MEV Sandwich Attack: A Systemic Challenge in the Blockchain Ecosystem

With the continuous maturation of blockchain technology and the increasing complexity of the ecosystem, MEV (Maximum Extractable Value) has evolved from being initially viewed as an incidental flaw caused by transaction ordering defects into a highly complex and systematic profit extraction mechanism. Among them, sandwich attacks have garnered significant attention due to their unique operational methods, becoming one of the most controversial and destructive attack techniques in the DeFi ecosystem.

1. Basic Concepts of MEV and Sandwich Attacks

The source and technological evolution of MEV

MEV originally refers to the extra economic benefits obtained by miners or validators during the block construction process by manipulating the order of transactions, as well as the inclusion or exclusion rights. With the development of tools such as flash loans and transaction packaging, the originally sporadic arbitrage opportunities have gradually been magnified, forming a complete profit harvesting chain. The MEV phenomenon exists not only in Ethereum but also exhibits different characteristics on other public chains.

The principle of sandwich attacks

Sandwich attacks are a typical operational means in MEV extraction. Attackers monitor transactions in the mempool in real-time and submit their own transactions before and after the target transaction, forming the sequence of "front-run---target transaction---back-run" to achieve arbitrage through price manipulation. The core steps include:

1. Front-running: After detecting large or high-slippage trades, immediately submit buy orders to push up or suppress market prices.
2. Target transaction ambush: The target transaction is executed after the price is manipulated, resulting in a deviation between the actual transaction price and the expected price.
3. Post-trade: Immediately following the target trade, submit a reverse trade to lock in the price difference profit.

2. The Evolution and Current Status of MEV Sandwich Attacks

From sporadic vulnerabilities to systemic mechanisms

MEV attacks have evolved from sporadic small-scale events into a systematic and industrialized arbitrage model. Attackers build highly automated arbitrage systems that utilize high-speed networks and sophisticated algorithms to deploy front-running and back-running trades in a very short time, achieving substantial profits.

Different platforms' attack characteristics

Due to differences in design concepts, transaction processing mechanisms, and validator structures, sandwich attacks exhibit different characteristics across various blockchain networks:

• Ethereum: Attackers prioritize transaction packaging order by paying higher Gas fees.
• A certain high-performance public chain: Although there is no traditional memory pool, the validator nodes are relatively centralized, which may collude with attackers to leak transaction data.
• Certain smart chains: lower transaction costs and simplified structures provide space for arbitrage activities.

Latest Data and Cases

In March 2025, a trading incident occurred on a certain DEX platform, where a user suffered a loss of up to $732,000 during a transaction worth approximately 5 SOL due to a sandwich attack. This indicates that MEV sandwich attacks have become a systemic issue, evolving alongside the increasing transaction volume and complexity of blockchain networks.

3. Mechanism of Sandwich Attack and Technical Challenges

To implement a sandwich attack, the following conditions must be met:

1. Transaction Monitoring and Capture: Real-time monitoring of unconfirmed transactions in the memory pool.
2. Priority Packaging Rights Competition: Using higher gas fees or priority fees to compete for transaction packaging.
3. Accurate calculation and slippage control: Precisely calculate the trading volume and expected slippage to ensure that the target trade does not fail due to exceeding the set slippage.

This type of attack not only requires high-performance trading bots and fast network responses but also incurs high miner fees. In intense competition, multiple bots may simultaneously target the same transaction, further squeezing profit margins.

4. Industry Response and Prevention Strategies

Prevention strategies for ordinary users

• Set reasonable slippage protection: set slippage tolerance appropriately according to market volatility and expected liquidity conditions.
• Use privacy trading tools: Leverage private RPC, order bundling auctions, and other technologies to reduce the risk of being attacked.

Suggestions for technical improvements at the ecosystem level

1. Transaction Ordering and Proposer-Builder Separation (PBS): Limiting the control of a single node over transaction ordering.
2. Transparency Mechanism: Introduce third-party relay services and related solutions to enhance the transparency of the block construction process.
3. Off-chain order flow auction and outsourcing mechanism: Achieve batch matching of orders and improve price acquisition efficiency.
4. Smart Contracts and Algorithm Upgrades: Utilizing AI and machine learning technologies to enhance the monitoring and forecasting capabilities of abnormal fluctuations.

V. Conclusion

The MEV sandwich attack has evolved from an occasional vulnerability into a systemic profit extraction mechanism, posing a severe challenge to the DeFi ecosystem and the security of user assets. Recent cases indicate that the risk of attacks on mainstream platforms still exists and is continuously escalating. To protect user assets and market fairness, the blockchain ecosystem needs to work together on technological innovation, trading mechanism optimization, and regulatory collaboration to achieve sustainable development of the DeFi ecosystem.