Skip to content

Latest commit

 

History

History
237 lines (193 loc) · 22.4 KB

sec-design-deep-analysis.md

File metadata and controls

237 lines (193 loc) · 22.4 KB

Deep Security Analysis of Pyxel Game Engine

1. Objective, Scope, and Methodology

Objective:

This deep analysis aims to provide a thorough security evaluation of the Pyxel game engine, focusing on its architecture, components, and data flow as inferred from the provided security design review and codebase context. The objective is to identify potential security vulnerabilities within the Pyxel engine itself and its development/distribution lifecycle, and to recommend specific, actionable mitigation strategies tailored to the project's nature and business posture. This analysis will not focus on security vulnerabilities within games built using Pyxel, but will consider how the engine's design can impact the security of those games and provide relevant guidance for game developers.

Scope:

The scope of this analysis encompasses the following aspects of the Pyxel project, as defined in the security design review:

  • Pyxel Library (Python Package): Analyzing the core engine functionalities and APIs for potential vulnerabilities.
  • Pyxel Editor (Desktop Application): Assessing the security of the editor application, including asset handling and project management.
  • Build Process: Examining the security of the build pipeline, including dependency management, security checks, and artifact signing.
  • Deployment Scenarios: Considering security implications across different deployment options (desktop, web).
  • Dependencies: Evaluating the security risks associated with external Python libraries used by Pyxel.
  • Security Controls: Reviewing existing and recommended security controls outlined in the design review.

The analysis will primarily focus on the Pyxel engine itself and its immediate ecosystem. Security considerations for games built using Pyxel will be addressed in terms of guidance and best practices for game developers using the engine.

Methodology:

This analysis will employ the following methodology:

  1. Document Review: In-depth review of the provided Security Design Review document, including business and security posture, C4 diagrams (Context, Container, Deployment, Build), risk assessment, and questions/assumptions.
  2. Architecture Inference: Based on the C4 diagrams and the description of Pyxel as a retro game engine in Python, infer the high-level architecture, key components, and data flow within the Pyxel system.
  3. Threat Modeling: Identify potential security threats and vulnerabilities for each key component, considering common attack vectors relevant to software libraries, desktop applications, and build/distribution processes. This will be informed by common web application and software security vulnerabilities (OWASP, CWE, etc.) adapted to the context of a game engine.
  4. Risk Assessment (Qualitative): Evaluate the potential impact and likelihood of identified threats, considering the business risks outlined in the security design review.
  5. Mitigation Strategy Development: For each identified threat, develop specific, actionable, and tailored mitigation strategies. These strategies will be practical for an open-source project and aligned with the recommended security controls.
  6. Recommendation Prioritization: Prioritize mitigation strategies based on risk level and feasibility of implementation.

2. Security Implications of Key Components

Based on the C4 diagrams and descriptions, the key components of Pyxel and their security implications are analyzed below:

2.1. Pyxel Library (Python Package)

  • Component Description: The core game engine, providing Python APIs for graphics, sound, input, and game logic.

  • Inferred Architecture & Data Flow:

    • Input: Receives input from game developers through Python APIs and from game players through OS input events (keyboard, mouse, gamepad, audio, file inputs).
    • Processing: Handles game logic execution, rendering, sound processing, and resource management. Relies on Python libraries for underlying functionalities.
    • Output: Generates graphics and sound output to the OS for display and audio playback.
    • Data Flow: Game developers interact with the library via Python code. Games built with Pyxel process game data, assets, and player input using the library's APIs.

  • Security Implications:

    • Input Validation Vulnerabilities:
      • Threat: Malicious or malformed input to Pyxel APIs (e.g., loading corrupted image or sound files, providing unexpected input data) could lead to crashes, denial of service, or potentially even code execution if vulnerabilities exist in input handling routines. This is especially relevant for APIs dealing with file loading and external data.
      • Specific Pyxel Context: APIs for loading images (pyxel.image), sounds (pyxel.sound), music (pyxel.music), and tilemaps are potential areas for input validation vulnerabilities. Incorrectly handled file formats or sizes could be exploited.
    • Dependency Vulnerabilities:
      • Threat: Pyxel relies on external Python libraries (e.g., Pygame, Pillow). Vulnerabilities in these dependencies could be indirectly exploitable through Pyxel.
      • Specific Pyxel Context: Vulnerabilities in image processing libraries (Pillow), audio libraries (potentially through Pygame or other audio backends), or even core Python libraries could impact Pyxel's security.
    • Logic Errors and Resource Exhaustion:
      • Threat: Logic errors within the Pyxel library code could lead to unexpected behavior, crashes, or resource exhaustion (e.g., memory leaks, infinite loops) that could be exploited for denial of service.
      • Specific Pyxel Context: Bugs in rendering routines, sound processing, or game state management could be exploited.
    • API Misuse by Game Developers:
      • Threat: While not a vulnerability in Pyxel itself, insecure usage of Pyxel APIs by game developers (e.g., improper handling of user input in games built with Pyxel) can lead to vulnerabilities in those games.
      • Specific Pyxel Context: Game developers might incorrectly handle player input, leading to injection vulnerabilities in their game logic if they are processing external data based on player actions.

