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Security Audit
March 28, 2024
Version 1.0.0
Presented by 0xMacro
This document includes the results of the security audit for Illuvium's smart contract code as found in the section titled ‘Source Code’. The security audit was performed by the Macro security team on March 27, 2024.
The purpose of this audit is to review the source code of certain Illuvium Solidity contracts, and provide feedback on the design, architecture, and quality of the source code with an emphasis on validating the correctness and security of the software in its entirety.
Disclaimer: While Macro’s review is comprehensive and has surfaced some changes that should be made to the source code, this audit should not solely be relied upon for security, as no single audit is guaranteed to catch all possible bugs.
The following is an aggregation of issues found by the Macro Audit team:
| Severity | Count | Acknowledged | Won't Do | Addressed |
|---|---|---|---|---|
| Medium | 2 | - | - | 2 |
| Code Quality | 3 | - | - | 3 |
Illuvium was quick to respond to these issues.
Our understanding of the specification was based on the following sources:
Notable features of the contract include minting and burning, pausability, and upgradeability. The contract implements a roles-based access control with dedicated roles for each of the aforementioned functionalities. The roles include:
ADMIN_ROLE - can grant rolesUPGRADER_ROLE - can upgrade the contractPAUSER_ROLE - can pause and unpause the contractBURNER_ROLE - can burn tokensMINTER_ROLE - can mint tokensThe following source code was reviewed during the audit:
ddf9761591e0593f9132283d219c41fc2ed6fb31
d1a3ab8a3a354237d7b2984facf6a0731a411380
Specifically, we audited the following contract within this repository:
| Source Code | SHA256 |
|---|---|
| contracts/Fuel.sol |
|
Note: This document contains an audit solely of the Solidity contracts listed above. Specifically, the audit pertains only to the contracts themselves, and does not pertain to any other programs or scripts, including deployment scripts.
Click on an issue to jump to it, or scroll down to see them all.
We quantify issues in three parts:
This third part – the severity level – is a summary of how much consideration the client should give to fixing the issue. We assign severity according to the table of guidelines below:
| Severity | Description |
|---|---|
|
(C-x) Critical |
We recommend the client must fix the issue, no matter what, because not fixing would mean significant funds/assets WILL be lost. |
|
(H-x) High |
We recommend the client must address the issue, no matter what, because not fixing would be very bad, or some funds/assets will be lost, or the code’s behavior is against the provided spec. |
|
(M-x) Medium |
We recommend the client to seriously consider fixing the issue, as the implications of not fixing the issue are severe enough to impact the project significantly, albiet not in an existential manner. |
|
(L-x) Low |
The risk is small, unlikely, or may not relevant to the project in a meaningful way. Whether or not the project wants to develop a fix is up to the goals and needs of the project. |
|
(Q-x) Code Quality |
The issue identified does not pose any obvious risk, but fixing could improve overall code quality, on-chain composability, developer ergonomics, or even certain aspects of protocol design. |
|
(I-x) Informational |
Warnings and things to keep in mind when operating the protocol. No immediate action required. |
|
(G-x) Gas Optimizations |
The presented optimization suggestion would save an amount of gas significant enough, in our opinion, to be worth the development cost of implementing it. |
The Fuel contracts inherits from ERC20PausableUpgradeable contract with the goal to support pausing and unpausing of certain functions via the whenNotPaused modifier.
However, inheriting the ERC20PausableUpgradeable contract requires to provide a public pause and unpause function to make use of the pausing capability.
Remediation to Consider
Add a public pause and unpause function to the contract. The functions should only be callable by a privileged role.
The whenNotPaused modifier is applied to the burn, mint, and _authorizeUpgrade functions, enabling pausing capability for those.
While allowing pausing for burn and mint functions makes sense in case of an emergency, it doesn’t necessarily for the _authorizeUpgrade function. A common scenario is to pause any ERC-20 functionality in case of an issue and then upgrade the contract with a fixed version. However, applying whenNotPaused to the _authorizeUpgrade function would prevent fixing the contract when it is paused.
Remediation to Consider
Remove the whenNotPaused modifier from _authorizeUpgrade to allow the contract to be upgraded when in paused state.
whenNotPaused modifier
The whenNotPaused modifier is applied to the burn and mint functions, with the intention to pause/unpause the burning and minting of tokens.
However, the contracts already inherits from ERC20PausableUpgradeable, applying pausability to mint, burn, and transfers. Thus, whenNotPaused modifier is not explicitly required on respective mint and burn functions.
Remediation to Consider
Remove whenNotPaused modifier from burn and mint functions.
init instead of init_unchained
In the initialize function, the ERC20 contract is initialized with
__ERC20_init_unchained(name, symbol);
whereas the other parent contracts are all initialized using the init function instead of init_unchained.
Remediation to Consider
For consistency reasons, use the __ERC20_init function for initializing the ERC20 contract.
external instead of public for functions
The public functions initialize, burn, and mint are not used internally and thus can be safely marked as external.
Remediation to Consider
To follow Solidity conventions, mark the above functions as external instead of public.
Macro makes no warranties, either express, implied, statutory, or otherwise, with respect to the services or deliverables provided in this report, and Macro specifically disclaims all implied warranties of merchantability, fitness for a particular purpose, noninfringement and those arising from a course of dealing, usage or trade with respect thereto, and all such warranties are hereby excluded to the fullest extent permitted by law.
Macro will not be liable for any lost profits, business, contracts, revenue, goodwill, production, anticipated savings, loss of data, or costs of procurement of substitute goods or services or for any claim or demand by any other party. In no event will Macro be liable for consequential, incidental, special, indirect, or exemplary damages arising out of this agreement or any work statement, however caused and (to the fullest extent permitted by law) under any theory of liability (including negligence), even if Macro has been advised of the possibility of such damages.
The scope of this report and review is limited to a review of only the code presented by the Illuvium team and only the source code Macro notes as being within the scope of Macro’s review within this report. This report does not include an audit of the deployment scripts used to deploy the Solidity contracts in the repository corresponding to this audit. Specifically, for the avoidance of doubt, this report does not constitute investment advice, is not intended to be relied upon as investment advice, is not an endorsement of this project or team, and it is not a guarantee as to the absolute security of the project. In this report you may through hypertext or other computer links, gain access to websites operated by persons other than Macro. Such hyperlinks are provided for your reference and convenience only, and are the exclusive responsibility of such websites’ owners. You agree that Macro is not responsible for the content or operation of such websites, and that Macro shall have no liability to your or any other person or entity for the use of third party websites. Macro assumes no responsibility for the use of third party software and shall have no liability whatsoever to any person or entity for the accuracy or completeness of any outcome generated by such software.