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- [SCA] TraderBros | TraderBros-Contracts | Nov2025
Audit name:
[SCA] TraderBros | TraderBros-Contracts | Nov2025
Date:
Nov 21, 2025
Table of Content
Introduction
We express our gratitude to the TraderBros team for the collaborative engagement that enabled the execution of this Smart Contract Security Assessment.
TraderBros is an NFT auction system designed for the Trader Bros community. The project consists of a 10k ERC721 NFT collection where 1 NFT is auctioned every day.
Document | |
|---|---|
| Name | Smart Contract Code Review and Security Analysis Report for TraderBros |
| Audited By | Turgay Arda Usman, David Camps Novi |
| Approved By | Ataberk Yavuzer |
| Website | https://traderbros.com/→ |
| Changelog | 17/11/2025 - Preliminary Report |
| 21/11/2025 - Final Report | |
| Platform | Ethereum |
| Language | Solidity |
| Tags | Non-fungible Token (NFT), Auction, Upgradeable, ERC721, Collectibles. |
| Methodology | https://docs.hacken.io/methodologies/smart-contracts→ |
Document
- Name
- Smart Contract Code Review and Security Analysis Report for TraderBros
- Audited By
- Turgay Arda Usman, David Camps Novi
- Approved By
- Ataberk Yavuzer
- Website
- https://traderbros.com/→
- Changelog
- 17/11/2025 - Preliminary Report
- 21/11/2025 - Final Report
- Platform
- Ethereum
- Language
- Solidity
- Tags
- Non-fungible Token (NFT), Auction, Upgradeable, ERC721, Collectibles.
Review Scope | |
|---|---|
| Repository | https://github.com/TraderBrosCom/traderbros-club→ |
| Initial Commit | b271598 |
| Final Commit | 58760ed |
Review Scope
- Initial Commit
- b271598
- Final Commit
- 58760ed
Audit Summary
The system users should acknowledge all the risks summed up in the risks section of the report
Documentation quality
Functional requirements are well documented.
Technical description is not provided.
Key function descriptions are missing.
Implementation assumptions are missing.
Used technologies are missing
Code quality
The code mostly follows best practices and style guides:
See informational findings for more details
The development environment is configured.
Test coverage
Code coverage of the project is 89.55% (branch coverage).
Deployment and basic user interactions are covered with tests.
Negative test cases for the NFT implementation are missing.
Multiple user interactions for NFT are not provided
System Overview
TraderBros is an NFT auction system designed for the Trader Bros community. The project consists of a 10k ERC721 NFT collection where 1 NFT is auctioned every day.
It comprises the following contracts:
TraderBrosClub: ERC721 with minting and burning functionality. Every 10 minted token ids, a token is minted to the treasury address.
TraderBrosAuction: contract managing the auction system, where anybody can place a bid by fulfilling some requirements, and the winner will get an ERC721 token.
Privileged roles
The owner of the
TraderBrosClubcontract can arbitrarily change the treasury address (which receives every 10th NFT) and the minter address (the only account authorized to create NFTs).The owner of the
TraderBrosClubcontract can change the base metadata URI for all tokens.The minter in the
TraderBrosClubcontract is the only role authorized to call the mint function.The owner of the
TraderBrosAuctioncontract can arbitrarily pause/unpause the auction mechanism, modify auction parameters like the bid increment and extension window, and change the payment token and starting bid for future auctions.
Potential Risks
The project's contracts are upgradable, allowing the administrator to update the contract logic at any time. While this provides flexibility in addressing issues and evolving the project, it also introduces risks if upgrade processes are not properly managed or secured, potentially allowing for unauthorized changes that could compromise the project's integrity and security.
The absence of restrictions on state variable modifications by the owner leads to arbitrary changes, affecting contract integrity and user trust, especially during critical operations like minting phases.
The broad authorization model increases the risk of protocol control loss if any authorized address is compromised, potentially leading to unauthorized actions and significant financial loss.
The token contract’s design allows for centralized control over the minting process, posing a risk of unauthorized token issuance, potentially diluting the token value and undermining trust in the project's economic governance.
