DeFi Smart Contract Vulnerabilities Audit Guide

Here are three of the most common DeFi smart contract vulnerabilities, along with specific detection methods used by security auditors and automated tools.

1. Reentrancy Attacks

Description:

An attacker exploits a function that makes an external call (e.g., sending ETH or tokens to a user) before updating the contract’s internal state. If the external call triggers a callback into the same contract, the attacker can repeatedly drain funds before the state is updated.

Specific Detection Methods:

• Static Analysis with Control-Flow Graphs (CFG): Tools like Slither or Mythril analyze the CFG to identify patterns where an external call (e.g., call.value(), transfer(), approve()) occurs before state variable updates. Example pattern to flag:

solidity
  // Vulnerable: External call before state update
  function withdraw() public {
      uint