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Description

The following analytic detects the upload of a new container image to AWS Elastic Container Registry (ECR) outside of standard business hours. It leverages AWS CloudTrail logs to identify PutImage events occurring between 8 PM and 8 AM or on weekends. This activity is significant because container uploads outside business hours can indicate unauthorized or suspicious activity, potentially pointing to a compromised account or insider threat. If confirmed malicious, this could allow an attacker to deploy unauthorized or malicious containers, leading to potential data breaches or service disruptions.

  • Type: Anomaly

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

  • Last Updated: 2024-05-25
  • 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 repository 
| 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, repository, 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

source | version: 3