At the heart of most modern cryptocurrencies is a decentralized block validation system that works on Proof-of-Work (PoW) technology. Under this mechanism, miners are authorized to sign blocks if they successfully solve a computationally intensive problem. The PoW protocol is believed to provide a high degree of security, as the behavior of miners is motivated by a general rule: follow the actions of the majority.
However, in recent years, evidence has begun to emerge that some miners are deliberately violating the protocol by employing so-called selfish mining strategies. This is a form of covert manipulation in which miners deliberately do not immediately publish the blocks they find, but wait for a convenient moment to gain an advantage and increase their income.
The essence of a selfish mining attack
Selfish mining is a type of attack in which miners deliberately hide some information about the extracted blocks, which allows them to:
- create a temporary “private” chain of blocks,
- undermine trust in the distributed network,
- increase their share of the reward at the expense of others.
This strategy undermines a fundamental principle of fairness in decentralized networks: equal access to information and mining chances.
Research Methodology
The authors of the paper (Sheng-Nan Li, Carlo Campajola, Claudio Tessone) developed a statistical test capable of detecting anomalous behavior of miners based on the analysis of block detection sequence. They tested activity in the following cryptocurrencies:
- Bitcoin;
- Litecoin;
- Monacoin;
- Ethereum;
- Bitcoin Cash.
Key hypothesis: if a miner is engaged in selfish mining, the periods between his blocks will be irregular – those that cannot be explained by a normal random distribution.
To improve the accuracy of the analysis, we also used address clustering, which allows us to group activity by real miners, even if they used different wallets or pools.
Results
- Monacoin and Bitcoin Cash show the most pronounced anomalous behavior.
- Ethereum also shows signs of selfish strategies, although less pronounced.
- In some cases, coordinated attacks have been detected where multiple miners join together and share found blocks in advance, indicating the existence of mining cartels – closed associations that violate network ethics.
What does this mean for the mining community?
- Decentralization is not a guarantee of integrity. Even in large cryptocurrencies with open source and transparent pools, hidden, coordinated behavior is possible.
- Selfish mining affects the profitability of honest participants. This leads to farms losing money without even knowing that they have fallen victim to other people’s strategies.
- Need for new monitoring tools. Block tracking, activity anomalies and clustering of miners’ behavior should become part of the standard practice of farm and pool operators.
Additions from NtdBleae
We recommend that farms:
- Use dashboards and open-source tools to analyze blocks and pool share.
- Monitor the public reputations of pools and avoid low-transparency ones.
- Implement internal systems for logging and verifying inbound/outbound traffic to pools.
For pools and developers:
- Support the implementation of countermeasures against selfish mining in protocols.
- Promote the idea of information parity: all blocks are published immediately and synchronously.
- Develop auditing and reporting tools within the pools themselves.
Conclusion
The article “Twisted by the Pools” for the first time provides empirical evidence that selfish mining is indeed realized in real networks. This is a wake-up call for users and blockchain developers alike: an attacker may not just exist – they may thrive.
For the PoW ecosystem to remain fair and sustainable, it is not only necessary to update firmware and hardware, but also to watch out for network strategies that can erode the principles of fair competition.
