DeFi Smart Contract Vulnerabilities Audit Guide

Here are three of the most common DeFi smart contract vulnerabilities, along with specific detection methods and mitigation strategies.

1. Reentrancy Attack

Description:

A reentrancy attack occurs when a smart contract calls an external contract before updating its internal state. If the external contract is malicious, it can recursively call the vulnerable function multiple times before the state update completes, allowing the attacker to drain funds.

Specific Detection Methods:

• Static Analysis Tools: Use tools like Slither (by Crytic) or Mythril. These tools flag functions that perform external calls (via .call() or .transfer()) before state variable updates.
  • Example Slither output: Reentrancy in Contract.function()
• Code Pattern Inspection: Look for the "CEI" (Checks-Effects-Interactions) pattern violation:
  • Vulnerable Pattern:

solidity
    function withdraw(uint amount