Basic Security Audit Summary

Original Contract Problems

1. Anyone can withdraw all money - The biggest problem
2. Missing semicolon - Won't compile
3. Empty attack() function - Suspicious

Fixed Version

The audited-VulnerablePiggyBank.sol fixes these issues:

1. Only owner can withdraw - Added onlyOwner modifier
2. Fixed syntax - Added missing semicolon
3. Removed attack() - Removed unnecessary function
4. Better transfer method - Used call instead of transfer

Key Changes

// OLD - BROKEN
function withdraw() public { 
    payable(msg.sender).transfer(address(this).balance); 
}

// NEW - SECURE
function withdraw() public onlyOwner {
    (bool success, ) = payable(owner).call{value: address(this).balance}("");
    require(success, "Transfer failed");
}

Result

• ❌ Old contract: Anyone can steal all funds
• ✅ New contract: Only owner can withdraw funds