GKE Certificate Signing Request for Privileged Identity

Description

Detects creation of a GKE CertificateSigningRequest (CSR) whose decoded subject requests a highly privileged Kubernetes identity in the Common Name (CN), such as system:masters, system:kube-controller-manager, or system:admin. This rule is scoped to identities with cluster-admin-equivalent or control-plane impersonation value. Attackers who can create and approve CSRs can use this technique to clone credentials for powerful identities and obtain durable cluster access. This signal applies to any actor, including compromised node identities that use legitimate kubelet signers but request a privileged CN.

Detection logic

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Detection requirements

Platform: Containers ESXi IaaS Identity Provider Linux macOS Network Devices Office Suite SaaS Windows
The rule states no platform. This is derived from the ATT&CK technique it maps to.

Known benign triggers

Legitimate GKE automation does not request certificates for system:masters, system:kube-controller-manager, or system:admin as the CSR subject. Node bootstrap and kubelet rotation use system:node:* identities instead. Alerts should be rare; tune exclusions only for documented custom PKI workflows that intentionally mint these identities.

References

Links the source published beside this detection. Reference is the link the source wrote, unmodified. Class is decided by this catalogue from the host and path, not stated by the source. Cited by counts published detections citing the same resource, including this one, and the sources beneath it count the repositories this catalogue ingests, which is not the same as independent research.
Reference	Class	Cited by
kubernetes.io/docs/concepts/security/rbac-good-practices/	Product documentation	4
kubernetes.io/docs/reference/access-authn-authz/certificate-signing-requests/	Product documentation	6
raesene.github.io/blog/2022/12/21/Kubernetes-persistence-with-Tocan-and-Teisteanas/	Unclassified	4
rhinosecuritylabs.com/cloud-security/kubelet-tls-bootstrap-privilege-escalation/	Unclassified	Only this detection cites it
stratus-red-team.cloud/attack-techniques/kubernetes/k8s.persistence.create-client-certificate/	Unclassified	4

Detection rules

GKE Certificate Signing Request for Privileged Identity

Description

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules