Reinforcing Cloud Attack Tolerance on a Large Scale: Advanced Blockchain Technologies With Hierarchical Risk and Smart Contracts

ABSTRACT The distributed denial of service (DDoS) attacks represent a real danger on cloud computing systems, the existing security approaches have notable limitations such as centralization, lack of adaptability and scalability, and focusing on detection over mitigation. In this paper, we present a novel blockchain‐based system to enhance attack tolerance of cloud systems against DDoS attacks by integrating a hierarchical risk‐based cloud attack tolerance mechanism with smart contracts, The proposed approach ensures comprehensive threat detection and mitigation by estimating risks at all three layers: local, cluster, and global dynamically using Dempster–Shafer theory. Simulations validated the superiority of our approach compared to similar systems in terms of availability, attack detection rate, and packet loss metrics in large‐scale cloud simulation of 10,000 nodes. The results demonstrate that our system not only improves security but also maintains service quality under high‐intensity attack scenarios. Additionally, the implementation of our blockchain architecture shows significant scalability and cost‐efficiency, thus, confirming its suitability for large cloud deployments. Furthermore, the reliability of the smart contracts against potential threats were confirmed by a formal security analysis using the Echidna tool.