Explore a sophisticated technique for circumventing staking safeguards in utility-based NFTs and learn about exploiting off-chain marketplace logic in this 28-minute Black Hat conference talk. Delve into the world of Ethereum blockchain and discover how cross-contract ricochet attacks can be used to manipulate NFTs across smart contracts. Examine the vulnerabilities in implementing ERC-721 and ERC-1155 standards through off-chain marketplace logic. Presented by Nitesh Dhanjani, this talk challenges the narrative of Ethereum as a secure decentralized world-computer and highlights potential risks in billion-dollar NFT collections.