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sec-design.md

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Okay, let's create a design document for the Gorilla Mux project, focusing on aspects relevant to threat modeling.

BUSINESS POSTURE

Gorilla Mux is a popular Go package used for building HTTP servers, particularly RESTful APIs. It acts as a request multiplexer (router) and dispatcher. It's a foundational component, meaning many applications rely on its correct and secure operation.

Priorities:

  • Reliability: Mux must reliably route requests to the correct handlers. Incorrect routing can lead to application errors, denial of service, or even unintended exposure of functionality.
  • Performance: As a core component in the request handling pipeline, Mux needs to be performant. Slow routing adds latency to every request.
  • Maintainability: The project must be maintainable and extensible to adapt to evolving HTTP standards and community needs.
  • Security: While Mux itself doesn't handle authentication or authorization directly, it plays a crucial role in ensuring that security policies implemented by the application are correctly enforced. Incorrect routing could bypass security checks.
  • Ease of Use: The library should be easy to use and understand, reducing the likelihood of developers introducing security vulnerabilities due to misconfiguration.

Business Risks:

  • Routing Errors: Incorrectly configured routes could expose sensitive endpoints or internal functionality to unauthorized users.
  • Denial of Service (DoS): Poorly designed routing or inefficient regular expressions used in routes could be exploited for DoS attacks.
  • Dependency Vulnerabilities: Vulnerabilities in Mux's dependencies could be exploited to compromise applications using it.
  • Future Vulnerabilities: As with any software, undiscovered vulnerabilities in Mux itself could be found and exploited.

SECURITY POSTURE

Existing Security Controls:

  • security control: Input Validation (Partial): Mux performs some basic input validation related to URL parsing and matching. However, it does not validate the content of request bodies or headers beyond what's necessary for routing. This is described in the project's documentation and Go code.
  • security control: Regular Expression Handling: Mux uses Go's regexp package. Care must be taken by developers using Mux to avoid ReDoS (Regular Expression Denial of Service) vulnerabilities. This is implicitly part of using the library and understanding Go's regexp package.
  • security control: Community Scrutiny: Being a popular open-source project, Mux benefits from community scrutiny, increasing the likelihood of vulnerabilities being discovered and reported. This is inherent to its open-source nature.
  • security control: Testing: Mux has a comprehensive test suite that helps ensure the correctness of its routing logic and prevent regressions. This is visible in the project's GitHub repository.
  • security control: Code Reviews: Contributions to Mux are subject to code review, providing another layer of defense against introducing vulnerabilities. This is part of the project's contribution guidelines.

Accepted Risks:

  • accepted risk: ReDoS Vulnerability Responsibility: Mux relies on developers to use regular expressions safely. The library itself does not provide specific ReDoS protection mechanisms.
  • accepted risk: Application-Level Security: Mux explicitly does not handle authentication, authorization, or other application-level security concerns. These are the responsibility of the application using Mux.
  • accepted risk: Dependency Vulnerabilities: Mux, like any software, may have dependencies with vulnerabilities. While the project aims to keep dependencies up-to-date, there's always a risk.

Recommended Security Controls:

  • security control: ReDoS Mitigation Guidance: Provide clear documentation and examples demonstrating how to avoid ReDoS vulnerabilities when defining routes.
  • security control: Dependency Management: Implement automated dependency scanning and updating to minimize the risk of known vulnerabilities in dependencies.
  • security control: Security Audits: Consider periodic security audits by external experts to identify potential vulnerabilities.

Security Requirements:

  • Authentication: Mux itself does not handle authentication. Applications using Mux must implement their own authentication mechanisms before request routing occurs (e.g., using middleware).
  • Authorization: Mux does not handle authorization. Applications must implement authorization checks within their request handlers, after Mux has routed the request.
  • Input Validation: While Mux performs basic URL validation, applications must perform thorough input validation on all request data (headers, bodies, query parameters) within their handlers. This includes validating data types, lengths, and formats.
  • Cryptography: Mux does not directly handle cryptography. Applications requiring secure communication (HTTPS) should configure their servers appropriately. Mux should be used in conjunction with a properly configured TLS setup.

DESIGN

C4 CONTEXT

graph LR
    User(("User"))
    MuxProject[("Gorilla Mux Project")]
    ExternalAPIs(("External APIs"))
    Databases(("Databases"))

    User -- "HTTPS" --> MuxProject
    MuxProject -- "HTTP" --> ExternalAPIs
    MuxProject -- "DB Protocol" --> Databases
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Element Descriptions:

  • Element:

    • Name: User
    • Type: Person
    • Description: Represents a user interacting with an application that uses Gorilla Mux.
    • Responsibilities: Sends HTTP requests to the application.
    • Security controls: Uses HTTPS for secure communication.

