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Security Audit
August 23, 2024
Version 1.0.0
Presented by 0xMacro
This document includes the results of the security audit for Orange's smart contract code as found in the section titled ‘Source Code’. The security audit was performed by the Macro security team on June 10th to 11th, 2024.
The purpose of this audit is to review the source code of certain Orange 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 |
|---|---|---|---|---|
| Low | 2 | - | 1 | 1 |
| Code Quality | 7 | - | 1 | 6 |
Orange was quick to respond to these issues.
Our understanding of the specification was based on the following sources:
The following source code was reviewed during the audit:
3dc15bac175c5e1c6d6e18daa2d1df51b2ee2034
Specifically, we audited the following contract within this repository:
| Contract | SHA256 |
|---|---|
| ./contracts/AvaxBridge.sol |
|
| ./contracts/BridgeDeposit.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.
bridge() and mistakenly lock their assets
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 current signature verification scheme, verifies the correct targe chainId is provided in the message data but has no domain separator specified in EIP712. This means that if this contract is re-used in the same chain, all previous valid signatures would be replayable in different contracts, as they do not include the intended verifying contract address, version and name. Consider using EIP712 signature validation.
bridge() and mistakenly lock their assets
In AvaxBridge.sol, bridge() function can be called by any user, locking their tokens in the contract. Since the intended use case is to distribute and migrate tokens as protocol, consider adding an onlyOwner modifier to this function to avoid this case.
The current sigData message has the following encoded parameters:
uint64 oracleQuantity = 0;
uint64 id;
uint32 ts;
uint64 fromAddr;
uint64 symbolRaw;
uint8 chainId;
address toAddress;
Reference: AvaxBridge.sol#L820-826
However, parameters fromAddr and symbolRaw are currently not used by the bridge/claim logic. Consider removing these unused parameters and adapting the signature generation to this.
The BridgeDeposit contract, intended to receive and burn users’ tokens, allows the owner to transfer them to any arbitrary address. Consider hardcoding the burn address in the withdraw function to disallow the owner from arbitrarily or atomically transferring tokens in the deposit function.
The current AvaxBridge solidity pragma version is set to ^0.6.12. Consider using the same specific solidity version as the deployed reference codebase v0.6.12. Also, consider setting the same specific EVM version to istambul.
Variables rfox and chainId can be marked as immutable, as they are only being set in the contract’s constructor during deployment.
The following code is not being used in AvaxBridge contract and can be removed:
ApproveAndCallFallBack is not being inherited from or implemented.onlyOracle modifier is not being used.As its name suggests, the AvaxBridge contract was previously used to bridge and claim tokens through off-chain signatures. However, the current intended use case is not transparent with the current comments and function description, and some functions are missing NatSpecs comments. Consider adding and updating comments to the current intended use case.
While checking each signature validity on each provided signatures parameter, the logic iterates over all and verifies breaks if the numberSigs is higher or equal than hardcoded 10.
for (uint8 i = 0; i < signatures.length; i++) {
address potential = _getSigner(message, signatures[i]);
// Check that they are an oracle and they haven't signed twice
if (oracles[potential] && !signed[td.id][potential]) {
signed[td.id][potential] = true;
numberSigs++;
if (numberSigs >= 10) {
break;
}
}
}
Reference: AvaxBridge.sol#L878-890
However, numberSigs will never be higher than 10 as it is always incremented by one and checked after that, and the length of the signatures parameter is required to be <= 10.
require(
signatures.length <= 10,
"Maximum of 10 signatures can be provided"
);
Reference: AvaxBridge.sol#L869-872
Consider changing the comparison statement to numberSigs == 10.
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The scope of this report and review is limited to a review of only the code presented by the Orange 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.