Prepared by:
HALBORN
Last Updated 03/18/2025
Date of Engagement: March 5th, 2025 - March 7th, 2025
Summary
100% of all REPORTED Findings have been addressed
All findings
3
Critical
0
High
0
Medium
0
Low
0
Informational
3
Table of Contents
1. Introduction
Send Earn Protocol engaged Halborn to conduct a security assessment on their smart contracts beginning on March 5th, 2025 and ending on March 7th, 2025. The security assessment was scoped to the smart contracts provided to Halborn. Commit hashes and further details can be found in the Scope section of this report.
The Send Earn Protocol codebase in scope consists of permissionless, non-custodial USDC vaults with built-in referral rewards for community-driven yield generation.
2. Assessment Summary
Halborn was provided 3 days for the engagement and assigned 1 full-time security engineer to review the security of the smart contracts in scope. The engineer is a blockchain and smart contract security expert with advanced penetration testing and smart contract hacking skills, and deep knowledge of multiple blockchain protocols.
The purpose of the assessment is to:
Identify potential security issues within the smart contracts.
Ensure that smart contract functionality operates as intended.
In summary, Halborn identified some improvements to reduce the likelihood and impact of risks, which were mostly addressed by the Send Earn Protocol team. The main ones are the following:
Implement input validation to ensure that the input addresses are not 0.Remove the duplicated code from the contract.
3. Test Approach and Methodology
Halborn performed a combination of manual review of the code 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 smart contracts and can quickly identify items that do not follow security best practices.
The following phases and associated tools were used throughout the term of the assessment:
Research into architecture, purpose and use of the platform.
Smart contract manual code review and walkthrough to identify any logic issue.
Thorough assessment of safety and usage of critical Solidity variables and functions in scope that could led to arithmetic related vulnerabilities.
Local testing with custom scripts (
Foundry).Fork testing against main networks (
Foundry).Static analysis of security for scoped contract, and imported functions (
Slither).
4. Static Analysis Report
4.1 Description
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.
The security team assessed all findings identified by the Slither software, however, findings with related to external dependencies are not included in the below results for the sake of report readability.
4.2 Output
The findings obtained as a result of the Slither scan were reviewed, and many were not included in the report because they were determined as false positives.
5. RISK METHODOLOGY
5.1 EXPLOITABILITY
Attack Origin (AO):
Attack Cost (AC):
Attack Complexity (AX):
Metrics:
| EXPLOITABILITY METRIC () | METRIC VALUE | NUMERICAL VALUE |
|---|---|---|
| Attack Origin (AO) | Arbitrary (AO:A) Specific (AO:S) | 1 0.2 |
| Attack Cost (AC) | Low (AC:L) Medium (AC:M) High (AC:H) | 1 0.67 0.33 |
| Attack Complexity (AX) | Low (AX:L) Medium (AX:M) High (AX:H) | 1 0.67 0.33 |
5.2 IMPACT
Confidentiality (C):
Integrity (I):
Availability (A):
Deposit (D):
Yield (Y):
Metrics:
| IMPACT METRIC () | METRIC VALUE | NUMERICAL VALUE |
|---|---|---|
| Confidentiality (C) | None (I:N) Low (I:L) Medium (I:M) High (I:H) Critical (I:C) | 0 0.25 0.5 0.75 1 |
| Integrity (I) | None (I:N) Low (I:L) Medium (I:M) High (I:H) Critical (I:C) | 0 0.25 0.5 0.75 1 |
| Availability (A) | None (A:N) Low (A:L) Medium (A:M) High (A:H) Critical (A:C) | 0 0.25 0.5 0.75 1 |
| Deposit (D) | None (D:N) Low (D:L) Medium (D:M) High (D:H) Critical (D:C) | 0 0.25 0.5 0.75 1 |
| Yield (Y) | None (Y:N) Low (Y:L) Medium (Y:M) High (Y:H) Critical (Y:C) | 0 0.25 0.5 0.75 1 |
5.3 SEVERITY COEFFICIENT
Reversibility (R):
Scope (S):
Metrics:
| SEVERITY COEFFICIENT () | COEFFICIENT VALUE | NUMERICAL VALUE |
|---|---|---|
| Reversibility () | None (R:N) Partial (R:P) Full (R:F) | 1 0.5 0.25 |
| Scope () | Changed (S:C) Unchanged (S:U) | 1.25 1 |
| Severity | Score Value Range |
|---|---|
| Critical | 9 - 10 |
| High | 7 - 8.9 |
| Medium | 4.5 - 6.9 |
| Low | 2 - 4.4 |
