DeFi Smart Contract Vulnerabilities Audit Guide

Here are three common DeFi smart contract vulnerabilities, along with specific techniques and tools for detecting them.

1. Reentrancy Attacks

Description:

Reentrancy occurs when a smart contract calls an external contract before completing its internal state changes. If the external contract is malicious, it can re-enter the vulnerable function before the state is updated, allowing an attacker to drain funds multiple times. The classic example is a withdrawal function that sends Ether before decrementing the user’s balance.

How to Detect:

• Static Analysis with Slither:
  
  Use Slither, a Solidity static analysis tool. Look for warnings like reentrancy-eth or reentrancy-no-eth. Slither flags functions that make external calls (e.g., .call(), .send()) before updating state variables.

• **Pattern Matching for Checks-Effects-Interactions (CEI