Ten Protocol - Obscu/TEN

Prepared by:

HALBORN

Last Updated 06/18/2025

Date of Engagement: May 5th, 2025 - May 8th, 2025

Summary

100% of all REPORTED Findings have been addressed

All findings

Critical

High

Medium

Low

Informational

1. Introduction
2. Assessment summary
3. Test approach and methodology
4. Risk methodology
5. Scope
6. Assessment summary & findings overview
7. Findings & Tech Details

7.1 Missing validation of callbackid existence in canreattemptcallback modifier
7.2 Lack of callback cancellation and lifecycle controls
7.3 Inadequate callback array management
7.4 Single step ownership transfer process
7.5 Fixed token minting regardless of transaction value
7.6 Lack of transaction processing tracking mechanism
7.7 Missing error handling for callbacks
7.8 Unnecessary external call in _internalrefund when refund amount is zero
7.9 Missing input validation
7.10 Use of low-level transfer method
7.11 Floating pragma
7.12 Use of revert strings instead of custom errors
7.13 Unhandled return value in _payforcallback function
7.14 Missing events
7.15 Open to-dos
7.16 Redundant default value assignment
7.17 Public functions can be marked external
7.18 Commented functionality
7.19 Missing variable visibility
7.20 Lack of named mappings
7.21 Unused import
7.22 Unoptimized for loops

8. Automated Testing

1. Introduction

Ten Protocol engaged Halborn to conduct a security assessment on their smart contracts beginning on May 5th, 2025 and ending on May 8th, 2025. The security assessment was scoped to the smart contracts provided to Halborn. Commit hashes and further details can be found in the Scope section of this report.

The Ten Protocol codebase in scope mainly consists of an infrastructure with an upgradeable token system, cross-chain messaging, and transaction processing mechanisms.

2. Assessment Summary

Halborn was provided 4 days for the engagement and assigned 1 full-time security engineer to review the security of the smart contracts in scope. The engineer is a blockchain and smart contract security expert with advanced penetration testing and smart contract hacking skills, and deep knowledge of multiple blockchain protocols.

The purpose of the assessment is to:

Identify potential security issues within the smart contracts.
Ensure that smart contract functionality operates as intended.

In summary, Halborn identified some improvements to reduce the likelihood and impact of risks, which were partially addressed by the Ten Protocol team. The main ones are the following:

Add validation in the canReattemptCallback modifier to ensure the callbackId exists.
Consider adding functionality to allow callback originators to cancel their pending callbacks when they're no longer needed or desired.
Consider implementing a comprehensive callback management system.

3. Test Approach and Methodology

Halborn performed a combination of manual review of the code and automated security testing to balance efficiency, timeliness, practicality, and accuracy in regard to the scope of this assessment. While manual testing is recommended to uncover flaws in logic, process, and implementation; automated testing techniques help enhance coverage of smart contracts and can quickly identify items that do not follow security best practices.

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

Research into architecture, purpose and use of the platform.
Smart contract manual code review and walkthrough to identify any logic issue.
Thorough assessment of safety and usage of critical Solidity variables and functions in scope that could led to arithmetic related vulnerabilities.
Local testing with custom scripts (Foundry).
Fork testing against main networks (Foundry).
Static analysis of security for scoped contract, and imported functions (Slither).

4. RISK METHODOLOGY

Every vulnerability and issue observed by Halborn is ranked based on two sets of Metrics and a Severity Coefficient. This system is inspired by the industry standard Common Vulnerability Scoring System.

The two Metric sets are: Exploitability and Impact. Exploitability captures the ease and technical means by which vulnerabilities can be exploited and Impact describes the consequences of a successful exploit.

The Severity Coefficients is designed to further refine the accuracy of the ranking with two factors: Reversibility and Scope. These capture the impact of the vulnerability on the environment as well as the number of users and smart contracts affected.

The final score is a value between 0-10 rounded up to 1 decimal place and 10 corresponding to the highest security risk. This provides an objective and accurate rating of the severity of security vulnerabilities in smart contracts.

