Snowman Merkle Airdrop

[High] Missing Access Control on Snowman.sol::mintSnowman function

Description

The mintSnowman function in Snowman.sol lacks any form of access control (e.g., onlyOwner, onlyRole, or a similar modifier). This design allows any external address to call this function and mint an unlimited number of Snowman NFTs to any receiver address, without restriction.

Risk

This vulnerability has severe consequences:

1. Sybil Attack: Malicious users can exploit this to mint an endless supply of NFTs, effectively flooding the system and devaluing the entire collection.

2. Token Devaluation: An uncontrolled, unlimited supply inherently diminishes any potential value or scarcity the NFTs are intended to hold.

3. Denial-of-Service (DoS) Risk: The s_TokenCounter (which represents the total supply) could rapidly increase to extremely high values. This could lead to potential gas issues, overflows, or performance degradation in future operations that rely on iterating over token IDs or that assume a bounded total supply.

Proof of Concept

The existing testMintSnowman function within TestSnowman.t.sol implicitly serves as proof. This test function successfully mints Snowman NFTs without requiring any special permissions, demonstrating the absence of access control.

Recommended Mitigation

Implement a robust access control mechanism, such as an onlyOwner modifier (if the contract should be administered by a single address) or a role-based access control (RBAC) system. This ensures that only authorized entities can control the minting process and prevent abuse.

Proposed Fix in Snowman.sol: