GKE Admission Webhook Created or Modified

Last updated 8 days ago on 2026-06-30

Created 8 days ago on 2026-06-30

About

Detects creation or modification of GKE mutating or validating admission webhook configurations by non-system identities. Malicious webhooks can inject workloads, block security tooling, or intercept API traffic for persistence and defense evasion.

Tags

Domain: CloudDomain: KubernetesData Source: GCPData Source: Google Cloud PlatformUse Case: Threat DetectionTactic: PersistenceTactic: Defense EvasionLanguage: kuery

Severity

medium

Risk Score

MITRE ATT&CK™

Persistence (TA0003)(external, opens in a new tab or window)

↳ Event Triggered Execution (T1546)(external, opens in a new tab or window)

Defense Evasion (TA0005)(external, opens in a new tab or window)

↳ Impair Defenses (T1562)(external, opens in a new tab or window)

False Positive Examples

GitOps and platform controllers (cert-manager, Gatekeeper, Kyverno, service mesh) legitimately manage webhooks. Validate change tickets and controller identities before tuning.

License

Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type: Query (Kibana Query Language)
Integration Pack: Prebuilt Security Detection Rules
Index Patterns: logs-gcp.audit-*
Related Integrations: gcp(external, opens in a new tab or window)
Query

✄𐘗text code block:
✄𐘗data_stream.dataset:gcp.audit and event.outcome:success and event.action:(
  "io.k8s.admissionregistration.v1.mutatingwebhookconfigurations.create" or
  "io.k8s.admissionregistration.v1.mutatingwebhookconfigurations.update" or
  "io.k8s.admissionregistration.v1.mutatingwebhookconfigurations.patch" or
  "io.k8s.admissionregistration.v1.validatingwebhookconfigurations.create" or
  "io.k8s.admissionregistration.v1.validatingwebhookconfigurations.update" or
  "io.k8s.admissionregistration.v1.validatingwebhookconfigurations.patch"
) and not user.email:(
  "system:kube-controller-manager" or "system:kube-scheduler" or system\:serviceaccount\:kube-system\:* or
  system\:serviceaccount\:gke-managed-system\:* or system\:serviceaccount\:cert-manager\:* or
  system\:serviceaccount\:gatekeeper-system\:* or system\:serviceaccount\:kyverno\:* or "system:addon-manager" or
  *-operator or *-cainjector or *-webhook or *argocd* or "system:gke-common-webhooks"
)

Install detection rules in Elastic Security

Detect GKE Admission Webhook Created or Modified in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).