DeFi Smart Contract Vulnerabilities Audit Guide

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

1. Reentrancy Vulnerability

Description:

Reentrancy occurs when a contract calls an external contract (e.g., to send ETH) before it has finished updating its internal state variables. A malicious external contract can then re-enter the original function, exploiting the stale state to drain funds or manipulate logic.

Specific Example:

A withdraw() function that sends ETH to the caller before reducing the caller’s balance in the contract’s ledger.

How to Detect:

• Static Analysis Tools: Use tools like Slither, Mythril, or Echidna to flag functions that perform external calls (.call{value: ...}) before state changes.
  • Slither rule: reentrancy-eth or reentrancy-benign.
• **Code Review