Kubernetes Anonymous Request Authorized

This rule detects when an unauthenticated user request is authorized within the cluster. Attackers may attempt to use anonymous accounts to gain initial access to the cluster or to avoid attribution of their activities within the cluster. This rule excludes the /healthz, /livez and /readyz endpoints which are commonly accessed anonymously.

Rule type: query

Rule indices:

logs-kubernetes.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: None (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://media.defense.gov/2022/Aug/29/2003066362/-1/-1/0/CTR_KUBERNETES_HARDENING_GUIDANCE_1.2_20220829.PDF

Tags:

Elastic
Kubernetes
Continuous Monitoring
Execution
Initial Access
Defense Evasion

Version: 2

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

edit

Rule query

edit

event.dataset : "kubernetes.audit_logs"
  and kubernetes.audit.annotations.authorization_k8s_io/decision:"allow"
  and (kubernetes.audit.user.username:("system:anonymous" or "system:unauthenticated") or not kubernetes.audit.user.username:*)
  and not kubernetes.audit.objectRef.resource:("healthz" or "livez" or "readyz")

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Initial Access
- ID: TA0001
- Reference URL: https://attack.mitre.org/tactics/TA0001/
Technique:
- Name: Valid Accounts
- ID: T1078
- Reference URL: https://attack.mitre.org/techniques/T1078/
Sub-technique:
- Name: Default Accounts
- ID: T1078.001
- Reference URL: https://attack.mitre.org/techniques/T1078/001/

« Kubernetes Denied Service Account Request Kubernetes Container Created with Excessive Linux Capabilities »