In this work, we reexamine the vulnerability of Payment Channel Networks (PCNs) to bribing attacks, where an adversary incentivizes blockchain miners to deliberately ignore a specific transaction to undermine the punishment mechanism of PCNs. While previous studies have posited a prohibitive cost for such attacks, we show that this cost may be dramatically reduced (to approximately \$125), thereby increasing the likelihood of these attacks. To this end, we introduce Bribe & Fork, a modified bribing attack that leverages the threat of a so-called feather fork which we analyze with a novel formal model for the mining game with forking. We empirically analyze historical data of some real-world blockchain implementations to evaluate the scale of this cost reduction. Our findings shed more light on the potential vulnerability of PCNs and highlight the need for robust solutions.

翻译：在本文中，我们重新审视了支付通道网络（PCN）面临贿赂攻击的脆弱性——攻击者通过激励区块链矿工故意忽略特定交易，从而破坏PCN的惩罚机制。尽管先前的研究认为此类攻击成本极高，但我们证明这一成本可能大幅降低（至约125美元），进而显著增加攻击发生的可能性。为此，我们提出“贿赂与分叉”这一改进型贿赂攻击方法，该方法利用所谓的“轻量级分叉”威胁，并通过一个针对含分叉挖矿博弈的新型形式化模型进行分析。我们基于真实区块链实现的历史数据开展实证研究，以评估此成本降低的规模。研究结果进一步揭示了PCN的潜在脆弱性，并凸显了开发稳健解决方案的紧迫性。