Impact of Conflicting Transactions in Blockchain: Detecting and Mitigating Potential Attacks

TL;DR

Conflicting transactions create new attack surfaces in both permissioned and permissionless blockchains. The authors model and simulate four attacks—block withholding, double spending, balance, and DDoS—driven by conflicting transactions and implement four countermeasures at the ordering layer: dependency checking, priority-based ordering, parallel processing, and per-orderer queues. Results show substantial reductions in attack success rates (from about 90% to around 42% under high conflict loads) with only modest memory overhead and a large throughput boost (from ~150 to ~1800 TPS). This work provides a practical mitigation strategy for conflicting transactions with implications for both enterprise and public blockchain deployments, illustrating how ordering-layer defenses can improve security and performance with low overhead.

Abstract

Conflicting transactions within blockchain networks not only pose performance challenges but also introduce security vulnerabilities, potentially facilitating malicious attacks. In this paper, we explore the impact of conflicting transactions on blockchain attack vectors. Through modeling and simulation, we delve into the dynamics of four pivotal attacks - block withholding, double spending, balance, and distributed denial of service (DDoS), all orchestrated using conflicting transactions. Our analysis not only focuses on the mechanisms through which these attacks exploit transaction conflicts but also underscores their potential impact on the integrity and reliability of blockchain networks. Additionally, we propose a set of countermeasures for mitigating these attacks. Through implementation and evaluation, we show their effectiveness in lowering attack rates and enhancing overall network performance seamlessly, without introducing additional overhead. Our findings emphasize the critical importance of actively managing conflicting transactions to reinforce blockchain security and performance.

Figures (7)

• Figure 1: Conflicting Transactions in Blockchain
• Figure 2: Sequence Diagram of Block Withholding Attack
• Figure 3: Sequence Diagram of Double Spending Attack
• Figure 4: Sequence Diagram of Balance Attack
• Figure 5: Sequence Diagram of DDoS Attack