DeFi Smart Contract Vulnerabilities Audit Guide

Here are three of the most common and damaging DeFi smart contract vulnerabilities, along with specific technical methods to detect them.

1. Reentrancy Attacks

Mechanism:

An attacker calls a smart contract function that sends ETH or tokens to an external address. Before the contract updates its internal state (e.g., user balances), it calls back into the same contract. This allows the attacker to withdraw funds multiple times before the balance is debited.

Specific Detection Methods:

• Static Analysis with Tooling: Use tools like Slither (by Consensys) or Mythril. These tools analyze the control flow graph (CFG) to detect functions that:
  • Make an external call (call, send, or transfer) before state-changing operations (e.g., balance[msg.sender] -= amount).
  • Lack a reentrancy guard (e.g., OpenZeppelin’s `ReentrancyGuard