MetaMask Snap Audit Report For Tezos

Management Summary

Tezos contacted Sayfer Security in order to perform a security audit on Tezos MetaMask Snap in June 2023.

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

Over the research period of 2 weeks, we discovered 4 findings in the system.

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

Vulnerabilities by Risk

High – Direct threat to key business processes.
Medium – Indirect threat to key business processes or partial threat to business processes.
Low – No direct threat exists. The vulnerability may be exploited using other vulnerabilities.
Informational – This finding does not indicate vulnerability, but states a comment that notifies about design flaws and improper implementation that might cause a problem in the long run.

# of issues



Tezos contacted Sayfer to perform penetration testing on Tezos MetaMask Snap application.

This report documents the research carried out by Sayfer targeting the selected resources defined under the research scope. Particularly, this report displays the security posture review for the Tezos MetaMask Snap application and its surrounding infrastructure and process implementations.

Our penetration testing project life cycle:


Scope Overview


Technical Overview


Scope Validation


Threat Model


Security Evaluation


Security Assessment

Scope Overview

During our first meeting and after understanding the company’s needs, we defined the application’s scope that resides at the following URLs as the scope of the project:

  • Tezos MetaMask Snap

Commit hash: 0e0d653b85cbd11365771ad9c2ee5726b10a7d26

Our tests were performed from 01.06 to 23.06 2023

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Scope Validation

We began by ensuring that the scope defined to us by the client was technically logical. Deciding what scope is right for a given system is part of the initial discussion. Getting the scope right is key to deriving maximum business value from the research.

Threat Model

During our kickoff meetings with the client we defined the most important assets the application possesses.

We defined that the largest current threat to the system is sensitive user information.

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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

ID The OWASP ID of the issue. Additional tests that we conduct and are not included in the OWASP table will have Sayfer ID.
Example ID: WSTG-INFO-002
WSTG – Web Security Test Guide.
INFO – A shorthand for the topic to which the issue belongs.
002 – Issue number.
Risk Represents the risk factor of the issue. For further description refer to the Vulnerabilities by Risk section.
Required Skill Describes the skill level required to conduct successful exploitation. The lower the skill level the easier the exploitation process.
A link to the relevant OWASP page for further knowledge.
Location The URL in which this issue was detected. Issues with no location have no particular location and refer to the product as a whole.
Tools The tools used to detect the issue.


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. .


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

Security Evaluation

The following tests were conducted while auditing the system

Information Gathering

Information Gathering Test Name
WSTG-INFO-01 Conduct Search Engine Discovery Reconnaissance for Information Leakage
WSTG-INFO-02 Fingerprint Web Server
WSTG-INFO-03 Review Webserver Metafiles for Information Leakage
WSTG-INFO-04 Enumerate Applications on Webserver
WSTG-INFO-05 Review Webpage Content for Information Leakage
WSTG-INFO-06 Identify application entry points
WSTG-INFO-07 Map execution paths through application
WSTG-INFO-08 Fingerprint Web Application Framework
WSTG-INFO-09 Fingerprint Web Application
WSTG-INFO-10 Map Application Architecture

Configuration and Deploy Management Testing

Configuration and Deploy Management Testing Test Name
WSTG-CONF-01 Test Network Infrastructure Configuration
WSTG-CONF-02 Test Application Platform Configuration
WSTG-CONF-03 Test File Extensions Handling for Sensitive Information
WSTG-CONF-04 Review Old Backup and Unreferenced Files for Sensitive Information
WSTG-CONF-05 Enumerate Infrastructure and Application Admin Interfaces
WSTG-CONF-06 Test HTTP Methods
WSTG-CONF-07 Test HTTP Strict Transport Security
WSTG-CONF-08 Test RIA cross domain policy
WSTG-CONF-09 Test File Permission
WSTG-CONF-10 Test for Subdomain Takeover
WSTG-CONF-11 Test Cloud Storage

Identity Management Testing

Identity Management Testing Test Name
WSTG-IDNT-01 Test Role Definitions
WSTG-IDNT-02 Test User Registration Process
WSTG-IDNT-03 Test Account Provisioning Process
WSTG-IDNT-04 Testing for Account Enumeration and Guessable User Account
WSTG-IDNT-05 Testing for Weak or unenforced username policy

