← Back to Audits

Beefy Hedera Contracts - Bonzo Finance

Prepared by:

Halborn Logo

HALBORN

Last Updated 09/11/2025

Date of Engagement: July 22nd, 2025 - August 11th, 2025

Summary

100% of all REPORTED Findings have been addressed

All findings

7

Critical

0

High

2

Medium

1

Low

0

Informational

4

Table of Contents

1. Introduction

Bonzo Finance engaged Halborn to conduct a security assessment on their smart contracts beginning on July 22nd, 2025 and ending on August 11th, 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 Bonzo Finance codebase in scope consists of different smart contracts, allowing users to generate yield on their assets, using underlying protocols like Uniswap and Aave forks. The contracts are forked from Beefy, with a good amount of modifications.

2. Assessment Summary

Halborn was provided 21 days for the engagement and assigned a full-time security engineer to review the security of the smart contracts in scope.

 

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 areas for improvement to reduce the likelihood and impact of potential risks, which were partially addressed by the Bonzo finance Team:

    • Handle conversions between assets correctly.

    • Handle precision properly when calculating pool prices.

    • Choose ticks according to the way Uniswap works to avoid DoS.

    • Avoid insecure use of 'slot0' for liquidity calculation to prevent sandwich attacks.

    • Prevent griefing attacks via 'permit' in 'stakeWithPermit'.

    • Ensure event arguments in '_harvest' are correct.

    • Correct looping approves to avoid an extra unnecessary iteration.


3. Test Approach and Methodology

Halborn performed a manual review of the code. Manual testing is great to uncover flaws in logic, process, and implementation.

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.


4. 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 (mem_e)METRIC VALUENUMERICAL 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
Exploitability EE is calculated using the following formula:

E=∏meE = \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 (mIm_I)METRIC VALUENUMERICAL VALUE
Confidentiality (C)None (C:N)
Low (C:L)
Medium (C:M)
High (C:H)
Critical (C: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
Impact II is calculated using the following formula:

I=max(mI)+∑mI−max(mI)4I = 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 (CC)COEFFICIENT VALUENUMERICAL VALUE
Reversibility (rr)None (R:N)
Partial (R:P)
Full (R:F)		1
0.5
0.25
Scope (ss)Changed (S:C)
Unchanged (S:U)		1.25
1
Severity Coefficient CC is obtained by the following product:

C=rsC = rs

The Vulnerability Severity Score SS is obtained by:

S=min(10,EIC∗10)S = min(10, EIC * 10)

The score is rounded up to 1 decimal places.
SeverityScore Value Range
Critical9 - 10
High7 - 8.9
Medium4.5 - 6.9
Low2 - 4.4
Informational0 - 1.9

5. SCOPE

REPOSITORY
(a) Repository: beefy-hedera-contracts
(b) Assessed Commit ID: 9540de1
(c) Items in scope:
  • BeefyOracleSupra.sol
  • BeefyOracle.sol
  • BonzoHBARXLevergedLiqStaking.sol
↓ Expand ↓
Out-of-Scope: External dependencies and economic attacks.
Remediation Commit ID:
Out-of-Scope: New features/implementations after the remediation commit IDs.

6. Assessment Summary & Findings Overview

Critical

0

High

2

Medium

1

Low

0

Informational

4

Security analysisRisk levelRemediation Date
Incorrect sauce token conversionsHighSolved - 08/14/2025
Pool price is computed incorrectlyHighSolved - 08/14/2025
Wrong tick choice causes DoS of vault operationsMediumSolved - 08/14/2025
Liquidity calculation based on unvalidated slot0 priceInformationalAcknowledged - 08/21/2025
Griefing Attack via permit in stakeWithPermitInformationalSolved - 08/21/2025
Looping approves for 1 extra iterationInformationalAcknowledged - 08/14/2025
Incorrect Event Argument in _harvestInformationalSolved - 08/21/2025

7. Findings & Tech Details

7.1 Incorrect sauce token conversions

//

High

Description
BVSS
Recommendation
Remediation Comment
Remediation Hash
https://github.com/Bonzo-Labs/beefy-hedera-contracts/commit/68a0cfd5e29d86c2ab2585d3b94bf26e347f03d0

7.2 Pool price is computed incorrectly

//

High

Description
BVSS
Recommendation
Remediation Comment
Remediation Hash
https://github.com/Bonzo-Labs/beefy-hedera-contracts/commit/68a0cfd5e29d86c2ab2585d3b94bf26e347f03d0

7.3 Wrong tick choice causes DoS of vault operations

//

Medium

Description
BVSS
Recommendation
Remediation Comment
Remediation Hash
https://github.com/Bonzo-Labs/beefy-hedera-contracts/commit/68a0cfd5e29d86c2ab2585d3b94bf26e347f03d0

7.4 Liquidity calculation based on unvalidated slot0 price

//

Informational

Description
BVSS
Recommendation
Remediation Comment

7.5 Griefing Attack via permit in stakeWithPermit

//

Informational

Description
BVSS
Recommendation
Remediation Comment
Remediation Hash
https://github.com/Bonzo-Labs/beefy-hedera-contracts/commit/8ea5565e53341f331826ad07a635a3223a913870

7.6 Looping approves for 1 extra iteration

//

Informational

Description
BVSS
Recommendation
Remediation Comment
Remediation Hash
https://github.com/Bonzo-Labs/beefy-hedera-contracts/commit/68a0cfd5e29d86c2ab2585d3b94bf26e347f03d0

7.7 Incorrect Event Argument in _harvest

//

Informational

Description
BVSS
Recommendation
Remediation Comment
Remediation Hash
https://github.com/Bonzo-Labs/beefy-hedera-contracts/commit/516f1a2b2bd96c9810f4ec2032c911c667194087

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.

// Download the full report

Beefy Hedera Contracts

* Use Google Chrome for best results

** Check "Background Graphics" in the print settings if needed

© Halborn 2025. All rights reserved.