COTI Fixes This! #1: The $215,000 Sandwich
About the “COTI Fixes This” Series
It’s a jungle out there. The Web3 world is unforgiving of mistakes. Put a foot wrong and there is very often someone there to exploit it, as many crypto users have found out. Being forewarned is part of the solution, and the other part is in privacy. Keeping data and transactions under wraps is one of the best defence mechanisms we have against bad actors in an industry where blockchain transparency is a core enabler of financial loss.
The “COTI Fixes This” series is a whistle-stop tour of some of the most famous instances where blockchain transparency has had unintended consequences. We’ll look at what went wrong, and how things could have ended quite differently if users had practiced privacy.
The $215,000 Sandwich
In March 2025, a Uniswap trader attempted to exchange 220,000 USDT for USDC. The tokens should exchange 1:1, so they expected to receive around 220,000 USDC, but instead, they were left with just $5,000 after a bot carried out a ‘sandwich attack’!
The MEV bot saw the user’s trade in mempool and front-ran it. They placed a large trade, paying enough gas to ensure it would be confirmed ahead of their victim’s trade. This ate up available liquidity in a specific price range, so the next trade executed with terrible slippage. The attacker followed this up with a second trade, returning the pool to almost its original state, but benefiting from the victim’s liquidity.
The whole process took just 8 seconds and netted $215,000 for the attacker. It’s worth stating that Uniswap’s interface has controls to avoid such slippage, but in this instance the trader was using a different interface for one reason or another.
This is an extreme example, but sandwich attacks are carried out every day, especially when bots see large trades in the mempool. They are programmed to push up prices for regular traders by buying and selling immediately before and after the victim’s swap — meaning the attacker benefits with very little risk, and regular traders have to deal with worse slippage. Often referred to as an “invisible tax”, MEV bots managed to extract over $700 million from Ethereum users alone in 2024, according to reports.
COTI Fixes This
If the Uniswap trade had been made using COTI privacy, the transaction details could have been concealed and the trade would have settled without any way for MEV bots to launch an attack.
How? COTI is a first-of-its-kind implementation of garbled circuits on public blockchains. COTI can be used to obscure transaction details, ensuring that they never hit the public mempool in cleartext. This gives no opportunity to attackers to know the price or volume of a trade, for example, in order to exploit it.
COTI’s solution offers programmable privacy at the protocol level, not through wrappers or mixers, but through secure multi-party computation (MPC) embedded directly into blockchain execution. It delivers fast and lightweight privacy to all major chains with the fastest speed of settlement for any decentralized confidential computing (DeCC) solution to date.
COTI means MEV-proof DeFi transactions, for private DEX trading, AI Trading Agents, RWAs, stablecoins and more.
Welcome to the new era.
Stay COTI
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