Skip to content

Latest commit

 

History

History
294 lines (258 loc) · 16.3 KB

sec-design.md

File metadata and controls

294 lines (258 loc) · 16.3 KB

Okay, let's create a design document for the Pundit library, focusing on its use within a larger application context. I'll assume we're integrating Pundit into a Ruby on Rails web application, as that's its primary use case. I'll also assume a mid-sized company with an established online presence, meaning they have a moderate risk tolerance and existing security practices, but also need to move quickly.

BUSINESS POSTURE

  • Priorities and Goals:

    • Provide a clean and maintainable authorization system for a Ruby on Rails application.
    • Ensure consistent application of authorization rules across the application.
    • Reduce the risk of unauthorized access to sensitive data and functionality.
    • Enable developers to easily define and understand authorization policies.
    • Improve the overall security posture of the application.
    • Minimize code complexity related to authorization.

  • Business Risks:

    • Data Breach: Unauthorized access to sensitive user data (PII, financial data, etc.) due to flaws in authorization logic.
    • Reputational Damage: A security incident related to authorization could damage the company's reputation and erode customer trust.
    • Compliance Violations: Failure to meet regulatory requirements (e.g., GDPR, CCPA) related to data access control.
    • Business Disruption: Exploitation of authorization vulnerabilities could lead to service disruption or data loss.
    • Development Overhead: Poorly designed authorization can lead to increased development time and maintenance costs.

SECURITY POSTURE

  • Existing Security Controls:

    • security control: Authentication system (e.g., Devise, a custom solution) is assumed to be in place and securely implemented. This is a prerequisite for Pundit, as it only handles authorization. (Described in application's authentication implementation documentation).
    • security control: Secure coding practices are followed, including input validation, output encoding, and protection against common web vulnerabilities (e.g., OWASP Top 10). (Described in company's secure coding guidelines).
    • security control: Regular security audits and penetration testing are conducted. (Described in company's security audit policy).
    • security control: Rails framework security features are enabled and properly configured (e.g., CSRF protection, strong parameters). (Described in Rails application configuration).
    • security control: Deployment pipeline includes security checks (e.g., static code analysis, vulnerability scanning). (Described in deployment pipeline configuration).

  • Accepted Risks:

    • accepted risk: Pundit relies on the developer to correctly implement policies. Incorrectly written policies can lead to authorization bypasses. This is mitigated by code reviews and testing.
    • accepted risk: Performance overhead of authorization checks. While Pundit is generally performant, complex policies or excessive checks can impact application performance. This is mitigated by careful policy design and performance testing.
    • accepted risk: The application is at risk from vulnerabilities that are not covered by the OWASP Top 10.

  • Recommended Security Controls:

    • security control: Implement comprehensive test coverage for all Pundit policies, including both positive and negative test cases.
    • security control: Conduct regular code reviews with a specific focus on authorization logic and policy implementation.
    • security control: Integrate a policy linter or static analysis tool to help identify potential issues in Pundit policies.
    • security control: Monitor application logs for authorization-related events (e.g., policy violations, unauthorized access attempts).
    • security control: Establish a clear process for updating and reviewing authorization policies as the application evolves.

  • Security Requirements:

    • Authentication: Pundit does not handle authentication. The application must have a separate, securely implemented authentication system.
    • Authorization:
      • All controller actions must be authorized using Pundit policies.
      • Policies must be defined for all resources (models) that require access control.
      • Policies must follow the principle of least privilege, granting only the necessary permissions to users.
      • Authorization logic must be centralized in Pundit policies, not scattered throughout the application code.
    • Input Validation: While not directly related to Pundit, input validation is crucial for preventing many security vulnerabilities. All user input must be validated before being used in authorization logic or any other part of the application.
    • Cryptography: Pundit itself does not handle cryptography. However, any sensitive data used in authorization decisions (e.g., user roles, permissions) must be stored securely, potentially using encryption.

