Skip to content

Latest commit

 

History

History
157 lines (116 loc) · 19.7 KB

sec-design-deep-analysis.md

File metadata and controls

157 lines (116 loc) · 19.7 KB

Okay, let's proceed with creating the deep analysis of security considerations for Ruffle based on the provided Security Design Review.

Deep Analysis of Security Considerations for Ruffle

1. Objective, Scope, and Methodology

Objective:

This deep analysis aims to provide a thorough security evaluation of the Ruffle Flash Player emulator project. The primary objective is to identify potential security vulnerabilities and risks associated with Ruffle's architecture, components, and development processes. A key focus is on understanding how Ruffle emulates Flash Player functionality and the inherent security challenges this emulation introduces. The analysis will culminate in specific, actionable security recommendations and mitigation strategies tailored to the Ruffle project to enhance its security posture and protect users.

Scope:

The scope of this analysis is limited to the information provided in the Security Design Review document, including:

  • Business and Security Posture: Business goals, risks, security controls, accepted risks, recommended security controls, and security requirements.
  • C4 Architecture Diagrams: Context, Container, Deployment (Web Browser), and Build diagrams, including descriptions of components and their interactions.
  • Questions and Assumptions: Identified questions and assumptions related to the project's future and current state.

This analysis will focus on the security aspects of the Ruffle project itself and its immediate interactions with users, web browsers, and operating systems. It will not extend to a general security review of web security or Flash content security beyond its relevance to Ruffle.

Methodology:

The methodology for this deep analysis will involve the following steps:

  1. Document Review: Thorough review of the provided Security Design Review document to understand the project's goals, architecture, security controls, and identified risks.
  2. Architecture Analysis: Analysis of the C4 diagrams to understand the key components of Ruffle (Web Player, Desktop Player, Browser Extension, Core Library), their responsibilities, and interactions. This will involve inferring data flow and potential attack surfaces based on the diagrams and descriptions.
  3. Threat Modeling: Identification of potential threats and vulnerabilities for each key component, considering the nature of Flash emulation and the project's architecture. This will be guided by common web application and software security vulnerabilities, as well as vulnerabilities specific to emulators and media players.
  4. Security Control Evaluation: Assessment of the existing and recommended security controls outlined in the Security Design Review, evaluating their effectiveness and identifying gaps.
  5. Recommendation and Mitigation Strategy Development: Formulation of specific, actionable security recommendations and tailored mitigation strategies for the identified threats and vulnerabilities. These recommendations will be practical and applicable to the Ruffle project's open-source nature and development environment.
  6. Prioritization: Implicit prioritization of recommendations based on potential impact and feasibility of implementation.

2. Security Implications of Key Components

Based on the Container Diagram and descriptions, we can break down the security implications of each key component:

a) Core Library Container (RCL):

  • Architecture & Data Flow Inference: The Core Library is the heart of Ruffle, written in Rust. It's responsible for parsing SWF files, interpreting ActionScript, and rendering graphics and audio. Data flows from SWF files into the Core Library, where it's processed and transformed into rendered output.
  • Security Implications:
    • SWF Parsing Vulnerabilities: The SWF format is complex and historically prone to parsing vulnerabilities (buffer overflows, integer overflows, format string bugs, etc.). A vulnerability in the SWF parser could allow malicious SWF files to execute arbitrary code on the user's machine.
    • ActionScript Engine Vulnerabilities: The ActionScript engine is responsible for executing potentially untrusted code from SWF files. Vulnerabilities in the engine (type confusion, prototype pollution, logic errors) could lead to sandbox escapes or arbitrary code execution.
    • Rendering Engine Vulnerabilities: Rendering complex graphics and handling various media formats can introduce vulnerabilities, especially related to memory management and resource handling.
    • Memory Safety (Despite Rust): While Rust's memory safety features significantly mitigate memory corruption vulnerabilities, logic errors in the code can still lead to exploitable conditions. Incorrect use of unsafe blocks in Rust could also reintroduce memory safety issues.
    • Dependency Vulnerabilities: The Core Library likely depends on external Rust crates. Vulnerabilities in these dependencies could indirectly affect Ruffle.

