Friendly Casper Token Minter Audit | Casper Association

Summary

95% of all REPORTED Findings have been addressed

About this report

Assessment Type

Assurance Assessment

Date of Engagement

July 4th, 2025 - August 8th, 2025

Source Code

csprfun-core

Assessed Commit ID

0dde699

Severity Breakdown

1Not Solved
1Partially Solved
11Acknowledged
1Risk Accepted
6Solved
20All Findings

Critical0
High2
- 2Solved
Medium0
Low5
- 1Risk A.
- 2Solved
- 1P. Solved
- 1Not Solved
Informational13
- 11Ack.
- 2Solved

Introduction#

Casper Association engaged Halborn to conduct a security assessment of the DAO contracts, beginning on July 4th, 2025 and ending on August 8th, 2025. This security assessment was scoped to the smart contracts in the csprfun-core contracts GitHub repository.

The engagement involved a detailed, line-by-line security review of all smart contracts within the Friendly Casper Token Minter ecosystem. This included analysis of the contract code, entry point implementations, bonding curve mechanics, DEX integration, and related administrative controls.

Assessment Summary#

Halborn's team of blockchain security specialists conducted a rigorous smart contract audit on the Friendly Casper Token Minter ecosystem. The review involved a cross-functional team of experts working over a 4 week period to uncover deeply embedded logic flaws, economic design risks, and practical implementation bugs. The primary goal was to stress-test the security posture for token issuance and trading.

The overall architecture demonstrates robust on-chain controls and correct use of Casper primitives. Most critical business logic passed all functional test cases, supporting safe minting, trading, and graduation to DEX liquidity.

However, the audit identified important areas for improvement, which have been partially addressed:

Insufficient input validation. Some functions accept parameters (like tax or fee rates) that can break economic incentives or degrade product safety.
Unexposed getter/setter functions and excessive token approvals—potentially reducing transparency and exposing contracts to privilege escalation or attack in edge cases.
Lack of event emissions, inconsistent error handling, and documentation gaps—reducing upgrade transparency and maintainability.
Numerous minor code hygiene issues: debug code, commented/dead code, naming mismatches.

Test Approach and Methodology#

Halborn employs a combined approach of manual code review and automated security testing to ensure a balanced assessment of efficiency, thoroughness, and practicality within the scope of the smart contract review. Manual testing is essential for uncovering logical flaws, process weaknesses, and implementation issues, while automated techniques expand coverage and rapidly identify security best practice violations. The following phases and tools were utilized throughout the assessment:

Research into the architecture, purpose, and usage of the platform.
Manual code review and walkthrough.
Manual assessment of critical Rust variables and functions to evaluate their use and safety, focusing on identifying potential arithmeticrelated vulnerabilities.
Verification of cross-contract call controls.
Review of architecture-related logical controls.
Scanning Rust files for vulnerabilities using cargo audit)
Analysis and review of unit tests and integration tests.
Deployment to testnet via casper-client.

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:csprfun-core

(b) Assessed Commit ID:0dde699aafb5326be04003c065f042056392bc6d

32 files

contract / src

19 files

cep18

10 files

allowances.rs

rust

balances.rs

rust

constants.rs

rust

error.rs

rust

events.rs

rust

lib.rs

rust

mod.rs

rust

modalities.rs

rust

security.rs

rust

utils.rs

rust

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

97fce36cc81f3a76c12bddcbfc719f699da0e40f ab4249021fd5eb002321f1bba1379ab18b363273 6f916d052131c854de26f7038055b8de2267facf 86b789cf97f498118668f2a12d4fca700fd8cdb7 a8f1a70318afeeb324cf190acb85bc783f25604f

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

Assessment Summary & Findings Overview#

#	Title	Severity	Score	Status
HAL-01	Missing Contract Address Update Functions Break Protocol When External Contracts Upgrade	High	8.8	Solved07/16/2025
HAL-02	Incorrect Tax Calculation in Bonding Curve Leads to Reduced Output Amount, Protocol Fee Loss and Reserve Imbalances	High	8.4	Solved07/16/2025
HAL-03	Malicious Tax Configuration Enables DEX Pool Drainage and Blocks WCSPR Returns	Low	4.1	Risk Accepted07/16/2025
HAL-04	Missing Getter Functions Lead to Blind Trading	Low	3.8	Solved07/16/2025
HAL-05	Excessive Token Approvals in DEX Liquidity Addition	Low	3.3	Partially Solved07/16/2025
HAL-06	Missing Getter Function for Token Metadata	Low	2.5	Solved07/16/2025
HAL-07	Missing Upper Limit Validation for Protocol Fee Configuration	Low	2.4	Not Solved
HAL-08	Missing Zero Amount Validation in Trade Function	Informational	1.7	Acknowledged
HAL-09	Lacking Event Emissions for Critical Parameter Changes	Informational	1.7	Acknowledged
HAL-10	Missing Input Validation For Graduation Parameters	Informational	0.3	Acknowledged
HAL-11	Mismatch Between EntryPoint Type Signatures and Their Implementations	Informational	0.0	Solved07/17/2025
HAL-12	Unused Contract Installation Function	Informational	0.0	Acknowledged
HAL-13	Unnecessary Runtime Arguments in CEP18 Initialization	Informational	0.0	Acknowledged
HAL-14	Unnecessary Type Conversion in Return Statement	Informational	0.0	Acknowledged
HAL-15	Unnecessary Wrapper Function Adds Code Bloat	Informational	0.0	Acknowledged
HAL-16	Commented Out Code and Dead Code Indicates Code Quality Issues	Informational	0.0	Acknowledged
HAL-17	Documentation Inconsistencies	Informational	0.0	Acknowledged
HAL-18	Inconsistent Error Handling Patterns	Informational	0.0	Acknowledged
HAL-19	Debug Code Present in Production	Informational	0.0	Solved07/16/2025
HAL-20	Inconsistent Naming Conventions For Fee and Tax Parameters	Informational	0.0	Acknowledged

Findings & Tech Details#

HAL-01Solved

Missing Contract Address Update Functions Break Protocol When External Contracts Upgrade

High

8.8AO:A/AC:L/AX:M/R:N/S:U/C:N/A:C/I:N/D:H/Y:MAO:A/AC:L/AX:M/R:N/S:U/C:N/A:C/I:N/D:H/Y:M

Description

Proof of Concept

Recommendation

Remediation Comment

Addressed in:

Remediation Comment

Addressed in:

Remediation Comment

Addressed in:

a8f1a70318afeeb324cf190acb85bc783f25604f

HAL-20Acknowledged

Inconsistent Naming Conventions For Fee and Tax Parameters

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

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.