A transaction worth 50 million US dollars was exchanged for 30000 US dollars core background • Transaction content: The victim attempted to exchange approximately $50.5 million worth of aEthUSDT for AAVE. Path problem: Although Aave interface and CoW Swap were used, the final transaction was directed towards a SushiSwap pool with extremely poor liquidity. Extreme slippage: Due to orders far exceeding the depth of the pool, the price impact of the initial quote has already reached 99%. • Human error: The victim ignored the sliding point warning while using the mobile device and forcibly approved the transaction. Public Mempool: This transaction is directly exposed to the view of all MEV robots before being packaged. Sandwich Attack Episode Four 1. Robot detection opportunity: MEV searchers scan this huge AAVE bill that is about to be executed in a low liquidity pool. 2. Front-run： The robot borrowed approximately $29 million in ETH (without collateral) from the Morpho protocol Lightning Loan. Before the victim makes a transaction, buy AAVE in the pool to raise the price (the market price at that time was about $111- $120). 3. Victim transaction: The victim's payment is then executed and forced to accept extreme prices pushed up by robots. According to reports, the instantaneous price of AAVE in the pool skyrocketed to $154000. The victim ultimately only received 324 AAVEs (worth only about $36000), and almost all of the tens of thousands of AAVEs they should have received evaporated. 4. Back run transactions: The robot then poured all the newly purchased AAVE back into the pool, using the "high price liquidity" created by the victims to sell and profit. Pay off the lightning loan and swallow the huge profit difference. Results settlement (approximate estimate) Net profit of robots: approximately 9.9 million to 12 million US dollars. Victim losses: Approximately $50 million (this was not 'stolen', but died from poor transaction efficiency). • Transaction fees and profit sharing: CoW Swap received approximately $600000 in fees (Aave has since refunded compensation), with the remaining amount distributed as bribes (Tips) to the block builders and proposers. Why did it happen? Lack of privacy protection: Private RPC such as Flashbots Protect is not used, and transactions are completely transparent. • Liquidity mismatch: Huge funds collide with extremely shallow pools. • High slippage tolerance: The victim's setting allows for this' legal robbery '. Lightning Loan Amplifier: Robots can access millions of dollars in assets for harvesting without the need for capital. This is a textbook level Ethereum L1 toxic MEV case. Although CoW Swap claims to be resistant to MEV, it still cannot escape a disaster due to routing and liquidity selection errors. This once again reminds large transactions to confirm privacy submission and sliding point protection. @Aave team response: https://(x.com)/stanikulechov/status/2032193345414664659 @Response from CoWSwap team: https://(x.com)/coWSwap/status/2032265762916757614 What is' reordering within blocks'? -In each block of Ethereum (generated in approximately 12 seconds), the execution order of all transactions is not determined by the submission time, but is freely determined by the block builder or proposer. -This is the core of MEV: builders can reorder transactions in the mempool as long as the overall block is valid -For example, the original user's tx is seen first in the memory pool, but the bot can insert its front run tx at the front, the victim tx in the middle, and the back run tx at the back. -This is the reordering of 'within the same block': all three tx (before bot+user+after bot) are squeezed into the same block, and the order is controlled by the bot. -Why do we have to do this? Because only within the same block, price distortion (pump by front run+victim buy) will temporarily exist, allowing bots to safely sell and make money in the back run. If it crosses blocks, the price is likely to have been corrected by other arb bots, and the bot will lose money or be unable to repay the lightning loan.