DeFi Smart Contract Vulnerabilities Audit Guide

Here are three common DeFi smart contract vulnerabilities, along with specific detection methods for each:

1. Reentrancy Attacks

Description:

A reentrancy attack occurs when a smart contract makes an external call (e.g., sending ETH or tokens to another contract) before updating its internal state. A malicious contract can intercept this call and re-enter the vulnerable function before the state change is committed, allowing the attacker to drain funds repeatedly.

How to Detect:

• Static Analysis with Slither/Oyente:
  • Use tools like Slither (by Trail of Bits) to identify external calls (call, transfer, delegatecall) that occur before state variable updates.
  • Look for patterns where msg.sender is called or tokens are transferred before balance[msg.sender] is decremented.
• Manual Code Review:
  • Apply the Checks-Effects-Interactions (CEI)