DeFi Smart Contract Vulnerabilities Audit Guide

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

1. Reentrancy Attacks

Description:

An attacker exploits a vulnerability where an external call is made before state variables are updated. By recursively calling the same function, the attacker can drain funds before the contract’s state reflects the withdrawal. This was famously exploited in the 2016 DAO hack.

Specific Detection Methods:

• Static Analysis for Call-then-State Pattern: Use tools like Slither or Mythril to flag functions that make external calls (.call(), .transfer(), or interface calls) before updating internal state variables (e.g., balances[msg.sender] -= amount).
• CEI Pattern Check: Verify adherence to the Checks-Effects-Interactions pattern:
  1. Checks: Validate input and permissions.
  2. Effects: Update all state variables.