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Description

This analytic searches for a specific behavior in CircleCI pipelines such as the disabling of security jobs. The detection is made by using a Splunk query that renames certain fields and retrieves values for specified job names, workflow IDs and names, user information, commit messages, URLs, and branches. Then, the query identifies mandatory jobs for each workflow and searches for instances where they were run. The search also identifies the phase of the pipeline as "build" and extracts the repository name from the URL using regular expressions. The detection is important because it detects attempts to bypass security measures in CircleCI pipelines, which can potentially lead to malicious code being introduced into the pipeline, data breaches, system downtime, and reputational damage. False positives might occur since legitimate use cases can require the disabling of security jobs. However, you can proactively monitor and identify any suspicious activity in the pipeline using this analytic and mitigate potential threats through early detection.

  • Type: Anomaly

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

  • Last Updated: 2021-09-02
  • Author: Patrick Bareiss, Splunk
  • ID: 4a2fdd41-c578-4cd4-9ef7-980e352517f2

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1554 Compromise Client Software Binary Persistence
Kill Chain Phase
  • Installation
NIST
  • DE.AE
CIS20
  • CIS 13
CVE 


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`circleci` 
| rename vcs.committer_name as user vcs.subject as commit_message vcs.url as url workflows.* as *  
| stats values(job_name) as job_names by workflow_id workflow_name user commit_message url branch 
| lookup mandatory_job_for_workflow workflow_name OUTPUTNEW job_name AS mandatory_job 
| search mandatory_job=* 
| eval mandatory_job_executed=if(like(job_names, "%".mandatory_job."%"), 1, 0) 
| where mandatory_job_executed=0 
| eval phase="build" 
| rex field=url "(?<repository>[^\/]*\/[^\/]*)$" 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `circle_ci_disable_security_job_filter`

Macros

The SPL above uses the following Macros:

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

Lookups

The SPL above uses the following Lookups:

Required fields

List of fields required to use this analytic.

  • _times

How To Implement

You must index CircleCI logs.

Known False Positives

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
72.0 80 90 disable security job $mandatory_job$ in workflow $workflow_name$ 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: 1