Prepared by:
HALBORN
Last Updated 09/20/2024
Date of Engagement by: May 20th, 2024 - May 31st, 2024
100% of all REPORTED Findings have been addressed
All findings
1
Critical
0
High
0
Medium
1
Low
0
Informational
0
The 1kx team engaged Halborn to conduct a security assessment on their smart contracts and circuits, beginning on May 20, 2024, and ending on May 31, 2024. The security assessment was scoped to the smart contracts and circuits inside their zksafe GitHub repository, located at https://github.com/1kx-network/zksafe/blob/main, commit 5d55130d7a9deddf15025a479dff65ba8582def6.
The team at Halborn was provided two weeks for the engagement and assigned two full-time security engineers to assess the security of the smart contracts and the zero knowledge circuits. Both security engineers are blockchain, smart-contract, and ZK security experts with advanced penetration testing, smart-contract hacking, and deep knowledge of multiple blockchain protocols.
The purpose of this assessment is to achieve the following:
Ensure that the system operates as intended.
Identify potential security issues.
Identify lack of best practices within the codebase.
Identify systematic risks that may pose a threat in future releases.
Identify common ZK issues found in ZK circuits.
In summary, Halborn identified one security issue that was addressed by the 1kx team.
Halborn performed a combination of manual and automated security testing to balance efficiency, timeliness, practicality, and accuracy in regard to the scope of this assessment. While manual testing is recommended to uncover flaws in logic, process, and implementation; automated testing techniques help enhance coverage of the code and can quickly identify items that do not follow the security best practices. The following phases and associated tools were used during the assessment:
Research into architecture and purpose.
Smart contract manual code review and walkthrough.
Graphing out functionality and contract logic/connectivity/functions (solgraph).
Manual assessment of use and safety for the critical Solidity variables and functions in scope to identify any arithmetic-related vulnerability classes.
Manual testing by custom scripts.
Static Analysis of security for scoped contract, and imported functions (slither).
Testnet deployment (Foundry).
Running ZK tests with nargo.
Critical
0
High
0
Medium
1
Low
0
Informational
0
Impact x Likelihood
HAL-01
| Security analysis | Risk level | Remediation Date |
|---|---|---|
| Loss of ETH when executing a transaction from the module | Medium | Solved - 05/31/2024 |
// Medium
Due to adding the payable keyword and not implementing a way to pull out the ETH sent, if the call to sendZkSafeTransaction carries ETH, then those funds will remain locked within the module.
It can be seen in the function definition that it accepts calls with ETH attached due to having the payable keyword:
function sendZkSafeTransaction(
GnosisSafe safeContract,
// The Safe address to which the transaction will be sent.
Transaction calldata transaction,
// The proof blob.
bytes calldata proof
) public payable virtual returns (bool)However, through the Safe module, there is no way to pull such tokens out, as it purpose is to validate transactions and executing them in the context of the Safe contract, not to hold funds. Moreover, the only place where it would make sense to do that would be in the last call to the Safe contract's execTransactionFromModule:
return safeContract.execTransactionFromModule(
transaction.to,
transaction.value,
transaction.data,
transaction.operation
);But
Such a function does NOT accept ETH, as it is not payable.
To pass ETH, it would need to add the syntax {value : transaction.value in between the function name and the first (, which is not the case.
Because of that, the ETH that a tx carries will be locked within the module forever.
Remove the payable keyword to prevent the transaction from carrying ETH. This makes sense, as the funds that the approved transaction will use will be those of the Safe contract, not the ones carried with the send one.
SOLVED: The 1kx team solved this issue as recommended, removing the payable keyword from the function definition.
Halborn used automated testing techniques to enhance the coverage of certain areas of the smart contracts in scope. Among the tools used was Slither, a Solidity static analysis framework. After Halborn verified the smart contracts in the repository and was able to compile them correctly into their ABIs and binary format, Slither was run against the contracts. This tool can statically verify mathematical relationships between Solidity variables to detect invalid or inconsistent usage of the contracts' APIs across the entire code-base.
Overall, the reported issues were not mostly low/informational issues that did not pose a real threat to the system, so they were not considered to be part of this report.
Halborn strongly recommends conducting a follow-up assessment of the project either within six months or immediately following any material changes to the codebase, whichever comes first. This approach is crucial for maintaining the project’s integrity and addressing potential vulnerabilities introduced by code modifications.
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