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BUSINESS POSTURE

Parsedown is a Markdown parser library written in PHP. The primary business goal for a project utilizing Parsedown is to efficiently and accurately convert Markdown formatted text into HTML for display or further processing within web applications or other systems.

Business priorities for projects using Parsedown typically include:

  • Ease of integration: Parsedown should be simple to incorporate into existing PHP projects.
  • Performance: The parsing process should be fast and efficient to minimize server load and ensure a responsive user experience.
  • Accuracy: Parsedown should correctly interpret the Markdown specification to render content as intended.
  • Security: The parsing process must be secure and not introduce vulnerabilities into applications using it, such as Cross-Site Scripting (XSS) vulnerabilities.

Key business risks associated with using Parsedown include:

  • Security vulnerabilities: If Parsedown has vulnerabilities, applications using it could be exposed to security risks, especially if processing user-supplied Markdown.
  • Performance bottlenecks: Inefficient parsing could lead to slow page load times or server overload, negatively impacting user experience and potentially availability.
  • Incompatibility or bugs: Incorrect parsing or incompatibility with certain Markdown features could lead to content being displayed incorrectly, affecting user trust and potentially business operations if content accuracy is critical.

SECURITY POSTURE

Existing security controls:

  • security control: Input validation inherent in Markdown parsing logic to handle various Markdown syntax elements. (Implemented within Parsedown PHP code)

Accepted risks:

  • accepted risk: Reliance on the application integrating Parsedown to handle output sanitization if necessary to prevent XSS based on the context where the parsed HTML is used.
  • accepted risk: Assumption that the PHP environment and server infrastructure where Parsedown is deployed are secured according to general best practices.

Recommended security controls:

  • security control: Implement automated security testing, including static analysis security testing (SAST) and potentially fuzzing, to identify potential vulnerabilities in Parsedown code.
  • security control: Integrate Parsedown into a secure software development lifecycle (SSDLC) that includes security reviews and code analysis.
  • security control: Consider output sanitization of the HTML generated by Parsedown within the integrating application, especially when handling user-provided Markdown, to mitigate potential XSS risks.

Security requirements:

  • Authentication: Not directly applicable to Parsedown as a library. Authentication is the responsibility of the application using Parsedown.
  • Authorization: Not directly applicable to Parsedown as a library. Authorization is the responsibility of the application using Parsedown to control access to content and functionality.
  • Input validation: Parsedown must perform robust input validation to correctly parse Markdown syntax and handle potentially malicious or unexpected input without causing errors or security issues. This is critical to prevent injection attacks.
  • Cryptography: Not directly applicable to Parsedown as a Markdown parsing library. Cryptographic functions might be used by applications that utilize Parsedown, but are not a core requirement for Parsedown itself.

DESIGN

C4 CONTEXT

flowchart LR
    subgraph "Application Context"
    A["Web Application"]
    end
    B["User"]
    C["Parsedown Library"]

    B --> A: Uses
    A --> C: Uses
    A --> B: Displays HTML Content

    style C fill:#f9f,stroke:#333,stroke-width:2px
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Context Diagram Elements:

  • Name: User

    • Type: Person
    • Description: End-user interacting with the Web Application.
    • Responsibilities: Accessing and viewing content through the Web Application. Potentially providing Markdown content as input.
    • Security controls: User authentication and authorization are handled by the Web Application.

  • Name: Web Application

    • Type: Software System
    • Description: A web-based application that needs to display content formatted using Markdown. This application integrates the Parsedown library.
    • Responsibilities: Receiving user requests, processing application logic, using Parsedown to convert Markdown to HTML, and displaying HTML content to the user. Managing user sessions, authentication, and authorization.
    • Security controls: security control: Web Application Firewall (WAF), security control: Input validation (application level), security control: Output sanitization, security control: Session management, security control: Authentication and Authorization mechanisms.

  • Name: Parsedown Library

    • Type: Software System
    • Description: A PHP library responsible for parsing Markdown formatted text and converting it into HTML.
    • Responsibilities: Parsing Markdown input, generating HTML output.
    • Security controls: security control: Input validation (Markdown syntax parsing).

C4 CONTAINER

flowchart LR
    subgraph "Web Application Container"
        A["Web Server"]
        B["PHP Runtime"]
        C["Parsedown Library"]
        D["Application Code"]
    end
    E["User Browser"]

    E --> A: HTTP Requests/Responses
    A --> B: Executes PHP
    B --> C: Includes/Uses
    B --> D: Executes Application Logic
    D --> C: Calls Parsing Functions
    B --> A: HTTP Responses

    style C fill:#f9f,stroke:#333,stroke-width:2px
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Container Diagram Elements:

  • Name: User Browser

    • Type: Container
    • Description: User's web browser used to access the Web Application.
    • Responsibilities: Rendering HTML content, sending HTTP requests to the Web Server.
    • Security controls: Browser security features (e.g., Content Security Policy, XSS protection).