| Informational | 0 - 1.9 |
6. SCOPE
- src/Platform.sol
- src/SendEarn.sol
- src/SendEarnAffiliate.sol
7. Assessment Summary & Findings Overview
Critical
0
High
0
Medium
0
Low
0
Informational
3
| Security analysis | Risk level | Remediation Date |
|---|---|---|
| Unrestricted functions allow for token movements | Informational | Acknowledged - 03/11/2025 |
| Missing input validation | Informational | Solved - 03/11/2025 |
| Duplicated code | Informational | Solved - 03/11/2025 |
8. Findings & Tech Details
8.1 Unrestricted functions allow for token movements
//
Description
The SendEarn contract includes a collect() function with no access restrictions:
function collect(address token) external {
if (collections == address(0)) revert Errors.ZeroAddress();
uint256 amount = IERC20(token).balanceOf(address(this));
IERC20(token).safeTransfer(collections, amount);
emit Events.Collect(_msgSender(), token, amount);
}Similarly, the SendEarnAffiliate contract contains an unrestricted pay() function that anyone can call:
function pay(IERC4626 vault) external {
IERC20 asset = IERC20(vault.asset());
if (address(asset) != address(payVault.asset())) revert Errors.AssetMismatch();
// find the amount of tokens to pay
uint256 amount = vault.balanceOf(address(this));
if (amount == 0) revert Errors.ZeroAmount();
// convert to the underlying asset
uint256 assets = vault.redeem(amount, address(this), address(this));
// calculate the split
uint256 split = splitConfig.split();
uint256 platformSplit = assets.mulDiv(split, Constants.SPLIT_TOTAL);
uint256 affiliateSplit = assets.mulDiv(Constants.SPLIT_TOTAL - split, Constants.SPLIT_TOTAL);
// transfer the split to the platform and affiliate
platformVault.deposit(platformSplit, splitConfig.platform());
payVault.deposit(affiliateSplit, affiliate);
emit Events.AffiliatePay(msg.sender, address(vault), address(asset), assets, platformSplit, affiliateSplit);
}Even though tokens are only sent to a trusted address, the lack of access control means that users can unexpectedly trigger token movements that might disrupt operations or cause accounting issues at inopportune times.
BVSS
Recommendation
If public access is intentional, document this behavior in the protocol's technical documentation and explain the rationale. If not intended, add appropriate access control to both functions.
Remediation Comment
ACKNOWLEDGED: The Send Earn Protocol team made a business decision to acknowledge this finding and not alter the contracts.
References
8.2 Missing input validation
//
Description
Some functions throughout the contracts in scope lack input validation. Instances of this issue include:
- SendEarn.setFeeRecipient()
- SendEarn.setCollections()
BVSS
Recommendation
Implement input validation to ensure that the input addresses are not 0.
Remediation Comment
SOLVED: The Send Earn Protocol team solved this finding in commit 646d000 by following the mentioned recommendation.
Remediation Hash
References
8.3 Duplicated code
//
Description
In the Platform contract, there's a redundant event emission in the platform management functions. When setPlatform() is called, it internally calls _setPlatform() which emits the Events.SetPlatform(newPlatform) event. However, after this call, setPlatform() also emits the exact same event with the same parameter:
function setPlatform(address newPlatform) external onlyPlatform {
if (newPlatform == platform()) revert Errors.AlreadySet();
_setPlatform(newPlatform);
emit Events.SetPlatform(newPlatform); // Duplicate emission
}
function _setPlatform(address newPlatform) internal {
if (newPlatform == platform()) revert Errors.AlreadySet();
if (newPlatform == address(0)) revert Errors.ZeroAddress();
_platform = newPlatform;
emit Events.SetPlatform(newPlatform); // Already emitted here
}Additionally, there's a duplicated error check (if (newPlatform == platform()) revert Errors.AlreadySet();) that appears in both functions.
BVSS
Recommendation
Remove the duplicated code from the contract.
Remediation Comment
SOLVED: The Send Earn Protocol team solved this finding in commit c575d46 by following the mentioned recommendation.
Remediation Hash
References
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.
Table of Contents
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