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sec-design.md

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Okay, let's create a design document for the Fat-Free Framework (F3) based on the provided GitHub repository.

BUSINESS POSTURE

Business Priorities and Goals:

  • Provide a lightweight, easy-to-use, and fast PHP framework for web developers.
  • Minimize the learning curve for developers familiar with PHP.
  • Offer a modular design, allowing developers to use only the components they need.
  • Enable rapid prototyping and development of web applications.
  • Maintain a small codebase for easy understanding and contribution.
  • Provide sufficient features for common web development tasks without unnecessary bloat.

Most Important Business Risks:

  • Security vulnerabilities in the framework could lead to widespread exploitation of applications built with it.
  • Lack of maintenance or updates could lead to the framework becoming obsolete or incompatible with newer PHP versions.
  • Insufficient documentation or community support could hinder adoption and usage.
  • Competition from other, more feature-rich or popular PHP frameworks.
  • Performance bottlenecks could limit the scalability of applications built with the framework.

SECURITY POSTURE

Existing Security Controls:

  • security control: Input validation: F3 provides mechanisms for filtering and validating user input (e.g., the scrub() method, input filtering rules). Described in documentation and implemented in core components.
  • security control: Output encoding: F3 encourages proper encoding of output to prevent XSS vulnerabilities (e.g., using template engines with built-in escaping). Described in documentation.
  • security control: Session management: F3 provides a session management component with options for secure session handling (e.g., using HTTPS, setting appropriate session cookie parameters). Described in documentation and implemented in lib/session.php.
  • security control: CSRF protection: F3 includes features to mitigate CSRF attacks (e.g., generating and validating CSRF tokens). Described in documentation.
  • security control: SQL injection prevention: F3's database abstraction layer (if used) provides parameterized queries or prepared statements to prevent SQL injection. Described in documentation and implemented in database related components.
  • security control: Password hashing: F3 recommends using strong password hashing algorithms (e.g., bcrypt, Argon2) via PHP's built-in functions. Described in documentation.
  • security control: File upload handling: F3 provides guidance on securely handling file uploads (e.g., validating file types, storing files outside the web root). Described in documentation.

Accepted Risks:

  • accepted risk: The framework's minimalist nature means developers are responsible for implementing some security best practices themselves, which may lead to vulnerabilities if not handled correctly.
  • accepted risk: Reliance on third-party plugins or extensions may introduce security risks if those components are not properly vetted or maintained.
  • accepted risk: Older versions of PHP (below the officially supported minimum version) may have known vulnerabilities that F3 cannot mitigate.

Recommended Security Controls:

  • security control: Implement a Content Security Policy (CSP) to mitigate XSS and other code injection attacks.
  • security control: Regularly update the framework and all dependencies to patch security vulnerabilities.
  • security control: Implement robust logging and monitoring to detect and respond to security incidents.
  • security control: Use a dependency analysis tool to identify and address vulnerabilities in third-party libraries.
  • security control: Conduct regular security audits and penetration testing of applications built with F3.

Security Requirements:

  • Authentication:
    • The framework should provide mechanisms or guidance for secure user authentication, including password hashing, session management, and optional multi-factor authentication.
  • Authorization:
    • The framework should support role-based access control (RBAC) or other authorization mechanisms to restrict access to sensitive resources.
  • Input Validation:
    • All user input must be validated and sanitized to prevent common web vulnerabilities like XSS, SQL injection, and command injection.
  • Cryptography:
    • The framework should provide or recommend secure cryptographic practices for handling sensitive data, including encryption and key management.
    • Use secure hashing algorithms (e.g., bcrypt, Argon2) for password storage.
    • Use authenticated encryption (e.g., AES-GCM) for data confidentiality and integrity.

DESIGN

C4 CONTEXT

graph LR
    User["User (Web Browser)"] -- "HTTPS" --> F3App["Fat-Free Framework Application"]
    F3App -- "Database Connection" --> Database["Database (MySQL, PostgreSQL, SQLite, etc.)"]
    F3App -- "SMTP" --> MailServer["Mail Server"]
    F3App -- "HTTP/HTTPS" --> ExternalAPI["External APIs (Optional)"]
    F3App -- "Filesystem" --> Cache["Cache (Filesystem, Memcached, Redis, etc.)"]
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Element Descriptions:

  • Element:

    • Name: User (Web Browser)
    • Type: Person
    • Description: A user interacting with the Fat-Free Framework application through a web browser.
    • Responsibilities: Sends requests to the application, receives and renders responses.
    • Security controls: Browser-based security mechanisms (e.g., same-origin policy, HTTPS).