b) Web Player Container (RPW):

  • Architecture & Data Flow Inference: The Web Player is a JavaScript/WebAssembly component that runs in a web browser. It uses the Core Library (likely compiled to WebAssembly) to process SWF files. It interacts with the browser's DOM to display content and handle user interactions. Data flows from websites (SWF files) to the Web Player, then to the Core Library (WASM), and finally rendered in the browser.
  • Security Implications:
    • Browser Security Sandbox: The Web Player operates within the browser's JavaScript/WebAssembly sandbox. Exploiting vulnerabilities to escape this sandbox is a primary concern.
    • WebAssembly Vulnerabilities: While WebAssembly adds a layer of security, vulnerabilities in the WebAssembly runtime or in the compiled Core Library (WASM) could still exist.
    • JavaScript Interop Vulnerabilities: The Web Player likely uses JavaScript to interact with the DOM and browser APIs. Vulnerabilities in this JavaScript code or in the interface between JavaScript and WebAssembly could be exploited.
    • Cross-Site Scripting (XSS) via SWF: If the Web Player doesn't properly sanitize or isolate content from SWF files, it could be vulnerable to XSS attacks. Malicious SWF content could potentially manipulate the DOM of the hosting website.
    • Content Security Policy (CSP) Bypasses: If not carefully implemented, vulnerabilities in the Web Player could potentially bypass CSP restrictions on websites.
    • Dependency Vulnerabilities (JS Libraries): The Web Player might use JavaScript libraries, which could have their own vulnerabilities.

c) Desktop Player Container (RPD):

  • Architecture & Data Flow Inference: The Desktop Player is a standalone application built with Rust, likely embedding the Core Library. It runs directly on the operating system and plays local SWF files. Data flows from local SWF files to the Desktop Player, then to the Core Library, and finally rendered on the desktop.
  • Security Implications:
    • Operating System Security: The Desktop Player's security relies on the underlying operating system's security features.
    • Native Application Vulnerabilities: As a native application, it's susceptible to typical application vulnerabilities like buffer overflows (less likely due to Rust, but still possible in unsafe code or dependencies), format string bugs, and logic errors.
    • Privilege Escalation: If vulnerabilities exist, attackers might try to escalate privileges from the Desktop Player process.
    • File System Access: The Desktop Player needs to access local files. Improper handling of file paths or permissions could lead to vulnerabilities.
    • Dependency Vulnerabilities (Rust Crates): Similar to the Core Library, the Desktop Player depends on Rust crates, which could have vulnerabilities.

d) Browser Extension Container (RPE):

  • Architecture & Data Flow Inference: The Browser Extension intercepts Flash content on web pages and replaces the Flash Player with the Web Player. It likely injects the Web Player (RPW) into web pages. Data flow involves intercepting network requests for SWF files, potentially downloading them, and then using the Web Player to render them within the browser context.
  • Security Implications:
    • Browser Extension Security Model: Browser extensions have specific security models and permission systems. Vulnerabilities could arise from misusing browser extension APIs or bypassing security restrictions.
    • Content Script Isolation: Ensuring proper isolation of content scripts to prevent interference with other website scripts or extensions is crucial.
    • Permission Abuse: Overly broad extension permissions could be abused if vulnerabilities are found. The extension should request only the necessary permissions.
    • Injection Vulnerabilities: Improper injection of the Web Player into web pages could introduce vulnerabilities or conflicts with website scripts.
    • Update Mechanism Security: If the extension has an update mechanism, it needs to be secure to prevent malicious updates.
    • Communication with Web Player: Secure communication between the Browser Extension and the injected Web Player is important to prevent tampering or information leakage.