DESIGN

C4 CONTEXT

graph LR
    subgraph "Internet"
        User(("User"))
    end
    subgraph "Internal Network"
        WebApp[("Web Application")]
        DB[("Database")]
        ExternalService[("External Service")]
    end

    User -- "Uses" --> WebApp
    WebApp -- "Reads/Writes" --> DB
    WebApp -- "Uses" --> ExternalService
    classDef default fill:#fff,stroke:#000,stroke-width:2px;
Loading
  • Elements Description:
    • User:
      • Name: User
      • Type: Person
      • Description: A user interacting with the web application.
      • Responsibilities: Accessing and using the application's features.
      • Security Controls: Authentication (handled separately), session management.
    • Web Application:
      • Name: Web Application
      • Type: System
      • Description: The Ruby on Rails application using Pundit for authorization.
      • Responsibilities: Handling user requests, enforcing authorization policies, interacting with the database and external services.
      • Security Controls: Pundit policies, input validation, output encoding, CSRF protection, secure configuration.
    • Database:
      • Name: Database
      • Type: System
      • Description: The application's database (e.g., PostgreSQL, MySQL).
      • Responsibilities: Storing application data.
      • Security Controls: Access control, encryption at rest, regular backups.
    • External Service:
      • Name: External Service
      • Type: System
      • Description: Any external service the application interacts with (e.g., payment gateway, email provider).
      • Responsibilities: Providing specific functionality to the application.
      • Security Controls: API keys, authentication, secure communication (HTTPS).

C4 CONTAINER

graph LR
    subgraph "Web Application"
        User(("User"))
        Controllers[("Controllers")]
        Policies[("Pundit Policies")]
        Models[("Models")]
        DB[("Database")]
        ExternalService[("External Service API")]

        User -- "HTTPS" --> Controllers
        Controllers -- "Uses" --> Policies
        Policies -- "Uses" --> Models
        Models -- "Reads/Writes" --> DB
        Controllers -- "Uses" --> ExternalService
    end
    classDef default fill:#fff,stroke:#000,stroke-width:2px;
Loading
  • Elements Description:
    • User:
      • Name: User
      • Type: Person
      • Description: A user interacting with the web application.
      • Responsibilities: Accessing and using the application's features.
      • Security Controls: Authentication (handled separately), session management.
    • Controllers:
      • Name: Controllers
      • Type: Container
      • Description: Rails controllers that handle user requests.
      • Responsibilities: Receiving requests, invoking actions, rendering views, interacting with models and policies.
      • Security Controls: authorize calls to Pundit policies, input validation, CSRF protection.
    • Pundit Policies:
      • Name: Pundit Policies
      • Type: Container
      • Description: Ruby classes that define authorization rules.
      • Responsibilities: Encapsulating authorization logic, determining whether a user is allowed to perform an action on a resource.
      • Security Controls: Policy logic itself, following the principle of least privilege.
    • Models:
      • Name: Models
      • Type: Container
      • Description: Rails models representing application data.
      • Responsibilities: Interacting with the database, encapsulating business logic.
      • Security Controls: Data validation, potentially data-level access control (though this is often handled by Pundit).
    • Database:
      • Name: Database
      • Type: Container
      • Description: The application's database.
      • Responsibilities: Storing application data.
      • Security Controls: Access control, encryption at rest, regular backups.
    • External Service API:
      • Name: External Service API
      • Type: Container
      • Description: API of external service.
      • Responsibilities: Providing specific functionality to the application.
      • Security Controls: API keys, authentication, secure communication (HTTPS).

DEPLOYMENT

Possible deployment solutions:

  1. Traditional server deployment (e.g., using Capistrano to deploy to a VPS).
  2. Platform as a Service (PaaS) deployment (e.g., Heroku, AWS Elastic Beanstalk).
  3. Containerized deployment (e.g., Docker, Kubernetes).

We'll describe the containerized deployment using Docker and Kubernetes, as it's a modern and common approach.

graph LR
    subgraph "Kubernetes Cluster"
        subgraph "Production Namespace"
            WebAppPod1[("Web App Pod 1")]
            WebAppPod2[("Web App Pod 2")]
            DBPod[("Database Pod")]
            Ingress[("Ingress")]
        end
    end
    Internet(("Internet"))

    Internet -- "HTTPS" --> Ingress
    Ingress -- "Routes traffic" --> WebAppPod1
    Ingress -- "Routes traffic" --> WebAppPod2
    WebAppPod1 -- "Internal Network" --> DBPod
    WebAppPod2 -- "Internal Network" --> DBPod

