DeFi Smart Contract Vulnerabilities Audit Guide

Here are three of the most common and dangerous DeFi smart contract vulnerabilities, along with specific methods to detect them during auditing or development.

1. Reentrancy Attacks

Description:

Reentrancy occurs when an external call is made to an untrusted contract before the state variables of the calling contract are updated. This allows the external contract to re-enter the vulnerable function before the first execution completes, potentially draining funds or corrupting state.

Common Scenario:

A withdrawal function that sends ETH to a user via call or transfer before updating the user’s balance in the mapping.

How to Detect It:

• Static Analysis Tools: Use tools like Slither, Mythril, or Echidna. These tools automatically flag functions that make external calls without preceding state updates.

  - Example Slither flag: reentrancy-eth or reentrancy warnings.