Kubernetes Anonymous Request Authorized

Elastic Stack Serverless Security

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 (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[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: 3

Rule authors:

• Elastic

Rule license: Elastic License v2

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&CKTM

• 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/