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VOLO

Audit name:

[SCA] VOLO | Liquid Staking | Aug2023

Date:

Sep 20, 2023

Table of Content

→Introduction
→Audit Summary
→Document Information
→System Overview
→Executive Summary
→Risks
→Findings
→Appendix 1. Severity Definitions
→Appendix 2. Scope
→Disclaimer

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Introduction

We express our gratitude to the VOLO team for the collaborative engagement that enabled the execution of this Smart Contract Security Assessment.

Volo is an LSD platform that integrates decentralized Liquid Staking and LSD Vaults on SUI Network.

titlecontent
PlatformSui
LanguageMove
TagsLiquid Staking
Timeline15/08/2023 - 22/09/2023
Methodologyhttps://hackenio.cc/sc_methodology→

    Review Scope

    Repositoryhttps://github.com/Ankr-network/stakefi-sui-smart-contract/→
    Commit6662d76109670a458cde7f739938b203cf183780

    Audit Summary

    Total8.5/10
    Security Score

    9/10

    Test Coverage

    82.16%

    Code Quality Score

    9/10

    Documentation Quality Score

    10/10

    6Total Findings
    4Resolved
    0Accepted
    0Mitigated

    The system users should acknowledge all the risks summed up in the risks section of the report

    Document Information

    This report may contain confidential information about IT systems and the intellectual property of the Customer, as well as information about potential vulnerabilities and methods of their exploitation.

    The report can be disclosed publicly after prior consent by another Party. Any subsequent publication of this report shall be without mandatory consent.

    Document

    NameSmart Contract Code Review and Security Analysis Report for VOLO
    Audited ByHacken
    Websitehttp://volo.fi/→
    Changelog22/08/2023 - Initial Review
    22/09/2023 - Second Review

    • Document

      Name
      Smart Contract Code Review and Security Analysis Report for VOLO
      Audited By
      Hacken
      Website
      http://volo.fi/→
      Changelog
      22/08/2023 - Initial Review
      22/09/2023 - Second Review

    System Overview

    The VOLO Liquid Staking is a protocol that allows users to exchange SUI tokens for special voloSUI tokens that could be used in the VOLO Ecosystem and other DeFi protocols partnered with VOLO Protocol.

    The SUI tokens are staked using the native suisystem_ module, whose implementation is out of the audit scope.

    Stakers are able to request exchanging their voloSUI for SUI with rewards accrued, unstaked funds will be returned in the current or the next epoch.

    There are several smart contracts in the audit scope:

    • ownership — manages owner and operator capabilities.

    • cert — voloSUI token contract, stores and updates SUI to voloSUI exchange rate.

    • nativepool — contract allows exchange SUI for voloSUI_ and requests to exchange it back at a possibly better rate.

    • math — math utility contract.

    • validatorset_ — a contract that manages validators.

    • unstaketicket_ — a contract that handles tickets, which serve as proof of unstaking, while waiting to exchange tokens.

    Privileged roles

    The Owner and Operator are able to transfer their permission independently of each other.

    • cert:

      • Owner — Update the contract and migrate the associated objects to it.

    • ownership:

      • Owner — Transfer the owner role to another address.

      • Operator - Transfer operator role to another address.

    • nativepool_:

      • Owner - Change min stake amount.

      • Owner - Change unstake fee threshold (not more than 100%).

      • Owner - Change base unstake fee (not more than 100%).

      • Owner - Change base reward fee (not more than 100%).

      • Owner - Update rewards threshold.

      • Owner - Can withdraw fees from the contract.

      • Owner - Can pause or unpause contract. In the paused contract it is not possible for the owner to withdraw fees, sort validators, burn tickets to release unstaking, stake SUI and update rewards.

      • Owner — Update the contract and migrate the associated objects to it.

      • Operator — Add new validators with specified priorities.

      • Operator - Can increase the ratio of reward tokens.

    Executive Summary

    Documentation quality

    The total Documentation quality score is 10 out of 10.

    • Public documentation provides the system basics.

    • Internal documentation provides valuable insights into the system architecture and general interaction flow.

    • The configuration instructions are insufficient.

    Code quality

    The total Code quality score is 9 out of 10.

    • The code is well-written and designed.

    • The code contains unused variables.

    • Contradiction in variable naming exists.

    Test coverage

    Code coverage of the project is 82.16%.

    Security score

    Upon auditing, the code was found to contain 0 critical, 2 high, 1 medium, and 2 low severity issues. Out of these, 3 issues have been addressed and resolved, leading to a Security score of 9 out of 10.

    All identified issues are detailed in the “Findings” section of this report.

    Summary

    The comprehensive audit of the customer's smart contract yields an overall score of 8.5. This score reflects the combined evaluation of documentation, code quality, test coverage, and security aspects of the project.

    Scoring Methodologyarrow right

    Risks

    Users are unable to withdraw their funds immediately. They burn their voloSUI and register in a queue to get SUI in return.

    The smart contracts system is designed to be upgradeable. The owner may change the system logic in the future.

    The owner is able to pause all the pool functionality.

    The owner may set arbitrary minimum thresholds for stake and unstake amounts.

    Findings

    Code
    ―
    Title
    Status
    Severity
    F-2023-0404Requirements Violation; Data Consistency
    fixed

    High
    F-2023-0403Invalid Calculations; Data Consistency
    fixed

    High
    F-2023-0405Denial Of Service & Inefficient Gas Model
    unfixed

    Medium
    F-2023-0407Missing Event Emit
    fixed

    Low
    F-2023-0406Unused Variables/Structs
    unfixed

    Low
    I-2023-0084Contradiction
    fixed

    Observation
    1-6 of 6 findings

    Identify vulnerabilities in your smart contracts.

    Appendix 1. Severity Definitions

    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, do not affect security score but can affect code quality score.

    • 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, do not affect security score but can affect code quality score.

    Appendix 2. Scope

    The scope of the project includes the following smart contracts from the provided repository:

    Scope Details

    Repositoryhttps://github.com/Ankr-network/stakefi-sui-smart-contract/→
    Commit6662d76109670a458cde7f739938b203cf183780
    WhitepaperNot Provided
    RequirementsProvided→
    Technical RequirementsProvided→

    Contracts in Scope

    cert.move - cert.move
    math.move - math.move
    native_pool.move - native_pool.move
    ownership.move - ownership.move
    unstake_ticket.move - unstake_ticket.move
    validator_set.move - validator_set.move

    Disclaimer

    VOLO audit by Hacken