SynthToken - Synthr

Prepared by:

HALBORN

Last Updated 11/28/2024

Date of Engagement by: November 28th, 2024 - November 28th, 2024

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 Owner can renounce ownership
7.2 Use of revert strings instead of custom errors

8. Automated Testing

1. Introduction

The Synthr team engaged Halborn to conduct a security assessment on their smart contracts beginning on April 24th, 2024 and ending on May 3rd, 2024. The security assessment was scoped to the smart contracts provided in the GitHub repository. Commit hashes and further details can be found in the Scope section of this report. This specific report is a dedicated portion of the broader assessment, focusing exclusively on the SynthToken contract.

2. Assessment Summary

Halborn was provided 1 day for the engagement and assigned 1 full-time security engineer to review the security of the smart contract 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 acknowledged by the Synthr team. The main ones were the following:

Limit access to renounceOwnership by ensuring ownership is transferred to another address first.
Replace hard-coded revert strings in require statements for custom errors.

Additionally, a centralization concern was noted, as the entire initial supply is minted to a single recipient, and the owner’s ability to pause and unpause the contract requires careful governance to mitigate potential misuse.

3. Test Approach and Methodology

Halborn performed a combination of manual 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 the code and can quickly identify items that do not follow the security best practices. The following phases and associated tools were used during the assessment:

Research into architecture and purpose.
Smart contract manual code review and walkthrough.
Graphing out functionality and contract logic/connectivity/functions (solgraph).
Manual assessment of use and safety for the critical Solidity variables and functions in scope to identify any arithmetic related vulnerability classes.
Manual testing by custom scripts.
Scanning of solidity files for vulnerabilities, security hot-spots or bugs. (MythX)
Static Analysis of security for scoped contract, and imported functions (slither).
Testnet deployment (Foundry).

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 (I:N) Low (I:L) Medium (I:M) High (I:H) Critical (I: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

Files and Repository

(a) Repository: synthr-staking

(b) Assessed Commit ID: 226556e

contracts/SynthToken.sol

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

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
HAL-01 - Owner Can Renounce Ownership	Informational	Acknowledged - 11/28/2024
HAL-02 - Use of Revert Strings Instead of Custom Errors	Informational	Acknowledged - 11/28/2024

7. Findings & Tech Details

7.1 (HAL-01) Owner Can Renounce Ownership

// Informational

Description

It was identified that the contracts inherited from OpenZeppelin's Ownable2Step library. In the Ownable contracts, the renounceOwnership() function is used to renounce the Owner permission. Renouncing ownership before transferring would result in the contract having no owner, eliminating the ability to call privileged functions.

BVSS

AO:A/AC:L/AX:L/C:N/I:N/A:L/D:N/Y:N/R:P/S:U (1.3)

Recommendation

It is recommended that the Owner cannot call renounceOwnership() without first transferring ownership to another address. In addition, if a multi-signature wallet is used, the call to the renounceOwnership() function should be confirmed for two or more users.

Remediation

ACKNOWLEDGED: The Synthr team acknowledged the issue.

7.2 (HAL-02) Use of Revert Strings Instead of Custom Errors

// Informational

Description

In Solidity smart contract development, replacing hard-coded revert message strings with the Error() syntax is an optimization strategy that can significantly reduce gas costs. Hard-coded strings, stored on the blockchain, increase the size and cost of deploying and executing contracts.

The Error() syntax allows for the definition of reusable, parameterized custom errors, leading to a more efficient use of storage and reduced gas consumption. This approach not only optimizes gas usage during deployment and interaction with the contract but also enhances code maintainability and readability by providing clearer, context-specific error information.

Score

AO:S/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:N/S:U (0.0)

Recommendation

It is recommended to replace hard-coded revert strings in require statements for custom errors, which can be done following the logic below:

1. Standard require statement (to be replaced):

require(condition, "Condition not met");

2. Declare the error definition to state:

error ConditionNotMet();

3. As currently is not possible to use custom errors in combination with require statements, the standard syntax is:

if (!condition) revert ConditionNotMet();

More information about this topic in the official Solidity documentation.

Remediation

ACKNOWLEDGED: The Synthr team acknowledged the issue.

8. Automated Testing

Static Analysis Report

Description

Halborn used automated testing techniques to enhance the coverage of certain areas of the smart contracts in scope. Among the tools used was Slither, a Solidity static analysis framework. After Halborn verified the smart contracts in the repository and was able to compile them correctly into their abis and binary format, Slither was run against the contracts. This tool can statically verify mathematical relationships between Solidity variables to detect invalid or inconsistent usage of the contracts' APIs across the entire code-base.

All issues identified by Slither were proved to be false positives or have been added to the issue list in this report.

Output

INFO:Slither:contracts/SynthToken.sol analyzed (12 contracts with 93 detectors), 0 result(s) found

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

SynthToken

Synthr

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 (HAL-01) Owner Can Renounce Ownership

Description

BVSS

Recommendation

Remediation

7.2 (HAL-02) Use of Revert Strings Instead of Custom Errors

Description

Score

Recommendation

Remediation

8. Automated Testing

Static Analysis Report

Description

Output

Table of Contents