Public internet access!
  ports:
  - port: 443
    targetPort: 8443
  selector:
    k8s-app: kubernetes-dashboard
# Dashboard bound to cluster-admin service account
# No authentication required — full cluster access!

# Dashboard accessible only via kubectl proxy
apiVersion: v1
kind: Service
metadata:
  name: kubernetes-dashboard
  namespace: kubernetes-dashboard
spec:
  type: ClusterIP           # Internal only
  ports:
  - port: 443
    targetPort: 8443
  selector:
    k8s-app: kubernetes-dashboard
---
# Access via: kubectl proxy, then browse to:
# http://localhost:8001/api/v1/namespaces/kubernetes-dashboard/services/https:kubernetes-dashboard:/proxy/
# Or use kubectl port-forward for secure access

# kubelet with insecure configuration
# /var/lib/kubelet/config.yaml
apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
authentication:
  anonymous:
    enabled: true              # Anyone can access kubelet API!
  webhook:
    enabled: false             # No authorization!
authorization:
  mode: AlwaysAllow            # All requests permitted!
readOnlyPort: 10255            # Unauthenticated read port open!

# Hardened kubelet configuration
apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
authentication:
  anonymous:
    enabled: false             # Deny anonymous access
  webhook:
    enabled: true              # Use API server for auth
  x509:
    clientCAFile: /etc/kubernetes/pki/ca.crt
authorization:
  mode: Webhook                # API server authorizes requests
readOnlyPort: 0                # Disable read-only port
protectKernelDefaults: true
eventRecordQPS: 5

# Node IAM role with excessive permissions
resource "aws_iam_role_policy_attachment" "node_admin" {
  role       = aws_iam_role.node_role.name
  policy_arn = "arn:aws:iam::aws:policy/AdministratorAccess"
  # All pods on this node inherit admin access!
}

# No IMDS restrictions — any pod can get node credentials
# curl http://169.254.169.254/latest/meta-data/iam/security-credentials/

# Use IAM Roles for Service Accounts (IRSA)
resource "aws_iam_role" "app_role" {
  name = "my-app-role"
  assume_role_policy = jsonencode({
    Version = "2012-10-17"
    Statement = [{
      Effect = "Allow"
      Principal = {
        Federated = aws_iam_openid_connect_provider.eks.arn
      }
      Action = "sts:AssumeRoleWithWebIdentity"
      Condition = {
        StringEquals = {
          "${aws_iam_openid_connect_provider.eks.url}:sub" =
            "system:serviceaccount:my-ns:my-app"
        }
      }
    }]
  })
}

# Pod-level scoped IAM via service account annotation
# Only this specific pod gets these specific permissions

# Static token file for API server authentication
# /etc/kubernetes/token-auth-file.csv
# token,user,uid,"groups"
# abc123,admin,1,"system:masters"  # Static token, never expires!

# Pod with auto-mounted service account token
apiVersion: v1
kind: Pod
metadata:
  name: app
spec:
  # automountServiceAccountToken defaults to true!
  # Token mounted at /var/run/secrets/kubernetes.io/serviceaccount/token
  containers:
  - name: app
    image: myapp:latest
    # App doesn't need K8s API access but has a token anyway

# Disable auto-mounted token for pods that don't need API access
apiVersion: v1
kind: ServiceAccount
metadata:
  name: my-app
  namespace: my-app-ns
automountServiceAccountToken: false  # No auto-mount
---
# For pods that need API access, use bound tokens with expiry
apiVersion: v1
kind: Pod
metadata:
  name: api-consumer
spec:
  serviceAccountName: api-consumer-sa
  automountServiceAccountToken: false
  containers:
  - name: app
    image: myapp@sha256:abc123...
    volumeMounts:
    - name: token
      mountPath: /var/run/secrets/tokens
      readOnly: true
  volumes:
  - name: token
    projected:
      sources:
      - serviceAccountToken:
          expirationSeconds: 3600  # 1-hour expiry
          audience: api-server

# API server with no audit logging configured
# kube-apiserver flags:
#   --audit-log-path=""           # No audit log!
#   --audit-policy-file=""        # No audit policy!

# No runtime security monitoring
# No alerting on suspicious activities
# Container logs not collected centrally
# Default log retention — logs lost on pod restart

# Comprehensive audit policy
apiVersion: audit.k8s.io/v1
kind: Policy
rules:
# Log all secret access at Metadata level
- level: Metadata
  resources:
  - group: ""
    resources: ["secrets"]
# Log RBAC changes at RequestResponse level
- level: RequestResponse
  resources:
  - group: rbac.authorization.k8s.io
    resources: ["clusterroles", "clusterrolebindings", "roles", "rolebindings"]
# Log pod exec/attach (potential attacks)
- level: Request
  resources:
  - group: ""
    resources: ["pods/exec", "pods/attach", "pods/portforward"]
# Default: log at Metadata level
- level: Metadata