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sec-design.md

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Okay, let's create a design document for the rc project, keeping in mind its purpose and potential security implications.

Project Design Document: rc

BUSINESS POSTURE

The rc project (runtime configuration) is a fundamental utility for managing application configurations in Node.js environments. It simplifies loading configurations from various sources (command-line arguments, environment variables, configuration files) with a defined precedence. It's widely used, indicating its importance to a large number of applications.

Business Priorities:

  • Reliability: The rc library must be highly reliable. Incorrect configuration loading can lead to application failures or unexpected behavior.
  • Maintainability: Given its widespread use, the project needs to be easily maintainable to address bugs and security vulnerabilities promptly.
  • Simplicity: The library should remain simple and easy to use, avoiding unnecessary complexity that could introduce bugs or security issues.
  • Compatibility: Maintain backward compatibility where possible to avoid breaking existing applications that rely on rc.

Business Goals:

  • Provide a consistent and predictable way to load application configurations.
  • Minimize configuration-related errors in applications using the library.
  • Facilitate easy updates and maintenance of the library itself.

Most Important Business Risks:

  • Configuration Injection: Malicious actors could inject unexpected configurations, potentially leading to remote code execution, data breaches, or denial of service. This is the most critical risk.
  • Denial of Service: Specially crafted configuration files or inputs could cause the library to crash or consume excessive resources, leading to application downtime.
  • Dependency Vulnerabilities: Vulnerabilities in rc's dependencies could be exploited to compromise applications using rc.
  • Information Disclosure: Incorrectly handled configuration loading might expose sensitive information (e.g., API keys, passwords) present in the environment or configuration files.

SECURITY POSTURE

Existing Security Controls:

  • security control: Code Reviews: The GitHub repository shows evidence of code reviews, although their rigor and consistency are unknown. (Inferred from GitHub pull requests).
  • security control: Dependency Management: The project uses package.json and package-lock.json to manage dependencies, which helps ensure consistent builds and reduces the risk of introducing vulnerable dependencies unintentionally. (Visible in the repository).
  • security control: Testing: The project includes a test suite (test/ directory), which helps identify bugs and regressions. The extent and effectiveness of the tests are crucial for security. (Visible in the repository).
  • security control: Linter: .eslintrc file suggest that project is using linter. (Visible in the repository).

Accepted Risks:

  • accepted risk: Limited Input Validation: The library primarily focuses on loading configurations from various sources and doesn't perform extensive validation on the content of the configuration values. This is partially by design, as rc is meant to be flexible, but it increases the risk of configuration injection.
  • accepted risk: Reliance on User Environment: The library's behavior is influenced by environment variables and files in the user's system, which are outside the direct control of the library.

Recommended Security Controls:

  • security control: Enhanced Input Validation: Implement optional, configurable input validation to allow users to specify schemas or rules for configuration values. This could be integrated as a separate module or plugin to maintain flexibility.
  • security control: Secure Configuration Best Practices Documentation: Provide clear documentation and examples on securely using rc, including recommendations for avoiding sensitive data in configuration files, using environment variables securely, and validating configuration values within the application.
  • security control: Regular Security Audits: Conduct periodic security audits, including penetration testing and code reviews focused on security vulnerabilities.
  • security control: Dependency Scanning: Integrate automated dependency scanning tools (e.g., npm audit, Snyk, Dependabot) into the build process to identify and address known vulnerabilities in dependencies.
  • security control: Fuzz Testing: Introduce fuzz testing to identify unexpected behavior or crashes when processing malformed or malicious input.

Security Requirements:

  • Authentication: Not directly applicable to rc itself, as it's a configuration loading library, not an authentication system. Authentication should be handled by the applications using rc.
  • Authorization: Not directly applicable to rc itself. Authorization logic should reside within the applications using rc.
  • Input Validation:
    • The library should provide mechanisms (either built-in or through extensions) to allow applications to validate the structure and content of configuration values.
    • Validation rules should be configurable by the user.
    • The library should handle invalid configuration gracefully, providing informative error messages without crashing.
  • Cryptography:
    • rc itself doesn't handle cryptographic operations. However, if configuration values contain sensitive data (e.g., API keys, secrets), applications using rc must handle these values securely, using appropriate encryption and key management practices. rc should not be responsible for decrypting or encrypting sensitive data.
    • Documentation should emphasize the importance of securely storing and handling sensitive configuration values.

