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BUSINESS POSTURE

Business Priorities and Goals:

  • Provide a web-based, open-source PDF renderer that is widely accessible and compatible across different browsers and platforms.
  • Maintain high accuracy and fidelity in rendering PDF documents, ensuring that they appear as intended by the document creator.
  • Offer a performant and efficient PDF viewing experience, minimizing resource consumption and loading times.
  • Ensure the security and privacy of users by preventing potential vulnerabilities associated with PDF rendering.
  • Foster a community-driven development model, encouraging contributions and collaboration from external developers.
  • Maintain compatibility with the latest PDF specifications and features.
  • Provide a customizable and extensible platform for developers to integrate PDF rendering capabilities into their applications.

Most Important Business Risks:

  • Security vulnerabilities in the PDF parsing and rendering engine could expose users to malicious code execution or data breaches.
  • Incompatibility with certain PDF files or features could lead to rendering errors or incomplete display of documents.
  • Performance issues could result in slow loading times or excessive resource consumption, degrading the user experience.
  • Lack of community engagement or contributions could slow down development and innovation.
  • Failure to keep up with evolving PDF standards could lead to compatibility issues in the future.
  • Legal or licensing issues related to PDF specifications or third-party libraries could pose risks to the project.

SECURITY POSTURE

Existing Security Controls:

  • security control: The project is written in JavaScript, which inherently benefits from the security features of modern web browsers, such as sandboxing and same-origin policy.
  • security control: The project undergoes regular code reviews and testing to identify and address potential security vulnerabilities. (Described in CONTRIBUTING.md and test/README.md)
  • security control: The project utilizes a continuous integration (CI) system to automate testing and ensure code quality. (Described in .github/workflows)
  • security control: The project has a security policy in place for reporting and handling vulnerabilities. (Described in SECURITY.md)
  • security control: The project uses a Content Security Policy (CSP) to mitigate the risk of cross-site scripting (XSS) attacks. (Described in web/app.js)
  • security control: Input sanitization is performed to prevent injection vulnerabilities. (Described in various parts of the codebase, e.g., src/core/primitives.js)
  • security control: The project is open-source, allowing for public scrutiny and contributions to security improvements.

Accepted Risks:

  • accepted risk: The project relies on the security of the underlying browser environment and its handling of PDF data.
  • accepted risk: While efforts are made to ensure compatibility, there may be edge cases or rare PDF features that are not fully supported, potentially leading to rendering issues.
  • accepted risk: The project's performance may be affected by the complexity of the PDF document being rendered and the capabilities of the user's device.

Recommended Security Controls:

  • security control: Implement a robust fuzzing framework to proactively discover vulnerabilities in the PDF parsing and rendering engine.
  • security control: Regularly conduct penetration testing to identify and address potential attack vectors.
  • security control: Integrate static application security testing (SAST) and dynamic application security testing (DAST) tools into the CI/CD pipeline.
  • security control: Consider using a memory-safe language or runtime environment for critical components of the PDF parsing engine to mitigate memory corruption vulnerabilities.

Security Requirements:

  • Authentication:

    • Not directly applicable, as the project is a library for rendering PDFs and does not handle user authentication itself. Authentication would be the responsibility of the application integrating pdf.js.

  • Authorization:

    • Not directly applicable, as the project is a library. Authorization would be handled by the integrating application.

  • Input Validation:

    • The project must thoroughly validate and sanitize all input data, including PDF data streams, font data, and image data, to prevent injection vulnerabilities and ensure data integrity.
    • The project must handle malformed or corrupted PDF data gracefully, without crashing or exposing vulnerabilities.

  • Cryptography:

    • If the project handles encrypted PDF documents, it must use strong, industry-standard cryptographic algorithms and protocols for decryption and signature verification.
    • Cryptographic keys must be managed securely, following best practices for key generation, storage, and usage.

DESIGN

C4 CONTEXT

graph LR
    User["User"]
    pdfjs["pdf.js (Project)"]
    Browser["Web Browser"]
    WebApplication["Web Application"]
    ExternalPDF["External PDF Source"]

    User -- Uses --> Browser
    Browser -- Renders --> pdfjs
    WebApplication -- Integrates --> pdfjs
    pdfjs -- Fetches --> ExternalPDF
Loading

Element Descriptions:

  • Element:

    • Name: User
    • Type: Person
    • Description: A person who views PDF documents using a web browser.
    • Responsibilities: Interacts with a web browser to view PDF documents.
    • Security controls: Relies on the security controls of the web browser.

  • Element:

    • Name: pdf.js (Project)
    • Type: Software System
    • Description: A JavaScript library for rendering PDF documents in web browsers.
    • Responsibilities: Parses and renders PDF documents, handles user interaction, and provides an API for integration with web applications.
    • Security controls: Input sanitization, CSP, sandboxing (via browser), code reviews, CI, security policy.

  • Element:

    • Name: Web Browser
    • Type: Software System
    • Description: A software application for accessing and displaying web content, including PDF documents.
    • Responsibilities: Provides the runtime environment for pdf.js, handles network requests, and manages user interaction.
    • Security controls: Sandboxing, same-origin policy, regular security updates.

