DeFi Smart Contract Vulnerabilities Audit Guide

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

1. Reentrancy Attacks

Description:

Reentrancy occurs when a contract makes an external call to an untrusted contract before updating its internal state. The external contract can then re-enter the vulnerable function before the first call completes, potentially draining funds or corrupting state. This was famously exploited in the 2016 DAO hack.

Specific Detection Methods:

• Static Analysis Tools: Use tools like Slither (by Consensys) or Mythril. These tools automatically flag functions that perform external calls (call, send, or transfer to an address) before updating related state variables (e.g., balance mappings).
  • Example Slither output: Reentrancy on variable balances[msg.sender]
• Manual Code Review Pattern: Look for the "CEI" (Checks-Effects-Interactions)