How Do Bots Exploit Pools With No Anti-MEV Protections Like Transaction Throttles?

In the realm of DeFi, MEV attacks have grown into one of the most persistent threats against liquidity providers, traders, and DEXs. It's critical to underline the key point: bots attack liquidity pools that lack anti-MEV protections, such as throttles, private mempools, or sandwich defenses, by manipulating transaction ordering to extract profit at users' expense. These resultant exploits often lead to a series of slippage losses, inflated trading fees, and reduced confidence in AMMs.

The article explains how these bots work, why unprotected crypto pools are particularly susceptible, and what patterns traders should be aware of.

Understanding MEV and Why It Exists

First of all, before proceeding with the exploitation, one needs to know what Maximal Extractable Value (MEV) is. MEV refers to the profit miners, validators, or external bots can extract by reordering, inserting, or censoring transactions within a blockchain block.

Bots utilize the MEV opportunities presented in unprotected pools in order to:

• Front-run trades

• Back-run trades

• Users of the sandwich attack

• Drain liquidity opportunistically

• Capture arbitrage spreads

• Manipulate block ordering for profit

Without MEV protection, every transaction in the pool becomes a target.

How Bots Detect Vulnerable Liquidity Pools

Bots constantly scan the mempool and smart contracts. Pools attract bots when they exhibit characteristics such as:

• No throttling of transactions, which means unlimited pending transactions are allowed to make it very easy for bots to issue a flood of requests to the pool in rapid succession.

• No sandwich protection included within the DEX/router, allowing for predictable front-run and back-run positioning.

• Public mempool with visible pending trades, showing user intent in real time

• Slow block times or poor validator diversity that give bots more time to react and place competitive transactions

• Large liquidity gaps or volatile assets that can be used to their advantage in profitable price swings

• Outdated AMM logic that doesn't take modern MEV-resistant mechanisms into account and is easier to manipulate

Key Signals Bots Look For:

• Significant price impact from user's pending trade, reflecting an exploitable price movement.

• Large slippage tolerance, for example, >2%, which allows bots more room to manipulate execution.

• Repeated failures of transactions or sudden spikes in gas, showing that a pool is already under bot activity

• Thin liquidity in some token pairs, allowing for quicker and cheaper manipulation for automated systems

How Bots Exploit Pools With No Anti-MEV Protections

1. The Sandwich Attack (Most Common)

A sandwich attack consists of the following three steps:

How it works:

• Bot detects user's trade in the public mempool.

• The bot front-runs the trade by buying before the user to push the price up.

• The user's trade executes at a worse price because of greater slippage.

• The bot back-runs, selling the tokens at the new inflated price.

Why it succeeds on unprotected pools:

• No protections stop bots from placing transactions before/after the user

• No slippage guards that counter rapid price manipulation

• No private order flow concealing pending transactions

Results:

• User pays higher prices

• Bot extracts profit

• Pool experiences increased price volatility

2. Liquidity Sniping During Volatile Events

Bots rush to submit transactions faster than retail users in a race when a token listing, whale trade, or major news event happens.

Bot Strategy:

• Detect a large incoming swap

• Enter the pool milliseconds before

• Extract profit from predictable price movements

Why unprotected pools fail:

They lack:

• Transaction rate limits

• Priority fee controls

• MEV-resistant block sequencing

3. Back-Running Arbitrage (MEV Backruns)

Some bots also do not frontrun, but rather wait for large trades to profit from price impact.

Steps:

1. Detect large trade

2. Wait for price impact

3. Execute arbitrage trade across multiple DEXs

4. Capture spread

5. Exit in the same block

Impact:

• Distortions in pool prices

• LPs bear the cost through impermanent loss

4. Liquidity Drain Attacks

Specifically, one sophisticated exploitation pattern is a Liquidity Drain Bot that strategically will drain value from thin pools by executing rapid multi-hop swaps exploiting slippage settings and using back-running sequences to extract liquidity as profit. These bots cause sudden price collapses and leave LPs with depreciated assets.

5. Flash Loans for Zero Slippage Exploits

Flash loans amplify MEV attacks, allowing bots to borrow millions in one transaction.

Flash loans utilize bots to:

• Conduct massive arbitrage cycles

• Manipulate pool reserves

• Distort temporarily prices

• Create artificial liquidity gaps Unprotected pools cannot counteract sudden reserve imbalance.

6. Priority Gas Auctions (PGAs)

Bots fight each other for top spot using a gas war. Unprotected pools suffer because:

• Higher gas fees incentivize aggressive MEV strategies

• Retail users are priced out

• Trades become unpredictable

Comparison Table: Protected vs. Unprotected Pools