Nakamoto consensus are the most widely adopted decentralized consensus mechanism in cryptocurrency systems. Since it was proposed in 2008, many studies have focused on analyzing its security. Most of them focus on maximizing the profit of the adversary. Examples include the selfish mining attack [FC '14] and the recent riskless uncle maker (RUM) attack [CCS '23]. In this work, we introduce the Staircase-Unrestricted Uncle Maker (SUUM), the first block withholding attack targeting the timestamp-based Nakamoto-style blockchain. Through block withholding, timestamp manipulation, and difficulty risk control, SUUM adversaries are capable of launching persistent attacks with zero cost and minimal difficulty risk characteristics, indefinitely exploiting rewards from honest participants. This creates a self-reinforcing cycle that threatens the security of blockchains. We conduct a comprehensive and systematic evaluation of SUUM, including the attack conditions, its impact on blockchains, and the difficulty risks. Finally, we further discuss four feasible mitigation measures against SUUM.

翻译：中本聪共识是加密货币系统中应用最广泛的去中心化共识机制。自2008年提出以来，大量研究聚焦于其安全性分析，其中多数关注攻击者收益最大化，例如自私挖矿攻击[FC '14]与近期无风险叔块制造者攻击[CCS '23]。本研究提出阶梯式无限制叔块制造者攻击，这是首个针对基于时间戳的中本聪式区块链的区块截留攻击。通过区块截留、时间戳操纵与难度风险控制，SUUM攻击者能够以零成本与最小难度风险特征发起持续性攻击，无限期攫取诚实参与者的收益，形成威胁区块链安全的自增强循环。我们对SUUM进行了全面系统评估，涵盖攻击条件、对区块链的影响及难度风险分析。最后进一步探讨了四种可行的SUUM缓解措施。