Sandwich-attack victim swapped $732,583 for $18,636

A cryptocurrency trader swapped about $732,583 in USDC for about $18,636 in USDT across six separate swaps, falling victim to a large sandwich attack.

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

The trader used the USDC–USDT liquidity pool on Uniswap v3.

According to The DeFi Report founder Michael Nadeau, an MEV bot front-ran the trader’s transaction, creating a price disparity between the two assets. The bot also instructed block builder bobTheBuilder to process its transaction first.

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

“This is insane. Keep in mind that this was a pool that had over $35m in USDC and USDT,” he lamented.

To extract additional profit, the attacker uses specialised bot software to scan the mempool for large pending swap trades on decentralised platforms.

He then initiates two transactions — before and after the victim’s planned swap — forming a “sandwich”. The first inflates the price of the coins the victim is buying. The second realises profit by selling the assets.

The specialist offered several recommendations to avoid a similar fate:

1. Reduce slippage on your transactions.
2. Do not use Uniswap. Switch to Cowswap or another aggregator that can provide better execution and prevent MEV.
3. Use a custom RPC that does not broadcast your transactions publicly.

DeFi Llama developer 0xngmi suggested that “really bad swaps” disguised money laundering.

i think some of these really bad swaps could be 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

that way you wash all the money with close to 0 losses

— 0xngmi (@0xngmi) March 12, 2025

“You can create an MEV-compatible transaction, then privately send it to a bot to include it in a bundle and achieve your aim with almost zero losses,” he explained.

A user going by TheDEFIac agreed with 0xngmi’s hypothesis, noting the movement of assets before each of the sandwich transactions.

They follow a long, unusual path — funds arrived from accounts on Binance and Bybit and, after 15–20 days, from “clean” addresses were deposited via transfers to Aave and Compound into the USDC–USDT pool to other wallets.

“This could be either someone ‘burning’ a lot of money or some odd attempt at laundering it,” he concluded.

In November 2024, a record 35.5% of blocks on the EVM-compatible BNB Chain suffered “sandwich attacks”.

Earlier, a well-known MEV bot on Solana earned about $30m from arbitraging user trades in just two months.

Not all such manoeuvres are effective. In September, the software took a $11.7m flash loan for a “sandwich attack” on a $5,000 Shuffle (SHFL) trade. The bot executed 14 transactions across various DeFi platforms and made $20 in profit.