DeFi Smart Contract Vulnerabilities Audit Guide

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

1. Reentrancy Attacks

Description:

A reentrancy attack occurs when a smart contract calls an external contract (e.g., a user-controlled wallet or another DeFi protocol) before updating its internal state (such as balances). An attacker can exploit this by using a malicious fallback function (receive() or fallback()) to re-enter the vulnerable function multiple times before the initial call completes, draining funds.

How to Detect:

• Static Analysis Tools: Use tools like Slither, Mythril, or Echidna to identify external calls that occur before state updates. Slither, for example, flags functions where call or send operations are not guarded by proper state changes.
• Code Pattern Review: Look for the **"CEI" (Checks-