Ransomware Campaign Encrypting Amazon S3 Buckets using SSE-C
On January 13, 2025, Halcyon released a research blog about the Codefinger group conducting a ransomware campaign targeting Amazon S3 buckets. The attacks leverage AWS’s Server-Side Encryption with Customer Provided Keys (SSE-C) to encrypt data. The threat actors then demand ransom payments for the symmetric AES-256 keys required to decrypt it.