3. Specific Recommendations for Ruffle

Based on the identified security implications, here are specific recommendations tailored to the Ruffle project:

a) Core Library Container (RCL):

  1. Prioritize Rigorous SWF Parsing Security: Implement a layered and robust SWF parsing library. Focus on comprehensive input validation at every stage of parsing to prevent vulnerabilities like buffer overflows, integer overflows, and format string bugs. Consider using a formal grammar and parser generator to aid in creating a robust parser.
  2. Fuzzing for SWF Parsing and ActionScript Engine: Develop and integrate a comprehensive fuzzing strategy specifically targeting SWF parsing and the ActionScript engine. Use a variety of malformed and malicious SWF files as fuzzing inputs. Integrate fuzzing into the CI/CD pipeline for continuous testing.
  3. ActionScript Engine Security Hardening: Focus on security hardening of the ActionScript engine. Implement strict type checking, memory management, and sandbox enforcement within the engine. Regularly review and audit the ActionScript engine code for potential vulnerabilities.
  4. Memory Safety Audits (Especially unsafe blocks): Conduct focused security audits specifically reviewing any unsafe Rust code blocks in the Core Library. Ensure that unsafe code is absolutely necessary and implemented with extreme care and thorough validation.
  5. Dependency Scanning and Management: Implement automated dependency scanning for Rust crates used in the Core Library. Regularly update dependencies to patch known vulnerabilities. Use a dependency management tool to track and manage dependencies effectively.
  6. Regular Security Audits by External Experts: Engage external security experts to conduct regular security audits and penetration testing of the Core Library, focusing on SWF parsing, ActionScript engine, and rendering logic.

b) Web Player Container (RPW):

  1. Strict WebAssembly Security Review: Conduct a thorough security review of the WebAssembly code generated from the Core Library. Ensure that the WebAssembly compilation process does not introduce new vulnerabilities and that the WebAssembly runtime environment is secure.
  2. Secure JavaScript Interop Design: Carefully design and review the JavaScript interface between the Web Player and WebAssembly. Minimize the attack surface and ensure secure communication and data exchange between JavaScript and WebAssembly.
  3. XSS Prevention Measures: Implement robust measures to prevent XSS vulnerabilities originating from SWF content played by the Web Player. This includes strict output encoding and potentially sandboxing or isolating SWF content within the browser environment.
  4. CSP Compliance and Recommendations: Ensure the Web Player is designed to be compatible with Content Security Policy (CSP). Provide clear recommendations to website developers on how to configure CSP to further enhance security when using Ruffle.
  5. JavaScript Dependency Security: If using JavaScript libraries, implement dependency scanning and management for these libraries as well. Regularly update JavaScript dependencies to address known vulnerabilities.

c) Desktop Player Container (RPD):

  1. Operating System Security Best Practices: Follow operating system security best practices when developing the Desktop Player. Minimize required privileges, implement principle of least privilege, and consider application sandboxing techniques provided by the OS (if feasible and doesn't hinder functionality significantly).
  2. Secure File Handling: Implement secure file handling practices in the Desktop Player. Validate file paths, sanitize inputs, and avoid vulnerabilities related to file system access and permissions.
  3. Code Signing for Distribution: Implement code signing for the Desktop Player executables to ensure users can verify the integrity and authenticity of the downloaded software.
  4. Automated Security Testing in CI/CD: Integrate automated security testing (SAST, DAST, vulnerability scanning) into the CI/CD pipeline for the Desktop Player to detect potential vulnerabilities early in the development process.

d) Browser Extension Container (RPE):

  1. Minimize Extension Permissions: Request only the minimum necessary browser permissions for the extension to function. Avoid requesting broad permissions that could be abused if vulnerabilities are found.
  2. Secure Content Script Injection: Implement secure and robust content script injection mechanisms. Ensure that injection does not introduce vulnerabilities or conflicts with website scripts. Regularly review and audit the injection code.
  3. Strict Content Script Isolation: Enforce strict isolation of content scripts to prevent interference with other website scripts or extensions.
  4. Secure Update Mechanism: If the extension implements an update mechanism, ensure it is secure and prevents malicious updates. Use HTTPS for update checks and verify signatures of updates.
  5. User Privacy Considerations: Be mindful of user privacy when developing the browser extension. Avoid collecting unnecessary user data and be transparent about any data collection practices.
  6. Regular Extension Security Audits: Conduct regular security audits of the browser extension code, focusing on permission usage, content script injection, and update mechanisms.

e) General Recommendations for the Ruffle Project:

