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Security Audit
August 29th, 2023
Version 1.0.0
Presented by 0xMacro
This document includes the results of the security audit for Farcaster's smart contract code as found in the section titled ‘Source Code’. The security audit was performed by the Macro security team from August 23, 2023 to August 25, 2023.
The purpose of this audit is to review the source code of certain Farcaster 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 |
|---|---|---|---|---|
| Code Quality | 1 | - | - | 1 |
Farcaster 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:
5cf9b4ab044a40c84af8801fffb46390cd6f6099
Specifically, we audited the following contracts within this repository:
| Contract | SHA256 |
|---|---|
| src/Bundler.sol |
|
| src/FnameResolver.sol |
|
| src/IdRegistry.sol |
|
| src/KeyRegistry.sol |
|
| src/StorageRegistry.sol |
|
| src/interfaces/IMetadataValidator.sol |
|
| src/interfaces/IdRegistryLike.sol |
|
| src/lib/EIP712.sol |
|
| src/lib/Signatures.sol |
|
| src/lib/TransferHelper.sol |
|
| src/lib/TrustedCaller.sol |
|
| src/validators/SignedKeyRequestValidator. |
|
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. |
In KeyRegistry:
Consider correcting the in line comments in the bulk add and reset functions to reflect the correct name of the items array.
function bulkAddKeysForMigration(BulkAddData[] calldata items) external onlyOwner {
...
// Safety: i and j can be incremented unchecked since they are bound by items.length and
// item[i].keys.length respectively.
//== Corrected below ==
// Safety: i and j can be incremented unchecked since they are bound
//by items.length and items[i].keys.length respectively.
...
}
function bulkResetKeysForMigration(BulkResetData[] calldata items) external onlyOwner {
...
// Safety: i and j can be incremented unchecked since they are bound by items.length and
// fidKeys[i].length respectively.
//== Corrected below ==
// Safety: i and j can be incremented unchecked since they are bound
//by items.length and items[i].keys.length respectively.
...
}
Consider making the following corrections to the notice tags for the pause and unpause functions in the KeyRegistry.
//Originally
/**
* @notice Pause add, remove, and reset.e registration, transfer, and recovery.
* Must be called by the owner.
*/
//Corrected
/**
* @notice Pause add, remove, and reset.
* Must be called by the owner.
*/
function pause() external onlyOwner {
_pause();
}
//Originally
/**
* @notice Unpause add, remove, and reset.otice Unpause registration, transfer, and recovery.
* Must be called by the owner.
*/
//Corrected
/**
* @notice Unpause add, remove, and reset.
* Must be called by the owner.
*/
function unpause() external onlyOwner {
_unpause();
}
In IdRegistry:
Consider updating the notice for recoverFor() function to reflect that one of the signatures is from the recovery address associated with the fid being recovered rather than the from address.
/**
* @notice Transfer the fid owned by the from address to another address that does not
* have an fid. Caller must provide two signed Transfer messages: one signed by
* the from address and one signed by the to address.
// Corrected
/**
* @notice Transfer the fid owned by the from address to another address that does not
* have an fid. Caller must provide two signed Transfer messages: one signed by
* the recovery address and one signed by the to address.
In Bundler:
signers param natspec for register() function is missing metadataType in its list of fields
@param signers Array of structs containing signer parameters: keyType, key, metadata, deadline, and signature.
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 Farcaster 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.