Entropy Sharing in Ransomware: Bypassing Entropy-Based Detection of Cryptographic Operations

Abstract

This study presents a groundbreaking approach to the ever-evolving challenge of ransomware detection. A lot of detection methods predominantly rely on pinpointing high-entropy blocks, which is a hallmark of the encryption techniques commonly employed in ransomware. These blocks, typically difficult to recover, serve as key indicators of malicious activity. So far, many neutralization techniques have been introduced so that ransomware utilizing standard encryption can effectively bypass these entropy-based detection systems. However, these have limited capabilities or require relatively high computational costs. To address these problems, we introduce a new concept entropy sharing. This method can be seamlessly integrated with every type of cryptographic algorithm and is also composed of lightweight operations, masking the high-entropy blocks undetectable. In addition, the proposed method cannot be easily nullified, contrary to simple encoding methods, without knowing the order of shares. Our findings demonstrate that entropy sharing can effectively bypass entropy-based detection systems. Ransomware utilizing such attack methods can cause significant damage, as they are difficult to detect through conventional detection methods.