AWS EKS Unusual Decision by User Agent

Last updated 2 days ago on 2026-10-21

Created 3 months ago on 2026-08-03

About

This rule detects unusual request responses in Kubernetes audit logs through the use of the "new_terms" rule type. In production environments, default API requests are typically made by system components or trusted users, who are expected to have a consistent user agent and allowed response annotations. By monitoring for anomalies in the username and response annotations, this rule helps identify potential unauthorized access or misconfigurations in the Kubernetes environment.

Tags

Domain: CloudDomain: ContainersPlatform: AWSPlatform: KubernetesData Source: AWSData Source: Amazon Web ServicesData Source: Kubernetes API Server Audit LogsService: AWS EKSUse Case: Threat DetectionTactic: ExecutionTactic: Defense EvasionTactic: Initial AccessRule Type: New TermsProfile: BetaLanguage: kuery

Severity

low

Risk Score

MITRE ATT&CK™

Execution (TA0002)(external, opens in a new tab or window)

Defense Evasion (TA0005)(external, opens in a new tab or window)

↳ Valid Accounts (T1078)(external, opens in a new tab or window)

Initial Access (TA0001)(external, opens in a new tab or window)

↳ Valid Accounts (T1078)(external, opens in a new tab or window)

License

Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type: New Terms Rule
Integration Pack: Prebuilt Security Detection Rules
Index Patterns: logs-aws.eks_audit-*
Related Integrations: aws(external, opens in a new tab or window)
Query

✄𐘗text code block:
✄𐘗data_stream.dataset:"aws.eks_audit" and aws.eks.audit.stage:"ResponseComplete" and
user_agent.original:(* and not (*kubernetes/$Format)) and
not (
  user_agent.original:kubelet* and
  not aws.eks.audit.objectRef.resource:(pods or nodes or csinodes or csidrivers or configmaps or secrets or events or leases or runtimeclasses) and
  aws.eks.audit.verb:(get or list or watch or patch)
)

Install detection rules in Elastic Security

Detect AWS EKS Unusual Decision by User Agent in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).