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Gas Optimization Challenge

🏃 Front-Running: MEV Attacks Explained

Learn how bots exploit transaction ordering for profit

What is Front-Running?

Front-running is a **Maximal Extractable Value (MEV)** attack where bots monitor the public mempool for profitable transactions, then submit their own transactions with higher gas prices to get executed first. This allows attackers to profit from price movements before the victim's transaction completes.

The attack is possible because **all pending transactions are visible** in the mempool before being included in a block. Sophisticated bots scan for large trades, calculate expected profit, and race to front-run with gas price bidding wars.

💰 Sandwich Attack Example

The most common form of front-running is the "sandwich attack":

1.Victim submits large buy order: 100 ETH → USDC (expects ~$300,000)
2.Bot detects transaction in mempool, buys USDC first with higher gas (front-run)
3.Victim's transaction executes at worse price due to slippage ($295,000 received)
4.Bot immediately sells USDC for profit (back-run), extracting ~$5,000 MEV

Interactive: Transaction Race Visualizer

Watch how a front-running bot intercepts and profits from a victim's transaction in real-time.

👤 Victim Transaction

Buy 100 ETH100 ETH
Gas Price50 gwei
Expected Profit$1000

🤖 MEV Bot Attack

Front-run + Back-runSandwich
Gas Price100 gwei
Extracted MEV$0
Transaction Status:📡 In Mempool

Real-World Impact

$1.4B+
Total MEV extracted (2020-2024)
~8%
Average sandwich attack slippage
30,000+
Daily front-running attempts

Why Front-Running Works

🔍 Transparent Mempool

All pending transactions are publicly visible, allowing bots to analyze and react before block inclusion.

⛽ Gas Price Auctions

Higher gas prices get priority ordering, enabling attackers to pay to jump ahead in the execution queue.

💹 Price Impact

Large trades move market prices, creating predictable profit opportunities for those who execute first.

⚡ Low Latency Advantage

Bots with direct RPC connections and optimized infrastructure can detect and execute faster than retail users.