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EverValue Coin

Audit name:

[SCA] EverValue Coin / BurnVault / May2024

Date:

Jun 11, 2024

Table of Content

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Introduction

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Audit Summary

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Document Information

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System Overview

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Executive Summary

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Risks

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Findings

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Appendix 1. Severity Definitions

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Appendix 2. Scope

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Disclaimer

Introduction

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

EverValue Coin (EVA) is an ERC20 token designed to work on the Arbitrum network, offering a decentralized finance (DeFi) ecosystem centered around token burns and exchanges. EVA is burnable and interacts with various smart contracts, allowing holders to increase their value by burning tokens for a share of wBTC reserves, thus creating a dynamic share system.

    Audit Summary

    Total9.6/10
    Security Score

    10/10

    Code Quality Score

    8/10

    Test Coverage

    100%

    Documentation Quality Score

    10/10

    8Total Findings
    1Resolved
    7Accepted
    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

      Name
      Smart Contract Code Review and Security Analysis Report for EverValue Coin
      Audited By
      Eren Gönen
      Approved By
      Ataberk Yavuzer
      Changelog
      28/05/2024 - Preliminary Report
      03/07/2024 - Final Report

    System Overview

    EverValue Coin is an ERC20 token with a burnable feature that interacts with other contracts like EVAMarket and EVABurnVault. These contracts allow users to buy, sell, or burn EVA tokens and receive market tokens or wBTC in return. The following contracts are involved:

    EverValueCoin  — A burnable ERC20 token with a limited supply, designed to work on the Arbitrum network. This contract manages the minting and burning of EVA tokens, with a capped total supply of 21,000,000 tokens. It has the following attributes:

    • Name: EverValueCoin

    • Symbol: EVA

    • Decimals: 18

    • Total supply: 21 m tokens.

    EVABurnVault  — A vault that allows users to burn EVA tokens in exchange for backing wBTC tokens. The contract facilitates the burning of EVA tokens and ensures fair distribution of wBTC tokens.

    EVAMarket  — A centralized market for buying and selling EVA tokens at administratively defined rates. The contract allows users to buy or sell EVA tokens using a defined market token, with adjustable rates and fees.

    Privileged roles

    • The owner of the EVAMarket contract can set the transaction fee for selling EVA tokens and withdraw all tokens from the contract.

    Executive Summary

    Documentation quality

    The total Documentation quality score is 10 out of 10.

    • Functional requirements are provided

    • Technical description is provided.

    Code quality

    The total Code quality score is 8 out of 10.

    • The development environment is configured.

    • Some best practices are missed.

    Test coverage

    Code coverage of the project is 100% (branch coverage).

    • Everything covered with tests.

    Security score

    Upon auditing, the code was found to contain 0 critical, 0 high, 1 medium, and 0 low severity issues. Out of these, 1 issues have been addressed and resolved, leading to a security score of 10 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 9.6. This score reflects the combined evaluation of documentation, code quality, test coverage, and security aspects of the project.

    Risks

    Solidity Version Compatibility: The Solidity version 0.8.20 employs the recently introduced PUSH0 opcode in the Shanghai EVM. This opcode might not be universally supported across all blockchain networks and Layer 2 solutions. Thus, as a result, it might be not possible to deploy solution with version 0.8.20 >= on some blockchains.

    Centralized Minting to a Single Address: The project concentrates minting tokens in a single address, raising the risk of fund mismanagement or theft, especially if key storage security is compromised.

    Absence of Pausable Feature for Unexpected Events: Without the pausable feature, the contract cannot be immediately paused in the event of unexpected occurrences.

    Insufficient Multi-signature Controls for Critical Functions: The lack of multi-signature requirements for key operations centralizes decision-making power, increasing vulnerability to single points of failure or malicious insider actions, potentially leading to unauthorized transactions or configuration changes.

    Findings

    Code
    ―
    Title
    Status
    Severity
    F-2024-4200
    		Sales made with low amounts can be made for free due to lack of control
    Fixed

    Medium
    F-2024-3282
    		Inadequate Management of Transaction Fees in Token Sale Function
    Accepted

    Observation
    F-2024-3279
    		Lack of Upper Bound on marketTokenPer100Eva Parameter
    Accepted

    Observation
    F-2024-3274
    		Redundant _msgSender(), Meta-Transactions Not Implemented
    Accepted

    Observation
    F-2024-3273
    		State Variables Only Set in The Constructor Should Be Declared immutable
    Accepted

    Observation
    F-2024-3272
    		Redundant imports
    Accepted

    Observation
    F-2024-3271
    		Functions that Can Be Declared External
    Accepted

    Observation
    F-2024-3270
    		Missing Events
    Accepted

    Observation
    1-8 of 8 findings

    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

      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:

    • Deployed Contracts

      addrEva

      Arbitrum

      0x45d9831d8751b2325f3dbf48db748723726e1c8c

      Deployed Contracts

      addrBurnVault

      Arbitrum

      0xA89d65deF0A001947d8D5fDda93F9C4f8453902e

      Deployed Contracts

      addrMarket

      Arbitrum

      0x53314ba4c6015466b881d614F3840CF0d038e94C

    Contracts in Scope

    contracts
    EverValueCoin.sol - contracts/EverValueCoin.sol
    EVABurnVault.sol - contracts/EVABurnVault.sol
    EVAMarket.sol - contracts/EVAMarket.sol

    Disclaimer