  • Name: Web Server

    • Type: Container
    • Description: Web server (e.g., Apache, Nginx) that receives HTTP requests and serves the Web Application.
    • Responsibilities: Handling HTTP requests, serving static content, routing requests to the PHP Runtime.
    • Security controls: security control: HTTPS configuration, security control: Web server security hardening, security control: Access control lists.

  • Name: PHP Runtime

    • Type: Container
    • Description: PHP runtime environment responsible for executing the Web Application's PHP code.
    • Responsibilities: Executing PHP scripts, managing application logic, interacting with the Parsedown Library.
    • Security controls: security control: PHP security configuration (e.g., disable dangerous functions), security control: Regular security updates for PHP runtime.

  • Name: Parsedown Library

    • Type: Container
    • Description: The Parsedown PHP library files integrated into the Web Application.
    • Responsibilities: Parsing Markdown text and generating HTML output when called by the Application Code.
    • Security controls: security control: Input validation within parsing logic.

  • Name: Application Code

    • Type: Container
    • Description: Custom PHP code of the Web Application that utilizes Parsedown.
    • Responsibilities: Handling application logic, receiving user input, calling Parsedown to parse Markdown, processing and displaying the generated HTML.
    • Security controls: security control: Application-level input validation, security control: Output sanitization, security control: Authorization logic, security control: Secure coding practices.

DEPLOYMENT

Deployment Architecture Option: Cloud-based Web Hosting

flowchart LR
    subgraph "Cloud Environment"
        subgraph "Load Balancer"
            A["Load Balancer"]
        end
        subgraph "Web Servers"
            B1["Web Server Instance 1"]
            B2["Web Server Instance 2"]
        end
        subgraph "Database Server"
            C["Database Server"]
        end
    end
    D["User Browser"]

    D --> A: HTTP/HTTPS Requests
    A --> B1: HTTP/HTTPS Requests
    A --> B2: HTTP/HTTPS Requests
    B1 --> C: Database Queries
    B2 --> C: Database Queries

    subgraph "Web Server Instance 1"
        E1["Operating System"]
        F1["Web Server Software"]
        G1["PHP Runtime"]
        H1["Parsedown Library Files"]
        I1["Application Files"]
    end
    B1 --> E1: Runs on
    E1 --> F1: Hosts
    F1 --> G1: Executes
    G1 --> H1: Includes
    G1 --> I1: Executes

    subgraph "Web Server Instance 2"
        E2["Operating System"]
        F2["Web Server Software"]
        G2["PHP Runtime"]
        H2["Parsedown Library Files"]
        I2["Application Files"]
    end
    B2 --> E2: Runs on
    E2 --> F2: Hosts
    F2 --> G2: Executes
    G2 --> H2: Includes
    G2 --> I2: Executes

    style H1 fill:#f9f,stroke:#333,stroke-width:2px
    style H2 fill:#f9f,stroke:#333,stroke-width:2px
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Deployment Diagram Elements (Cloud-based Web Hosting):

  • Name: User Browser

    • Type: Environment
    • Description: User's web browser.
    • Responsibilities: Accessing the application.
    • Security controls: Browser security features.

  • Name: Load Balancer

    • Type: Infrastructure
    • Description: Distributes incoming traffic across multiple Web Server Instances.
    • Responsibilities: Traffic distribution, high availability.
    • Security controls: security control: DDoS protection, security control: SSL termination.

  • Name: Web Server Instance 1 & 2

    • Type: Infrastructure
    • Description: Virtual machines or containers hosting the Web Application.
    • Responsibilities: Running the Web Application, processing requests.
    • Security controls: security control: Operating system hardening, security control: Firewall, security control: Intrusion detection system.

  • Name: Operating System (Web Servers)

    • Type: Software
    • Description: Operating system for the Web Server Instances (e.g., Linux).
    • Responsibilities: Providing base system functionality.
    • Security controls: security control: OS security hardening, security control: Regular patching.

  • Name: Web Server Software (Web Servers)

    • Type: Software
    • Description: Web server software (e.g., Apache, Nginx) running on the Web Server Instances.
    • Responsibilities: Handling HTTP requests, serving web content.
    • Security controls: security control: Web server security configuration, security control: Regular updates.

  • Name: PHP Runtime (Web Servers)

    • Type: Software
    • Description: PHP runtime environment installed on the Web Server Instances.
    • Responsibilities: Executing PHP application code.
    • Security controls: security control: PHP security configuration, security control: Regular updates.

  • Name: Parsedown Library Files (Web Servers)

    • Type: Software
    • Description: Parsedown PHP library files deployed on the Web Server Instances.
    • Responsibilities: Providing Markdown parsing functionality to the application.
    • Security controls: Inherits security of the Web Server Instance and PHP Runtime.

