Cryptocurrencies have gained popularity due to their transparency, security, and accessibility compared to traditional financial systems, with Bitcoin, introduced in 2009, leading the market. Bitcoin's security relies on blockchain technology - a decentralized ledger consisting of a consensus and an incentive mechanism. The consensus mechanism, Proof of Work (PoW), requires miners to solve difficult cryptographic puzzles to add new blocks, while the incentive mechanism rewards them with newly minted bitcoins. However, as Bitcoin's acceptance grows, it faces increasing threats from attacks targeting these mechanisms, such as selfish mining, double-spending, and block withholding. These attacks compromise security, efficiency, and reward distribution. Recent research shows that these attacks can be combined with each other or with either malicious strategies, such as network-layer attacks, or non-malicious strategies, like honest mining. These combinations lead to more sophisticated attacks, increasing the attacker's success rates and profitability. Therefore, understanding and evaluating these attacks is essential for developing effective countermeasures and ensuring long-term security. This paper begins by examining individual attacks executed in isolation and their profitability. It then explores how combining these attacks with each other or with other malicious and non-malicious strategies can enhance their overall effectiveness and profitability. The analysis further explores how the deployment of attacks such as selfish mining and block withholding by multiple competing mining pools against each other impacts their economic returns. Lastly, a set of design guidelines is provided, outlining areas future work should focus on to prevent or mitigate the identified threats.

翻译：相较于传统金融体系，加密货币因其透明度、安全性与可访问性而日益普及，其中2009年推出的比特币引领市场发展。比特币的安全性依赖于区块链技术——一种由共识机制与激励机制构成的去中心化账本。其共识机制工作量证明（PoW）要求矿工通过解决复杂密码学难题来添加新区块，而激励机制则以新铸造的比特币作为奖励。然而，随着比特币接受度的提升，针对这些机制的攻击威胁日益加剧，例如自私挖矿、双花攻击和区块扣留攻击。这些攻击会破坏系统的安全性、效率与奖励分配。近期研究表明，此类攻击可相互结合，或与恶意策略（如网络层攻击）及非恶意策略（如诚实挖矿）协同实施。这些组合催生了更复杂的攻击模式，显著提升了攻击者的成功概率与收益。因此，深入理解并评估这些攻击对于制定有效防御策略、保障系统长期安全至关重要。本文首先剖析了孤立执行的独立攻击及其盈利性，进而探讨如何通过攻击间组合或与恶意/非恶意策略结合以提升整体效能与收益。研究进一步分析了多个竞争矿池相互实施自私挖矿、区块扣留等攻击时对其经济回报的影响。最后，本文提出一套设计准则，为未来研究指明方向，以预防或缓解已识别的安全威胁。