Explore the critical aspects of blockchain security in this conference talk from BSidesSF 2019. Delve into Coinbase's strategies for safeguarding funds against protocol subversion and asset exploitation. Learn about the increasing challenges faced by cryptocurrency platforms as blockchain assets and projects proliferate. Understand the detection methods employed for threats to Proof of Work blockchains and Ethereum smart contracts. Gain insights into specific attack vectors such as 51% attacks, administrative privilege takeovers, and contract probing. Discover the importance of liquidity in blockchain security and examine real-world examples, including the Ethereum Classic 51% attack. Investigate the role of superuser privileges in blockchain protocols and their potential vulnerabilities. Enhance your knowledge of cryptocurrency security measures and protocol subversion prevention techniques in this informative presentation.