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attack-surface.md

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Attack Surface Analysis for go-kratos/kratos

Attack Surface: Unintended Endpoint Exposure (gRPC/HTTP)

  • Description: Kratos applications can unintentionally expose both gRPC and HTTP endpoints, potentially bypassing intended security controls or exposing services to unintended audiences.
  • Kratos Contribution: Kratos's dual-protocol nature (gRPC and HTTP) and flexible endpoint configuration can lead to developers inadvertently exposing gRPC services over HTTP or vice versa, especially if not fully understanding the configuration options.
  • Example: A developer intends to expose only HTTP REST APIs for public consumption but mistakenly configures the gRPC service to also be accessible over HTTP on a public port. An attacker could then bypass HTTP-specific security measures and directly interact with the gRPC service, potentially exploiting vulnerabilities in gRPC handling or accessing internal APIs not meant for public access.
  • Impact: Unauthorized access to internal services, data breaches, service disruption, bypassing intended security controls.
  • Risk Severity: High
  • Mitigation Strategies:
    • Explicitly define and review which services are exposed over which protocols (gRPC, HTTP) and on which interfaces/ports.
    • Use network firewalls and segmentation to restrict access to gRPC and HTTP endpoints based on intended audience and security zones.
    • Periodically audit exposed endpoints to ensure they align with intended design and security requirements.
    • Apply the principle of least exposure: only expose necessary endpoints and services. Keep internal services internal.

Attack Surface: Debug/Health Endpoint Misconfiguration

  • Description: Kratos provides built-in endpoints for health checks and debugging. If not properly secured, these can leak sensitive information or provide attack vectors.
  • Kratos Contribution: Kratos's default inclusion of health and potentially debug endpoints can be overlooked during production deployment, leading to accidental exposure.
  • Example: A Kratos application exposes its /debug/vars endpoint without authentication in production. An attacker can access this endpoint to gather information about the application's internal state, dependencies, environment variables, and potentially sensitive configuration details.
  • Impact: Information disclosure, potential insights into application vulnerabilities, aid in reconnaissance for further attacks.
  • Risk Severity: High
  • Mitigation Strategies:
    • Disable or remove debug-related endpoints (like /debug/vars) in production builds.
    • Implement authentication and authorization for health and debug endpoints, restricting access to authorized personnel only.
    • Limit access to health and debug endpoints to internal networks or specific IP ranges using firewalls or network policies.
    • Configure health and debug endpoints to expose only necessary information, avoiding leakage of sensitive data.

Attack Surface: Insecure Middleware Chains

  • Description: Misconfiguration or vulnerabilities in middleware chains can lead to bypasses of security controls or introduce new vulnerabilities.
  • Kratos Contribution: Kratos's middleware-centric architecture makes middleware configuration crucial for security. Incorrect ordering or flawed custom middleware directly impacts the application's security posture.
  • Example: An authentication middleware is placed after a logging middleware that logs request bodies. Sensitive data in unauthenticated requests is logged, violating data privacy and potentially exposing credentials if logs are compromised. Another example is a custom authorization middleware with a logic flaw that allows unauthorized access to certain resources.
  • Impact: Authentication bypass, authorization bypass, data leakage, injection vulnerabilities, other middleware-specific vulnerabilities.
  • Risk Severity: High
  • Mitigation Strategies:
    • Thoroughly review and test middleware chain order to ensure security middleware (authentication, authorization) executes before logging or other potentially sensitive middleware.
    • Properly configure all middleware components, paying attention to security-related settings and defaults.
    • Conduct thorough security reviews and testing of all custom middleware components to identify and fix vulnerabilities.
    • Apply the principle of least privilege for middleware: grant middleware only the necessary permissions and access to resources.

