Denial-of-Service Attacks on Permissioned Blockchains: A Practical Study

Hyperledger Fabric (HLF) is a leading permissioned blockchain platform designed for enterprise applications. However, it faces significant security risks from Denial-of-Service (DoS) attacks targeting its core components. This study systematically investigated network-level DoS attack vectors against HLF, with a focus on threats to its ordering service, Membership Service Provider (MSP), peer nodes, consensus protocols, and architectural dependencies. In this research, we performed experiments on an HLF test bed to demonstrate how compromised components can be exploited to launch DoS attacks and degrade the performance and availability of the blockchain network. Key attack scenarios included manipulating block sizes to induce latency, discarding blocks to disrupt consensus, issuing malicious certificates via MSP, colluding peers to sabotage validation, flooding external clients to overwhelm resources, misconfiguring Raft consensus parameters, and disabling CouchDB to cripple data access. The experimental results reveal severe impacts on the availability, including increased latency, decreased throughput, and inaccessibility of the ledger. Our findings emphasize the need for proactive monitoring and robust defense mechanisms to detect and mitigate DoS threats. Finally, we discuss some future research directions, including lightweight machine learning tailored to HLF, enhanced monitoring by aggregating logs from multiple sources, and collaboration with industry stakeholders to deploy pilot studies of security-enhanced HLF in operational environments.