047.md

Odd Tartan Gerbil

High

Potential Reentrancy Vulnerability

Summary

The contract may be vulnerable to reentrancy attacks if functions involve external calls that transfer Ether or interact with untrusted contracts.

Root Cause

In vaultV2Deployer.sol, functions may interact with external contracts without implementing protection mechanisms such as reentrancy guards or the Checks-Effects-Interactions pattern, leaving the contract exposed to reentrancy risks.

Internal pre-conditions

1. The contract calls external contracts or transfers Ether or tokens, but does not use reentrancy guards or follow the Checks-Effects-Interactions pattern to prevent reentrancy attacks.

External pre-conditions

1. An external malicious contract must exist that can exploit the reentrancy vulnerability by re-entering the vulnerable contract during the execution of a state-changing function.

Attack Path

1. A function in the contract makes an external call (e.g., transferring Ether or interacting with an external contract).
2. The external contract calls back into the vulnerable contract before the initial state changes are completed.
3. The vulnerable contract processes the malicious call and allows unauthorized actions, such as withdrawing funds, exploiting the vulnerability.

Impact

Reentrancy attacks can allow attackers to withdraw more funds than intended or perform unauthorized actions within the contract, leading to a loss of assets or other malicious behavior.

PoC

Numa/contracts/deployment/vaultV2Deployer.sol

// Example of the Checks-Effects-Interactions pattern with a reentrancy guard
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

contract Vault is ReentrancyGuard {
    mapping(address => uint) public balances;

    function withdraw(uint256 amount) public nonReentrant {
        require(balances[msg.sender] >= amount, "Insufficient balance");
        
        // Update state before interacting with external contract (if any)
        balances[msg.sender] -= amount;
        
        // External call: transfer funds to the user
        (bool success, ) = msg.sender.call{value: amount}("");
        require(success, "Transfer failed");
    }
}

Mitigation

1. Implement the Checks-Effects-Interactions pattern: ensure that all state changes are completed before interacting with external contracts.
2. Use ReentrancyGuard from OpenZeppelin or similar mechanisms to protect against reentrancy attacks.