Findings
Code ― | Title | Status | Severity | |
|---|---|---|---|---|
| F-2025-1403 | Uncapped NFT Minting | fixed | Medium | |
| F-2025-1403 | Unsafe Transfer Method may Lead to NFT Loss | mitigated | Medium | |
| F-2025-1402 | NFT Minting Bypasses ERC721 Receiver Safety Checks | mitigated | Low | |
| F-2025-1403 | Owner can change auction parameters mid-auction, enabling front-running and manipulation. | fixed | Low | |
| F-2025-1403 | Redundant payable cast for bidder address | fixed | Observation | |
| F-2025-1403 | Missing Zero Address Validation | fixed | Observation | |
| F-2025-1402 | Floating Pragma | fixed | Observation |
Appendix 1. Definitions
Severities
When auditing smart contracts, Hacken is using a risk-based approach that considers Likelihood, Impact, Exploitability and Complexity metrics to evaluate findings and score severities.
Reference on how risk scoring is done is available through the repository in our Github organization:
Severity | Description |
|---|---|
Critical | Critical vulnerabilities are usually straightforward to exploit and can lead to the loss of user funds or contract state manipulation. |
High | High vulnerabilities are usually harder to exploit, requiring specific conditions, or have a more limited scope, but can still lead to the loss of user funds or contract state manipulation. |
Medium | Medium vulnerabilities are usually limited to state manipulations and, in most cases, cannot lead to asset loss. Contradictions and requirements violations. Major deviations from best practices are also in this category. |
Low | Major deviations from best practices or major Gas inefficiency. These issues will not have a significant impact on code execution. |
Severity
- Critical
Description
- Critical vulnerabilities are usually straightforward to exploit and can lead to the loss of user funds or contract state manipulation.
Severity
- High
Description
- High vulnerabilities are usually harder to exploit, requiring specific conditions, or have a more limited scope, but can still lead to the loss of user funds or contract state manipulation.
Severity
- Medium
Description
- Medium vulnerabilities are usually limited to state manipulations and, in most cases, cannot lead to asset loss. Contradictions and requirements violations. Major deviations from best practices are also in this category.
Severity
- Low
Description
- Major deviations from best practices or major Gas inefficiency. These issues will not have a significant impact on code execution.
Potential Risks
The "Potential Risks" section identifies issues that are not direct security vulnerabilities but could still affect the project’s performance, reliability, or user trust. These risks arise from design choices, architectural decisions, or operational practices that, while not immediately exploitable, may lead to problems under certain conditions. Additionally, potential risks can impact the quality of the audit itself, as they may involve external factors or components beyond the scope of the audit, leading to incomplete assessments or oversight of key areas. This section aims to provide a broader perspective on factors that could affect the project's long-term security, functionality, and the comprehensiveness of the audit findings.
Appendix 2. Scope
The scope of the project includes the following smart contracts from the provided repository:
Scope Details | |
|---|---|
| Repository | https://github.com/TraderBrosCom/traderbros-club→ |
| Initial Commit | b271598 |
| Final Commit | 58760ed |
| Whitepaper | N/A |
| Requirements | ./README.md |
| Technical Requirements | N/A |
Scope Details
- Initial Commit
- b271598
- Final Commit
- 58760ed
- Whitepaper
- N/A
- Requirements
- ./README.md
- Technical Requirements
- N/A
Assets in Scope
Appendix 3. Additional Valuables
Additional Recommendations
The smart contracts in the scope of this audit could benefit from the introduction of automatic emergency actions for critical activities, such as unauthorized operations like ownership changes or proxy upgrades, as well as unexpected fund manipulations, including large withdrawals or minting events. Adding such mechanisms would enable the protocol to react automatically to unusual activity, ensuring that the contract remains secure and functions as intended.
To improve functionality, these emergency actions could be designed to trigger under specific conditions, such as:
Detecting changes to ownership or critical permissions.
Monitoring large or unexpected transactions and minting events.
Pausing operations when irregularities are identified.
These enhancements would provide an added layer of security, making the contract more robust and better equipped to handle unexpected situations while maintaining smooth operations.
Frameworks and Methodologies
This security assessment was conducted in alignment with recognised penetration testing standards, methodologies and guidelines, including the NIST SP 800-115 – Technical Guide to Information Security Testing and Assessment →, and the Penetration Testing Execution Standard (PTES) →, These assets provide a structured foundation for planning, executing, and documenting technical evaluations such as vulnerability assessments, exploitation activities, and security code reviews. Hacken’s internal penetration testing methodology extends these principles to Web2 and Web3 environments to ensure consistency, repeatability, and verifiable outcomes.