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

BUSINESS POSTURE

Kratos is a Go framework for building cloud-native microservices. It aims to simplify the development of robust, scalable, and maintainable applications. Given its open-source nature and focus on microservices, the following business priorities and risks are apparent:

Priorities:

  • Rapid Development: Enable developers to quickly build and deploy new services.
  • Scalability: Support applications that can handle a large number of users and requests.
  • Reliability: Ensure services are resilient to failures.
  • Maintainability: Make it easy to update and maintain services over time.
  • Community Adoption: Grow a strong community around the framework to ensure its long-term viability and support.
  • Reduced Operational Overhead: Simplify deployment and management of microservices.

Business Risks:

  • Security Vulnerabilities: Vulnerabilities in the framework could be exploited to compromise applications built using it. This is the most critical risk, as it directly impacts the security of all systems built with Kratos.
  • Supply Chain Attacks: Compromised dependencies could introduce vulnerabilities into the framework.
  • Lack of Adoption: If the framework doesn't gain sufficient traction, it may become difficult to maintain and support.
  • Complexity: Microservices architectures can be complex to manage, potentially leading to operational issues.
  • Inconsistent Implementations: If developers don't follow best practices when using the framework, it could lead to inconsistent and potentially insecure applications.
  • Data Breaches: Applications built with Kratos may handle sensitive data, making them targets for data breaches.
  • Compliance Violations: Applications may need to comply with various regulations (e.g., GDPR, HIPAA), and the framework should facilitate this.

SECURITY POSTURE

Existing Security Controls:

  • security control: Dependency Management: Kratos uses Go modules for dependency management, allowing for version pinning and checksum verification (go.mod and go.sum files).
  • security control: Code Linting: The project uses linters (as seen in the Makefile and CI workflows) to enforce code style and identify potential issues.
  • security control: Testing: The project includes unit and integration tests (evident from the directory structure and CI workflows).
  • security control: CI/CD Pipeline: GitHub Actions are used for continuous integration and continuous delivery, automating builds, tests, and deployments.
  • security control: Documentation: The project provides documentation on its website and within the repository, including security considerations.
  • security control: Community Support: An active community can help identify and address security issues.
  • security control: Transport Layer Security: Kratos supports secure communication via TLS, as indicated in documentation and examples.
  • security control: Error Handling: The framework provides mechanisms for consistent error handling, reducing the risk of information leakage.

Accepted Risks:

  • accepted risk: The framework itself is under continuous development, and new vulnerabilities may be discovered.
  • accepted risk: Developers using the framework may introduce security vulnerabilities in their own code.
  • accepted risk: Third-party dependencies may introduce vulnerabilities, even with dependency management.
  • accepted risk: The framework relies on the underlying security of the Go runtime and operating system.

Recommended Security Controls:

  • Static Application Security Testing (SAST): Integrate SAST tools into the CI/CD pipeline to automatically scan for vulnerabilities in the framework's code.
  • Dynamic Application Security Testing (DAST): Perform regular DAST scans on deployed instances of applications built with Kratos to identify runtime vulnerabilities.
  • Software Composition Analysis (SCA): Use SCA tools to identify known vulnerabilities in third-party dependencies.
  • Security Audits: Conduct regular security audits of the framework's codebase and infrastructure.
  • Fuzz Testing: Implement fuzz testing to identify unexpected behavior and potential vulnerabilities.
  • Threat Modeling: Perform regular threat modeling exercises to identify and mitigate potential security threats.

Security Requirements:

  • Authentication:
    • The framework should provide mechanisms for implementing secure authentication, such as supporting standard protocols like OAuth 2.0 and OpenID Connect.
    • Support for multi-factor authentication (MFA) should be considered.
    • Secure storage of credentials (e.g., hashing and salting passwords) is crucial.
  • Authorization:
    • The framework should support role-based access control (RBAC) or attribute-based access control (ABAC) to restrict access to resources.
    • Fine-grained authorization policies should be configurable.
  • Input Validation:
    • All input from external sources (e.g., user requests, API calls) must be validated to prevent injection attacks (e.g., SQL injection, cross-site scripting).
    • The framework should provide utilities or guidance for implementing input validation.
  • Cryptography:
    • The framework should use strong cryptographic algorithms and libraries for secure communication (TLS) and data protection.
    • Key management should be handled securely.
    • Support for data encryption at rest should be considered.

DESIGN

C4 CONTEXT

graph LR
    subgraph Kratos Application Ecosystem
        User(("User")) --> KratosApp("Kratos Application")
        KratosApp --> Database(("Database"))
        KratosApp --> OtherService(("Other Microservice"))
        KratosApp --> ExternalAPI(("External API"))
    end
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Context Diagram Element Descriptions:

  • Element: User

    • Name: User
    • Type: Person
    • Description: Represents a user interacting with the Kratos application.
    • Responsibilities: Initiates requests, provides input, receives responses.
    • Security controls: Browser security features, user-side security software.