  • Element:

    • Name: Fat-Free Framework Application
    • Type: Software System
    • Description: The web application built using the Fat-Free Framework.
    • Responsibilities: Handles user requests, processes data, interacts with other systems, renders responses.
    • Security controls: Input validation, output encoding, session management, CSRF protection, SQL injection prevention, password hashing, file upload handling.

  • Element:

    • Name: Database (MySQL, PostgreSQL, SQLite, etc.)
    • Type: Software System
    • Description: A database system used to store application data.
    • Responsibilities: Stores and retrieves data, ensures data integrity.
    • Security controls: Database access controls, encryption at rest, regular backups.

  • Element:

    • Name: Mail Server
    • Type: Software System
    • Description: A mail server used to send emails (e.g., notifications, password resets).
    • Responsibilities: Sends emails on behalf of the application.
    • Security controls: Secure SMTP configuration, spam filtering, authentication.

  • Element:

    • Name: External APIs (Optional)
    • Type: Software System
    • Description: Any external APIs the application interacts with (e.g., payment gateways, social media APIs).
    • Responsibilities: Provides specific functionalities as per the API provider.
    • Security controls: API keys, OAuth, rate limiting, input validation.

  • Element:

    • Name: Cache (Filesystem, Memcached, Redis, etc.)
    • Type: Software System
    • Description: A caching system used to improve application performance.
    • Responsibilities: Stores frequently accessed data for faster retrieval.
    • Security controls: Cache invalidation mechanisms, access controls.

C4 CONTAINER

graph LR
    User["User (Web Browser)"] -- "HTTPS" --> WebServer["Web Server (Apache, Nginx)"]
    WebServer -- "FastCGI/PHP-FPM" --> F3App["F3 Application"]
    F3App -- "Database Connection" --> Database["Database"]
    F3App -- "SMTP" --> MailServer["Mail Server"]
    F3App -- "HTTP/HTTPS" --> ExternalAPI["External APIs"]
    F3App -- "Filesystem" --> Cache["Cache"]
    F3App -- "Filesystem" --> Views["Views (Templates)"]
    F3App -- "" --> Models["Models"]
    F3App -- "" --> Controllers["Controllers"]
    F3App -- "" --> Lib["F3 Core Library"]
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Element Descriptions:

  • Element:

    • Name: User (Web Browser)
    • Type: Person
    • Description: A user interacting with the application.
    • Responsibilities: Sends requests, receives responses.
    • Security controls: Browser security mechanisms.

  • Element:

    • Name: Web Server (Apache, Nginx)
    • Type: Container
    • Description: The web server that receives requests and forwards them to the F3 application.
    • Responsibilities: Handles HTTP requests, serves static files, manages PHP processes.
    • Security controls: Web server configuration hardening, HTTPS configuration, request filtering.

  • Element:

    • Name: F3 Application
    • Type: Container
    • Description: The Fat-Free Framework application code.
    • Responsibilities: Processes requests, interacts with other components, generates responses.
    • Security controls: Input validation, output encoding, session management, CSRF protection, etc.

  • Element:

    • Name: Database
    • Type: Container
    • Description: The database system.
    • Responsibilities: Stores and retrieves data.
    • Security controls: Database access controls, encryption.

  • Element:

    • Name: Mail Server
    • Type: Container
    • Description: The mail server.
    • Responsibilities: Sends emails.
    • Security controls: Secure SMTP configuration.

  • Element:

    • Name: External APIs
    • Type: Container
    • Description: External API services.
    • Responsibilities: Provides external functionalities.
    • Security controls: API keys, OAuth.

  • Element:

    • Name: Cache
    • Type: Container
    • Description: The caching system.
    • Responsibilities: Stores cached data.
    • Security controls: Cache invalidation, access controls.