  • Element:

    • Name: Gorilla Mux Project
    • Type: Software System
    • Description: The Gorilla Mux request multiplexer, the core of this design document.
    • Responsibilities: Routes incoming HTTP requests to the appropriate handlers based on defined routes.
    • Security controls: Basic URL parsing and validation. Relies on application-level security for authentication, authorization, and input validation.

  • Element:

    • Name: External APIs
    • Type: Software System
    • Description: External APIs that the application using Gorilla Mux might interact with.
    • Responsibilities: Provides services to the application.
    • Security controls: Assumed to have their own security mechanisms.

  • Element:

    • Name: Databases
    • Type: Software System
    • Description: Databases that the application using Gorilla Mux might interact with.
    • Responsibilities: Stores and retrieves data for the application.
    • Security controls: Assumed to have their own security mechanisms (authentication, authorization, encryption).

C4 CONTAINER

Since Gorilla Mux is a library, the container diagram is essentially an extension of the context diagram. The "container" is the application that uses Mux.

graph LR
    User(("User"))
    App[("Application using Gorilla Mux")]
    ExternalAPIs(("External APIs"))
    Databases(("Databases"))
    MuxLibrary[("Gorilla Mux Library")]

    User -- "HTTPS" --> App
    App -- "HTTP" --> ExternalAPIs
    App -- "DB Protocol" --> Databases
    App -. "Uses" .-> MuxLibrary
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Element Descriptions:

  • Element:

    • Name: User
    • Type: Person
    • Description: Represents a user interacting with the application.
    • Responsibilities: Sends HTTP requests to the application.
    • Security controls: Uses HTTPS for secure communication.

  • Element:

    • Name: Application using Gorilla Mux
    • Type: Container (Web Application)
    • Description: A web application that uses Gorilla Mux for request routing.
    • Responsibilities: Handles user requests, interacts with external APIs and databases, and implements business logic.
    • Security controls: Implements authentication, authorization, input validation, and other application-level security measures.

  • Element:

    • Name: External APIs
    • Type: Container (External Service)
    • Description: External APIs that the application interacts with.
    • Responsibilities: Provides services to the application.
    • Security controls: Assumed to have their own security mechanisms.

  • Element:

    • Name: Databases
    • Type: Container (Database)
    • Description: Databases that the application interacts with.
    • Responsibilities: Stores and retrieves data for the application.
    • Security controls: Assumed to have their own security mechanisms (authentication, authorization, encryption).

  • Element:

    • Name: Gorilla Mux Library
    • Type: Library
    • Description: The Gorilla Mux library, used by the application for request routing.
    • Responsibilities: Routes incoming HTTP requests to the appropriate handlers.
    • Security controls: Basic URL parsing and validation.

DEPLOYMENT

Gorilla Mux, being a library, is deployed as part of the application that uses it. There isn't a separate deployment for Mux itself. Therefore, the deployment diagram depends entirely on the application using it. Here are a few common scenarios, with one described in detail:

Possible Deployment Solutions:

  1. Standalone Go Application: The Go application (with Mux embedded) is compiled into a single executable and run directly on a server.
  2. Docker Container: The Go application is packaged into a Docker container and deployed to a container orchestration platform (e.g., Kubernetes, Docker Swarm).
  3. Serverless Function: The Go application (or parts of it) is deployed as a serverless function (e.g., AWS Lambda, Google Cloud Functions).

Chosen Solution (Docker Container on Kubernetes):

graph LR
    Internet(("Internet"))
    LoadBalancer[("Load Balancer")]
    KubernetesCluster[("Kubernetes Cluster")]
    Pod1[("Pod (App Instance 1)")]
    Pod2[("Pod (App Instance 2)")]
    Pod3[("Pod (App Instance 3)")]

    Internet -- "HTTPS" --> LoadBalancer
    LoadBalancer -- "HTTPS" --> KubernetesCluster
    KubernetesCluster -- "HTTPS" --> Pod1
    KubernetesCluster -- "HTTPS" --> Pod2
    KubernetesCluster -- "HTTPS" --> Pod3
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Element Descriptions:

  • Element:

    • Name: Internet
    • Type: Network
    • Description: The public internet.
    • Responsibilities: Routes traffic to the load balancer.
    • Security controls: Standard internet security protocols.

