DeFi Smart Contract Vulnerabilities Audit Guide

Here are three common DeFi smart contract vulnerabilities, along with specific technical methods to detect them.

1. Reentrancy Attack

Description:

An attacker calls a function in a contract that allows them to withdraw funds (e.g., withdraw()) before the contract’s state is updated to reflect the withdrawal. The attacker re-enters the function via an external call, exploiting the EVM’s sequential execution to drain multiple times before the balance is reduced.

Specific Detection Methods:

• Static Analysis for External Calls Before State Changes: Use tools like Slither or MythX to scan for functions where an external call (e.g., call.value()) occurs before a state variable (e.g., balances[msg.sender]) is modified. Example Flag:

solidity
  function withdraw(uint amount) public {
      require(balances[msg.sender] >= amount, "