  • Element:

    • Name: Views (Templates)
    • Type: Component
    • Description: Template files used to render dynamic content.
    • Responsibilities: Generates HTML output.
    • Security controls: Output encoding, template engine security features.

  • Element:

    • Name: Models
    • Type: Component
    • Description: Application logic related to data access and manipulation.
    • Responsibilities: Interacts with the database, encapsulates business logic.
    • Security controls: Data validation, secure database interactions.

  • Element:

    • Name: Controllers
    • Type: Component
    • Description: Handles user requests and interacts with models and views.
    • Responsibilities: Processes requests, coordinates application flow.
    • Security controls: Input validation, authorization checks.

  • Element:

    • Name: F3 Core Library
    • Type: Component
    • Description: The core components of the Fat-Free Framework.
    • Responsibilities: Provides framework functionalities.
    • Security controls: Built-in security features, regular updates.

DEPLOYMENT

Possible Deployment Solutions:

  1. Traditional LAMP/LEMP Stack: Apache/Nginx, MySQL/PostgreSQL, PHP on a single server or virtual machine.
  2. Cloud-based Virtual Machines: Deploying the application on a VM in a cloud environment (e.g., AWS EC2, Google Compute Engine, Azure VM).
  3. Containerized Deployment: Using Docker and container orchestration platforms like Kubernetes or Docker Swarm.
  4. Platform as a Service (PaaS): Deploying to a PaaS provider like Heroku, AWS Elastic Beanstalk, or Google App Engine.

Chosen Solution (for detailed description): Containerized Deployment with Docker and Kubernetes.

graph LR
    Developer["Developer"] -- "Code Commit" --> GitRepo["Git Repository (GitHub)"]
    GitRepo -- "Webhook Trigger" --> CI_CD["CI/CD Pipeline (GitHub Actions)"]
    CI_CD -- "Build & Push" --> DockerRegistry["Docker Registry (Docker Hub, ECR)"]
    DockerRegistry -- "Pull Image" --> KubernetesCluster["Kubernetes Cluster"]
    KubernetesCluster -- "" --> WebServerPod["Web Server Pod (Nginx)"]
    KubernetesCluster -- "" --> AppPod["Application Pod (F3)"]
    KubernetesCluster -- "" --> DatabasePod["Database Pod (MySQL)"]
    KubernetesCluster -- "" --> CachePod["Cache Pod (Redis)"]
    Ingress["Ingress Controller"] -- "" --> WebServerPod
    User["User"] -- "HTTPS" --> Ingress
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Element Descriptions:

  • Element:

    • Name: Developer
    • Type: Person
    • Description: A developer working on the application code.
    • Responsibilities: Writes code, commits changes to the Git repository.
    • Security controls: Code review, secure coding practices.

  • Element:

    • Name: Git Repository (GitHub)
    • Type: System
    • Description: The source code repository.
    • Responsibilities: Stores code, tracks changes.
    • Security controls: Access controls, branch protection rules.

  • Element:

    • Name: CI/CD Pipeline (GitHub Actions)
    • Type: System
    • Description: The continuous integration and continuous deployment pipeline.
    • Responsibilities: Automates building, testing, and deploying the application.
    • Security controls: Secure pipeline configuration, vulnerability scanning.

  • Element:

    • Name: Docker Registry (Docker Hub, ECR)
    • Type: System
    • Description: The registry for storing Docker images.
    • Responsibilities: Stores and distributes Docker images.
    • Security controls: Access controls, image signing.

  • Element:

    • Name: Kubernetes Cluster
    • Type: Infrastructure
    • Description: The Kubernetes cluster where the application is deployed.
    • Responsibilities: Manages containerized application deployment and scaling.
    • Security controls: Network policies, RBAC, pod security policies.

  • Element:

    • Name: Web Server Pod (Nginx)
    • Type: Container Instance
    • Description: A pod running the Nginx web server.
    • Responsibilities: Serves static files, proxies requests to the application pod.
    • Security controls: Web server configuration hardening.

  • Element:

    • Name: Application Pod (F3)
    • Type: Container Instance
    • Description: A pod running the Fat-Free Framework application.
    • Responsibilities: Handles application logic.
    • Security controls: Application-level security controls.

