Mastering Blockchain Programming with Solidity

Front-running attack on the approve function

The implementation of the approve() function that we looked at in the previous section is prone to front-running attacks. First, understand what is the front-running attack.

An attacker who initiates a transaction which is to be executed before a specific pending transaction that could benefit an attacker financially is called a front-running attack.

On the Ethereum blockchain, the transaction gets executed based on the GasPrice someone is offering to process their transaction. The more GasPrice you provide for a transaction, the more likely it is that your transaction will be executed and added in the block. Also, anyone can read the transactions that are still pending and waiting to be executed ...