DeFi Smart Contract Vulnerabilities Audit Guide

Here are three of the most common and high-impact DeFi smart contract vulnerabilities, along with specific technical methods for detecting them.

1. Reentrancy Vulnerability

What it is:

Reentrancy occurs when a contract sends a value to an external contract before it has finished updating its own state. If the external contract is malicious, it can call back into the vulnerable function before the first call completes, allowing an attacker to drain funds multiple times.

Specific Detection Techniques:

• State-Change-After-External-Call Audit: Manually inspect functions that perform transfer() or call{value: amount}(). Verify that all state variables (e.g., user balances, total supply) are updated before the external call is made (the "Checks-Effects-Interactions" pattern). Example of vulnerable code:

solidity
  function withdraw(uint amount) public {