  • Element:

    • Name: Database Pod (MySQL)
    • Type: Container Instance
    • Description: A pod running the MySQL database.
    • Responsibilities: Stores application data.
    • Security controls: Database access controls, encryption.

  • Element:

    • Name: Cache Pod (Redis)
    • Type: Container Instance
    • Description: A pod running the Redis cache.
    • Responsibilities: Stores cached data.
    • Security controls: Cache access controls.

  • Element:

    • Name: Ingress Controller
    • Type: Infrastructure
    • Description: Manages external access to the services in the cluster.
    • Responsibilities: Routes traffic to the appropriate pods.
    • Security controls: TLS termination, request filtering.

  • Element:

    • Name: User
    • Type: Person
    • Description: External user accessing application.
    • Responsibilities: Accessing application.
    • Security controls: HTTPS.

BUILD

graph LR
    Developer["Developer"] -- "Code Commit" --> GitRepo["Git Repository (GitHub)"]
    GitRepo -- "Webhook Trigger" --> CI_CD["CI/CD Pipeline (GitHub Actions)"]
    CI_CD -- "Checkout Code" --> Workspace["Workspace"]
    Workspace -- "Run Tests" --> TestResults["Test Results"]
    Workspace -- "Run SAST" --> SASTResults["SAST Results"]
    Workspace -- "Build Docker Image" --> DockerImage["Docker Image"]
    DockerImage -- "Push Image" --> DockerRegistry["Docker Registry"]
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Build Process Description:

  1. Developer commits code changes to the Git repository (GitHub).
  2. A webhook triggers the CI/CD pipeline (GitHub Actions).
  3. The pipeline checks out the code into a workspace.
  4. The pipeline runs unit tests and integration tests.
  5. The pipeline runs a Static Application Security Testing (SAST) tool (e.g., PHPStan, Psalm) to identify potential security vulnerabilities.
  6. If tests and SAST checks pass, the pipeline builds a Docker image for the application.
  7. The Docker image is tagged with a version number and pushed to a Docker registry (e.g., Docker Hub, Amazon ECR).
  8. Supply chain security:
    • Use signed commits in the Git repository.
    • Use a dependency analysis tool (e.g., Dependabot) to identify and update vulnerable dependencies.
    • Use a container image scanning tool (e.g., Trivy, Clair) to scan the Docker image for vulnerabilities.
  9. Build automation:
    • The entire build process is automated using GitHub Actions.
  10. Security checks during build:
    • Unit tests and integration tests verify the functionality of the code.
    • SAST tools analyze the code for potential security vulnerabilities.
    • Container image scanning identifies vulnerabilities in the Docker image.

RISK ASSESSMENT

Critical Business Processes:

  • User registration and authentication.
  • Data storage and retrieval (database interactions).
  • Email sending (if applicable).
  • API interactions (if applicable).
  • Serving web content.

Data Sensitivity:

  • User credentials (passwords, email addresses): High sensitivity.
  • Personal data (names, addresses, etc.): High sensitivity (depending on the application).
  • Financial data (payment information): High sensitivity (if applicable).
  • Application-specific data: Sensitivity varies depending on the nature of the application.
  • Session data: Medium sensitivity.

QUESTIONS & ASSUMPTIONS

Questions:

  • What specific types of applications are typically built with F3 in this context (e.g., blogs, e-commerce sites, internal tools)? This helps determine the specific data sensitivity and business processes.
  • Are there any existing security policies or compliance requirements (e.g., GDPR, PCI DSS) that need to be considered?
  • What is the expected traffic volume and scalability requirements for applications built with F3?
  • Are there any specific third-party integrations that are commonly used with F3?
  • What is the level of security expertise of the developers who will be using F3?

Assumptions:

  • BUSINESS POSTURE: The organization has a moderate risk appetite, balancing the need for rapid development with the importance of security.
  • SECURITY POSTURE: Developers have a basic understanding of web security principles but may not be security experts. The framework is kept up-to-date, and security patches are applied promptly.
  • DESIGN: The deployment environment will be a containerized environment using Docker and Kubernetes. A standard LAMP/LEMP stack is used for simpler deployments. The application uses a relational database (e.g., MySQL, PostgreSQL). The application may use a caching system (e.g., Redis, Memcached).