  1. Establish a Clear Vulnerability Disclosure Policy: Create and publicize a clear vulnerability disclosure policy and process. Provide a dedicated channel (e.g., [email protected] or a security-specific email) for security researchers and the community to report vulnerabilities.
  2. Implement a Security Response Plan: Develop a security incident response plan to handle reported vulnerabilities effectively. This plan should include steps for triage, patching, communication, and disclosure.
  3. Community Engagement for Security: Actively engage the open-source community in security efforts. Encourage security contributions, bug bounty programs (if feasible), and public security discussions (while being mindful of responsible disclosure).
  4. Security Training for Developers: Provide security training to Ruffle developers, focusing on secure coding practices, common web application vulnerabilities, and Rust-specific security considerations.
  5. Continuous Security Monitoring: Implement continuous security monitoring of the project's infrastructure and code repositories. Utilize automated tools for vulnerability scanning and code analysis.

4. Tailored Mitigation Strategies Applicable to Identified Threats

Here are tailored mitigation strategies for specific threats identified earlier:

  • Threat: SWF Parsing Vulnerabilities (Buffer Overflows, etc.) in Core Library.

    • Mitigation:
      • Implement a Memory-Safe SWF Parser: Leverage Rust's memory safety features to build a parser that is inherently resistant to buffer overflows and similar memory corruption issues.
      • Input Validation at Parsing Stage: Perform rigorous input validation at each stage of SWF parsing. Validate data types, sizes, and formats to prevent unexpected or malicious data from being processed.
      • Fuzzing-Driven Parser Development: Use fuzzing to continuously test the SWF parser with a wide range of inputs, including malformed and malicious SWF files. Fix any crashes or errors identified by the fuzzer.

  • Threat: ActionScript Engine Vulnerabilities (Sandbox Escape, Arbitrary Code Execution).

    • Mitigation:
      • Strict Sandbox Enforcement: Design and implement a robust sandbox for the ActionScript engine to prevent malicious ActionScript code from escaping the sandbox and gaining access to system resources or the browser environment.
      • Type Safety in ActionScript Engine: Implement strong type checking within the ActionScript engine to prevent type confusion vulnerabilities.
      • Regular Security Audits of ActionScript Engine: Conduct regular security audits of the ActionScript engine code to identify and fix potential vulnerabilities.

  • Threat: XSS via SWF Content in Web Player.

    • Mitigation:
      • Output Encoding/Sanitization: Implement strict output encoding or sanitization of any data from SWF files that is rendered in the browser DOM. Prevent SWF content from directly manipulating the DOM in a way that could lead to XSS.
      • Content Isolation: Explore techniques to isolate SWF content within the Web Player to prevent it from interacting with the surrounding web page's DOM in a harmful way. Consider using iframe sandboxing or similar browser security features.
      • CSP Recommendations: Provide clear guidance to website developers on how to use CSP effectively to mitigate potential XSS risks when embedding Ruffle Web Player.

  • Threat: Dependency Vulnerabilities in Rust Crates and JavaScript Libraries.

    • Mitigation:
      • Automated Dependency Scanning: Integrate automated dependency scanning tools into the CI/CD pipeline to regularly scan for known vulnerabilities in Rust crates and JavaScript libraries.
      • Dependency Management Policy: Establish a policy for managing dependencies, including regular updates to patch vulnerabilities and careful review of new dependencies before inclusion.
      • Vulnerability Monitoring: Continuously monitor security advisories and vulnerability databases for reported vulnerabilities in used dependencies.

  • Threat: Browser Extension Permission Abuse.

    • Mitigation:
      • Principle of Least Privilege for Permissions: Request only the minimum necessary browser permissions for the extension to function. Avoid requesting broad permissions that are not strictly required.
      • Permission Justification and Review: Document and justify each requested browser permission. Regularly review the requested permissions to ensure they are still necessary and appropriate.
      • User Education on Permissions: Clearly explain to users the permissions requested by the extension and why they are needed.

By implementing these specific recommendations and mitigation strategies, the Ruffle project can significantly enhance its security posture and provide a safer alternative for accessing legacy Flash content. Continuous security efforts, community engagement, and proactive vulnerability management are crucial for the long-term security and success of Ruffle.