Brink Audit | Lendle | Halborn Audit Reports

Summary

100% of all REPORTED Findings have been addressed

About this report

Assessment Type

Assurance Assessment

Date of Engagement

July 25th, 2025 - July 31st, 2025

Source Code

brink-v2

Assessed Commit ID

cdb4a0a

Severity Breakdown

0Risk Accepted
1Acknowledged
8Solved
9All Findings

Critical1
- 1Solved
High0
Medium0
Low4
- 4Solved
Informational4
- 3Solved
- 1Ack.

Summary#

Brink engaged Halborn to perform a security assessment of their smart contracts beginning on July 25th, 2025 and ending on August 12th, 2025. The assessment scope was limited to the smart contracts provided to Halborn. Commit hashes and additional details are available in the Scope section of this report.

Assessment Summary#

Halborn assigned 1 full-time security engineer to conduct a comprehensive review of the smart contracts within scope. The engineer is an expert in blockchain and smart contract security, with advanced skills in penetration testing and smart contract exploitation, as well as extensive knowledge of multiple blockchain protocols.

The objectives of this assessment were to:

Identify potential security vulnerabilities within the smart contracts.
Verify that the smart contract functionality operates as intended.

In summary, Halborn identified several areas for improvement to reduce the likelihood and impact of security risks. These were completely addressed by the Brink team. The main ones were:

Add access control on strategies implementations.
Use abi.encode rather than abi.encodePacked in the factory.
Restrict strategy allowances.

Test Approach and Methodology#

Halborn conducted a combination of manual code review and automated security testing to balance efficiency, timeliness, practicality, and accuracy within the scope of this assessment. While manual testing is crucial for identifying flaws in logic, processes, and implementation, automated testing enhances coverage of smart contracts and quickly detects deviations from established security best practices.

The following phases and associated tools were employed throughout the term of the assessment:

Research into the platform's architecture, purpose and use.
Manual code review and walkthrough of smart contracts to identify any logical issues.
Comprehensive assessment of the safety and usage of critical Solidity variables and functions within scope that could lead to arithmetic-related vulnerabilities.
Local testing using custom scripts (Foundry).
Fork testing against main networks (Foundry).
Static security analysis of scoped contracts, and imported functions (Slither).

Risk Methodology#

Every vulnerability and issue observed by Halborn is ranked based on two sets of Metrics and a Severity Coefficient. This system is inspired by the industry standard Common Vulnerability Scoring System.

The two Metric sets are: Exploitability and Impact. Exploitability captures the ease and technical means by which vulnerabilities can be exploited and Impact describes the consequences of a successful exploit.

The Severity Coefficients is designed to further refine the accuracy of the ranking with two factors: Reversibility and Scope. These capture the impact of the vulnerability on the environment as well as the number of users and smart contracts affected.

The final score is a value between 0-10 rounded up to 1 decimal place and 10 corresponding to the highest security risk. This provides an objective and accurate rating of the severity of security vulnerabilities in smart contracts.

The system is designed to assist in identifying and prioritizing vulnerabilities based on their level of risk to address the most critical issues in a timely manner.

4.1 EXPLOITABILITY

Attack Origin (AO):

Captures whether the attack requires compromising a specific account.

Attack Cost (AC):

Captures the cost of exploiting the vulnerability incurred by the attacker relative to sending a single transaction on the relevant blockchain. Includes but is not limited to financial and computational cost.

Attack Complexity (AX):

Describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Includes but is not limited to macro situation, available third-party liquidity and regulatory challenges.

Metrics:

EXPLOITABILITY METRIC ( $m_e$ )	METRIC VALUE	NUMERICAL VALUE
Attack Origin (AO)	Arbitrary (AO:A)	1
Attack Origin (AO)	Specific (AO:S)	0.2
Attack Cost (AC)	Low (AC:L)	1
	Medium (AC:M)	0.67
	High (AC:H)	0.33
Attack Complexity (AX)	Low (AX:L)	1
	Medium (AX:M)	0.67
	High (AX:H)	0.33

Exploitability

E

is calculated using the following formula:

$E = \prod m_e$

4.2 IMPACT

Confidentiality (C):

Measures the impact to the confidentiality of the information resources managed by the contract due to a successfully exploited vulnerability. Confidentiality refers to limiting access to authorized users only.

Integrity (I):

Measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of data stored and/or processed on-chain. Integrity impact directly affecting Deposit or Yield records is excluded.

Availability (A):

Measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. This metric refers to smart contract features and functionality, not state. Availability impact directly affecting Deposit or Yield is excluded.

Deposit (D):

Measures the impact to the deposits made to the contract by either users or owners.

Yield (Y):

Measures the impact to the yield generated by the contract for either users or owners.