Authentication Testing

Authentication Testing Test Name
WSTG-ATHN-01 Testing for Credentials Transported over an Encrypted Channel
WSTG-ATHN-02 Testing for Default Credentials
WSTG-ATHN-03 Testing for Weak Lock Out Mechanism
WSTG-ATHN-04 Testing for Bypassing Authentication Schema
WSTG-ATHN-05 Testing for Vulnerable Remember Password
WSTG-ATHN-06 Testing for Browser Cache Weaknesses
WSTG-ATHN-07 Testing for Weak Password Policy
WSTG-ATHN-08 Testing for Weak Security Question Answer
WSTG-ATHN-09 Testing for Weak Password Change or Reset Functionalities
WSTG-ATHN-10 Testing for Weaker Authentication in Alternative Channel

Authorization Testing

Authorization Testing Test Name
WSTG-ATHZ-01 Testing Directory Traversal File Include
WSTG-ATHZ-02 Testing for Bypassing Authorization Schema
WSTG-ATHZ-03 Testing for Privilege Escalation
WSTG-ATHZ-04 Testing for Insecure Direct Object References

Session Management Testing

Session Management Testing Test Name
WSTG-SESS-01 Testing for Session Management Schema
WSTG-SESS-02 Testing for Cookies Attributes
WSTG-SESS-03 Testing for Session Fixation
WSTG-SESS-04 Testing for Exposed Session Variables
WSTG-SESS-05 Testing for Cross Site Request Forgery
WSTG-SESS-06 Testing for Logout Functionality
WSTG-SESS-07 Testing Session Timeout
WSTG-SESS-08 Testing for Session Puzzling
WSTG-SESS-09 Testing for Session Hijacking

Data Validation Testing

Data Validation Testing Test Name
WSTG-INPV-01 Testing for Reflected Cross Site Scripting
WSTG-INPV-02 Testing for Stored Cross Site Scripting
WSTG-INPV-03 Testing for HTTP Verb Tampering
WSTG-INPV-04 Testing for HTTP Parameter Pollution
WSTG-INPV-05 Testing for SQL Injection
WSTG-INPV-06 Testing for LDAP Injection
WSTG-INPV-07 Testing for XML Injection
WSTG-INPV-08 Testing for SSI Injection
WSTG-INPV-09 Testing for XPath Injection
WSTG-INPV-10 Testing for IMAP SMTP Injection
WSTG-INPV-11 Testing for Code Injection
WSTG-INPV-12 Testing for Command Injection
WSTG-INPV-13 Testing for Format String Injection
WSTG-INPV-14 Testing for Incubated Vulnerability
WSTG-INPV-15 Testing for HTTP Splitting Smuggling
WSTG-INPV-16 Testing for HTTP Incoming Requests
WSTG-INPV-17 Testing for Host Header Injection
WSTG-INPV-18 Testing for Server-side Template Injection
WSTG-INPV-19 Testing for Server-Side Request Forgery

Error Handling

Error Handling Test Name
WSTG-ERRH-01 Testing for Improper Error Handling
WSTG-ERRH-02 Testing for Stack Traces


Cryptography Test Name
WSTG-CRYP-01 Testing for Weak Transport Layer Security
WSTG-CRYP-02 Testing for Padding Oracle
WSTG-CRYP-03 Testing for Sensitive Information Sent via Unencrypted Channels
WSTG-CRYP-04 Testing for Weak Encryption

Business logic Testing

Business logic Testing Test Name
WSTG-BUSL-01 Test Business Logic Data Validation
WSTG-BUSL-02 Test Ability to Forge Requests
WSTG-BUSL-03 Test Integrity Checks
WSTG-BUSL-04 Test for Process Timing
WSTG-BUSL-05 Test Number of Times a Function Can be Used Limits
WSTG-BUSL-06 Testing for the Circumvention of Work Flows
WSTG-BUSL-07 Test Defenses Against Application Mis-use
WSTG-BUSL-08 Test Upload of Unexpected File Types
WSTG-BUSL-09 Test Upload of Malicious Files

Client Side Testing

Client Side Testing Test Name
WSTG-CLNT-01 Testing for DOM-Based Cross Site Scripting
WSTG-CLNT-02 Testing for JavaScript Execution
WSTG-CLNT-03 Testing for HTML Injection
WSTG-CLNT-04 Testing for Client Side URL Redirect
WSTG-CLNT-05 Testing for CSS Injection
WSTG-CLNT-06 Testing for Client Side Resource Manipulation
WSTG-CLNT-07 Test Cross Origin Resource Sharing
WSTG-CLNT-08 Testing for Cross Site Flashing
WSTG-CLNT-09 Testing for Clickjacking
WSTG-CLNT-10 Testing WebSockets
WSTG-CLNT-11 Test Web Messaging
WSTG-CLNT-12 Testing Browser Storage
WSTG-CLNT-13 Testing for Cross Site Script Inclusion

API Testing

API Testing Test Name
WSTG-APIT-01 Testing GraphQL

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    Security Assessment Findings

    Dependencies with Known Vulnerabilities

    ID SAY-01
    Status Fixed
    Risk Low
    Business Impact Using vulnerable versions of node modules could expose the service to various attacks, some of them less critical, but others severe.