2.2. Pyxel Editor (Desktop Application)

  • Component Description: A desktop application for creating and editing game assets (images, sounds, tilesets) and running Pyxel games.

  • Inferred Architecture & Data Flow:

    • Input: User input through GUI (mouse, keyboard), file inputs (loading/saving assets, projects).
    • Processing: Asset editing functionalities, project management, execution of Pyxel games using the Pyxel Library.
    • Output: GUI display, saved asset files, game execution output.
    • Data Flow: Users interact with the editor to create and modify game assets. The editor uses the Pyxel Library to run games for testing. It reads and writes project files and asset files.

  • Security Implications:

    • File Handling Vulnerabilities:
      • Threat: Vulnerabilities in how the editor handles project files and asset files (loading, saving, parsing) could lead to attacks. Maliciously crafted project or asset files could exploit parsing vulnerabilities, potentially leading to code execution or denial of service.
      • Specific Pyxel Context: Loading and saving .pyxres resource files, image files, sound files, and project files are potential areas for file handling vulnerabilities.
    • Cross-Site Scripting (XSS) in Editor UI (If using web technologies):
      • Threat: If the Pyxel Editor is built using web technologies (e.g., Electron, web-based UI frameworks), it could be vulnerable to XSS if user-controlled data is not properly sanitized when displayed in the UI. This is less likely for a purely native desktop application but worth considering if web technologies are involved.
      • Specific Pyxel Context: Displaying project names, asset names, or potentially user-provided descriptions within the editor UI could be vulnerable if not handled carefully in a web-based UI.
    • Privilege Escalation (Less likely but consider desktop app context):
      • Threat: In a desktop application context, vulnerabilities could potentially be exploited to escalate privileges on the user's system, although this is less common for application-level vulnerabilities and more related to OS-level exploits.
      • Specific Pyxel Context: Unlikely to be a major concern for Pyxel Editor, but if the editor requires elevated privileges for certain operations or interacts with system resources in a privileged manner, vulnerabilities could theoretically be exploited.
    • Update Mechanism Vulnerabilities:
      • Threat: If the Pyxel Editor has an auto-update mechanism, vulnerabilities in this mechanism could be exploited to distribute malicious updates.
      • Specific Pyxel Context: If Pyxel Editor implements auto-updates, ensure secure update channels (HTTPS), integrity checks (signatures), and proper handling of update downloads and installations.

2.3. Python Interpreter & Python Libraries

  • Component Description: The runtime environment for Pyxel and its dependencies.
  • Security Implications:
    • Python Interpreter Vulnerabilities:
      • Threat: Vulnerabilities in the Python interpreter itself could indirectly affect Pyxel. While Python is generally considered secure, vulnerabilities can be discovered and patched.
      • Mitigation: Rely on the Python community to maintain the security of the interpreter and encourage users to use up-to-date Python versions.
    • Python Libraries (Dependencies) Vulnerabilities:
      • Threat: As mentioned earlier, vulnerabilities in external Python libraries used by Pyxel are a significant concern.
      • Mitigation: Implement dependency scanning and regular updates as recommended in the security design review.

2.4. Build Process (CI/CD, Build Environment, Distribution)

  • Component Description: The automated process for building, testing, and distributing Pyxel Library and Editor.

  • Inferred Architecture & Data Flow:

    • Input: Source code from the remote repository (GitHub), dependencies.
    • Processing: Compilation (if any), packaging, security checks (SAST, dependency scanning), signing.
    • Output: Build artifacts (Pyxel Library package, Pyxel Editor executables), distribution packages.
    • Data Flow: Code flows from developer machines to the remote repository, then to the CI/CD system for building and distribution.

