Mystery Box

Summary

The claimAllRewards function is vulnerable to a reentrancy attack, allowing an attacker to drain more funds than they are entitled to.

Vulnerability Details

The claimAllRewards function sends Ether to the caller before updating the state. This allows the attacker to call the function again before their rewards are cleared, potentially draining the contract of more Ether than intended.

Impact

High. An attacker could potentially drain all the Ether from the contract, far exceeding their legitimate rewards.

Tools Used

Manual code review.

Recommendations

Implement the checks-effects-interactions pattern:

• First, calculate the total value

• Then, delete the rewards

• Finally, transfer the Ether