A user who was swapping stablecoins (Swap) on Uniswap v3 was hit by an "MEV bot sandwich attack" and lost over $220,000 in just 8 seconds. At the same time, other traders were also hit by at least 6 similar attacks that day, and some DeFi researchers speculate that this may involve illegal money laundering activities.
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ToggleUser Swap stablecoins and was hit by a sandwich attack, losing over $220,000
A cryptocurrency trader on March 12 conducted a $220,000 stablecoin swap and was hit by a "sandwich attack", ultimately receiving only $5,271 worth of USDT, losing over 98% of his assets, and being successfully sandwiched and arbitraged by an MEV (Maximum Extractable Value) bot.
Blockchain data shows that this MEV attack occurred within the USDC-USDT liquidity pool of DEX Uniswap v3, which currently has a locked asset value of about $19.8 million.
("jaredfromsubway" is back with new MEV Bot attack strategies to hit multiple victims at once)
DeFi analyst Michael Nadeau stated that the MEV bot used a "front-running" operation to quickly withdraw all USDC liquidity from the Uniswap pool, and then returned the liquidity after the victim's transaction was executed, successfully pocketing about $215,000:
Is anyone safe using DeFi?
A user on @Uniswap v3 was just sandwiched attacked out of $216k while simply trying to swap $221k USDC to USDT.
Mind you, this was a pool that had over $35m of USDC and USDT it.
This is insane.
How did it happen?
An MEV bot front-ran the tx by… pic.twitter.com/cyzu4M6qfz
— Michael Nadeau | The DeFi Report (@JustDeauIt) March 12, 2025
The attacker subsequently paid $200,000 as a kickback to the Ethereum block builder "bob-the-builder.eth", and made $8,000 in profit from the transaction.
Related wallets were suspected to have been hit by six MEV attacks in one day
At the same time, DeFi researcher DeFiac suspected that a user, through different wallets, was suspiciously hit by six "sandwich attacks" the previous day, with all funds coming from the lending protocol Aave and ultimately flowing into Uniswap for Swap.
Unknown entity got sandwiched for 714k today on six separate USDC -> USDT swaps. (Traded with 100% slippage allowed.)
They swapped 732583.429405 USDC for 18636.232611 USDT.
A promised 🧵: pic.twitter.com/0rFNE4DfoP
— DeFiac (@TheDEFIac) March 12, 2025
He pointed out that the two Ethereum addresses "0xDDe...42a6D" and "0x999...1D215" were hit by MEV attacks around 9 AM UTC due to the same trading pattern:
The two wallets lost $138,000 and $128,000 respectively, and these transactions all occurred within three to four minutes.
defillama founder 0xngmi pointed out that these transactions may involve money laundering activities:
Some illegal fund holders may intentionally design transactions that are easy to be attacked by MEV bots, and then secretly send them to MEV bots for arbitrage-based money laundering, with almost zero loss.
(Solana Foundation Cracks Down on MEV: Malicious Sandwich Attacks Kicked Out of Delegation Program)
Uniswap was questioned for not having a good MEV protection mechanism
Faced with multiple MEV attack incidents resulting in losses, Nadeau initially criticized Uniswap, believing the trading platform lacked adequate and comprehensive MEV protection measures.
However, Uniswap CEO Hayden Adams clarified that Uniswap's frontend interface has MEV protection mechanisms and default slippage settings, which can effectively reduce the risk of such attacks:
Every good user interface (UI) and trading bot, since the launch of Uniswap V1, has been able to set slippage tolerance, which may have been a specific one-time operation oversight. DeFi itself is not the problem.
Ultimately, Nadeau also retracted his criticism of Uniswap and acknowledged that the attack incident was unrelated to the platform's frontend design. However, some still believe that since DeFi aims to reach the general public, MEV attack behavior should no longer occur.
(Aave Teams Up with Chainlink's New SVR Technology to Reclaim up to 40% of MEV Profits)
Risk Warning
Cryptocurrency investment is highly risky, and its price may fluctuate dramatically, and you may lose your entire principal. Please carefully evaluate the risks.
