DeFi Smart Contract Vulnerabilities Audit Guide

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

1. Reentrancy Attack

Description:

A reentrancy attack occurs when a smart contract makes an external call to an untrusted contract before updating its internal state. The external contract can then re-enter the vulnerable function, bypassing the state update and draining funds. This was famously exploited in the 2016 Ethereum DAO hack.

Vulnerability Pattern:

function withdraw() public {
    require(balances[msg.sender] > 0, "Insufficient balance");
    uint256 amount = balances[msg.sender];
    (bool success, ) = msg.sender.call{value: amount}(""); // External call before state update
    require(success, "Transfer failed");
    balances[msg.sender] = 0; // State update after external call
}

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