Mystery Box

Summary

The openBox function uses randomValue generated from msg.sender and block.timestamp, which can be predictable and vulnerable to exploitation.

Vulnerability Details

The openBox function attempts to generate a random number to determine the reward a user receives.

The function is designed to randomly select a reward for the user when they open a mystery box.
The random number is derived from block.timestamp and msg.sender. block.timestamp can be influenced slightly by miners, allowing them to manipulate the outcome. msg.sender is known to the user, enabling them to repeatedly call the function from different addresses to achieve a desired result.

Impact

An attacker could predict or manipulate the random number generated by the contract, allowing them to consistently obtain valuable rewards.This undermines the fairness of the reward distribution.

Tools Used

Manual Review

Recommendations

Using a secure method for random number generation such as Chainlink VRF, which provides provably fair and tamper-proof randomness. This ensures that the random number generation is resistant to manipulation, maintaining the integrity and fairness of the reward system.