Detection: AWS ECR Container Upload Outside Business Hours

Updated Date: 2024-09-30 ID: d4c4d4eb-3994-41ca-a25e-a82d64e125bb Author: Patrick Bareiss, Splunk Type: Anomaly Product: Splunk Enterprise Security

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.

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

Data Source

Name Platform Sourcetype Source
AWS CloudTrail PutImage AWS icon AWS 'aws:cloudtrail' 'aws_cloudtrail'

Macros Used

Name Value
cloudtrail sourcetype=aws:cloudtrail
aws_ecr_container_upload_outside_business_hours_filter search *
aws_ecr_container_upload_outside_business_hours_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
T1204.003 Malicious Image Execution
T1204 User Execution Execution
KillChainPhase.INSTALLATION
NistCategory.DE_AE
Cis18Value.CIS_13
TeamTNT
LAPSUS$
Scattered Spider

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

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

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Container uploaded outside business hours from $user$ 49 70 70
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset aws_cloudtrail aws:cloudtrail
Integration ✅ Passing Dataset aws_cloudtrail aws:cloudtrail

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: 4