  • Security Implications:

    • Compromised Build Environment:
      • Threat: If the build environment is compromised, malicious code could be injected into the Pyxel Library or Editor during the build process, leading to a supply chain attack.
      • Mitigation: Secure the build server, use hardened build environments, implement access controls, and monitor build processes.
    • Dependency Supply Chain Attacks:
      • Threat: Dependencies fetched during the build process could be compromised (e.g., malicious packages on PyPI).
      • Mitigation: Use dependency pinning, verify checksums of downloaded dependencies, and potentially use a private PyPI mirror for more control.
    • Insecure Build Scripts:
      • Threat: Vulnerabilities in build scripts could be exploited to manipulate the build process or gain access to sensitive information.
      • Mitigation: Secure coding practices for build scripts, code review of build scripts, and access control to modify build scripts.
    • Lack of Code Signing:
      • Threat: Without code signing, users cannot verify the integrity and authenticity of Pyxel Editor executables. This increases the risk of users downloading and running tampered versions.
      • Mitigation: Implement code signing for Pyxel Editor executables and potentially for the Pyxel Library package as well.
    • Insecure Distribution Channels:
      • Threat: If distribution channels (e.g., GitHub Releases, PyPI) are compromised, malicious versions of Pyxel could be distributed to users.
      • Mitigation: Use secure distribution channels (HTTPS), monitor for unauthorized modifications, and promote official distribution channels.

2.5. Games Built with Pyxel

  • Component Description: Applications created by game developers using the Pyxel engine.
  • Security Implications (Indirectly related to Pyxel engine):
    • Vulnerabilities due to insecure game development practices:
      • Threat: Game developers might introduce vulnerabilities in their games due to insecure coding practices, such as improper input validation, insecure data handling, or lack of awareness of security best practices.
      • Specific Pyxel Context: Games built with Pyxel, like any software, can be vulnerable. If Pyxel is used to create games that handle user data or interact with networks, developers need to be aware of common web and application security vulnerabilities.
      • Mitigation (for Pyxel project): Provide security guidelines and best practices for game developers using Pyxel, focusing on input validation, secure data handling, and awareness of common vulnerabilities.

3. Actionable and Tailored Mitigation Strategies

Based on the identified threats, here are actionable and tailored mitigation strategies for the Pyxel project:

For Pyxel Library:

  • Input Validation Hardening (High Priority):
    • Strategy: Implement robust input validation for all Pyxel APIs that handle external data, especially file loading functions (pyxel.image, pyxel.sound, etc.) and input processing.
    • Actionable Steps:
      • Define Input Validation Rules: For each API, clearly define valid input ranges, formats, and sizes.
      • Implement Validation Checks: Add checks at the beginning of API functions to validate input parameters. Use safe parsing libraries and techniques to handle file formats.
      • Error Handling: Implement proper error handling for invalid input, preventing crashes and providing informative error messages (for developers, not necessarily end-users).
      • Fuzz Testing: Consider using fuzzing tools to automatically test input validation robustness of file loading and data processing APIs.
  • Dependency Management and Scanning (High Priority):
    • Strategy: Implement automated dependency scanning and regular updates to address vulnerabilities in Python libraries used by Pyxel.
    • Actionable Steps:
      • Integrate Dependency Scanning Tool: Integrate a dependency scanning tool (e.g., safety, pip-audit) into the CI/CD pipeline to automatically check for known vulnerabilities in dependencies.
      • Regular Dependency Updates: Establish a process for regularly reviewing and updating dependencies. Prioritize security updates.
      • Dependency Pinning: Use dependency pinning in requirements.txt or pyproject.toml to ensure consistent builds and control dependency versions. However, balance pinning with the need for updates.
  • Static Application Security Testing (SAST) (Medium Priority):
    • Strategy: Integrate SAST tools into the CI/CD pipeline to automatically scan Pyxel's Python code for potential vulnerabilities and code quality issues.
    • Actionable Steps:
      • Choose a SAST Tool: Select a suitable SAST tool for Python (e.g., bandit, pylint with security plugins).
      • Integrate into CI/CD: Integrate the SAST tool into the build process to run automatically on each commit or pull request.
      • Address Findings: Review and address findings from the SAST tool, prioritizing security-related issues.
  • Code Review with Security Focus (Medium Priority):
    • Strategy: Implement a code review process for all contributions, with a specific focus on identifying potential security vulnerabilities and ensuring secure coding practices.
    • Actionable Steps:
      • Security Review Guidelines: Develop guidelines for code reviewers to specifically look for common security vulnerabilities (input validation, logic errors, etc.).
      • Training for Reviewers: Provide basic security training for code reviewers to enhance their ability to identify security issues.
      • Mandatory Code Reviews: Make code reviews mandatory for all code changes before merging them into the main branch.

