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Security Audit
December 09, 2024
Version 1.0.0
Presented by 0xMacro
This document includes the results of the security audit for Citrus Finance's smart contract code as found in the section titled ‘Source Code’. The security audit was performed by the Macro security team from December 6, 2024 to December 9, 2024.
The purpose of this audit is to review the source code of certain Citrus Finance 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 | - | 1 | 1 |
| Code Quality | 1 | - | - | 1 |
Citrus Finance 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:
0d6b674819b54f6b836430dc92eae16e6d35777e
b847a0b073a495c2fa02a08c95d605f91e81cb5e
Specifically, we audited the messaging layer contracts within this repository:
| Source Code | SHA256 |
|---|---|
| src/GlobalModule.sol |
|
| src/ModuleSetup.sol |
|
| src/interfaces/ISafe.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. |
| Topic | Protocol Design | |
| Status | Fixed | |
| Impact | High |
Lost funds |
|
Lost funds |
||
| Likelihood | Low |
Requires admin user error |
|
Requires admin user error |
||
The execTransaction() payable function allows to send a specific value to the safe call through the value input parameter:
function execTransaction(
ISafe safe,
address to,
uint256 value,
bytes calldata data,
uint8 operation,
bytes memory signatures
) external payable virtual returns (bool) {
...
// If execution fails, the whole transaction should fail
// so that the nonce is not updated.
// @dev If that transaction cannot be executed, use skipNonce.
if (!safe.execTransactionFromModule(to, value, data, operation)) {
revert ExecutionFailed(address(safe));
}
return true;
}
Reference: GlobalModule.sol#L44-80
However, this value is being sent to the GlobalModule contract itself, and not the Safe contract. If one were to accidentally send ETH with a execTransaction call, then that ETH would get stuck in the contract.
Consider removing the payable modifier to disallow calls with native value.
| Topic | Replay Attacks | |
| Status | Wont Do |
See client response below. |
| Impact | High |
Old configurations could create vulnerabilities in other parts of the system. |
|
Old configurations could create vulnerabilities in other parts of the system. |
||
| Likelihood | Low |
A copy of an existing Safe must be deployed to a new chain, likelihood increasing as more txs are run over time. However, also requires vulnerable contracts or assets in other parts of the Citrus system. |
|
A copy of an existing Safe must be deployed to a new chain, likelihood increasing as more txs are run over time. However, also requires vulnerable contracts or assets in other parts of the Citrus system. |
||
GlobalModule allows Safe’s owners to make cross-chain Safe calls by keeping track of each chain's call via that chain's GlobalModule instance's nonces mapping. In other words, once a call has been made on a chain, that nonce will increment, disallowing that same call from being made again (on that specific chain).
However, if one were to deploy a new Safe + GlobalModule, then its nonce starts at zero, exposing a potential replay attack.
For example:
10 GlobalModule transactions have executed for these Safes.Y.Y now has a new Safe (with the same owners, to get the same address), and a new GlobalModule with nonce zero.n fails, then calling skipNonce is required. This will take time for signers to coordinate, opening a potential replay attack window where an attacker can replay up to k transactions (where k < n), in order, to manipulate onchain state. Since these transactions are potentially quite old, they could potentially expose a vulnerability in the Citrus system.Consider one of the following options, depending on project needs:
setNonce that allows setting a Safe’s nonce to an arbitrary but strictly increasing value.We will warn users if their chain is not on the latest nonce and encourage them to sync it themselves. Additionally, we will ensure one of the following:
- The product operates independently of the transaction (current project).
- The product requires the transaction, preventing deposits until resolved (future projects).
- A circuit breaker is in place (future projects) to:
- Respond immediately in emergencies.
- Allow signers to coordinate fixes.
- Avoid blocking users from withdrawing funds where possible.
| Topic | Standards Interop | |
| Status | Fixed | |
| Quality Impact | High |
The current SAFE_TX_TYPEHASH value was generated by keccak hashing the string SafeTx(address safe, address to,uint256 value,bytes data,uint8 operation,uint256 nonce).
However, the encodeTransactionData() implementation uses bytes32 data instead of bytes data.
Although signing still works (as evidenced by the passing tests), this could still break offchain tooling and wallets that rely on the hash to be correct, so we recommend fixing this discrepancy.
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 Citrus Finance 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.