Audit name:
[SCA] Gotbit | Bridge | May2023
Date:
Jun 7, 2023
Table of Content
Introduction
We express our gratitude to the Gotbit team for the collaborative engagement that enabled the execution of this Smart Contract Security Assessment.
GotBit Labs is a provider of web3 development and consulting services. They perform in diverse areas within the web3 ecosystem, including blockchain technology, crafting decentralized applications (DApps), pioneering contract development, and other associated fields.
| title | content |
|---|---|
| Platform | EVM |
| Language | Solidity |
| Tags | Bridge |
| Timeline | 17/05/2023 - 09/06/2023 |
| Methodology | https://hackenio.cc/sc_methodology→ |
Review Scope | |
|---|---|
| Repository | https://github.com/GotBit/bridge→ |
| Commit | 82eb229f24dbb0d9a30203886420d6bc62cedf95 |
Review Scope
- Repository
- https://github.com/GotBit/bridge→
- Commit
- 82eb229f24dbb0d9a30203886420d6bc62cedf95
Audit Summary
10/10
100%
10/10
10/10
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 Gotbit |
| Audited By | Hacken |
| Changelog | 22/05/2023 - Initial Review |
| 07/06/2023 - Second Review | |
| 09/06/2023 - Third Review |
Document
- Name
- Smart Contract Code Review and Security Analysis Report for Gotbit
- Audited By
- Hacken
- Changelog
- 22/05/2023 - Initial Review
- 07/06/2023 - Second Review
- 09/06/2023 - Third Review
System Overview
The audit of the scope consists of a bridge contract for ERC20 transfers between chains. The aim is to implement a bridge that provides transfers both between EVM chains and from EVM to non-EVM chains and vice versa.
The system works using signature verification using the EIP712 standard. The transactions are signed by a relayer to be ready for fulfillment.
The files in the scope:
BridgeAssist.sol - The bridge contract that records requests for sending tokens between chains, and fulfills requests if signed by the relayer.
Privileged roles
Relayer: is the backend contract address, which is used for signing transactions to fulfill.
DefaultAdmin: can grant/revoke all roles, can set
fee,feeWallet,limitPerSend, pause/unpause contract and withdraw tokens from contract.
Executive Summary
Documentation quality
The total Documentation quality score is 10 out of 10.
Functional requirements are provided.
Technical description is provided.
Description of the development environment is given.
NatSpec is present.
Code quality
The total Code quality score is 10 out of 10.
The development environment is configured.
Test coverage
Code coverage of the project is 100% (branch coverage).
Deployment and basic user interactions are covered with tests.
Negative cases coverage is present.
Interactions by several users are not tested thoroughly.
Security score
Upon auditing, the code was found to contain 1 critical, 5 high, 6 medium, and 4 low severity issues. Out of these, 10 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 10. This score reflects the combined evaluation of documentation, code quality, test coverage, and security aspects of the project.
Risks
The project is highly centralized, with a Relayer role that controls the release of funds on each chain. If the private keys of the Relayer are lost or there is malicious intent, the protocol could be vulnerable to attack.
The fulfill() function has the whenNotPaused modifier, if the contract is paused, users will not be able to receive their funds.
There is a withdraw() function for the Admin role to withdraw any tokens from the contract, including the token that is bridged. If compromised, all tokens stored inside bridge contracts will be lost.
The bridge fee can be changed between sending and fulfilling and has an upper limit of 99.99%. This may lead to the losses of funds during bridging.
The chains have to be manually whitelisted by the admin and can be removed at any moment, rendering all pending transactions unclaimable.
The bridge supports fee on transfers tokens and reflective tokens only if the bridge is excluded from the fees.
The fee can be changed at any time by the owner, transfers that are already started, but not completely fulfilled will have the new fee value applied.
Findings
Code ― | Title | Status | Severity | |
|---|---|---|---|---|
| F-2023-0678 | Funds Lock; Denial of Service | fixed | Critical | |
| F-2023-0683 | Inconsistent Data | fixed | High | |
| F-2023-0682 | Funds Lock | mitigated | High | |
| F-2023-0681 | Inconsistent Data | mitigated | High | |
| F-2023-0680 | Undocumented Functionality | mitigated | High | |
| F-2023-0679 | Token Supply Manipulation | mitigated | High | |
| F-2023-0689 | Denial of Service | fixed | Medium | |
| F-2023-0688 | Highly Permissive Role Access | mitigated | Medium | |
| F-2023-0687 | Undocumented Functionality | fixed | Medium | |
| F-2023-0686 | Coarse-grained Access Control | mitigated | Medium |
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 | |
|---|---|
| Repository | https://github.com/GotBit/bridge→ |
| Commit | 82eb229f24dbb0d9a30203886420d6bc62cedf95 |
| Whitepaper | Not provided |
| Requirements | Provided→ |
| Technical Requirements | Provided→ |
Scope Details
- Repository
- https://github.com/GotBit/bridge→
- Commit
- 82eb229f24dbb0d9a30203886420d6bc62cedf95
- Whitepaper
- Not provided
- Requirements
- Provided→
- Technical Requirements
- Provided→