Crypto trader gets sandwich attacked in stablecoin swap, loses $215K

A crypto trader fell victim to a sandwich attack while making a $220,764 stablecoin transfer on March 12 — losing almost 98% of its value to a Maximum Extractable Value (MEV) bot.

$220,764 worth of the USD Coin (USDC) stablecoin was swapped to $5,271 of Tether (USDT) in eight seconds as the MEV bot successfully front-ran the transaction, banking over $215,500.

Data from Ethereum block explorer shows the MEV attack occurred on decentralized exchange Uniswap v3’s USDC-USDT liquidity pool, where $19.8 million worth of value is locked.

Crypto trader gets sandwich attacked in stablecoin swap, loses $215K

Details of the sandwich attack transaction. Source: Etherscan

The MEV bot front-ran the transaction by swapping all the USDC liquidity out of the Uniswap v3 USDC-USDT pool and then put it back in after the transaction was executed, according to founder of The DeFi Report Michael Nadeau.

The attacker tipped Ethereum block builder “bob-the-builder.eth” $200,000 from the $220,764 swap and profited $8,000 themselves, Nadeau said.

DeFi researcher “DeFiac” speculates the same trader using different wallets has fallen victim to a total of six sandwich attacks, citing “internal tools.” They pointed out that all funds traveled from borrowing and lending protocol Aave before being deposited on Uniswap.

Two of the wallets fell victim to an MEV bot sandwich attack on March 12 at around 9:00 am UTC. Ethereum wallet addresses “0xDDe…42a6D” and “0x999…1D215” were sandwich attacked for $138,838 and $128,003 in transactions that occurred three to four minutes earlier.

Both transactors made the same swap in the Uniswap v3 liquidity pool as the trader who made the $220,762 transfer.

Others speculate the trades could be attempts at money laundering.

“If you have NK illicit funds you could construct a very mev-able tx, then privately send it to a mev bot and have them arb it in a bundle,” said founder of crypto data dashboard DefiLlama, 0xngmi.

“That way you wash all the money with close to 0 losses.”

While initially criticizing Uniswap, Nadeau later acknowledged that the transactions didn’t come from Uniswap's front end, which has MEV protection and default slippage settings.

Nadeau backtracked on those criticisms after Uniswap CEO Hayden Adams and others clarified the protections Uniswap has in place to fight against sandwich attacks.