Metrics:

IMPACT METRIC ( $m_I$ )	METRIC VALUE	NUMERICAL VALUE
Confidentiality (C)	None (C:N)	0
	Low (C:L)	0.25
	Medium (C:M)	0.5
	High (C:H)	0.75
	Critical (C:C)	1
Integrity (I)	None (I:N)	0
	Low (I:L)	0.25
	Medium (I:M)	0.5
	High (I:H)	0.75
	Critical (I:C)	1
Availability (A)	None (A:N)	0
	Low (A:L)	0.25
	Medium (A:M)	0.5
	High (A:H)	0.75
	Critical (A:C)	1
Deposit (D)	None (D:N)	0
	Low (D:L)	0.25
	Medium (D:M)	0.5
	High (D:H)	0.75
	Critical (D:C)	1
Yield (Y)	None (Y:N)	0
	Low (Y:L)	0.25
	Medium (Y:M)	0.5
	High (Y:H)	0.75
	Critical (Y:C)	1

Impact

I

is calculated using the following formula:

$I = max(m_I) + \frac{\sum{m_I} - max(m_I)}{4}$

4.3 SEVERITY COEFFICIENT

Reversibility (R):

Describes the share of the exploited vulnerability effects that can be reversed. For upgradeable contracts, assume the contract private key is available.

Scope (S):

Captures whether a vulnerability in one vulnerable contract impacts resources in other contracts.

Metrics:

SEVERITY COEFFICIENT ( $C$ )	COEFFICIENT VALUE	NUMERICAL VALUE
Reversibility ( $r$ )	None (R:N)	1
	Partial (R:P)	0.5
	Full (R:F)	0.25
Scope ( $s$ )	Changed (S:C)	1.25
Scope ( $s$ )	Unchanged (S:U)	1

Severity Coefficient

C

is obtained by the following product:

$C = rs$

The Vulnerability Severity Score

S

is obtained by:

$S = min(10, EIC * 10)$

The score is rounded up to 1 decimal places.

Critical	High	Medium	Low	Informational
9 - 10	7 - 8.9	4.5 - 6.9	2 - 4.4	0 - 1.9

Scope#

(a) Repository:brink-v2

(b) Assessed Commit ID:cdb4a0afe8ad8082f2f31ed33f05bf5610bcc452

10 files

contracts

10 files

libraries

4 files

ErrorsLib.sol

solidity

MathLib.sol

solidity

SharesMathLib.sol

solidity

UtilsLib.sol

solidity

strategies

3 files

aave

1 file

AaveStrategy.sol

solidity

lendle

1 file

LendleStrategy.sol

solidity

morpho

1 file

Out-of-Scope:Third-party dependencies and economic attacks.

1de4677e8cdd214e76f0a3d85cede110ab840ae4 0369a6a19eab09d98efa5d5a35e027d8a14f6b2d c25558881a9f2930a51ceae023dd0f62cf9ef83c 82afb299819a42538047d68748e2dc1c9532d53a 0ae829120cc7e0db92e3566cb80f464f904f791d eb6279b8c3919c22bfd3de86c3b3cebd4b7368dc fa6c2b44e7f2a2e58fd8db256fe661a7841edf80 99b08dc5053cf16f1a20722bd1733f693e2a3270

Out-of-Scope: New features/implementations after the remediation commit IDs.

Assessment Summary & Findings Overview#

#	Title	Severity	Score	Status
HAL-01	Aave and Lendle strategies allow unauthorized withdraws	Critical	10.0	Solved08/19/2025
HAL-02	Salt uses abi.encodePacked with dynamic type (risk of ambiguous hashing)	Low	2.5	Solved08/19/2025
HAL-03	Unrestricted dust forwarding method allows minor griefing	Low	2.5	Solved08/19/2025
HAL-04	Mint function overwrite the shares requested by the user	Low	2.5	Solved08/19/2025
HAL-05	Unrestricted allowance allows malicious strategies to steal deposits	Low	2.0	Solved08/19/2025
HAL-06	Vault accepts duplicate strategies at initialization	Informational	0.5	Solved08/22/2025
HAL-07	setStrategist permits zero address	Informational	0.0	Acknowledged08/19/2025
HAL-08	Missing top-level reentrancy guards	Informational	0.0	Solved08/19/2025
HAL-09	Reliance on EnumerableSet.values() Ordering Causes Weight/Strategy Misalignment	Informational	0.0	Solved08/19/2025

Findings & Tech Details#

Missing top-level reentrancy guards

Informational

0.0AO:A/AC:L/AX:L/R:N/S:U/C:N/A:N/I:N/D:N/Y:NAO:A/AC:L/AX:L/R:N/S:U/C:N/A:N/I:N/D:N/Y:N

Description

Recommendation

Remediation Comment

Addressed in:

fa6c2b44e7f2a2e58fd8db256fe661a7841edf80

HAL-09Solved

Reliance on EnumerableSet.values() Ordering Causes Weight/Strategy Misalignment

Informational

0.0AO:A/AC:L/AX:L/R:N/S:U/C:N/A:N/I:N/D:N/Y:NAO:A/AC:L/AX:L/R:N/S:U/C:N/A:N/I:N/D:N/Y:N

Description

Proof of Concept

Recommendation

Remediation Comment

Addressed in:

99b08dc5053cf16f1a20722bd1733f693e2a3270

8. Automated Testing#

Disclaimer#

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.