The system is designed to assist in identifying and prioritizing vulnerabilities based on their level of risk to address the most critical issues in a timely manner.

4.1 EXPLOITABILITY

Attack Origin (AO):

Captures whether the attack requires compromising a specific account.

Attack Cost (AC):

Captures the cost of exploiting the vulnerability incurred by the attacker relative to sending a single transaction on the relevant blockchain. Includes but is not limited to financial and computational cost.

Attack Complexity (AX):

Describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Includes but is not limited to macro situation, available third-party liquidity and regulatory challenges.

Metrics:

EXPLOITABILITY METRIC ( $m_e$ )	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

Exploitability

E

is calculated using the following formula:

$E = \prod m_e$

4.2 IMPACT

Confidentiality (C):

Measures the impact to the confidentiality of the information resources managed by the contract due to a successfully exploited vulnerability. Confidentiality refers to limiting access to authorized users only.

Integrity (I):

Measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of data stored and/or processed on-chain. Integrity impact directly affecting Deposit or Yield records is excluded.

Availability (A):

Measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. This metric refers to smart contract features and functionality, not state. Availability impact directly affecting Deposit or Yield is excluded.

Deposit (D):

Measures the impact to the deposits made to the contract by either users or owners.

Yield (Y):

Measures the impact to the yield generated by the contract for either users or owners.

Metrics:

IMPACT METRIC ( $m_I$ )	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

Impact

I

is calculated using the following formula:

$I = max(m_I) + \frac{\sum{m_I} - max(m_I)}{4}$

4.3 SEVERITY COEFFICIENT

Reversibility (R):

Describes the share of the exploited vulnerability effects that can be reversed. For upgradeable contracts, assume the contract private key is available.

Scope (S):

Captures whether a vulnerability in one vulnerable contract impacts resources in other contracts.

Metrics:

SEVERITY COEFFICIENT ( $C$ )	COEFFICIENT VALUE	NUMERICAL VALUE
Reversibility ( $r$ )	None (R:N) Partial (R:P) Full (R:F)	1 0.5 0.25
Scope ( $s$ )	Changed (S:C) Unchanged (S:U)	1.25 1

Severity Coefficient

C

is obtained by the following product:

$C = rs$

The Vulnerability Severity Score

S

is obtained by:

$S = min(10, EIC * 10)$

The score is rounded up to 1 decimal places.

Severity	Score Value Range
Critical	9 - 10
High	7 - 8.9
Medium	4.5 - 6.9
Low	2 - 4.4
Informational	0 - 1.9

5. SCOPE

REPOSITORY

(a) Repository: go-ten

(b) Assessed Commit ID: 6cae341

src/common/Structs.sol
src/system/contracts/Fees.sol
src/system/contracts/PublicCallbacks.sol

↓ Expand ↓

Out-of-Scope: Third party dependencies and economic attacks.

Remediation Commit ID:

fdc1a72

Out-of-Scope: New features/implementations after the remediation commit IDs.

6. Assessment Summary & Findings Overview

Critical

High

Medium

Low

Informational

Security analysis	Risk level	Remediation Date
Missing validation of callbackId existence in canReattemptCallback modifier	Low	Solved - 05/20/2025
Lack of callback cancellation and lifecycle controls	Low	Solved - 05/20/2025
Inadequate callback array management	Low	Partially Solved - 05/20/2025
Single step ownership transfer process	Low	Partially Solved - 05/20/2025
Fixed token minting regardless of transaction value	Low	Risk Accepted - 06/11/2025
Lack of transaction processing tracking mechanism	Low	Risk Accepted - 06/11/2025
Missing error handling for callbacks	Low	Risk Accepted - 06/11/2025
Unnecessary external call in _internalRefund when refund amount is zero	Informational	Acknowledged - 06/11/2025
Missing input validation	Informational	Partially Solved - 05/20/2025
Use of low-level transfer method	Informational	Solved - 05/20/2025
Floating pragma	Informational	Acknowledged - 06/11/2025
Use of revert strings instead of custom errors	Informational	Acknowledged - 06/11/2025
Unhandled return value in _payForCallback Function	Informational	Acknowledged - 06/11/2025
Missing events	Informational	Solved - 05/20/2025
Open To-Dos	Informational	Partially Solved - 05/20/2025
Redundant default value assignment	Informational	Solved - 05/20/2025
Public functions can be marked external	Informational	Solved - 05/20/2025
Commented functionality	Informational	Partially Solved - 05/20/2025
Missing variable visibility	Informational	Solved - 05/20/2025
Lack of named mappings	Informational	Solved - 05/20/2025
Unused import	Informational	Solved - 05/20/2025
Unoptimized for loops	Informational	Solved - 05/20/2025

