DeFi Smart Contract Vulnerabilities Audit Guide

Here are three common DeFi smart contract vulnerabilities, along with specific detection methods and examples of how they manifest in code.

1. Reentrancy (Direct or Cross-Function)

Vulnerability Description:

Reentrancy occurs when a contract calls an external contract (e.g., another ERC-20 token or another DeFi protocol) and allows that external contract to call back into the vulnerable contract before the first execution has completed. This can lead to state inconsistencies, such as draining funds by repeating a transaction multiple times before balances are updated.

Specific Detection Methods:

• Static Analysis Tools: Use tools like Slither or Manticore with the reentrancy-eth check enabled. These tools flag functions that perform external calls before updating internal state variables (violating the Checks-Effects-Interactions pattern).
• Manual Code Review (Checks-Effects-Interactions):
  • Look for external calls (`