DeFi Smart Contract Vulnerabilities Audit Guide

Here are three common DeFi smart contract vulnerabilities, along with specific detection methods and tools:

1. Reentrancy

Description:

An attacker calls a contract function that sends ETH or tokens to an external contract (e.g., transfer or call). Before the state update (e.g., balance deduction) is completed, the external contract re-enters the same function, allowing the attacker to manipulate state multiple times.

How to Detect:

• Static Analysis Tools:
  • Slither: Use the reentrancy detector. It flags functions that perform external calls (call, delegatecall, send, transfer) before updating state variables.

python
    # Example Slither output
    [Medium] Reentrancy in Function:
    - Contract: `MyToken`
    - Function: `withdraw(uint256)`
      - External call: `address.transfer(amount)`