  • Element: Kratos Application

    • Name: Kratos Application
    • Type: Software System
    • Description: The application built using the Kratos framework.
    • Responsibilities: Handles user requests, processes data, interacts with other systems.
    • Security controls: Authentication, authorization, input validation, error handling, secure communication (TLS).

  • Element: Database

    • Name: Database
    • Type: Software System
    • Description: A database used by the Kratos application to store data.
    • Responsibilities: Stores and retrieves data.
    • Security controls: Database access controls, encryption at rest, auditing.

  • Element: Other Microservice

    • Name: Other Microservice
    • Type: Software System
    • Description: Another microservice that the Kratos application interacts with.
    • Responsibilities: Provides specific functionality to the Kratos application.
    • Security controls: Authentication, authorization, secure communication (TLS).

  • Element: External API

    • Name: External API
    • Type: Software System
    • Description: An external API that the Kratos application uses.
    • Responsibilities: Provides external data or functionality.
    • Security controls: API keys, rate limiting, authentication, authorization.

C4 CONTAINER

graph LR
    subgraph Kratos Application
        User(("User")) --> WebServer("Web Server")
        WebServer --> AppServer("Application Server")
        AppServer --> DataAccess("Data Access Layer")
        DataAccess --> Database(("Database"))
        AppServer --> OtherService("Other Microservice")
        AppServer --> ExternalAPI("External API")
    end
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Container Diagram Element Descriptions:

  • Element: User

    • Name: User
    • Type: Person
    • Description: Represents a user interacting with the Kratos application.
    • Responsibilities: Initiates requests, provides input, receives responses.
    • Security controls: Browser security features, user-side security software.

  • Element: Web Server

    • Name: Web Server
    • Type: Container (e.g., Nginx, Apache)
    • Description: Handles incoming HTTP requests and routes them to the application server.
    • Responsibilities: TLS termination, request routing, static content serving.
    • Security controls: TLS configuration, firewall rules, DDoS protection.

  • Element: Application Server

    • Name: Application Server
    • Type: Container (Go Kratos Application)
    • Description: Contains the core business logic of the application.
    • Responsibilities: Handles business logic, interacts with the data access layer and other services.
    • Security controls: Authentication, authorization, input validation, error handling.

  • Element: Data Access Layer

    • Name: Data Access Layer
    • Type: Component within Application Server
    • Description: Handles interactions with the database.
    • Responsibilities: Executes database queries, manages database connections.
    • Security controls: Prepared statements, parameterized queries, database connection security.

  • Element: Database

    • Name: Database
    • Type: Container (e.g., PostgreSQL, MySQL)
    • Description: Stores application data.
    • Responsibilities: Data storage and retrieval.
    • Security controls: Database access controls, encryption at rest, auditing.

  • Element: Other Microservice

    • Name: Other Microservice
    • Type: Container
    • Description: Another microservice that the Kratos application interacts with.
    • Responsibilities: Provides specific functionality.
    • Security controls: Authentication, authorization, secure communication (TLS).

  • Element: External API

    • Name: External API
    • Type: Container
    • Description: An external API used by the Kratos application.
    • Responsibilities: Provides external data or functionality.
    • Security controls: API keys, rate limiting, authentication, authorization.

DEPLOYMENT

Possible Deployment Solutions:

  1. Kubernetes: The most common and recommended deployment environment for Kratos applications, given its focus on microservices.
  2. Docker Compose: Suitable for development and testing environments, but less scalable than Kubernetes.
  3. Virtual Machines: Possible, but less efficient than containerized deployments.
  4. Serverless (e.g., AWS Lambda): Potentially suitable for specific parts of a Kratos application, but not the entire framework.

Chosen Solution (Kubernetes):

graph LR
    subgraph Kubernetes Cluster
        subgraph Node 1
            Pod1("Web Server Pod") --> Pod2("App Server Pod")
        end
        subgraph Node 2
            Pod3("App Server Pod")
            Pod4("Database Pod")
        end
        Internet(("Internet")) --> Ingress("Ingress Controller")
        Ingress --> Pod1
        Pod2 --> Pod4
    end
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Deployment Diagram Element Descriptions:

  • Element: Internet

    • Name: Internet
    • Type: External
    • Description: The public internet.
    • Responsibilities: Source of external traffic.
    • Security controls: Firewall, DDoS protection.

  • Element: Kubernetes Cluster

    • Name: Kubernetes Cluster
    • Type: Infrastructure
    • Description: The Kubernetes cluster where the application is deployed.
    • Responsibilities: Orchestrates containers, manages resources.
    • Security controls: Kubernetes RBAC, network policies, pod security policies.