    classDef default fill:#fff,stroke:#000,stroke-width:2px;
Loading
  • Elements Description:
    • Internet:
      • Name: Internet
      • Type: Node
      • Description: The public internet.
      • Responsibilities: Source of user traffic.
      • Security Controls: Firewall, DDoS protection (typically handled by the cloud provider).
    • Kubernetes Cluster:
      • Name: Kubernetes Cluster
      • Type: Node
      • Description: The Kubernetes cluster hosting the application.
      • Responsibilities: Orchestrating containers, managing resources, providing networking.
      • Security Controls: RBAC, network policies, pod security policies, regular security updates.
    • Production Namespace:
      • Name: Production Namespace
      • Type: Node
      • Description: A Kubernetes namespace isolating the production environment.
      • Responsibilities: Providing a logical separation for production resources.
      • Security Controls: Namespace-level access control, resource quotas.
    • Web App Pod 1 & 2:
      • Name: Web App Pod 1 & 2
      • Type: Node
      • Description: Instances of the web application container.
      • Responsibilities: Running the Rails application.
      • Security Controls: Read-only filesystem, limited privileges, resource limits.
    • Database Pod:
      • Name: Database Pod
      • Type: Node
      • Description: The database container.
      • Responsibilities: Running the database server.
      • Security Controls: Strong passwords, access control, encryption at rest, regular backups, limited network access.
    • Ingress:
      • Name: Ingress
      • Type: Node
      • Description: Kubernetes Ingress controller.
      • Responsibilities: Routing external traffic to the web application pods.
      • Security Controls: TLS termination, potentially a web application firewall (WAF).

BUILD

graph LR
    Developer[("Developer")]
    GitRepo[("Git Repository")]
    CI[("CI Server")]
    SAST[("SAST Tool")]
    SCA[("SCA Tool")]
    DockerRegistry[("Docker Registry")]
    Artifact[("Docker Image")]

    Developer -- "Pushes code" --> GitRepo
    GitRepo -- "Triggers build" --> CI
    CI -- "Runs SAST" --> SAST
    CI -- "Runs SCA" --> SCA
    CI -- "Builds image" --> Artifact
    Artifact -- "Pushes image" --> DockerRegistry
    classDef default fill:#fff,stroke:#000,stroke-width:2px;
Loading

  • Process Description:

    1. Developer pushes code changes to the Git Repository.
    2. The Git Repository triggers a build on the CI Server (e.g., GitHub Actions, Jenkins, CircleCI).
    3. The CI Server runs a series of steps:
      • Checks out the code.
      • Runs a SAST Tool (Static Application Security Testing) to analyze the code for vulnerabilities (e.g., Brakeman for Rails).
      • Runs an SCA Tool (Software Composition Analysis) to identify vulnerabilities in third-party dependencies (e.g., Bundler-Audit).
      • Builds a Docker Image containing the application and its dependencies.
      • Runs unit and integration tests.
      • If all checks and tests pass, pushes the Docker Image to a Docker Registry (e.g., Docker Hub, AWS ECR).

  • Security Controls:

    • security control: SAST identifies vulnerabilities in the application's code.
    • security control: SCA identifies vulnerabilities in third-party libraries.
    • security control: Automated build process ensures consistent and repeatable builds.
    • security control: Build artifacts (Docker images) are stored in a secure registry.
    • security control: Build fails if security checks or tests fail, preventing vulnerable code from being deployed.
    • security control: Code reviews are required before merging changes to the main branch.

RISK ASSESSMENT

  • Critical Business Processes:

    • User authentication and authorization.
    • Data access and manipulation (CRUD operations).
    • Any business-specific workflows that involve sensitive data or actions.

  • Data Sensitivity:

    • User Data: PII (Personally Identifiable Information), such as names, email addresses, passwords (hashed), and potentially other sensitive information depending on the application's purpose. Sensitivity: High.
    • Application Data: Data specific to the application's functionality. Sensitivity: Varies depending on the application, but could range from Low to High.
    • Financial Data: If the application handles payments or financial transactions, this data is highly sensitive. Sensitivity: High.
    • Session Data: Data related to user sessions. Sensitivity: Medium.

QUESTIONS & ASSUMPTIONS

  • Questions:

    • What specific types of user data are stored by the application?
    • Are there any specific compliance requirements (e.g., GDPR, CCPA, HIPAA) that apply?
    • What external services does the application interact with, and what data is exchanged?
    • What is the existing authentication mechanism?
    • What is the current testing strategy for authorization?
    • What is the expected load and performance requirements for the application?
    • Are there any existing security policies or guidelines that need to be followed?
    • What is the team's experience level with Pundit and secure coding practices?

  • Assumptions:

    • BUSINESS POSTURE: The company has a moderate risk tolerance and values security, but also needs to maintain development velocity.
    • SECURITY POSTURE: A basic level of security awareness and practices are already in place. A secure authentication system is already implemented.
    • DESIGN: The application is a Ruby on Rails web application. Pundit is used correctly and consistently throughout the application. The deployment environment is Kubernetes. The build process is automated using a CI/CD pipeline.