DESIGN

C4 CONTEXT

graph LR
    subgraph "External Systems"
        User[("User")]
        EnvironmentVariables[("Environment Variables")]
        CommandLineArguments[("Command-Line Arguments")]
        ConfigurationFiles[("Configuration Files\n(various formats)")]
        ExternalConfigurationService[("External Configuration Service\n(e.g., Consul, etcd)")]
    end

    subgraph "rc"
        rc[("rc Library")]
    end
    
    subgraph "Application"
        Application[("Application using rc")]
    end

    User -- "Provides config via" --> CommandLineArguments
    User -- "Sets config via" --> EnvironmentVariables
    User -- "Creates/Modifies" --> ConfigurationFiles
    ConfigurationFiles -- "Loads config from" --> rc
    CommandLineArguments -- "Loads config from" --> rc
    EnvironmentVariables -- "Loads config from" --> rc
    ExternalConfigurationService -- "Loads config from" --> rc
    rc -- "Provides config to" --> Application
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Context Diagram Element List:

  • Element:

    • Name: User
    • Type: Person
    • Description: The user interacting with the application, potentially providing configuration via command-line arguments or environment variables.
    • Responsibilities: Providing configuration inputs.
    • Security controls: None directly within rc. User-level security is the responsibility of the operating system and user practices.

  • Element:

    • Name: Environment Variables
    • Type: System
    • Description: Environment variables set in the user's shell or system.
    • Responsibilities: Storing configuration values.
    • Security controls: Access control to environment variables (OS-level).

  • Element:

    • Name: Command-Line Arguments
    • Type: System
    • Description: Arguments passed to the application when it's executed.
    • Responsibilities: Providing configuration values.
    • Security controls: None directly within rc.

  • Element:

    • Name: Configuration Files
    • Type: System
    • Description: Files in various formats (JSON, INI, YAML, etc.) containing configuration data.
    • Responsibilities: Storing configuration values.
    • Security controls: File system permissions (OS-level).

  • Element:

    • Name: External Configuration Service
    • Type: System
    • Description: An external service like Consul or etcd that provides configuration data.
    • Responsibilities: Storing and managing configuration data.
    • Security controls: Authentication, authorization, encryption in transit and at rest (within the external service).

  • Element:

    • Name: rc Library
    • Type: Software System
    • Description: The rc library itself.
    • Responsibilities: Loading configuration from various sources with defined precedence.
    • Security controls: Input validation (limited, but should be enhanced), secure dependency management.

  • Element:

    • Name: Application using rc
    • Type: Software System
    • Description: Application that is using rc library.
    • Responsibilities: Using provided configuration.
    • Security controls: Input validation, secure handling of sensitive configuration values.

C4 CONTAINER

Since rc is a single library, the container diagram is essentially an expansion of the context diagram.

graph LR
    subgraph "External Systems"
        User[("User")]
        EnvironmentVariables[("Environment Variables")]
        CommandLineArguments[("Command-Line Arguments")]
        ConfigurationFiles[("Configuration Files\n(various formats)")]
        ExternalConfigurationService[("External Configuration Service\n(e.g., Consul, etcd)")]
    end

    subgraph "rc - Node.js Library"
        rc[("rc Module")]
        Parser[("Parser\n(JSON, INI, YAML)")]
        Defaults[("Default Configuration")]
        
    end
    
     subgraph "Application"
        Application[("Application using rc")]
    end

    User -- "Provides config via" --> CommandLineArguments
    User -- "Sets config via" --> EnvironmentVariables
    User -- "Creates/Modifies" --> ConfigurationFiles
    ConfigurationFiles -- "Loads config from" --> rc
    CommandLineArguments -- "Loads config from" --> rc
    EnvironmentVariables -- "Loads config from" --> rc
    ExternalConfigurationService -- "Loads config from" --> rc
    rc -- "Parses with" --> Parser
    rc -- "Uses" --> Defaults
    rc -- "Provides config to" --> Application
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Container Diagram Element List:

  • Element:

    • Name: rc Module
    • Type: Module
    • Description: The main module of the rc library.
    • Responsibilities: Orchestrates the loading and merging of configuration from different sources.
    • Security controls: Input validation (limited, but should be enhanced).

  • Element:

    • Name: Parser
    • Type: Module
    • Description: Modules for parsing different configuration file formats (JSON, INI, YAML). This might be internal to rc or use external libraries.
    • Responsibilities: Parsing configuration files.
    • Security controls: Secure parsing libraries (avoiding vulnerabilities like YAML deserialization issues).

