Potential AWS S3 Bucket Ransomware Note Uploaded

Last updated 3 months ago on 2025-09-30

Created 2 years ago on 2024-04-17

About

Identifies potential ransomware note being uploaded to an AWS S3 bucket. This rule detects the PutObject S3 API call with a common ransomware note file name or extension such as ransom or .lock. Adversaries with access to a misconfigured S3 bucket may retrieve, delete, and replace objects with ransom notes to extort victims.

Tags

Domain: CloudData Source: AWSData Source: Amazon Web ServicesData Source: AWS S3Use Case: Threat DetectionTactic: ImpactLanguage: eql

Severity

medium

Risk Score

MITRE ATT&CK™

Impact (TA0040)(external, opens in a new tab or window)

↳ Data Destruction (T1485)(external, opens in a new tab or window)

↳ Data Encrypted for Impact (T1486)(external, opens in a new tab or window)

False Positive Examples

Administrators may legitimately access, delete, and replace objects in S3 buckets. Ensure that the uploaded files are not part of a legitimate operation before taking action.

License

Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type: Event Correlation Rule
Integration Pack: Prebuilt Security Detection Rules
Index Patterns: filebeat-*logs-aws.cloudtrail-*
Related Integrations: aws(external, opens in a new tab or window)
Query

✄𐘗text code block:
✄𐘗file where
  event.dataset == "aws.cloudtrail" and
  event.provider == "s3.amazonaws.com" and
  event.action == "PutObject" and
  event.outcome == "success" and
  /* Apply regex to match patterns only after the bucket name */
  aws.cloudtrail.resources.arn regex "arn:aws:s3:::[^/]+/.*?(ransom|lock|crypt|enc|readme|how_to_decrypt|decrypt_instructions|recovery|datarescue).*" and
  not aws.cloudtrail.resources.arn regex ".*(AWSLogs|CloudTrail|access-logs).*"

Install detection rules in Elastic Security

Detect Potential AWS S3 Bucket Ransomware Note Uploaded in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).