Auditing MetaMask Snaps – Essential Guidelines from an Approved Auditor

As the DeFi space continues to grow, the demand for customizable and adaptable tools increases. MetaMask Snaps, an extension system for the widely-used MetaMask browser add-on, caters to this need. These extensions, or “snaps,” enhance the wallet’s capabilities, enabling support for various blockchain networks, integration with different protocols, and tailored user interfaces. At Sayfer, as an approved MetaMask Snap auditor specializing in Web3 security, we recognize the potential of MetaMask Snaps and the security challenges they might pose. In this article, we will provide guidelines on the key aspects to examine when auditing MetaMask Snaps.

Code Quality

Secure snaps begin with high-quality code. We meticulously scrutinize the snap’s source code for adherence to industry best practices, appropriate error handling, and efficient resource management. Additionally, we ensure that the code is well-documented and straightforward, which helps us spot potential vulnerabilities or logic errors.

Authentication and Authorization

We validate that snaps implement robust authentication and authorization mechanisms. This involves confirming secure storage and encryption of private keys, and proper permission checks for sensitive actions, such as signing transactions or accessing user data.

Happy Path

A seamless user experience demands full compatibility between snaps and the MetaMask wallet and its underlying infrastructure. We test the snap’s integration with MetaMask, ensuring it doesn’t disrupt core wallet functions like managing accounts, signing transactions, and interacting with dApps.

User Privacy

Protecting user privacy is a top priority. Although there is usually no PII associated with the connected wallet, we still assess how snaps handle sensitive user information. We make sure it’s securely stored, encrypted, and not shared with unauthorized parties. Moreover, we verify that the snap offers transparent and concise privacy policies, detailing data collection and usage.

External Dependencies

Many snaps, like other JS applications, rely on external libraries or services for specific functions. We evaluate the security and reliability of these dependencies, ensuring they don’t introduce new vulnerabilities or negatively impact the snap’s performance.


As MetaMask Snaps gain popularity, security and reliability must remain top priorities. Leveraging our extensive experience in auditing Web3 applications, we at Sayfer can help identify and mitigate potential risks, contributing to a more secure and dependable decentralized ecosystem.

Written By
Or Duan

Or is a passionate cybersecurity expert and CTO & Co-founder of Sayfer, he brings a wealth of experience in web3, crypto, smart contract auditing, and penetration testing. Prior to establishing Sayfer, he played instrumental roles in various early-stage startups, driving them toward successful funding rounds and acquisitions.

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