DeFi Smart Contract Vulnerabilities Audit Guide

Here are three of the most common and critical DeFi smart contract vulnerabilities, along with specific methods for detecting them.

1. Reentrancy Attacks

Description:

Reentrancy occurs when a smart contract calls an external contract (e.g., sending ETH) and allows that external contract to call back into the vulnerable contract before the first transaction has finished updating its internal state. This allows an attacker to repeatedly withdraw funds before the contract’s balance is updated.

Specific Detection Methods:

• Static Analysis with Rules for External Calls: Use tools like Slither, Mythril, or Semgrep with rules that flag external calls (.send(), .call(), .transfer()) that occur before state variable updates (e.g., balance[msg.sender] -= amount). Example Slither rule: reentrancy-eth or reentrancy-balance flags functions where an external call is