DeFi Smart Contract Vulnerabilities Audit Guide

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

1. Reentrancy Attacks

Description:

Reentrancy occurs when a contract calls an external contract (e.g., a user’s wallet or another DEX) before updating its own internal state. A malicious external contract can then re-enter the vulnerable function before the state change is complete, allowing attackers to drain funds multiple times.

Specific Detection Methods:

• Static Analysis for State-After-Call Pattern: Use tools like Slither (a Python-based static analysis tool for Solidity) to flag functions that perform external calls (call, delegatecall) before updating state variables (e.g., balanceOf[msg.sender] -= amount). Example flag: ETH_TRANSFER followed by STATE_UPDATE in the same function.
• Control Flow Graph (CFG) Inspection: Man