  • Element:

    • Name: Web Application
    • Type: Software System
    • Description: A web application that integrates pdf.js to provide PDF viewing capabilities.
    • Responsibilities: Integrates pdf.js, handles user authentication and authorization (if applicable), and manages PDF document access.
    • Security controls: Depends on the specific web application; should follow secure coding practices.

  • Element:

    • Name: External PDF Source
    • Type: External System
    • Description: A source of PDF documents, such as a web server or local file system.
    • Responsibilities: Provides PDF documents to pdf.js for rendering.
    • Security controls: Depends on the specific source; may include access controls and data integrity checks.

C4 CONTAINER

graph LR
    User["User"]
    Browser["Web Browser"]
    WebApplication["Web Application"]
    ExternalPDF["External PDF Source"]
    pdfjsAPI["API"]
    pdfjsDisplay["Display"]
    pdfjsParsing["Parsing"]
    pdfjsRendering["Rendering"]

    User -- Uses --> Browser
    Browser -- Renders --> WebApplication
    WebApplication -- Integrates --> pdfjsAPI
    pdfjsAPI -- Uses --> pdfjsDisplay
    pdfjsAPI -- Uses --> pdfjsParsing
    pdfjsParsing -- Uses --> pdfjsRendering
    pdfjsParsing -- Fetches --> ExternalPDF
Loading

Element Descriptions:

  • Element:

    • Name: User
    • Type: Person
    • Description: A person who views PDF documents using a web browser.
    • Responsibilities: Interacts with a web browser to view PDF documents.
    • Security controls: Relies on the security controls of the web browser.

  • Element:

    • Name: Web Browser
    • Type: Software System
    • Description: A software application for accessing and displaying web content, including PDF documents.
    • Responsibilities: Provides the runtime environment for pdf.js, handles network requests, and manages user interaction.
    • Security controls: Sandboxing, same-origin policy, regular security updates.

  • Element:

    • Name: Web Application
    • Type: Software System
    • Description: A web application that integrates pdf.js to provide PDF viewing capabilities.
    • Responsibilities: Integrates pdf.js, handles user authentication and authorization (if applicable), and manages PDF document access.
    • Security controls: Depends on the specific web application; should follow secure coding practices.

  • Element:

    • Name: External PDF Source
    • Type: External System
    • Description: A source of PDF documents, such as a web server or local file system.
    • Responsibilities: Provides PDF documents to pdf.js for rendering.
    • Security controls: Depends on the specific source; may include access controls and data integrity checks.

  • Element:

    • Name: API
    • Type: Container (JavaScript Library)
    • Description: The public API of pdf.js, providing methods for loading, rendering, and interacting with PDF documents.
    • Responsibilities: Exposes functionality to web applications, manages communication between different components.
    • Security controls: Input validation, API rate limiting (if applicable).

  • Element:

    • Name: Display
    • Type: Container (JavaScript Module)
    • Description: Handles the display and presentation of PDF content in the browser.
    • Responsibilities: Manages page layout, rendering of text, images, and other elements, handles user interaction events.
    • Security controls: Output encoding, XSS prevention.

  • Element:

    • Name: Parsing
    • Type: Container (JavaScript Module)
    • Description: Parses the PDF data stream and extracts information about the document structure, objects, and resources.
    • Responsibilities: Reads and interprets the PDF file format, handles different PDF versions and features.
    • Security controls: Input validation, robust parsing logic, fuzzing.

  • Element:

    • Name: Rendering
    • Type: Container (JavaScript Module)
    • Description: Renders the PDF content into a visual representation, typically using HTML5 Canvas or SVG.
    • Responsibilities: Converts parsed PDF data into visual elements, handles font rendering, image decoding, and other rendering tasks.
    • Security controls: Secure handling of image and font data, protection against rendering-related vulnerabilities.

DEPLOYMENT

Possible Deployment Solutions:

  1. CDN (Content Delivery Network): pdf.js can be deployed to a CDN, allowing web applications to easily include it via a <script> tag. This is the most common and recommended approach.
  2. NPM (Node Package Manager): pdf.js is available as an NPM package, allowing developers to install and manage it as a dependency in their projects.
  3. Self-Hosting: Developers can download the pdf.js source code and host it on their own servers.
  4. Bundling: pdf.js can be bundled with other JavaScript code using tools like Webpack or Browserify.

Chosen Solution (CDN):

graph LR
    UserBrowser["User's Web Browser"]
    CDN["CDN (e.g., Cloudflare, jsDelivr)"]
    WebApplication["Web Application Server"]
    OriginServer["pdf.js Origin Server (Mozilla)"]

    UserBrowser -- Requests pdf.js --> CDN
    CDN -- Serves cached copy --> UserBrowser
    CDN -- Requests from Origin --> OriginServer
    WebApplication -- Includes script tag --> UserBrowser
Loading

Element Descriptions:

  • Element:

    • Name: User's Web Browser
    • Type: Software System
    • Description: The user's web browser, which requests and executes pdf.js.
    • Responsibilities: Downloads and executes JavaScript code, renders web pages, and interacts with the user.
    • Security controls: Sandboxing, same-origin policy, regular security updates.

