Full Report
Learn how to protect against the abuse of AWS Server-Side Encryption with Customer-Provided Keys (SSE-C) in ransomware campaigns.
Analysis Summary
# Tool/Technique: Abuse of AWS SSE-C (Server-Side Encryption with Customer-Provided Keys)
## Overview
The abuse of Amazon Web Services (AWS) Server-Side Encryption with Customer-Provided Keys (SSE-C) is a technique used by threat actors, particularly in ransomware campaigns, to encrypt victims' data stored in S3 buckets, making it unrecoverable unless the threat actor's provided key is used. This leverages a legitimate cloud security feature for malicious purposes.
## Technical Details
- Type: Technique (Leveraging a native cloud feature)
- Platform: AWS S3 / Cloud Environment
- Capabilities: Encrypting stored objects using keys provided by the attacker during the PUT operation, effectively taking control of the data's encryption lifecycle.
- First Seen: Mentioned in the context of recent threat actor campaigns (Date not specified beyond the article date of January 27, 2025).
## MITRE ATT&CK Mapping
- TA0040 - Impact
- T1486 - Data Encrypted for Impact
- T1486.005 - Cloud Storage Encrypted
## Functionality
### Core Capabilities
- Encrypting S3 objects using the attacker's chosen encryption key during the client upload process utilizing the SSE-C functionality.
- Rendering data unrecoverable to the legitimate owner unless the attacker supplies the decryption key (which they typically monetize as part of a ransomware demand).
### Advanced Features
- Exploitation relies on valid credentials or access to the targeted S3 bucket, often obtained via social engineering (phishing), credential stuffing, or leaks from public repositories.
## Indicators of Compromise
- File Hashes: N/A (This is an operational technique, not static malware)
- File Names: N/A
- Registry Keys: N/A
- Network Indicators: Specific credentials or access tokens used to perform the unauthorized S3 PUT operations with SSE-C headers.
- Behavioral Indicators: Unusual S3 PUT/COPY operations observed supplying custom `x-amz-server-side-encryption-customer-key` headers by unauthorized identities.
## Associated Threat Actors
- Threat actors engaged in cloud ransomware campaigns targeting AWS S3 environments.
## Detection Methods
- Signature-based detection: Not applicable for a feature misuse technique.
- Behavioral detection: Monitoring S3 access logs (CloudTrail) for PUT or COPY operations referencing SSE-C headers associated with non-standard or suspicious principals.
- YARA rules: Not applicable.
## Mitigation Strategies
- Prevention measures: Restricting the use of SSE-C at the bucket policy level when possible, or ensuring strict IAM policies govern which principals are allowed to upload data using customer keys.
- Hardening recommendations:
1. Implement **Bucket Versioning**: This allows restoration to a state before the high-value data was encrypted by the adversary.
2. Enforce **MFA Delete** on versioned buckets.
3. Strictly limit and audit principals authorized to use SSE-C.
## Related Tools/Techniques
- Standard cloud credential theft techniques often preceding this action (e.g., phishing, credential stuffing).
- Generic Ransomware frameworks targeting cloud storage.