Summary

The MysteryBox contract uses a fixed SEEDVALUE for initial funding and has a limited initial reward pool, which could lead to economic imbalances and sustainability issues as the contract scales.

Vulnerability Details

1. Fixed SEEDVALUE:

• Used only in the constructor

• No mechanism to adjust or add funds later

1. Limited initial reward pool:

• Fixed initial rewards

• Total value of non-zero rewards: 0.85 ether

• No automatic refill mechanism

1. Mismatch between SEEDVALUE and reward values:

   • SEEDVALUE (0.1 ether) is less than total non-zero rewards (0.85 ether)

Impact

• Potential for contract to become underfunded if many high-value rewards are claimed

• Risk of economic imbalance if box sales don't match reward distributions

• Lack of scalability as the contract grows in usage

• Possible user disappointment due to limited reward variety

Tools Used

Manual code review and economic analysis

Recommendations

1. Implement a dynamic funding mechanism:

   • Allow additional deposits to the contract

   • Consider a percentage-based fee on box purchases to sustain the reward pool

2. Create a more robust reward system:

   • Implement dynamic reward pools that adjust based on contract balance

   • Add functionality to update reward probabilities and values

3. Improve economic balancing:

   • Ensure initial funding (SEEDVALUE) matches or exceeds total possible rewards

   • Implement checks to maintain a minimum contract balance relative to outstanding potential rewards

4. Add monitoring and reporting:

   • Implement events to track reward distributions and contract balance changes

   • Create functions to report on current economic state of the contract

By implementing these recommendations, the contract can achieve better economic balance, scalability, and long-term sustainability, providing a more reliable and engaging experience for users.