unauthorized requests from service accounts are normal and expected behavior. analyze the user agent, pod and other node information to determine if the request is legitimate.

Techniques

T1613

Sample rules

Kubernetes Denied Service Account Request via Unusual User Agent

source: elastic
technicques:
- T1613

Description

This rule detects when a service account makes an unauthorized request for resources from the API server via an unusual user agent. Service accounts follow a very predictable pattern of behavior. A service account should never send an unauthorized request to the API server. This behavior is likely an indicator of compromise or of a problem within the cluster. An adversary may have gained access to credentials/tokens and this could be an attempt to access or create resources to facilitate further movement or execution within the cluster.

Detection logic

event.dataset:"kubernetes.audit_logs" and
kubernetes.audit.user.username:system\:serviceaccount\:* and
kubernetes.audit.annotations.authorization_k8s_io/decision:"forbid" and
kubernetes.audit.userAgent:(* and not (*kubernetes/$Format or karpenter or csi-secrets-store* or OpenAPI-Generator* or Prometheus* or dashboard* or cilium-agent*))