What happened
In June 2022 an attacker took 20 million OP tokens, reported at about $27.6M, that the Optimism Foundation had loaned to market maker Wintermute. On 27 May, Optimism sent the tokens on Optimism to an address Wintermute supplied, but that address was Wintermute's Gnosis Safe on Ethereum. No contract had been deployed at that address on Optimism, so Wintermute could not move the funds.
On 5 June, before Wintermute's planned recovery, an attacker deployed a Safe at the same address with themselves as owner. They sold 1M OP and sent 1M OP to Vitalik Buterin's address. Wintermute said it would buy back OP to make Optimism whole.
On 10 June the attacker returned 17M OP to Optimism, and Optimism said 2M OP were kept as a bounty.
How it happened
- On 27 May 2022 the Optimism Foundation sent 20M OP on Optimism to
0x4f3a120e72c76c22ae802d129f599bfdbc31cb81. Wintermute had created that Gnosis Safe on Ethereum in 2020 but had never deployed it on Optimism. Wintermute confirmed the test transfers without checking that it could move the funds. - Wintermute's Safe came from an old ProxyFactory that used
create, notcreate2. A proxy's address therefore depended only on the factory's address and nonce, not on who the owners were. - With the same factory address available on Optimism, the attacker (
0x60b28637879b5a09d21b68040020ffbf7dba5107) deployed new Safes through their own helper contract in batches, each time setting themselves as owner, until the factory nonce produced Wintermute's address. - On 5 June the attacker controlled the Safe that now held the 20M OP. They sold 1M OP for about 720 ETH and sent another 1M OP to Vitalik Buterin's address.
Protocol details
Funds Recovery
Recovered
$23.5M
Net Loss
$4,140,000
Evidence
- report Report wintermute.com
- report Wintermute - REKT rekt.news
- transaction optimistic.etherscan.io transaction 0xe949…e303 optimistic.etherscan.io
- address optimistic.etherscan.io address 0x4f3a…txns optimistic.etherscan.io
- address optimistic.etherscan.io address 0x60b2…5107 optimistic.etherscan.io
- analysis Website reference banteg.mirror.xyz
- analysis DeFiLlama defillama.com
- analysis Analysis & Solution to the Attack on Optimism by Fairyproof fairyproof.substack.com
- analysis Wintermute Makes "Optimistic" Assumption, Loses 20M Tokens cryptobriefing.com
- analysis Optimism Attacker Returns 17M Stolen OP Tokens coindesk.com
- analysis Message to Optimism community from Wintermute gov.optimism.io
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