Attack Surface: Insecure Service Registry Communication

  • Description: Unsecured communication between Kratos applications and service registries can lead to registry compromise and related attacks.
  • Kratos Contribution: Kratos's integration with service discovery systems (etcd, Consul, Nacos) relies on secure communication with these registries. Misconfiguration in this area is a Kratos-specific attack surface.
  • Example: Kratos applications communicate with an etcd service registry over unencrypted connections without authentication. An attacker on the same network can eavesdrop on communication, intercept service registration data, or even inject malicious service registrations.
  • Impact: Service registry poisoning, man-in-the-middle attacks, service disruption, redirection attacks, information disclosure.
  • Risk Severity: High
  • Mitigation Strategies:
    • Enforce TLS encryption for all communication between Kratos applications and the service registry.
    • Implement strong authentication and authorization mechanisms for accessing and modifying the service registry.
    • Deploy the service registry itself in a secure environment, following security best practices for the chosen registry system (etcd, Consul, Nacos).
    • Isolate the service registry within a secure network segment, limiting access to authorized applications and administrators.

Attack Surface: Insecure Configuration Storage

  • Description: Storing sensitive configuration data insecurely (plain text, unencrypted) exposes it to unauthorized access.
  • Kratos Contribution: Kratos applications rely on configuration. If developers don't use secure configuration management practices, Kratos applications become vulnerable.
  • Example: Database credentials, API keys, or encryption keys are stored in plain text configuration files within the application's codebase or deployed environment. An attacker gaining access to the application's file system or configuration store can easily retrieve these sensitive credentials.
  • Impact: Data breaches, unauthorized access to backend systems, compromise of sensitive services.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Encrypt sensitive configuration data at rest and in transit.
    • Use secure configuration management systems (e.g., HashiCorp Vault, Kubernetes Secrets, cloud provider secret management services) to store and manage sensitive configuration.
    • Avoid hardcoding secrets directly in the application code or configuration files.
    • Apply the principle of least privilege for configuration access: restrict access to configuration data to only authorized applications and personnel.

Attack Surface: Sensitive Data Logging

  • Description: Overly verbose logging can inadvertently log sensitive data, leading to information disclosure if logs are compromised.
  • Kratos Contribution: Kratos's logging capabilities, if not configured carefully, can lead to developers logging too much information, including sensitive data.
  • Example: A Kratos application logs full HTTP request and response bodies in production. This logging includes user credentials, personal information, or API keys transmitted in requests or responses. If these logs are accessed by an attacker, sensitive data is exposed.
  • Impact: Data breaches, privacy violations, exposure of credentials and sensitive information.
  • Risk Severity: High
  • Mitigation Strategies:
    • Carefully review logging configurations and avoid logging sensitive data in production.
    • Sanitize or redact sensitive data before logging (e.g., mask passwords, remove PII).
    • Store logs securely and implement access controls to restrict access to authorized personnel only.
    • Implement appropriate log rotation and retention policies to minimize the window of exposure for sensitive data in logs.

Attack Surface: Client-Side Insecure Configuration (Kratos Clients)

  • Description: When Kratos applications act as clients, insecure client configurations can expose them to client-side vulnerabilities.
  • Kratos Contribution: Kratos facilitates building client applications. Misconfiguring these clients introduces a Kratos-specific attack surface in client applications.
  • Example: A Kratos client application is configured to communicate with a backend service over HTTP instead of HTTPS, or disables TLS certificate verification. This makes the client vulnerable to man-in-the-middle attacks, allowing attackers to intercept or modify communication between the client and the backend service.
  • Impact: Man-in-the-middle attacks, data interception, data manipulation, unauthorized access to backend services.
  • Risk Severity: High
  • Mitigation Strategies:
    • Always use HTTPS/TLS for client-server communication.
    • Ensure TLS certificate verification is enabled and properly configured in client applications to prevent man-in-the-middle attacks.
    • Securely manage client-side credentials (if any) used for authentication with backend services.
    • Conduct regular security audits of client application configurations and dependencies to identify and address potential vulnerabilities.