When you swap tokens on a decentralized exchange like Uniswap or PancakeSwap, you might think you’re dealing directly with the blockchain. But behind the scenes, a hidden player—often a bot—is watching your trade, slipping in before and after it, and stealing your money. This is called a sandwich attack, a type of MEV (Maximal Extractable Value) exploit where bots frontrun and backrun a user’s transaction to profit at their expense. Also known as frontrunning, it’s not a glitch—it’s a business model built into how DeFi works.
Here’s how it plays out: You click ‘swap’ to buy 1000 units of a low-liquidity token. Before your transaction even confirms, a bot detects it, buys the same token ahead of you, and drives the price up. Then, your trade executes at the inflated price. Right after you buy, the bot sells its holdings at the new, higher price. You’re stuck with overpaying. The bot walks away with profit. You’re left with less than you expected. This is the classic sandwich attack, a three-part exploit where the victim’s trade is sandwiched between two malicious trades. It doesn’t need hacking or code exploits—it just uses public mempool data and faster network access. And yes, it’s legal on most chains.
These attacks thrive where liquidity is thin—exactly where meme coins, new tokens, and low-volume assets trade. That’s why you’ll see reports of sandwich attacks on tokens like MINI, COLLAR, or ASPIRIN in our posts. They’re not just risky because they’re scams—they’re risky because bots are actively hunting them. Even if a token has a real use case, if it’s on a DEX with low liquidity, your trade could get eaten alive. The same bots that target small traders also target large ones. The difference? Big players use tools to detect and avoid them. Regular users? They’re just hoping their transaction goes through.
So how do you fight back? Avoid low-liquidity tokens. Use DEXs with built-in MEV protection. Set tighter slippage limits—5% is already too high for most small trades. And never assume your transaction is private. On-chain activity is public. Every swap you make is visible before it confirms. That’s not a bug. It’s the system.
Below, you’ll find real examples of how these attacks play out in the wild—from dead tokens that got crushed by bots to exchanges that tried to block them. You’ll also see how other blockchain exploits like double-spending and cascade liquidations tie into the same ecosystem of risk. This isn’t theory. It’s happening right now. And if you’re trading on DeFi without understanding this, you’re not investing—you’re feeding the machines.
AMM vulnerabilities like flash loan attacks, sandwich trades, and impermanent loss manipulation are draining millions from DeFi users. Learn how these exploits work and how to protect yourself.