  • Element:

    • Name: Default Configuration
    • Type: Data
    • Description: Default configuration values.
    • Responsibilities: Providing fallback values if no configuration is found from other sources.
    • Security controls: None. Ensure defaults do not contain sensitive information.

  • Element:

    • Name: User
    • Type: Person
    • Description: The user interacting with the application.
    • Responsibilities: Providing configuration inputs.
    • Security controls: None directly within rc.

  • Element:

    • Name: Environment Variables
    • Type: System
    • Description: Environment variables set in the user's shell or system.
    • Responsibilities: Storing configuration values.
    • Security controls: Access control to environment variables (OS-level).

  • Element:

    • Name: Command-Line Arguments
    • Type: System
    • Description: Arguments passed to the application when it's executed.
    • Responsibilities: Providing configuration values.
    • Security controls: None directly within rc.

  • Element:

    • Name: Configuration Files
    • Type: System
    • Description: Files in various formats (JSON, INI, YAML, etc.) containing configuration data.
    • Responsibilities: Storing configuration values.
    • Security controls: File system permissions (OS-level).

  • Element:

    • Name: External Configuration Service
    • Type: System
    • Description: An external service like Consul or etcd that provides configuration data.
    • Responsibilities: Storing and managing configuration data.
    • Security controls: Authentication, authorization, encryption in transit and at rest (within the external service).

  • Element:

    • Name: Application using rc
    • Type: Software System
    • Description: Application that is using rc library.
    • Responsibilities: Using provided configuration.
    • Security controls: Input validation, secure handling of sensitive configuration values.

DEPLOYMENT

rc is a library, not a standalone application. Therefore, deployment is primarily about how it's included in other applications. There are several possibilities:

  1. npm Installation (Most Common): Developers use npm install rc to add rc as a dependency to their project. This downloads the package from the npm registry and adds it to the project's node_modules directory.
  2. GitHub Cloning (Less Common): Developers could clone the rc repository directly from GitHub, although this is less common for typical usage. This is more relevant for contributing to rc itself.
  3. Bundling (For Browser Use - Unlikely): While rc is primarily designed for Node.js, it could theoretically be bundled for browser use using tools like Webpack or Browserify. This is not a typical use case.

We'll focus on the most common scenario: npm installation.

graph LR
    subgraph "Developer Machine"
        Dev[("Developer")]
        Project[("Project using rc")]
        npm[("npm CLI")]
    end

    subgraph "npm Registry"
        npmRegistry[("npm Registry")]
        rcPackage[("rc Package")]
    end
    
    subgraph "Application Server"
        AppServer[("Application Server")]
        DeployedApp[("Deployed Application")]
        NodeModules[("node_modules")]
        rcDeployed[("rc (installed)")]
    end

    Dev -- "npm install rc" --> npm
    npm -- "Downloads" --> npmRegistry
    npmRegistry -- "Provides" --> rcPackage
    npm -- "Installs into" --> Project
    Project -- "Includes" --> DeployedApp
    Dev -- "Deploys" --> AppServer
    DeployedApp -- "Contains" --> NodeModules
    NodeModules -- "Contains" --> rcDeployed
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Deployment Diagram Element List:

  • Element:

    • Name: Developer
    • Type: Person
    • Description: The developer building the application that uses rc.
    • Responsibilities: Installing and using rc.
    • Security controls: Using a secure development environment.

  • Element:

    • Name: Project using rc
    • Type: Software System
    • Description: The developer's project that depends on rc.
    • Responsibilities: Using rc for configuration loading.
    • Security controls: Secure coding practices, dependency management.

  • Element:

    • Name: npm CLI
    • Type: Tool
    • Description: The npm command-line interface.
    • Responsibilities: Managing dependencies, downloading packages.
    • Security controls: Using a trusted npm registry, verifying package integrity (using package-lock.json).

  • Element:

    • Name: npm Registry
    • Type: System
    • Description: The public npm registry (or a private registry).
    • Responsibilities: Hosting and serving npm packages.
    • Security controls: Registry-level security measures (e.g., two-factor authentication for publishers, malware scanning).

  • Element:

    • Name: rc Package
    • Type: Package
    • Description: The rc package hosted on the npm registry.
    • Responsibilities: Providing the rc library code.
    • Security controls: Package signing (if used), vulnerability scanning.

