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

If you’ve built or used a crypto trading bot, chances are you’ve encountered the dreaded "sandwich attack." It’s one of the most frustrating and costly issues in decentralized finance (DeFi), especially for automated traders. In this article, I’ll explain what sandwich attacks are, why they happen, and—most importantly—how to protect your bot using techniques like Jito bundles. I’ll also share real-world examples and code snippets to help you implement these strategies effectively.

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What is a Sandwich Attack?

A sandwich attack is a type of Maximal Extractable Value (MEV) exploit where a malicious actor inserts their transaction before and after yours to profit at your expense. Here’s how it works:

1. You submit a transaction to buy or sell a token on a decentralized exchange (DEX) like Uniswap.
2. A bot detects your transaction in the mempool and frontruns it (executes a trade before yours) to influence the price.
3. The same bot backruns your transaction (executes a trade after yours) to capture the price difference.

For example, if you submit a buy order for ETH, a sandwich bot might:

• Buy ETH before you (increasing the price).
• Sell ETH after you (capturing the profit from the inflated price).

The result? You pay more for the token than you intended, and the attacker pockets the difference.

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Why Are Sandwich Attacks So Common?

Sandwich attacks thrive in DeFi because of two key factors:

1. Public Mempools: On blockchains like Ethereum, transactions are broadcast to the mempool before they’re included in a block. This transparency allows attackers to monitor and exploit pending trades.
2. High-Latency Bots: Many trading bots rely on Ethereum’s public RPC nodes, which introduce delays. Attackers use faster infrastructure to frontrun slower bots.

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Real-World Impact of Sandwich Attacks

For context, let’s look at some numbers:

• In 2023, MEV attacks extracted over $1 billion from Ethereum users.
• Sandwich attacks account for ~30% of all MEV revenue, according to Flashbots research.
• On high-volume DEXs, sandwich bots can capture 5-10% of the token price difference per trade.

These numbers highlight the urgency of protecting your bot from MEV exploits.

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How to Prevent Sandwich Attacks

The good news is that there are practical ways to shield your bot from sandwich attacks. One of the most effective solutions is Jito bundles on Solana. Let’s dive into how they work and how you can implement them.

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What Are Jito Bundles?

Jito is a Solana-based MEV capture and distribution protocol that introduces the concept of bundles. Unlike Ethereum’s mempool, Solana transactions are processed in batches, and Jito bundles allow users to group transactions together with priority.

By using Jito bundles, you can:

• Submit your transaction as part of a prioritized batch, reducing the risk of frontrunning.
• Leverage Jito’s infrastructure to minimize latency and maximize execution speed.

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Implementing Jito Bundles: A Practical Example

Here’s how you can integrate Jito bundles into your Solana trading bot:

1. Set Up Your Environment: Ensure you have the Solana CLI and Anchor framework installed. You’ll also need a Jito validator endpoint.

Example setup:

   npm install @project-serum/anchor @solana/web3.js

1. Create a Transaction Bundle: Use the Solana Transaction class to create and sign your transactions. Then, group them into a Jito bundle.

Code snippet:

   const { Transaction, SystemProgram, PublicKey } = require('@solana/web3.js');
   const anchor = require('@project-serum/anchor');

   const createBundle = async (transactions) => {
     const jitoEndpoint = "https://jito-api.example.com";
     const connection = new anchor.web3.Connection(jitoEndpoint);

     const bundle = transactions.map(tx => ({
       transaction: tx,
       signers: tx.signers
     }));

     const response = await connection.sendBundle(bundle);
     return response;
   };

1. Submit the Bundle: Use Jito’s API to submit the bundle for priority processing.

Code snippet:

   const submitBundle = async (bundle) => {
     const jitoEndpoint = "https://jito-api.example.com";
     const response = await fetch(`${jitoEndpoint}/submit`, {
       method: 'POST',
       body: JSON.stringify(bundle)
     });
     return response.json();
   };

1. Monitor Execution: Track the status of your bundle to ensure it’s included in the block without interference.

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Why Jito Bundles Work

Jito bundles mitigate sandwich attacks by:

• Reducing latency through optimized infrastructure.
• Prioritizing your transaction in the block-building process.
• Leveraging Solana’s high throughput to process transactions faster.

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Lessons Learned from Building Trading Bots

From my experience, here are a few key takeaways to avoid MEV exploits:

1. Use Private RPC Nodes: Avoid public nodes and use private, low-latency RPC endpoints to reduce exposure to frontrunning.
2. Optimize Gas Fees: Higher gas fees can discourage sandwich bots from targeting your transaction.
3. Monitor Mempool Activity: Tools like Etherscan and MEV-Inspect can help you identify potential MEV threats.
4. Experiment with Layer 2 Solutions: Platforms like Arbitrum and Optimism offer lower fees and faster transactions, reducing the risk of MEV attacks.

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Conclusion

Sandwich attacks are a major challenge for crypto bots, but they’re not insurmountable. By understanding how MEV works and leveraging solutions like Jito bundles, you can protect your bot from costly exploits. Remember to stay updated on emerging MEV mitigation techniques and continuously optimize your bot’s infrastructure.

If you found this guide helpful and want to learn more about advanced crypto bot strategies, check out my other articles and follow me on Dev.to for regular updates.

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