Recommendation

Remediation Comment

Remediation Hash

https://github.com/ten-protocol/go-ten/commit/fdc1a7261852e33e7818c28bdad391e34dbfa7e7

7.10 Use of low-level transfer method

Informational

Description

BVSS

AO:S/AC:L/AX:L/R:N/S:U/C:N/A:M/I:N/D:N/Y:N (1.0)

Recommendation

Remediation Comment

Remediation Hash

https://github.com/ten-protocol/go-ten/commit/fdc1a7261852e33e7818c28bdad391e34dbfa7e7

8. Automated Testing

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.

1. Introduction
2. Assessment summary
3. Test approach and methodology
4. Risk methodology
5. Scope
6. Assessment summary & findings overview
7. Findings & Tech Details

7.1 Missing validation of callbackid existence in canreattemptcallback modifier
7.2 Lack of callback cancellation and lifecycle controls
7.3 Inadequate callback array management
7.4 Single step ownership transfer process
7.5 Fixed token minting regardless of transaction value
7.6 Lack of transaction processing tracking mechanism
7.7 Missing error handling for callbacks
7.8 Unnecessary external call in _internalrefund when refund amount is zero
7.9 Missing input validation
7.10 Use of low-level transfer method
7.11 Floating pragma
7.12 Use of revert strings instead of custom errors
7.13 Unhandled return value in _payforcallback function
7.14 Missing events
7.15 Open to-dos
7.16 Redundant default value assignment
7.17 Public functions can be marked external
7.18 Commented functionality
7.19 Missing variable visibility
7.20 Lack of named mappings
7.21 Unused import
7.22 Unoptimized for loops

Ten Protocol

Obscu/TEN

Table of Contents

1. Introduction

2. Assessment Summary

3. Test Approach and Methodology

4. RISK METHODOLOGY

4.1 EXPLOITABILITY

Attack Origin (AO):

Attack Cost (AC):

Attack Complexity (AX):

Metrics:

4.2 IMPACT

Confidentiality (C):

Integrity (I):

Availability (A):

Deposit (D):

Yield (Y):

Metrics:

4.3 SEVERITY COEFFICIENT

Reversibility (R):

Scope (S):

Metrics:

5. SCOPE

6. Assessment Summary & Findings Overview

7. Findings & Tech Details

7.1 Missing validation of callbackId existence in canReattemptCallback modifier

Description

BVSS

Recommendation

Remediation Comment

Remediation Hash

7.2 Lack of callback cancellation and lifecycle controls

Description

BVSS

Recommendation

Remediation Comment

Remediation Hash

7.3 Inadequate callback array management

Description

BVSS

Recommendation

Remediation Comment

Remediation Hash

7.4 Single step ownership transfer process

Description

BVSS

Recommendation

Remediation Comment

Remediation Hash

7.5 Fixed token minting regardless of transaction value

Description

BVSS

Recommendation

Remediation Comment

7.6 Lack of transaction processing tracking mechanism

Description

BVSS

Recommendation

Remediation Comment

7.7 Missing error handling for callbacks

Description

BVSS

Recommendation

Remediation Comment

7.8 Unnecessary external call in _internalRefund when refund amount is zero

Description

BVSS

Recommendation

Remediation Comment

7.9 Missing input validation

Description

BVSS

Recommendation

Remediation Comment

Remediation Hash

7.10 Use of low-level transfer method

Description

BVSS

Recommendation