CMTAT - Taurus

1. Introduction

Taurus engaged Halborn to perform a security assessment of their smart contracts from July 1st, 2025, to July 9th, 2025. The assessment scope was limited to the smart contracts provided to Halborn. Commit hashes and additional details are available in the Scope section of this report.

The Taurus codebase in scope consists of a Solidity implementation of the CMTAT security token framework, featuring modular compliance and technical capabilities for regulated financial assets on EVM-compatible blockchains, featuring compliance controls and upgradeability.

2. Assessment Summary

Halborn was allocated 7 days for this engagement and assigned 1 full-time security engineer to conduct a comprehensive review of the smart contracts within scope. The engineer is an expert in blockchain and smart contract security, with advanced skills in penetration testing and smart contract exploitation, as well as extensive knowledge of multiple blockchain protocols.

The objectives of this assessment were to:

• Identify potential security vulnerabilities within the smart contracts.

• Verify that the smart contract functionality operates as intended.

In summary, Halborn identified several areas for improvement to reduce the likelihood and impact of potential risks, which were partially addressed by the Taurus team. The primary recommendations were as follows:

• Modify the _canMintBurnByModule() function to respect the paused state.

• Modify the _forcedTransfer() function to handle allowances in a safe and predictable manner.

• Lock the pragma version to the same version used during development and testing.

3. Test Approach and Methodology

Halborn conducted a combination of manual code review and automated security testing to balance efficiency, timeliness, practicality, and accuracy within the scope of this assessment. While manual testing is crucial for identifying flaws in logic, processes, and implementation, automated testing enhances coverage of smart contracts and quickly detects deviations from established security best practices.

The following phases and associated tools were employed throughout the term of the assessment:

• Research into the platform's architecture, purpose and use.

• Manual code review and walkthrough of smart contracts to identify any logical issues.

• Comprehensive assessment of the safety and usage of critical Solidity variables and functions within scope that could lead to arithmetic-related vulnerabilities.

• Local testing using custom scripts (Foundry).

• Fork testing against main networks (Foundry).

• Static security analysis of scoped contracts, and imported functions (Slither).

4. Caveats

After the initial assessment, Taurus reported an additional compliance issue affecting batch operations. Halborn performed a post-assessment review at commit 198d019 to verify the fixes, and confirmed that the issue has been addressed at that commit.