Unusual AWS S3 Object Encryption with SSE-C

Last updated 23 days ago on 2025-07-10

Created 7 months ago on 2025-01-15

About

Identifies when AWS S3 objects stored in a bucket are encrypted using Server-Side Encryption with Customer-Provided Keys (SSE-C). Adversaries with compromised AWS credentials can encrypt objects in an S3 bucket using their own encryption keys, rendering the objects unreadable or recoverable without the key. This can be used as a form of ransomware to extort the bucket owner for the decryption key. This is a New Terms rule that flags when this behavior is observed for the first time user and target bucket name.

Tags

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

Severity

high

Risk Score

MITRE ATT&CK™

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

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

False Positive Examples

Legitimate use of Server-Side Encryption with Customer-Provided Keys (SSE-C) to encrypt objects in an S3 bucket.

License

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

Definition

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

event.dataset: "aws.cloudtrail"
    and event.provider: "s3.amazonaws.com"
    and event.action: "PutObject"
    and event.outcome: "success"
    and aws.cloudtrail.flattened.request_parameters.x-amz-server-side-encryption-customer-algorithm: "AES256"

Install detection rules in Elastic Security

Detect Unusual AWS S3 Object Encryption with SSE-C 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(opens in a new tab or window).