  • Element:

    • Name: Application Server
    • Type: Server
    • Description: Server where application is deployed.
    • Responsibilities: Running application.
    • Security controls: Server hardening, firewall, intrusion detection.

  • Element:

    • Name: Deployed Application
    • Type: Software System
    • Description: Deployed application.
    • Responsibilities: Running application logic.
    • Security controls: Application-level security controls.

  • Element:

    • Name: node_modules
    • Type: Directory
    • Description: Directory with installed npm packages.
    • Responsibilities: Providing dependencies to application.
    • Security controls: None.

  • Element:

    • Name: rc (installed)
    • Type: Library
    • Description: Installed rc library.
    • Responsibilities: Loading configuration.
    • Security controls: Input validation (limited, but should be enhanced).

BUILD

The build process for rc itself (as opposed to applications using rc) involves:

  1. Development: Developers write code and tests.
  2. Testing: Running the test suite (npm test).
  3. Linting: Checking code style and potential errors (npm run lint).
  4. Publishing (to npm): Using npm publish to upload the package to the npm registry.
graph LR
    subgraph "Developer Machine"
        Dev[("Developer")]
        Code[("Source Code")]
        Tests[("Tests")]
        npm[("npm CLI")]
        Lint[("Linter")]
    end

    subgraph "npm Registry"
        npmRegistry[("npm Registry")]
        rcPackage[("rc Package")]
    end
    
    Dev -- "Writes" --> Code
    Dev -- "Writes" --> Tests
    Dev -- "Runs" --> Tests
    Dev -- "Runs" --> Lint
    Lint -- "Checks" --> Code
    Tests -- "Verify" --> Code
    Dev -- "npm publish" --> npm
    npm -- "Uploads" --> npmRegistry
    npmRegistry -- "Hosts" --> rcPackage
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Build Process Security Controls:

  • security control: Code Reviews: Before merging changes, code reviews should be conducted to identify potential security issues.
  • security control: Testing: The test suite should include security-focused tests (e.g., testing for injection vulnerabilities).
  • security control: Linting: A linter (like ESLint) helps enforce coding standards and can detect some potential security issues.
  • security control: Dependency Management: Using package-lock.json ensures consistent builds and reduces the risk of introducing vulnerable dependencies unintentionally.
  • security control: Secure npm Publishing: The developer publishing to npm should use two-factor authentication to prevent unauthorized package updates.
  • security control: (Recommended) Dependency Scanning: Integrate automated dependency scanning into the build process (e.g., using GitHub Actions or similar).
  • security control: (Recommended) Fuzz Testing: Add fuzz testing to the build pipeline.

RISK ASSESSMENT

Critical Business Processes:

  • Application Configuration Loading: This is the core function of rc. Failure here can lead to application failure or misbehavior.
  • Application Startup: rc is often used during application startup, making it critical for the application to function correctly.

Data We Are Trying to Protect:

  • Configuration Data: This includes application settings, potentially including sensitive information like API keys, database credentials, and other secrets.
    • Sensitivity: Varies widely. Some configuration data may be public, while other parts may be highly sensitive. The application using rc is responsible for determining the sensitivity of its configuration data and handling it appropriately. rc should provide mechanisms to help with this, but it's ultimately the application's responsibility.

QUESTIONS & ASSUMPTIONS

Questions:

  • What is the expected frequency of updates and releases for rc?
  • Are there any specific compliance requirements (e.g., PCI DSS, GDPR) that applications using rc typically need to meet? This would influence recommendations for secure configuration practices.
  • What is the level of security expertise within the rc maintainer team?
  • What is the process for handling reported security vulnerabilities?
  • Are there any plans to add features to rc that might introduce new security considerations (e.g., support for encrypted configuration files)?

Assumptions:

  • BUSINESS POSTURE: We assume a moderate risk appetite. While rc is a widely used library, it's also a relatively small and focused component. We prioritize reliability and maintainability, but also recognize the need for security.
  • SECURITY POSTURE: We assume that the existing security controls are in place (code reviews, testing, dependency management) but may not be comprehensive or rigorously enforced. We assume a reactive approach to security vulnerabilities rather than a proactive one.
  • DESIGN: We assume that the primary use case is Node.js applications using npm for dependency management. We assume that developers using rc have some understanding of security best practices, but may not be security experts.