  • Element:

    • Name: Load Balancer
    • Type: Infrastructure
    • Description: Distributes incoming traffic across multiple instances of the application.
    • Responsibilities: Load balancing, SSL termination.
    • Security controls: SSL/TLS termination, potentially a Web Application Firewall (WAF).

  • Element:

    • Name: Kubernetes Cluster
    • Type: Infrastructure
    • Description: A Kubernetes cluster managing the application's containers.
    • Responsibilities: Orchestrates container deployment, scaling, and networking.
    • Security controls: Kubernetes RBAC, network policies, pod security policies.

  • Element:

    • Name: Pod (App Instance 1/2/3)
    • Type: Container Instance
    • Description: A single instance of the application running within a Docker container. Contains the compiled Go application, including the Gorilla Mux library.
    • Responsibilities: Handles user requests.
    • Security controls: Application-level security controls, container security context.

BUILD

The build process for an application using Gorilla Mux typically involves the following steps:

  1. Developer writes code, including route definitions using Mux.
  2. Dependencies are managed using Go Modules (go mod).
  3. The code is compiled using the Go compiler (go build).
  4. (Optional) The compiled application is packaged into a Docker image.
graph LR
    Developer[("Developer")]
    CodeRepository[("Code Repository (GitHub)")]
    BuildServer[("Build Server (e.g., GitHub Actions)")]
    ArtifactRepository[("Artifact Repository (e.g., Docker Hub)")]

    Developer -- "Push Code" --> CodeRepository
    CodeRepository -- "Trigger Build" --> BuildServer
    BuildServer -- "Fetch Dependencies" --> CodeRepository
    BuildServer -- "Compile Code" --> BuildServer
    BuildServer -- "Run Tests" --> BuildServer
    BuildServer -- "Build Docker Image" --> BuildServer
    BuildServer -- "Push Image" --> ArtifactRepository
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Security Controls in Build Process:

  • security control: Dependency Management: Go Modules helps ensure that the correct versions of dependencies are used, reducing the risk of using vulnerable versions.
  • security control: Static Analysis: SAST tools (e.g., go vet, staticcheck, or dedicated security scanners) can be integrated into the build process to identify potential vulnerabilities in the code.
  • security control: Dependency Scanning: Tools like snyk or dependabot can scan dependencies for known vulnerabilities.
  • security control: Code Signing: The compiled binary or Docker image can be signed to ensure its integrity and authenticity.
  • security control: Build Automation: Using a CI/CD system (e.g., GitHub Actions, Jenkins) ensures that the build process is consistent and repeatable, reducing the risk of manual errors.

RISK ASSESSMENT

Critical Business Processes:

  • Request Handling: The core process is handling incoming HTTP requests and routing them to the appropriate application logic. Any disruption to this process directly impacts the application's functionality.
  • API Functionality (if applicable): If the application exposes an API, the correct and secure operation of that API is critical.

Data to Protect:

  • Sensitivity depends entirely on the application using Mux. Mux itself does not handle data persistence or storage.
  • Examples of data that might be handled by an application using Mux:
    • User Authentication Data (e.g., usernames, passwords, tokens): Highly sensitive.
    • Personal Data (e.g., names, addresses, email addresses): Sensitive, subject to privacy regulations (e.g., GDPR, CCPA).
    • Financial Data (e.g., credit card numbers, transaction details): Highly sensitive, subject to strict regulations (e.g., PCI DSS).
    • Application-Specific Data: The sensitivity of this data depends on the specific application.

QUESTIONS & ASSUMPTIONS

Questions:

  • What specific types of applications are most commonly built using Gorilla Mux? (This helps prioritize security considerations.)
  • Are there any plans to add built-in features for ReDoS protection or other security-related functionality?
  • What is the project's policy on addressing reported security vulnerabilities?

Assumptions:

  • BUSINESS POSTURE: Assumes that users of Gorilla Mux are aware of its role as a routing library and understand that they are responsible for implementing application-level security.
  • SECURITY POSTURE: Assumes that developers using Gorilla Mux will follow secure coding practices and take responsibility for securing their applications.
  • DESIGN: Assumes a standard deployment model (e.g., Docker containers on Kubernetes) for illustrative purposes. The actual deployment may vary.
  • BUILD: Assumes that the build process will include some form of dependency management and static analysis.