DeFi Smart Contract Vulnerabilities Audit Guide

Here are three of the most common and critical DeFi smart contract vulnerabilities, along with specific methods to detect them.

1. Reentrancy Attacks

Vulnerability Description:

Reentrancy occurs when a contract calls an external contract and allows the external contract to call back into the vulnerable function before the first call completes. This can drain funds if state variables (like balances) are not updated before the external call is made. The classic example is the 2016 DAO hack.

How to Detect It:

• State-Change-External Call Order (Check-Effects-Interactions): Manually audit code to ensure that all state changes (e.g., updating user balances) occur before any external calls. If you see a pattern like:

solidity
  function withdraw() public {
      uint256 amount = balances[msg.sender];
      (bool success, ) = payable(msg.sender).call