Block Double-Submission Attack: Block Withholding Can Be Self-Destructive

TL;DR

This paper analyzes Block Withholding attacks in blockchain mining pools, revealing that such attacks can be betrayed by malicious agents seeking additional benefits, which may lead to the attack's self-destruction and reduced effectiveness.

Contribution

It introduces the concept that BWH attacks have an inherent trust problem and can be betrayed by agents, potentially causing the attack to fail or self-destruct.

Findings

BWH agents can betray their mining pools for additional gains.

Betrayal by BWH agents can undermine the attack's success.

Self-destruction of attack revenue is possible due to betrayal.

Abstract

Proof-of-Work (PoW) is a Sybil control mechanism adopted in blockchain-based cryptocurrencies. It prevents the attempt of malicious actors to manipulate distributed ledgers. Bitcoin has successfully suppressed double-spending by accepting the longest PoW chain. Nevertheless, PoW encountered several major security issues surrounding mining competition. One of them is a Block WithHolding (BWH) attack that can exploit a widespread and cooperative environment called a mining pool. This attack takes advantage of untrustworthy relationships between mining pools and participating agents. Moreover, detecting or responding to attacks is challenging due to the nature of mining pools. In this paper, however, we suggest that BWH attacks also have a comparable trust problem. Because a BWH attacker cannot have complete control over BWH agents, they can betray the belonging mining pool and seek further benefits by trading with victims. We prove that this betrayal is not only valid in all attack parameters but also provides double benefits; finally, it is the best strategy for BWH agents. Furthermore, our study implies that BWH attacks may encounter self-destruction of their own revenue, contrary to their intention.