DeFi Smart Contract Vulnerabilities Audit Guide

Here are three of the most common and critical DeFi smart contract vulnerabilities, along with specific detection methods for each.

1. Reentrancy Attacks

Description:
Reentrancy occurs when a contract calls an external contract and then updates its state variables after the external call. If the external contract is malicious, it can recursively call the first contract before the state is updated, allowing an attacker to drain funds or manipulate state multiple times. This is the infamous class of vulnerability behind the 2016 DAO hack.

Specific Detection Methods:

• Static Analysis Tools: Use tools like Slither (by Trail of Bits) or Mythril. These tools analyze the control flow graph and flag "external calls" that occur before state variable updates. Look for warnings like reentrancy-eth or reentrancy-balance.
• Manual Code Review Pattern: Search for the "Check-Effect-Interact"