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Description

This search looks for AWS CloudTrail events from AWS Elastic Container Service (ECR). A upload of a new container is normally done during business hours. When done outside business hours, we want to take a look into it.

  • Type: Anomaly

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

  • Last Updated: 2021-08-19
  • Author: Patrick Bareiss, Splunk
  • ID: d4c4d4eb-3994-41ca-a25e-a82d64e125bb

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1204.003 Malicious Image Execution
T1204 User Execution Execution
Kill Chain Phase
  • Installation
NIST
  • DE.AE
CIS20
  • CIS 13
CVE 


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`cloudtrail` eventSource=ecr.amazonaws.com eventName=PutImage date_hour>=20 OR date_hour<8 OR date_wday=saturday OR date_wday=sunday 
| rename requestParameters.* as * 
| rename repositoryName AS image 
| eval phase="release" 
| eval severity="medium" 
| stats min(_time) as firstTime max(_time) as lastTime by awsRegion, eventName, eventSource, user, userName, src_ip, imageTag, registryId, image, phase, severity 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `aws_ecr_container_upload_outside_business_hours_filter`

Macros

The SPL above uses the following Macros:

:information_source: aws_ecr_container_upload_outside_business_hours_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.

  • eventSource
  • eventName
  • awsRegion
  • requestParameters.imageTag
  • requestParameters.registryId
  • requestParameters.repositoryName
  • user
  • userName
  • src_ip

How To Implement

You must install splunk AWS add on and Splunk App for AWS. This search works with AWS CloudTrail logs.

Known False Positives

When your development is spreaded in different time zones, applying this rule can be difficult.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
49.0 70 70 Container uploaded outside business hours from $user$

: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

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