Beanstalk Part 1

Summary

Hi team :)
A potential reentrancy vulnerability was identified in the SeasonFacet contract within the Beanstalk project. This vulnerability could allow an attacker to exploit the contract by repeatedly calling a function before the state changes are finalized, potentially leading to unexpected behavior or loss of funds.

Vulnerability Details

1. Set Up the Environment: Ensure you have a Hardhat project set up with the necessary dependencies, including @nomiclabs/hardhat-ethers for contract interaction.

2. Compile the Contracts: Run npx hardhat compile to compile the SeasonFacet contract and any associated libraries.

3. Deploy the Contracts: Deploy the SeasonFacet contract and any required libraries. Ensure that the SeasonFacet contract is correctly linked to its libraries.

4. Prepare the Malicious Contract: Create a malicious contract that simulates a reentrancy attack by calling back into the SeasonFacet contract's vulnerable function before the state changes are finalized.

5. Execute the Attack: Deploy the malicious contract and call its function that triggers the reentrancy attack on the SeasonFacet contract.

POC

Output:

Impact

A successful reentrancy attack could lead to unexpected behavior in the contract, such as incorrect state updates or even loss of funds. This vulnerability could be exploited by malicious actors to manipulate the contract's state to their advantage.

Tools Used

Manual code audit

Recommendations

To mitigate this vulnerability, ensure that the SeasonFacet contract uses the ReentrancyGuard modifier from OpenZeppelin on any function that could be susceptible to reentrancy attacks. This modifier prevents a contract from calling itself, directly or indirectly, during the execution of a function.

By applying the nonReentrant modifier to the vulnerable function, you can prevent reentrancy attacks and ensure the integrity and security of the contract.