The attack against Binance partly exploited wallet delegation functions on Ethereum. According to Protos, the attacker deployed a sweeper contract and sent 50 EIP-7702 authorizations to the address labeled Binance 14, all signed with the Binance 14 key. The authorizations used different nonce values, which had to match the wallet’s current nonce, before the contract could sweep the ether and tokens from Binance 14. Other wallets and Ethereum Virtual Machine chains, including Base, Optimism, Arbitrum, Avalanche, and Polygon, relied on standard transfers rather than the delegation. Binance eventually removed the delegation from Binance 14, while approximately $2.4 billion in funds withdrawn from Binance wallets on Ethereum were frozen or blacklisted.
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