Detection: Amazon EKS Kubernetes cluster scan detection

EXPERIMENTAL DETECTION

This detection status is set to experimental. The Splunk Threat Research team has not yet fully tested, simulated, or built comprehensive datasets for this detection. As such, this analytic is not officially supported. If you have any questions or concerns, please reach out to us at research@splunk.com.

Updated Date: 2024-05-15 ID: 294c4686-63dd-4fe6-93a2-ca807626704a Author: Rod Soto, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects unauthenticated requests to an Amazon EKS Kubernetes cluster, specifically identifying actions by the "system:anonymous" user. It leverages AWS CloudWatch Logs data, focusing on user agents and authentication details. This activity is significant as it may indicate unauthorized scanning or probing of the Kubernetes cluster, which could be a precursor to an attack. If confirmed malicious, this could lead to unauthorized access, data exfiltration, or disruption of services within the Kubernetes environment.

Search

1`aws_cloudwatchlogs_eks` "user.username"="system:anonymous" userAgent!="AWS Security Scanner" 
2| rename sourceIPs{} as src_ip 
3| stats count min(_time) as firstTime max(_time) as lastTime values(responseStatus.reason) values(source) as cluster_name values(responseStatus.code) values(userAgent) as http_user_agent values(verb) values(requestURI) by src_ip user.username user.groups{} 
4| `security_content_ctime(lastTime)` 
5| `security_content_ctime(firstTime)` 
6|`amazon_eks_kubernetes_cluster_scan_detection_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
N/A	N/A	N/A	N/A	N/A

Macros Used

Name	Value
aws_cloudwatchlogs_eks	`sourcetype="aws:cloudwatchlogs:eks"`
amazon_eks_kubernetes_cluster_scan_detection_filter	`search *`

amazon_eks_kubernetes_cluster_scan_detection_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1526	Cloud Service Discovery	Discovery

KillChainPhase.EXPLOITAITON

NistCategory.DE_AE

Cis18Value.CIS_10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Risk Event	False

This configuration file applies to all detections of type hunting.

Implementation

You must install the AWS App for Splunk (version 5.1.0 or later) and Splunk Add-on for AWS (version 4.4.0 or later), then configure your CloudWatch EKS Logs inputs.

Known False Positives

Not all unauthenticated requests are malicious, but frequency, UA and source IPs will provide context.

Associated Analytic Story

Kubernetes Scanning Activity

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
tbd	25	50	50

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	Not Applicable	N/A	N/A	N/A
Unit	❌ Failing	N/A	`N/A`	`N/A`
Integration	❌ Failing	N/A	`N/A`	`N/A`

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 2