How the Binance hack happened on-chain on Ethereum

The Binance hack is one of the largest heists of all time and relied, in part, on exploiting how wallet delegation functions on Ethereum. Specifically, the attacker appears to have deployed a sweeper contract and then sent 50 EIP-7702 authorizations targeting the address labeled as Binance 14, all signed with the Binance 14 key. It had to send a wide variety of approvals with different ‘nonce’ values because this was a hot wallet in rapid use, and for the delegation to be approved, the ‘nonce’ value (think of it as related to a count of the number of transactions the…