  • Element: Ingress Controller

    • Name: Ingress Controller
    • Type: Kubernetes Ingress
    • Description: Handles incoming traffic and routes it to the appropriate services.
    • Responsibilities: TLS termination, request routing.
    • Security controls: TLS configuration, firewall rules.

  • Element: Node 1 & Node 2

    • Name: Node 1 & Node 2
    • Type: Kubernetes Node
    • Description: Worker nodes in the Kubernetes cluster.
    • Responsibilities: Run pods.
    • Security controls: Node-level security hardening, OS-level security.

  • Element: Pod1 (Web Server Pod)

    • Name: Pod1 (Web Server Pod)
    • Type: Kubernetes Pod
    • Description: Contains the web server container (e.g., Nginx).
    • Responsibilities: Handles incoming HTTP requests.
    • Security controls: Network policies, resource limits.

  • Element: Pod2 & Pod3 (App Server Pod)

    • Name: Pod2 & Pod3 (App Server Pod)
    • Type: Kubernetes Pod
    • Description: Contains the Kratos application server container.
    • Responsibilities: Runs the application logic.
    • Security controls: Network policies, resource limits, secrets management.

  • Element: Pod4 (Database Pod)

    • Name: Pod4 (Database Pod)
    • Type: Kubernetes Pod
    • Description: Contains the database container (e.g., PostgreSQL).
    • Responsibilities: Runs the database.
    • Security controls: Network policies, resource limits, persistent volume security.

BUILD

graph LR
    Developer("Developer") --> GitRepo("Git Repository")
    GitRepo --> CI("CI/CD Pipeline (GitHub Actions)")
    CI --> SAST("SAST Scanner")
    CI --> SCA("SCA Scanner")
    CI --> UnitTest("Unit Tests")
    CI --> Build("Build Application")
    Build --> Artifact("Artifact Repository")
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Build Process Description:

  1. Developer: The developer writes code and pushes it to the Git repository (GitHub).
  2. Git Repository: The code is stored in the Git repository.
  3. CI/CD Pipeline (GitHub Actions): A GitHub Actions workflow is triggered on code push.
  4. SAST Scanner: A Static Application Security Testing tool scans the code for vulnerabilities.
  5. SCA Scanner: A Software Composition Analysis tool scans dependencies for known vulnerabilities.
  6. Unit Tests: Unit tests are executed to verify code correctness.
  7. Build Application: The application is built, creating an executable or container image.
  8. Artifact Repository: The built artifact (e.g., container image) is pushed to an artifact repository (e.g., Docker Hub, GitHub Container Registry).

Security Controls in Build Process:

  • Code Review: Manual code review before merging changes.
  • SAST: Automated static analysis to identify vulnerabilities in the code.
  • SCA: Automated analysis of dependencies to identify known vulnerabilities.
  • Signed Commits: Use signed commits to verify the integrity of the code.
  • Least Privilege: The CI/CD pipeline should run with the least necessary privileges.
  • Secrets Management: Sensitive information (e.g., API keys, passwords) should be stored securely and not hardcoded in the repository.

RISK ASSESSMENT

Critical Business Processes:

  • User Authentication and Authorization: Ensuring only authorized users can access the application and its resources.
  • Data Processing: Handling user data securely and correctly.
  • Service Availability: Maintaining the availability of the application.
  • Inter-service Communication: Secure communication between microservices.

Data Sensitivity:

  • The Kratos framework itself does not inherently handle specific data. The sensitivity of data depends entirely on the applications built using Kratos.
  • Applications built with Kratos could handle:
    • Personally Identifiable Information (PII): High sensitivity.
    • Financial Data: High sensitivity.
    • Health Data: High sensitivity (subject to HIPAA or similar regulations).
    • Authentication Credentials: Extremely high sensitivity.
    • Application-Specific Data: Sensitivity varies depending on the application.

QUESTIONS & ASSUMPTIONS

Questions:

  • What specific types of applications are intended to be built with Kratos (e.g., e-commerce, healthcare, finance)? This will significantly impact the data sensitivity and security requirements.
  • What are the target deployment environments (e.g., specific cloud providers, on-premise)?
  • What are the specific compliance requirements (e.g., GDPR, HIPAA, PCI DSS)?
  • What level of security expertise is available within the development teams using Kratos?
  • Are there any existing security tools or infrastructure that should be integrated with?

Assumptions:

  • BUSINESS POSTURE: It is assumed that the primary goal is to create a secure and reliable framework for building microservices, prioritizing security alongside rapid development and scalability.
  • SECURITY POSTURE: It is assumed that developers using Kratos have a basic understanding of security principles, but may not be security experts. The framework should provide guidance and tools to help them build secure applications.
  • DESIGN: It is assumed that Kubernetes will be the primary deployment environment for applications built with Kratos. The design reflects this assumption. It is also assumed that applications will follow a typical microservices architecture.