Binance hack drained $6.3B after EIP-7702 delegation turned a hot wallet into attacker code

What happened

On 29 October 2026, Binance hot wallets paid an attacker across several blockchains within roughly half an hour. Binance puts the loss at about $6.3 billion and Chainalysis at about $6.4 billion, which would make it, by either figure, the largest theft crypto has recorded. According to a Panda Security write-up on dev.to, about $3 billion of the stolen funds has been frozen by stablecoin issuers and partners.

Most of the transfers were ordinary signed withdrawals. The Ethereum leg was not: via EIP-7702, the attacker made the hot wallet Etherscan labels Binance 14 run attacker-controlled contract code, and less than four minutes later about 167,464 ETH and 63 tokens left it in a single transaction.

How EIP-7702 changed the equation

EIP-7702, live since Ethereum's Pectra upgrade in May 2025, adds a type-4 "set code" transaction whose authorization list carries tuples of chain ID, address and nonce, each signed by an externally owned account. Once processed, calls to that account execute the designated contract in the account's own context: its balance, storage, token holdings and any roles or admin rights it holds elsewhere.

As the write-up stresses, anyone can submit a signed authorization on-chain and pay the gas; the tuple only applies if its nonce matches at processing time; and it names no amount or recipient. Signing a 7702 authorization is closer to handing over the account than approving a payment.

The attack on-chain

Analyses by Tibane Labs and an IMD incident report trace the setup: an operator account reportedly funded through Tornado Cash deployed a sweeper contract around 16:00 UTC, after rehearsing an earlier version on wallets it controlled. Tibane Labs' decompilation shows a sweep function that forwards all ETH and listed token balances, plus an execute function for arbitrary calls, both gated to a hard-coded operator address.

At 20:20:59 UTC, the operator submitted a type-4 transaction carrying 50 authorizations, all pointing at the sweeper with consecutive nonces from 18,914,775 to 18,914,824. Analysts recovered every signer: all 50 were signed by Binance 14's key. The batch exists because the wallet transacts almost every block and its nonce never sits still; with a window of upcoming nonces, one signature was guaranteed to match, and EIP-7702 skips invalid entries without reverting the transaction. Tibane Labs also notes the wallet spent the range's first nonce minutes before the delegation landed, suggesting the signatures were produced live rather than taken from an old leak.

At 20:24:23 UTC the operator called Binance 14 directly; the delegated sweeper executed as the wallet itself and moved roughly 167,464 ETH and 63 tokens, about 1.6 billion USDT among them per CoinDesk, to the attacker in one transaction. Twenty-four seconds later, Binance 16 sent the same address 28,005.6 ETH through plain transfers with no delegation involved. The two wallets lost about 200,000 ETH combined.

The delegation also reached beyond balances. According to TRM Labs (via CoinDesk) and Tibane Labs, Binance 14 controlled a separate Binance smart-contract wallet holding USDC; through the sweeper's execute function the attacker had it release 823 million USDC in two calls, funds Circle later froze. Because Binance's systems kept routing deposits into the delegated wallet, the attacker swept again around 21:04 and 21:44 UTC. The delegation ended only at 00:10:35 UTC on 30 October, when Binance 14 sent a type-4 transaction delegating to the zero address, returning its code to empty.

Cause versus amplifier

A second dev.to analysis, citing reporting from Cryptonews, CCN and CryptoTicker, notes that most of the money left without EIP-7702 being involved: CCN counted $3.66 billion stolen outside the delegation path, against $2.8 billion attributed to it by CryptoTicker. TRM Labs has attributed the attack to North Korea. On that reading, EIP-7702 did not cause the breach, it amplified it.

What Binance says happened

Binance's initial investigation points to a compromised DevOps engineer's laptop that gave the attacker access to a service container able to submit withdrawal transactions, and found no evidence of a private key leak. Co-CEO Richard Teng later said investigators had found additional points of breach and that the EIP-7702 delegation did not pass through the exchange's normal approval controls. Nothing in the chain data shows a flaw in EIP-7702 itself: no smart contract bug, no forged signature.

Why it matters

For wallet and custody builders, the incident reprices a signing compromise: a 7702 authorization is standing control of an account and every permission that address holds, not a one-off payment, and it persists until explicitly cleared. The 50-nonce batch implies signatures generated inside a compromised pipeline, an authority-chain problem that code audits do not inspect. Operationally, the delegation stayed live for nearly four hours while deposits kept arriving in the delegated wallet, and clearing the code does not rotate the key. At $6.3 billion, the incident sets the ceiling for what an operational compromise plus a new transaction primitive can achieve, and the failure was in process, not cryptography.