Kubernetes NodePort Service Deployed

AnalysisType: rule
RuleID: "Kubernetes.Service.NodePort.Deployed"
DisplayName: "Kubernetes NodePort Service Deployed"
Enabled: true
Filename: k8s_service_nodeport.py
LogTypes:
  - Amazon.EKS.Audit
  - Azure.MonitorActivity
  - GCP.AuditLog
Severity: High
Description: >
  This detection monitors for any Kubernetes service deployed with type NodePort. A NodePort
  service allows an attacker to expose a set of pods hosting the service to the internet by
  opening their port and redirecting traffic here. This can be used to bypass network controls
  and intercept traffic, creating a direct line to the outside network.
Runbook: |
  1. Identify all services created by the username in the 48 hours before the alert to understand deployment patterns
  2. Check the NodePort service specification to determine if it exposes cluster-critical services or standard application workloads
  3. Review exposed ports and compare against documented internal services in the past 30 days to verify if this is authorized
Reference: https://kubernetes.io/docs/tutorials/kubernetes-basics/expose/expose-intro/
Tags:
  - Kubernetes
  - Exploit Public-Facing Application
  - Initial Access
  - Unified Detection
Reports:
  MITRE ATT&CK:
    - TA0001:T1190 # Exploit Public-Facing Application
Tests:
  - Name: EKS NodePort Service Created
    ExpectedResult: true
    Log:
      {
        "kind": "Event",
        "apiVersion": "audit.k8s.io/v1",
        "verb": "create",
        "user": {"username": "user@example.com"},
        "sourceIPs": ["1.2.3.4"],
        "userAgent": "kubectl/v1.28.2",
        "objectRef": {
          "resource": "services",
          "namespace": "default",
          "name": "test-ns",
          "apiVersion": "v1"
        },
        "responseStatus": {"code": 201},
        "requestObject": {
          "kind": "Service",
          "apiVersion": "v1",
          "spec": {
            "type": "NodePort",
            "ports": [{
              "port": 5678,
              "targetPort": 8080,
              "protocol": "TCP"
            }]
          }
        },
        "p_log_type": "Amazon.EKS.Audit",
        "p_source_label": "eks-cluster"
      }
  - Name: AKS NodePort Service Created
    ExpectedResult: true
    Log:
      {
        "p_log_type": "Azure.MonitorActivity",
        "category": "kube-audit",
        "operationName": "Microsoft.ContainerService/managedClusters/diagnosticLogs/Read",
        "properties": {
          "log": "{\"kind\":\"Event\",\"apiVersion\":\"audit.k8s.io/v1\",\"verb\":\"create\",\"user\":{\"username\":\"admin@example.com\"},\"sourceIPs\":[\"10.0.0.1\"],\"objectRef\":{\"resource\":\"services\",\"namespace\":\"default\",\"name\":\"test-svc\"},\"responseStatus\":{\"code\":201},\"requestObject\":{\"kind\":\"Service\",\"spec\":{\"type\":\"NodePort\",\"ports\":[{\"port\":80}]}}}"
        },
        "p_source_label": "aks-cluster"
      }
  - Name: GCP GKE NodePort Service Created
    ExpectedResult: true
    Log:
      {
        "protoPayload": {
          "authenticationInfo": {"principalEmail": "user@company.com"},
          "authorizationInfo": [{
            "granted": true,
            "permission": "io.k8s.core.v1.services.create",
            "resource": "core/v1/namespaces/default/services/test-ns"
          }],
          "methodName": "io.k8s.core.v1.services.create",
          "request": {
            "@type": "core.k8s.io/v1.Service",
            "apiVersion": "v1",
            "kind": "Service",
            "spec": {
              "type": "NodePort",
              "ports": [{"port": 5678, "targetPort": 8080}]
            }
          },
          "requestMetadata": {"callerIP": "1.2.3.4"},
          "resourceName": "core/v1/namespaces/default/services/test-ns",
          "serviceName": "k8s.io",
          "status": {}
        },
        "resource": {
          "labels": {"project_id": "test-project"},
          "type": "k8s_cluster"
        },
        "p_log_type": "GCP.AuditLog",
        "p_source_label": "gke-cluster"
      }
  - Name: ClusterIP Service Created
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "create",
        "objectRef": {"resource": "services", "namespace": "default"},
        "responseStatus": {"code": 201},
        "requestObject": {
          "spec": {"type": "ClusterIP"}
        },
        "p_log_type": "Amazon.EKS.Audit"
      }
  - Name: Service Creation Failed
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "create",
        "objectRef": {"resource": "services", "namespace": "default"},
        "responseStatus": {"code": 409, "status": "Failure"},
        "requestObject": {
          "spec": {"type": "NodePort"}
        },
        "p_log_type": "Amazon.EKS.Audit"
      }
  - Name: Not a Service Creation
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "get",
        "objectRef": {"resource": "services", "namespace": "default"},
        "p_log_type": "Amazon.EKS.Audit"
      }


# ------ paired body: k8s_service_nodeport.py ------

from panther_kubernetes_helpers import is_failed_request, k8s_alert_context


def rule(event):
    verb = event.udm("verb")
    resource = event.udm("resource")
    response_status = event.udm("responseStatus")

    # Only check service creation events
    if verb != "create" or resource != "services":
        return False

    # Skip failed requests
    if is_failed_request(response_status):
        return False

    # Check if service type is NodePort
    service_type = event.udm("serviceType") or ""
    if service_type == "NodePort":
        return True

    return False


def title(event):
    username = event.udm("username") or "<UNKNOWN_USER>"
    namespace = event.udm("namespace") or "<UNKNOWN_NAMESPACE>"
    name = event.udm("name") or "<UNKNOWN>"

    return f"[{username}] deployed NodePort service [{namespace}/{name}]"


def alert_context(event):
    return k8s_alert_context(
        event,
        extra_fields={
            "service_name": event.udm("name"),
            "service_type": event.udm("serviceType"),
        },
    )