For Pyxel Editor:

  • File Handling Security (High Priority):
    • Strategy: Harden file handling in the Pyxel Editor to prevent vulnerabilities related to malicious project and asset files.
    • Actionable Steps:
      • Secure File Parsing: Use secure and well-vetted libraries for parsing project files and asset files. Implement robust error handling for parsing errors.
      • Input Validation for File Names and Paths: Validate file names and paths to prevent path traversal vulnerabilities.
      • Sandboxing (If feasible): If the editor uses web technologies, explore sandboxing techniques to limit the editor's access to the file system and system resources.
  • Secure Update Mechanism (Medium Priority, if auto-updates are implemented):
    • Strategy: If auto-updates are implemented, ensure the update mechanism is secure to prevent malicious updates.
    • Actionable Steps:
      • HTTPS for Updates: Use HTTPS for downloading update files to prevent man-in-the-middle attacks.
      • Code Signing for Updates: Sign update packages to ensure integrity and authenticity. Verify signatures before applying updates.
      • Secure Update Server: Secure the update server to prevent unauthorized modifications to update files.
  • Address Potential XSS (Low Priority, if web technologies are used):
    • Strategy: If the editor UI uses web technologies, sanitize user-controlled data before displaying it in the UI to prevent XSS vulnerabilities.
    • Actionable Steps:
      • Output Encoding: Use appropriate output encoding techniques when displaying user-provided data in the UI.
      • Content Security Policy (CSP): Implement CSP headers to mitigate XSS risks if the editor is web-based.

For Build Process and Distribution:

  • Secure Build Environment (High Priority):
    • Strategy: Secure the build environment to prevent compromise and supply chain attacks.
    • Actionable Steps:
      • Harden Build Server: Harden the build server operating system and software.
      • Access Control: Implement strict access controls to the build server and build scripts.
      • Monitoring and Logging: Implement monitoring and logging of build processes to detect suspicious activity.
      • Isolated Build Environments: Use isolated build environments (e.g., containers, VMs) to limit the impact of potential compromises.
  • Code Signing for Distribution (High Priority):
    • Strategy: Implement code signing for Pyxel Editor executables to ensure integrity and authenticity.
    • Actionable Steps:
      • Obtain Code Signing Certificate: Obtain a valid code signing certificate.
      • Automate Signing in Build Process: Automate the code signing process in the CI/CD pipeline.
      • Publish Signing Information: Clearly communicate to users that Pyxel Editor executables are code-signed and provide instructions on how to verify signatures.
  • Secure Distribution Channels (Medium Priority):
    • Strategy: Use secure distribution channels and monitor for unauthorized modifications.
    • Actionable Steps:
      • HTTPS for Downloads: Ensure all downloads from official distribution channels (GitHub Releases, PyPI) are served over HTTPS.
      • Checksums and Hashes: Provide checksums or hashes of release files to allow users to verify file integrity.
      • Monitor Distribution Channels: Monitor official distribution channels for any signs of unauthorized modifications or malicious uploads.

For Game Developers using Pyxel:

  • Security Guidelines for Game Developers (High Priority):
    • Strategy: Provide clear security guidelines and best practices for game developers using Pyxel to build games securely.
    • Actionable Steps:
      • Documentation on Input Validation: Include documentation and examples on how to properly validate user input in games built with Pyxel.
      • Secure Data Handling Guidance: Provide guidance on secure data handling practices, especially if games store or transmit user data.
      • Awareness of Common Vulnerabilities: Educate game developers about common web and application security vulnerabilities (injection attacks, etc.) and how they might apply to game development.
      • Security Checklist for Game Developers: Create a security checklist for game developers to follow when building games with Pyxel.

4. Prioritization of Recommendations

Based on risk and feasibility, the recommendations are prioritized as follows:

High Priority:

  • Input Validation Hardening (Pyxel Library) - Directly addresses potential vulnerabilities in the core engine.
  • Dependency Management and Scanning - Mitigates risks from external libraries, a common source of vulnerabilities.
  • Secure Build Environment - Protects against supply chain attacks, which can have a wide impact.
  • Code Signing for Distribution (Pyxel Editor) - Builds trust and verifies integrity for users downloading the editor.
  • Security Guidelines for Game Developers - Proactively helps developers build more secure games with Pyxel.
  • File Handling Security (Pyxel Editor) - Addresses potential vulnerabilities in the editor application itself.

Medium Priority:

  • Static Application Security Testing (SAST) - Automated code analysis to find potential vulnerabilities.
  • Code Review with Security Focus - Human review to catch vulnerabilities and improve code quality.
  • Secure Update Mechanism (Pyxel Editor, if implemented) - Secures the update process if auto-updates are used.
  • Secure Distribution Channels - Ensures official distribution channels are secure.

Low Priority:

  • Address Potential XSS (Pyxel Editor, if web-based UI) - Only relevant if the editor uses web technologies.

This prioritized list provides a roadmap for the Pyxel development team to enhance the security of the engine and its ecosystem. Implementing these recommendations will significantly improve the security posture of Pyxel and build greater trust within the community.