    The NPM audit returns multiple results for known vulnerabilities in the installed packages:

      npm audit
    # npm audit report 5.1.0 - 6.4.1
    Severity: moderate Uncaught Exception vulnerability -
    fix available via `npm audit fix`
    node_modules/ 4.1.0 - 4.6.0-alpha1
    Depends on vulnerable versions of
    gatsby 1.9.130 - 4.25.7 || 5.4.0-next.0 - 5.9.1
    Depends on vulnerable versions of gatsby-cli
    Depends on vulnerable versions of latest-version
    Depends on vulnerable versions of
    got <11.8.5
    Severity: moderate
    Got allows a redirect to a UNIX socket -
    fix available via `npm audit fix`
    package-json <=6.5.0
    Depends on vulnerable versions of got
    latest-version 0.2.0 - 5.1.0
    Depends on vulnerable versions of package-json
    update-notifier 0.2.0 - 5.1.0
    Depends on vulnerable versions of latest-version
    gatsby-cli 1.1.27 - 4.25.0
    Depends on vulnerable versions of update-notifier
    request *
    Severity: moderate
    Server-Side Request Forgery in Request -
    fix available via `npm audit fix`
    node-gyp <=7.1.2
    Depends on vulnerable versions of request
    @npmcli/run-script 1.1.1 - 1.8.6
    Depends on vulnerable versions of node-gyp
    @lavamoat/allow-scripts <=2.3.0
    Depends on vulnerable versions of @npmcli/run-script
    node_modules/@lavamoat/allow-scripts 4.0.4 - 4.2.2
    Severity: high
    Insufficient validation when decoding a Socket.IO packet -
    fix available via `npm audit fix`
    webpack 5.0.0 - 5.75.0
    Severity: high
    Cross-realm object access in Webpack 5 -
    fix available via `npm audit fix`
    yaml 2.0.0-5 - 2.2.1
    Severity: high
    Uncaught Exception in yaml -
    fix available via `npm audit fix`

    We validated each one of them to make sure it is not affecting the production build, and found that even the high-severity ones do not have a direct effect on Tezos Snap. While this means there is no security risk right now, new features or new vulnerabilities might happen in the future.


    The first step would be to update the packages to the versions where possible On a bigger picture level, there is a need for an automated system to alert about new vulnerabilities and a process should be in place to mitigate them when critical ones arise.


    Magic Numbers

    ID SAY-02
    Status Fixed
    Risk Informational
    Business Impact Magic numbers impact code readability. Without inside knowledge, they appear to be rather arbitrary.


    During our assessment, we noticed the usage of seemingly arbitrary constants without explanatory comments:

    In the case above, it’s hard to guess what is the reason for dividing by 1000 or multiplying by 257 without knowing how the protocol and the blockchain itself work


    It’s considered good practice to give such hard-coded constants descriptive names, and if necessary, to add explanatory comments.


    Alarming Metamask Prompt

    ID SAY-03
    Status Fixed
    Risk Informational
    Business Impact This kind of prompt may dissuade users from installing Snap


    When installing Snap the following hard-to-understand metamask prompt appears:


    It may not be possible for Tezos to change this rather scary prompt. However, since it may be of interest, we decided to include this issue as informational.


    Alarming Metamask Prompt

    ID SAY-04
    Status Fixed
    Risk Informational
    Business Impact None


    During our assessment, we noticed this comment, implying a certain uncertainty, which might point to an underlying bigger issue

    We investigated and couldn’t verify what’s the issue here the comment referring about.


    These comments should be changed or removed on the release version, or if there is a deeper issue here, the developers should update the logic of why this

    Appendix A: Security Evaluation Fixes

    After a review by the Sayfer team, we can confirm that all the vulnerabilities have been fixed by the Tezos team

    Initial commit hash: 0e0d653b85cbd11365771ad9c2ee5726b10a7d26
    Fixes commit hash: 0d0c9381a1107c54647d927d4fe99694f332e24d

    You can find more information about it on our Blog

    Sayfer’s blog focuses on web3, security, and vulnerability research. We believe that in the cybersecurity industry it’s crucial to stay up to date on the latest trends and advancements. Currently, our team of experienced researchers enjoys researching cutting-edge blockchain and web3 technologies.
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