  • Name: Application Files (Web Servers)

    • Type: Software
    • Description: Web Application code files deployed on the Web Server Instances.
    • Responsibilities: Implementing application logic, using Parsedown.
    • Security controls: Application-level security controls.

  • Name: Database Server

    • Type: Infrastructure
    • Description: Database server storing application data.
    • Responsibilities: Data persistence, data management.
    • Security controls: security control: Database access control, security control: Database encryption, security control: Regular backups.

BUILD

flowchart LR
    A["Developer"] --> B["Code Repository (GitHub)"]: Code Commit
    B --> C["CI/CD Pipeline (GitHub Actions)"]: Trigger Build
    C --> D["Build Environment"]: Build Process
    D --> E["Build Artifacts (Parsedown PHP Files)"]: Output
    E --> F["Artifact Repository"]: Store Artifacts

    subgraph "Build Environment"
        G["Source Code Checkout"]
        H["Dependency Management (Composer)"]
        I["Static Analysis Security Testing (SAST)"]
        J["Unit Tests"]
        K["Package/Archive Creation"]
    end
    C --> G: Step 1
    G --> H: Step 2
    H --> I: Step 3
    I --> J: Step 4
    J --> K: Step 5
    D --> G: Includes
    D --> H: Includes
    D --> I: Includes
    D --> J: Includes
    D --> K: Includes

    style E fill:#f9f,stroke:#333,stroke-width:2px
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Build Process Description:

  1. Developer: Developers write and commit code changes to the Code Repository.
  2. Code Repository (GitHub): Hosts the source code of Parsedown.
  3. CI/CD Pipeline (GitHub Actions): Automated CI/CD pipeline triggered by code commits.
  4. Build Environment: A controlled environment for building and testing the software.
    • Source Code Checkout: Retrieves the latest code from the repository.
    • Dependency Management (Composer): Installs PHP dependencies using Composer.
    • Static Analysis Security Testing (SAST): Performs static code analysis to identify potential security vulnerabilities.
    • Unit Tests: Executes unit tests to ensure code quality and functionality.
    • Package/Archive Creation: Creates a distributable package (e.g., ZIP archive) containing the Parsedown PHP files.
  5. Build Artifacts (Parsedown PHP Files): The resulting packaged Parsedown library.
  6. Artifact Repository: Stores the build artifacts for distribution or deployment.

Build Process Security Controls:

  • security control: Code Repository Access Control: Restrict access to the code repository to authorized developers.
  • security control: CI/CD Pipeline Security: Secure configuration of the CI/CD pipeline to prevent unauthorized modifications and ensure integrity.
  • security control: Static Analysis Security Testing (SAST): Automated SAST tools integrated into the pipeline to detect potential vulnerabilities early in the development process.
  • security control: Dependency Management: Using Composer with verified package sources and dependency vulnerability scanning to ensure supply chain security.
  • security control: Unit Tests: Automated unit tests to verify code functionality and prevent regressions.
  • security control: Artifact Repository Access Control: Secure storage and access control for build artifacts.

RISK ASSESSMENT

Critical business process: Secure and accurate rendering of Markdown content within web applications to ensure correct information display and prevent security vulnerabilities like XSS.

Data we are trying to protect:

  • Markdown content: User-provided or application-managed Markdown text. Sensitivity depends on the application context. If it includes sensitive information, confidentiality and integrity are important.
  • Parsed HTML output: The HTML generated by Parsedown. Integrity is important to ensure it accurately represents the original Markdown and does not introduce malicious code.

Data sensitivity: Sensitivity of Markdown content and parsed HTML output is context-dependent. In many web applications, user-generated content can be considered moderately sensitive, requiring protection against unauthorized modification and malicious injection. In applications dealing with highly confidential data, the sensitivity would be higher.

QUESTIONS & ASSUMPTIONS

Questions:

  • What are the specific applications that will be using Parsedown? (e.g., blog platform, documentation system, forum)
  • What is the expected volume of Markdown content processing? (e.g., requests per second, data size)
  • Are there specific performance requirements for Markdown parsing? (e.g., latency, throughput)
  • What is the level of security risk tolerance for applications using Parsedown? (e.g., startup vs. Fortune 500)
  • Are there any specific compliance requirements that the applications using Parsedown must adhere to? (e.g., GDPR, HIPAA)

Assumptions:

  • BUSINESS POSTURE: The primary business goal is to enable efficient and secure Markdown rendering in web applications. Performance and security are key priorities.
  • SECURITY POSTURE: Applications using Parsedown are responsible for output sanitization and overall application security. Parsedown itself focuses on secure and accurate Markdown parsing. Regular security testing and secure development practices are recommended.
  • DESIGN: Parsedown is used as a library within PHP-based web applications. Deployment is typically in a cloud-based web hosting environment. A CI/CD pipeline is used for building and testing Parsedown.