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Description

The following analytic detects the creation of a Kubernetes cron job, which is a task scheduled to run automatically at specified intervals. It identifies this activity by monitoring Kubernetes Audit logs for the creation events of cron jobs. This behavior is significant for a SOC as it could allow an attacker to execute malicious tasks repeatedly and automatically, posing a threat to the Kubernetes infrastructure. If confirmed malicious, this activity could lead to persistent attacks, service disruptions, or unauthorized access to sensitive information.

  • Type: Anomaly

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-05-28
  • Author: Patrick Bareiss, Splunk
  • ID: 5984dbe8-572f-47d7-9251-3dff6c3f0c0d

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1053.007 Container Orchestration Job Execution, Persistence, Privilege Escalation
Kill Chain Phase
  • Installation
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 13
CVE 


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`kube_audit` verb=create "objectRef.resource"=cronjobs 
| fillnull 
| stats count values(user.groups{}) as user_groups by kind objectRef.name objectRef.namespace objectRef.resource requestObject.kind requestObject.spec.schedule requestObject.spec.jobTemplate.spec.template.spec.containers{}.image responseStatus.code sourceIPs{} stage user.username userAgent verb 
| rename sourceIPs{} as src_ip, user.username as user 
| `kubernetes_cron_job_creation_filter`

Macros

The SPL above uses the following Macros:

:information_source: kubernetes_cron_job_creation_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • user.groups{}
  • kind
  • objectRef.name
  • objectRef.namespace
  • objectRef.resource
  • requestObject.kind
  • requestObject.spec.schedule
  • requestObject.spec.jobTemplate.spec.template.spec.containers{}.image
  • responseStatus.code
  • sourceIPs{}
  • stage
  • user.username
  • userAgent
  • verb

How To Implement

The detection is based on data that originates from Kubernetes Audit logs. Ensure that audit logging is enabled in your Kubernetes cluster. Kubernetes audit logs provide a record of the requests made to the Kubernetes API server, which is crucial for monitoring and detecting suspicious activities. Configure the audit policy in Kubernetes to determine what kind of activities are logged. This is done by creating an Audit Policy and providing it to the API server. Use the Splunk OpenTelemetry Collector for Kubernetes to collect the logs. This doc will describe how to collect the audit log file https://github.com/signalfx/splunk-otel-collector-chart/blob/main/docs/migration-from-sck.md.

Known False Positives

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
49.0 70 70 Kubernetes cron job creation from user $user$

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

Reference

Test Dataset

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 | version: 2