Under the Dark: A Systematical Study of Stealthy Mining Pools (Ab)use in the Wild

Cryptocurrency mining is a crucial operation in blockchains, and miners often join mining pools to increase their chances of earning rewards. However, the energy-intensive nature of PoW cryptocurrency mining has led to its ban in New York State of the United States, China, and India. As a result, mining pools, serving as a central hub for mining activities, have become prime targets for regulatory enforcement. Furthermore, cryptojacking malware refers to self-owned stealthy mining pools to evade detection techniques and conceal profit wallet addresses. However, no systematic research has been conducted to analyze it, largely due to a lack of full understanding of the protocol implementation, usage, and port distribution of the stealth mining pool. To the best of our knowledge, we carry out the first large-scale and longitudinal measurement research of stealthy mining pools to fill this gap. We report 7,629 stealthy mining pools among 59 countries. Further, we study the inner mechanisms of stealthy mining pools. By examining the 19,601 stealthy mining pool domains and IPs, our analysis reveals that stealthy mining pools carefully craft their domain semantics, protocol support, and lifespan to provide underground, user-friendly, and robust mining services. What's worse, we uncover a strong correlation between stealthy mining pools and malware, with 23.3% of them being labeled as malicious. Besides, we evaluate the tricks used to evade state-of-the-art mining detection, including migrating domain name resolution methods, leveraging the botnet, and enabling TLS encryption. Finally, we conduct a qualitative study to evaluate the profit gains of malicious cryptomining activities through the stealthy pool from an insider perspective. Our results show that criminals have the potential to earn more than 1 million USD per year, boasting an average ROI of 2,750%. We have informed the relevant ISPs about uncovered stealthy mining pools and have received their acknowledgments.