Metamask Snap Audit Report for NuFi

Management Summary

NuFi contacted Sayfer Security in order to perform penetration testing on NuFi’s MetaMask Snap in 04/2024.

Before assessing the above services, we held a kickoff meeting with the NuFi technical team and received an overview of the system and the goals for this research.

Over the research period of 2 weeks, we discovered 2 vulnerabilities in the system.

In conclusion, several fixes should be implemented following the report, but the system’s security posture is competent.

After a review by the Sayfer team, we certify that all the security issues mentioned in this report have been addressed by the NuFi team.

Risk Methodology

At Sayfer, we are committed to delivering the highest quality penetration testing to our clients. That’s why we have implemented a comprehensive risk assessment model to evaluate the severity of our findings and provide our clients with the best possible recommendations for mitigation.

Our risk assessment model is based on two key factors: IMPACT and LIKELIHOOD. Impact refers to the potential harm that could result from an issue, such as financial loss, reputational damage, or a non-operational system. Likelihood refers to the probability that an issue will occur, taking into account factors such as the complexity of the attack and the number of potential attackers.

By combining these two factors, we can create a comprehensive understanding of the risk posed by a particular issue and provide our clients with a clear and actionable assessment of the severity of the issue. This approach allows us to prioritize our recommendations and ensure that our clients receive the best possible advice on how to protect their business.

Risk is defined as follows:

Security Evaluation Methodology

Sayfer uses OWASP WSTG as our technical standard when reviewing web applications. After gaining a thorough understanding of the system we decided which OWASP tests are required to evaluate the system.

Security Assessment

After understanding and defining the scope, performing threat modeling, and evaluating the correct tests required in order to fully check the application for security flaws, we performed our security assessment.

Issue Table Description

Issue title

Description

Here we provide a brief description of the issue and how it formed, the steps we made to find or exploit it, along with proof of concept (if present), and how this issue can affect the product or its users.

Mitigation

Suggested resolving options for this issue and links to advised sites for further remediation.

Security Assessment Findings

No Warning on Signing Arbitrary Data

Description

When signing arbitrary data, users might sign an off-chain approval or transaction data that can be later used for malicious activities. Therefore, it is worth reminding users that they should be confident that they understand what they are signing before commiting. It does not seem that any such warning is present.

• …/src/index.ts has a method of signing arbitrary data:

• Which is later defined in …/cardano__signData/index.ts:

• Finally, renderSignData() is defined in …/cardano__signData/ui.ts:

As you can see, the requested data is simply displayed and the user can sign it.

Mitigation

It is recommended to attach an additional warning for the user before letting them sign arbitrary data.

Floating Dependency Versions

Description

External dependencies of the snap are not pinned to an exact version but are instead set to a compatible version (ˆx.x.x).

• json:36-60

                    [...]
  "axios": "^0.28.0",
  "webpack-dev-middleware": "^5.3.4"
},
"devDependencies": {
  "@lavamoat/allow-scripts": "^3.0.0",
  "@lavamoat/preinstall-always-fail": "^2.0.0",
  "@metamask/eslint-config": "^12.0.0",
  "@metamask/eslint-config-jest": "^12.0.0",
  "@metamask/eslint-config-nodejs": "^12.0.0",
  "@metamask/eslint-config-typescript": "^12.0.0",
  "@typescript-eslint/eslint-plugin": "^5.42.1",
  "@typescript-eslint/parser": "^5.42.1",
  "eslint": "^8.45.0",
  "eslint-config-prettier": "^8.5.0",
  "eslint-plugin-import": "~2.26.0",
  "eslint-plugin-jest": "^27.1.5",
  "eslint-plugin-jsdoc": "^41.1.2",
  "eslint-plugin-n": "^15.7.0",
  "eslint-plugin-prettier": "^4.2.1",
  "eslint-plugin-promise": "^6.1.1",
  "prettier": "^2.7.1",
  "prettier-plugin-packagejson": "^2.2.18",
  "sharp": "^0.32.6",
  "typescript": "^4.7.4"
},
                    [...]

Mitigation

Pin dependencies to exact versions (=x.x.x), rather than indicating a minimally compatible one (ˆx.x.x).