Why Most Crypto Bots Get Sandwiched (And How to Prevent It)

If you've ever built or run a trading bot in the crypto space, you’ve likely encountered the dreaded "sandwich attack." It’s one of the most frustrating and costly experiences for bot operators. I’ve been there myself—watching helplessly as my bot’s trades were exploited by MEV (Miner Extractable Value) strategies like sandwich attacks. In this article, I’ll explain what sandwich attacks are, why they happen, and how you can protect your bot using advanced tools like Jito bundles.

What Is a Sandwich Attack?

A sandwich attack is a type of MEV strategy where an attacker exploits pending transactions in the mempool to profit from price slippage. Here’s how it works:

1. Front-Running: The attacker spots your bot’s transaction in the mempool (e.g., a buy order for a specific token).
2. Sandwiching: The attacker places a buy order before your transaction and a sell order immediately after it.
3. Profit Extraction: The attacker benefits from the price movement caused by your transaction.

For example, if your bot tries to buy 10 ETH worth of Token X, the attacker buys Token X first, drives the price up, sells it back after your transaction, and pockets the difference. This leaves your bot with a worse execution price.

Real-World Example

Let’s say your bot submits a transaction to buy 10 ETH worth of Token X at a price of $100 per token. The attacker front-runs your transaction, buying Token X at $100, and pushes the price up to $105. Your bot then buys Token X at $105, and the attacker immediately sells Token X back at $105, earning a profit of $5 per token.

Why Do Sandwich Attacks Happen?

Sandwich attacks are possible due to the transparent nature of blockchain mempools. Transactions are publicly visible before they are confirmed, giving attackers the opportunity to exploit them. Additionally, the lack of transaction privacy and the ability to pay higher gas fees for priority execution make these attacks easier to execute.

BY THE NUMBERS

• MEV Profit: In 2022, MEV bots extracted over $1 billion in profit from Ethereum users.
• Sandwich Attacks: Sandwich attacks accounted for approximately 30% of MEV-related losses.
• Gas Fees: Attackers often pay up to 50% more in gas fees to ensure their transactions are prioritized.

How to Prevent Sandwich Attacks

Preventing sandwich attacks requires a combination of strategies, including transaction privacy, smarter execution methods, and leveraging advanced tools like Jito bundles.

1. Use Jito Bundles for Priority Execution

Jito bundles are a powerful tool for protecting against sandwich attacks, particularly on Solana. Bundles allow you to group multiple transactions together and submit them to validators as a single unit. This reduces the risk of front-running because the transactions are executed atomically.

Here’s an example of how to create a Jito bundle using Solana’s web3.js library:

const { Connection, Keypair, Transaction } = require(’@solana/web3.js’);
const { Bundle } = require(’@jito/solana’);

const connection = new Connection(’https://api.mainnet-beta.solana.com’);
const wallet = Keypair.generate();

const transaction1 = new Transaction().add(...);
const transaction2 = new Transaction().add(...);

const bundle = new Bundle([transaction1, transaction2]);
await connection.sendBundle(bundle, [wallet]);

By using bundles, you ensure that your transactions are executed together, minimizing the window for an attacker to sandwich them.

2. Optimize Gas Fees

One common reason bots get sandwiched is submitting transactions with low gas fees, making them easy targets for attackers. To avoid this, I always set my gas fees at least 20–30% higher than the current average. This ensures my transactions are prioritized and reduces the likelihood of being front-run.

For example, if the average gas fee is 50 Gwei, I set my fee to 65 Gwei:

const tx = {
  to: ‘0x...’,
  value: ‘0x...’,
  gasPrice: web3.utils.toHex(65000000000), // 65 Gwei
};

3. Use Flashbots for Ethereum Transactions

Flashbots is a solution designed to protect Ethereum users from MEV attacks. It allows you to submit transactions directly to miners without exposing them to the public mempool. This prevents attackers from seeing your transactions and front-running them.

Here’s how to submit a transaction using Flashbots:

const { FlashbotsBundleProvider } = require(’@flashbots/ethers-provider-bundle’);
const { ethers } = require(’ethers’);

const provider = new ethers.providers.JsonRpcProvider(’https://mainnet.infura.io/v3/YOUR_PROJECT_ID’);
const wallet = new ethers.Wallet(’YOUR_PRIVATE_KEY’, provider);

const flashbotsProvider = await FlashbotsBundleProvider.create(provider, wallet);

const signedTransactions = await wallet.signTransaction({
  to: ‘0x...’,
  value: ethers.utils.parseEther(’0.1’),
  gasPrice: ethers.utils.parseUnits(’65’, ‘gwei’),
});

await flashbotsProvider.sendBundle([{ signedTransaction: signedTransactions }]);

4. Minimize Transaction Visibility

Another strategy is to reduce the visibility of your transactions. This can be achieved by using encrypted mempools or private transaction services like Taichi Network or Eden Network.

For example, Taichi Network allows you to submit transactions through private relayers, making them invisible to the public mempool:

const taichi = require(’taichi-network’);
const wallet = taichi.createWallet(’YOUR_PRIVATE_KEY’);

const tx = await wallet.sendTransaction({
  to: ‘0x...’,
  value: taichi.utils.parseEther(’0.1’),
});

5. Monitor Mempool Activity

Finally, I always monitor mempool activity to detect potential sandwich attacks. Tools like MEV-Inspect and EigenPhi provide real-time insights into MEV activity and can help you identify suspicious patterns.

Lessons Learned

From my experience, the key to preventing sandwich attacks is a combination of proactive measures and advanced tools. Here are the most important lessons I’ve learned:

1. Prioritize Transaction Privacy: Use solutions like Flashbots or private relayers to hide your transactions from attackers.
2. Optimize Execution: Leverage tools like Jito bundles to ensure atomic execution of your trades.
3. Stay Updated: Continuously monitor MEV trends and adapt your strategies accordingly.

Conclusion

Sandwich attacks are a persistent challenge in crypto trading, but they’re not unavoidable. By understanding how they work and implementing advanced tools like Jito bundles, Flashbots, and private relayers, you can protect your bot from exploitation. Always prioritize transaction privacy, optimize your gas fees, and stay vigilant about mempool activity. With these strategies, you can navigate the MEV landscape confidently and keep your bot’s trades safe.

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