  • Element:

    • Name: CDN (e.g., Cloudflare, jsDelivr)
    • Type: Infrastructure
    • Description: A content delivery network that caches and distributes pdf.js files globally.
    • Responsibilities: Serves pdf.js files to users from the nearest edge server, reducing latency and improving performance.
    • Security controls: HTTPS, DDoS protection, regular security audits.

  • Element:

    • Name: Web Application Server
    • Type: Software System
    • Description: Server that hosts web application which uses pdf.js.
    • Responsibilities: Serves web application files.
    • Security controls: HTTPS, DDoS protection, regular security audits.

  • Element:

    • Name: pdf.js Origin Server (Mozilla)
    • Type: Infrastructure
    • Description: The server where the official pdf.js releases are hosted.
    • Responsibilities: Provides the original source files for pdf.js to the CDN.
    • Security controls: Access controls, regular security updates, code signing (if applicable).

BUILD

graph LR
    Developer["Developer"]
    GitHub["GitHub Repository"]
    CI["Continuous Integration (GitHub Actions)"]
    Tests["Automated Tests"]
    Linters["Linters (ESLint)"]
    SAST["Static Analysis (CodeQL)"]
    BuildArtifacts["Build Artifacts (pdf.js, pdf.worker.js)"]
    CDN["CDN Deployment"]

    Developer -- Pushes code --> GitHub
    GitHub -- Triggers --> CI
    CI -- Runs --> Tests
    CI -- Runs --> Linters
    CI -- Runs --> SAST
    CI -- Produces --> BuildArtifacts
    CI -- Deploys to --> CDN
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Build Process Description:

  1. Code Development: Developers write code and push changes to the GitHub repository.
  2. Continuous Integration: GitHub Actions triggers a CI workflow on each push.
  3. Automated Tests: The CI workflow runs a suite of automated tests, including unit tests, integration tests, and regression tests. (test/README.md)
  4. Linting: Linters (ESLint) are used to enforce code style and identify potential errors. (.eslintrc.js)
  5. Static Analysis: Static analysis tools (CodeQL) are used to scan the codebase for security vulnerabilities and code quality issues. (.github/workflows/codeql.yml)
  6. Build Artifacts: If all tests and checks pass, the CI workflow builds the production artifacts (pdf.js, pdf.worker.js).
  7. Deployment: The build artifacts are deployed to a CDN (e.g., Cloudflare, jsDelivr) for distribution.

Security Controls in Build Process:

  • security control: Automated Tests: Ensure code correctness and prevent regressions.
  • security control: Linters: Enforce code style and identify potential errors.
  • security control: Static Analysis (SAST): Detect security vulnerabilities and code quality issues.
  • security control: Continuous Integration: Automates the build and testing process, ensuring consistency and repeatability.
  • security control: Dependency Management: NPM is used to manage dependencies, and package-lock.json ensures consistent versions.
  • security control: Code Reviews: All code changes are reviewed by other developers before merging. (CONTRIBUTING.md)

RISK ASSESSMENT

Critical Business Processes to Protect:

  • PDF Rendering: The core functionality of pdf.js, ensuring accurate and reliable rendering of PDF documents.
  • User Data Privacy: Protecting user data from unauthorized access or disclosure, especially when handling sensitive PDF documents.
  • Application Availability: Ensuring that pdf.js is available and accessible to users when needed.
  • Reputation: Maintaining the reputation of pdf.js as a secure and reliable PDF rendering library.

Data to Protect and Sensitivity:

  • PDF Document Content: This can range from publicly available documents to highly sensitive information, such as financial records, medical records, or legal documents. Sensitivity varies greatly depending on the content.
  • User Metadata: Information about the user's interaction with PDF documents, such as viewing history or annotations. Sensitivity is generally low, but privacy regulations may apply.
  • No direct user data is stored by pdf.js itself. It operates on the client-side within the browser's sandbox. The integrating application is responsible for handling any user data.

QUESTIONS & ASSUMPTIONS

Questions:

  • Are there any specific compliance requirements (e.g., HIPAA, GDPR) that need to be considered when integrating pdf.js into an application?
  • What are the expected performance requirements for pdf.js, in terms of document loading times and resource consumption?
  • Are there any plans to support advanced PDF features, such as digital signatures or form filling, in the future?
  • What is the process for handling security vulnerabilities reported by external researchers?

Assumptions:

  • BUSINESS POSTURE: The primary goal is to provide a free, open-source, and widely accessible PDF rendering solution.
  • BUSINESS POSTURE: The project prioritizes security and aims to minimize the risk of vulnerabilities.
  • SECURITY POSTURE: The web browser provides a secure execution environment for pdf.js.
  • SECURITY POSTURE: The integrating application is responsible for handling user authentication, authorization, and data security.
  • DESIGN: pdf.js will be primarily used as a client-side library within web browsers.
  • DESIGN: The CDN deployment model is the preferred method for distributing pdf.js.
  • DESIGN: The build process is automated and includes security checks.