WuBlockchain
Blockaid says an attacker took control of Binance’s Binance 14 hot wallet by exploiting Ethereum’s EIP-7702 authorization mechanism. The attacker submitted 50 authorizations with different nonces in one Type-4 transaction because they could not determine the wallet’s live nonce. Only one authorization matched and succeeded.
Why it matters
The successful authorization delegated the wallet’s account code to an unverified malicious asset-transfer contract. This shows how an authorization mechanism can become a route to wallet compromise when a malicious delegation takes effect.
Market impact
The contract restricts its sweep() function to an address designated by the attacker. It can transfer ETH and ERC-20 tokens from the wallet while retaining 1 ETH for gas fees. Blockaid’s analysis also warns that incoming assets may be transferred, extending the risk beyond assets already held.
Frequently asked questions
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How did the attacker get an EIP-7702 authorization accepted?
The attacker submitted 50 authorizations with different nonces in one Type-4 transaction. One matched Binance 14’s live nonce and succeeded.
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What happened after the authorization succeeded?
The authorization delegated the hot wallet’s account code to an unverified malicious asset-transfer contract.
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What can the malicious contract transfer?
Its sweep() function can transfer ETH and ERC-20 tokens from the wallet while retaining 1 ETH for gas fees.
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Who can call the contract’s sweep() function?
The function is restricted to an address designated by the attacker.
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Could assets sent to the wallet later also be affected?
Yes. Blockaid’s analysis says subsequent incoming assets may also be at risk of being transferred.
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