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:

A reentrancy attack occurs when a smart contract makes an external call to another contract (or itself) before updating its own state. An attacker can exploit this by calling the same function again during the external call, allowing them to drain funds before the state is updated. This was famously exploited in the DAO hack (2016).

Specific Detection Methods:

• Static Analysis Tools: Use tools like Slither (by Trail of Bits) or Mythril. These tools flag functions that perform external calls (e.g., transfer, call) before state changes (e.g., balanceOf[msg.sender] -= amount).
  • Example Slither Output: `warning: Reentrancy in .... External calls: ... State variable