Detection: Cisco Isovalent - Cron Job Creation

Updated Date: 2026-01-05 ID: 94531a31-a041-4777-909f-cd92ed3b71ad Author: Bhavin Patel, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects the creation of a cron job within the Cisco Isovalent environment. It identifies this activity by monitoring process execution logs for cron job creation events. 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.

Search

 1`cisco_isovalent_process_exec` process_name IN ("crond","cron","crontab")
 2
 3| search pod_name!=""
 4
 5| stats count 
 6        min(_time) as firstTime 
 7        max(_time) as lastTime 
 8        values(process) as process
 9    by cluster_name pod_name parent_process_name process_name process_exec process_id node_name
10
11| `security_content_ctime(firstTime)`
12
13| `security_content_ctime(lastTime)`
14
15| `cisco_isovalent___cron_job_creation_filter`

Data Source

Name	Platform	Sourcetype	Source
Cisco Isovalent Process Exec	Other	`'cisco:isovalent:processExec'`	`'not_applicable'`

Macros Used

Name	Value
cisco_isovalent_process_exec	`sourcetype=cisco:isovalent:processExec`
cisco_isovalent___cron_job_creation_filter	`search *`

cisco_isovalent___cron_job_creation_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
T1053.003	Cron	Execution
T1053.007	Container Orchestration Job	Persistence

Exploitation

Installation

DE.AE

CIS 13

APT5

Rocke

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	True

This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

The detection is based on process execution data generated by Cisco Isovalent Runtime Security. Ensure that Isovalent Runtime Security is deployed and configured in your Kubernetes environment to emit process_exec events. Configure the Cisco Security Cloud TA to collect these logs via HTTP Event Collector (HEC) and normalize them into the Splunk Common Information Model. This integration ensures that all relevant pod, container, and process activity is captured for monitoring and detection of suspicious behavior.

Known False Positives

This activity may be triggered by legitimate administrative scripts, container images, or third-party operators that use cron for scheduled tasks, so please investigate the alert in context to rule out benign operations.

Associated Analytic Story

Cisco Isovalent Suspicious Activity

Risk Based Analytics (RBA)

Risk Message:

cron job creation detected in pod [$pod_name$] in the cluster [$cluster_name$]

Risk Object	Risk Object Type	Risk Score	Threat Objects
pod_name	system	50	process_name

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`not_applicable`	`cisco:isovalent:processExec`
Integration	✅ Passing	Dataset	`not_applicable`	`cisco:isovalent:processExec`

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: 1