GKE Creation of a RoleBinding Referencing a ServiceAccount

  1[metadata]
  2creation_date = "2026/07/10"
  3integration = ["gcp"]
  4maturity = "production"
  5updated_date = "2026/07/10"
  6
  7[rule]
  8author = ["Elastic"]
  9description = """
 10Detects creation of a GKE RoleBinding or ClusterRoleBinding that grants permissions to a ServiceAccount, which may
 11indicate privilege delegation or RBAC misconfiguration leading to elevated access.
 12"""
 13false_positives = [
 14    """
 15    GitOps, namespace onboarding, and workload deployment commonly create RoleBindings for service accounts. Default
 16    bootstrap bindings from `system:apiserver` and GKE node bootstrap from `gcp:kube-bootstrap` are excluded.
 17    """,
 18]
 19from = "now-6m"
 20index = ["logs-gcp.audit-*"]
 21language = "kuery"
 22license = "Elastic License v2"
 23name = "GKE Creation of a RoleBinding Referencing a ServiceAccount"
 24note = """## Triage and analysis
 25
 26### Investigating GKE Creation of a RoleBinding Referencing a ServiceAccount
 27
 28This rule detects creation of a RoleBinding or ClusterRoleBinding whose subject is a ServiceAccount. Attackers often bind
 29over-privileged roles to an existing workload service account to operate with elevated rights.
 30
 31### Possible investigation steps
 32
 33- Review `client.user.email`, `source.ip`, `gcp.audit.request.roleRef`, and `gcp.audit.request.subjects`.
 34- Determine which workloads run under the bound service account and whether the referenced role is cluster-scoped.
 35- Correlate with secret access, exec, or additional RBAC changes from the same actor.
 36
 37### False positive analysis
 38
 39- Legitimate deployments and operators create service account bindings during routine releases.
 40
 41### Response and remediation
 42
 43- Remove unauthorized bindings, rotate the service account credentials, and tighten who can create RoleBindings.
 44
 45"""
 46setup = "The GCP Fleet integration with GKE audit logs enabled is required to be compatible with this rule."
 47references = [
 48    "https://kubernetes.io/docs/reference/access-authn-authz/rbac/",
 49    "https://heilancoos.github.io/research/2025/12/16/kubernetes.html#overly-permissive-role-based-access-control",
 50]
 51risk_score = 47
 52rule_id = "1e58e0a0-7674-4aa9-9409-f72f100a8b5e"
 53severity = "medium"
 54tags = [
 55    "Domain: Cloud",
 56    "Domain: Kubernetes",
 57    "Data Source: GCP",
 58    "Data Source: Google Cloud Platform",
 59    "Use Case: Threat Detection",
 60    "Tactic: Persistence",
 61    "Tactic: Privilege Escalation",
 62    "Resources: Investigation Guide",
 63]
 64timestamp_override = "event.ingested"
 65type = "query"
 66
 67query = '''
 68data_stream.dataset:gcp.audit and service.name:"k8s.io" and event.outcome:success and
 69event.action:(
 70  "io.k8s.authorization.rbac.v1.rolebindings.create" or
 71  "io.k8s.authorization.rbac.v1.clusterrolebindings.create"
 72) and gcp.audit.request.subjects.kind:"ServiceAccount" and not client.user.email:(
 73  "system:apiserver" or
 74  "gcp:kube-bootstrap"
 75)
 76'''
 77
 78[[rule.threat]]
 79framework = "MITRE ATT&CK"
 80
 81[[rule.threat.technique]]
 82id = "T1098"
 83name = "Account Manipulation"
 84reference = "https://attack.mitre.org/techniques/T1098/"
 85
 86[[rule.threat.technique.subtechnique]]
 87id = "T1098.006"
 88name = "Additional Container Cluster Roles"
 89reference = "https://attack.mitre.org/techniques/T1098/006/"
 90
 91[rule.threat.tactic]
 92id = "TA0003"
 93name = "Persistence"
 94reference = "https://attack.mitre.org/tactics/TA0003/"
 95
 96[[rule.threat]]
 97framework = "MITRE ATT&CK"
 98
 99[[rule.threat.technique]]
100id = "T1098"
101name = "Account Manipulation"
102reference = "https://attack.mitre.org/techniques/T1098/"
103
104[[rule.threat.technique.subtechnique]]
105id = "T1098.006"
106name = "Additional Container Cluster Roles"
107reference = "https://attack.mitre.org/techniques/T1098/006/"
108
109[rule.threat.tactic]
110id = "TA0004"
111name = "Privilege Escalation"
112reference = "https://attack.mitre.org/tactics/TA0004/"
113
114[rule.investigation_fields]
115field_names = [
116    "@timestamp",
117    "client.user.email",
118    "source.ip",
119    "user_agent.original",
120    "event.action",
121    "event.outcome",
122    "gcp.audit.resource_name",
123    "gcp.audit.request.roleRef.name",
124    "gcp.audit.request.roleRef.kind",
125    "gcp.audit.request.subjects.name",
126    "gcp.audit.request.subjects.namespace",
127    "data_stream.namespace",
128]