A trading exploit where attackers manipulate trade order timing to profit at the expense of others.
A Sandwich Attack is a malicious trading strategy where an attacker places one transaction before and one after a user’s trade to exploit price movement and extract profit. This form of MEV (Maximal Extractable Value) is most common on decentralized exchanges.
How a Sandwich Attack Works
A user submits a large swap on a DEX
The attacker sees it in the mempool
Attacker front-runs with a buy order, pushing the price up
User’s trade executes at a worse price due to slippage
Attacker back-runs by selling the tokens at the inflated price
The attacker profits; the user suffers increased slippage
Why Sandwich Attacks Happen
Public mempools reveal pending transactions
AMM pricing formulas are predictable
Attackers use bots with higher gas fees to jump ahead
How to Prevent Sandwich Attacks
Use private transaction relays
Set strict slippage limits
Trade on MEV-protected DEXs
Use limit orders instead of swaps during volatility
Summary
A sandwich attack is an MEV exploit where an attacker places trades around a user’s order to manipulate prices and profit at the user’s expense.
