Prepared by:
HALBORN
Last Updated 12/12/2025
Date of Engagement: December 4th, 2025 - December 4th, 2025
100% of all REPORTED Findings have been addressed
All findings
4
Critical
0
High
0
Medium
0
Low
0
Informational
4
Colend engaged Halborn to perform a security assessment of their smart contracts starting and ending on December 4th, 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 ATokenOTC codebase in scope consists of a non-custodial OTC trading smart contract designed to create, manage, and fill offers involving Receipt Tokens and their underlying ERC-20 assets. The system implements offer lifecycle functionality with configurable per-wallet limits, an optional allowlist for supported aTokens, and pausing controls via an Ownable admin.
Halborn was allocated 1 day for this engagement and assigned 1 full-time security engineers to conduct a comprehensive review of the smart contracts within scope. The engineers are experts 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 are 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 security risks, which were mostly addressed by the Colend team.The main recommendations were:
If not intended, remove POOL_ADDRESS and IPool.
Implement a two-step ownership transfer process.
Upgrade to the latest stable version.
Add a check to ensure newLimit differs from the current limit before allowing the update.
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).
| EXPLOITABILITY METRIC () | METRIC VALUE | NUMERICAL VALUE |
|---|---|---|
| Attack Origin (AO) | Arbitrary (AO:A) Specific (AO:S) | 1 0.2 |
| Attack Cost (AC) | Low (AC:L) Medium (AC:M) High (AC:H) | 1 0.67 0.33 |
| Attack Complexity (AX) | Low (AX:L) Medium (AX:M) High (AX:H) | 1 0.67 0.33 |
| IMPACT METRIC () | METRIC VALUE | NUMERICAL VALUE |
|---|---|---|
| Confidentiality (C) | None (C:N) Low (C:L) Medium (C:M) High (C:H) Critical (C:C) | 0 0.25 0.5 0.75 1 |
| Integrity (I) | None (I:N) Low (I:L) Medium (I:M) High (I:H) Critical (I:C) | 0 0.25 0.5 0.75 1 |
| Availability (A) | None (A:N) Low (A:L) Medium (A:M) High (A:H) Critical (A:C) | 0 0.25 0.5 0.75 1 |
| Deposit (D) | None (D:N) Low (D:L) Medium (D:M) High (D:H) Critical (D:C) | 0 0.25 0.5 0.75 1 |
| Yield (Y) | None (Y:N) Low (Y:L) Medium (Y:M) High (Y:H) Critical (Y:C) | 0 0.25 0.5 0.75 1 |
| SEVERITY COEFFICIENT () | COEFFICIENT VALUE | NUMERICAL VALUE |
|---|---|---|
| Reversibility () | None (R:N) Partial (R:P) Full (R:F) | 1 0.5 0.25 |
| Scope () | Changed (S:C) Unchanged (S:U) | 1.25 1 |
| Severity | Score Value Range |
|---|---|
| Critical | 9 - 10 |
| High | 7 - 8.9 |
| Medium | 4.5 - 6.9 |
| Low | 2 - 4.4 |
| Informational | 0 - 1.9 |
Critical
0
High
0
Medium
0
Low
0
Informational
4
| Security analysis | Risk level | Remediation Date |
|---|---|---|
| Unused Variables and Interface | Informational | Solved - 12/04/2025 |
| setMaxOffersPerWallet Allows Setting New Limit Equal to Existing Limit | Informational | Solved - 12/04/2025 |
| Ownership Transfer Uses Single-Step Pattern | Informational | Acknowledged - 12/05/2025 |
| Outdated Solidity Pragma Version | Informational | Solved - 12/04/2025 |
//Informational
//Informational
//Informational
//Informational
Halborn strongly recommends conducting a follow-up assessment of the project either within six months or immediately following any material changes to the codebase, whichever comes first. This approach is crucial for maintaining the project’s integrity and addressing potential vulnerabilities introduced by code modifications.
// Download the full report
ATokenOTC
* Use Google Chrome for best results
** Check "Background Graphics" in the print settings if needed
