Contracts Core and BSX Token (2nd round) Audit | BSX Exchange

Summary

100% of all REPORTED Findings have been addressed

About this report

Assessment Type

Assurance Assessment

Date of Engagement

October 9th, 2024 - October 23rd, 2024

Source Code

contracts-core bsx-token

Assessed Commit ID

d932bdf https://github.com/bsx-exchange/bsx-token/tree/ae321534940931779b8e7f550565c22890251ff8

Severity Breakdown

1Acknowledged
4Risk Accepted
6Solved
11All Findings

Critical0
High1
- 1Solved
Medium4
- 2Solved
- 2Risk A.
Low3
- 1Solved
- 2Risk A.
Informational3
- 2Solved
- 1Ack.

Introduction#

BSX engaged Halborn to conduct a security assessment on their smart contracts beginning on October 9th, 2024 and ending on October 23rd, 2024. The security assessment was scoped to the BSX Exchange smart contracts in the GitHub repository provided to the Halborn team. Commit hashes and further details can be found in the Scope section of this report.

Assessment Summary#

Halborn was provided two weeks for the engagement and assigned one full-time security engineer to review the security of the smart contract 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 partially addressed by the BSX team. The main identified issues were the following:

Guarantee solvency when opening new positions
Disable intializers in contracts constructors
Initialize inherited contracts
Take all inputs into account when signing payloads to guarantee total integrity
Keep the storage variable in the same place between two versions of a contract
Prevent integer silent signed to unsigned casting

Test Approach and Methodology#

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 contracts' solidity code 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 and purpose.
Smart contract manual code review and walk-through.
Manual assessment of use and safety for the critical Solidity variables and functions in scope to identify any arithmetic-related vulnerability classes.
Local testing with custom scripts (Foundry).
Fork testing against main networks (Foundry).
Static analysis of security for scoped contract, and imported functions

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:contracts-core

(b) Assessed Commit ID:d932bdf9b631cc5bfa50d86ab825033f801818d8

26 files

1000x

2 files

interfaces

1 file

IBSX1000x.sol

solidity

BSX1000x.sol

solidity

exchange

24 files

access

1 file

Access.sol

solidity

interfaces

11 files

external

5 files

IERC20Extend.sol

solidity

IERC3009Minimal.sol

solidity

IUniversalRouter.sol

solidity

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

(a) Repository:bsx-token

(b) Assessed Commit ID:https://github.com/bsx-exchange/bsx-token/tree/ae321534940931779b8e7f550565c22890251ff8

1 files

BsxToken.sol

solidity

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

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

Assessment Summary & Findings Overview#

#	Title	Severity	Score	Status
HAL-01	BSX1000 solvency not guaranteed	High	7.5	Solved10/27/2024
HAL-02	Missing constructor disabling initialization	Medium	5.8	Solved10/27/2024
HAL-03	Missing initialization of inherited upgradable contracts	Medium	5.8	Solved10/27/2024
HAL-04	Payloads to sign do not include all input parameters	Medium	5.0	Risk Accepted10/27/2024
HAL-05	Removing storage variables in upgradable contracts	Medium	5.0	Risk Accepted10/27/2024
HAL-06	Integer unsafe casting issues	Low	4.2	Solved10/27/2024
HAL-07	Order fees are charged twice	Low	3.1	Risk Accepted10/27/2024
HAL-08	Truncated balance not accrued to fund balance after withdrawal	Low	2.5	Risk Accepted10/27/2024
HAL-09	ETH deposit does not validate the amount sent	Informational	0.7	Solved10/27/2024
HAL-10	High fees can block the closing position process	Informational	0.7	Acknowledged10/27/2024
HAL-11	Confusing error messages	Informational	0.0	Solved10/27/2024

Findings & Tech Details#

HAL-01Solved

BSX1000 solvency not guaranteed

High

7.5AO:A/AC:L/AX:L/R:P/S:U/C:N/A:C/I:N/D:C/Y:CAO:A/AC:L/AX:L/R:P/S:U/C:N/A:C/I:N/D:C/Y:C

Description

Proof of Concept

Recommendation

Remediation Comment

HAL-02Solved

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.