mitigations.md

Mitigation Strategies Analysis for go-kit/kit

Mitigation Strategy: Explicit Endpoint Exposure Control (within go-kit/kit)

Description:

1. go-kit/kit Endpoint Definition Review: Examine all uses of endpoint.Endpoint within the codebase. Each of these represents a potential entry point into the service.
2. Transport-Specific Handler Separation: Within the go-kit/kit transport layer (e.g., kithttp.NewServer, kitgrpc.NewServer), ensure that public and internal endpoints are not mixed within the same handler. Create separate kithttp.Server (or equivalent) instances for public and internal endpoints. This leverages go-kit/kit's own mechanisms for handling different sets of endpoints.

   // Public endpoints (using kithttp)
   publicHandler := kithttp.NewServer(
       makePublicEndpoint(myService),
       decodePublicRequest,
       encodePublicResponse,
   )
   
   // Internal endpoints (using kithttp - separate instance)
   internalHandler := kithttp.NewServer(
       makeInternalEndpoint(myService),
       decodeInternalRequest,
       encodeInternalResponse,
   )

3. go-kit/kit Options for Security: Utilize go-kit/kit's server options (e.g., kithttp.ServerErrorHandler, kithttp.ServerBefore) to implement security-related logic specifically within the go-kit/kit framework. For example, use ServerErrorHandler to customize error responses and avoid leaking internal details. Use ServerBefore to perform authentication/authorization checks before the endpoint logic is executed.

Threats Mitigated:

• Unintentional Information Disclosure (High Severity): Prevents internal go-kit/kit endpoints from being accidentally exposed through misconfiguration of the transport layer.
• Unauthorized Access (High Severity): Ensures that only intended public endpoints are accessible, reducing the attack surface within the go-kit/kit framework.

Impact:

• Unintentional Information Disclosure: Risk significantly reduced (from High to Low).
• Unauthorized Access: Risk significantly reduced (from High to Low).

Currently Implemented:

• Partially implemented. Public endpoints are handled using kithttp.NewServer. Internal endpoints are currently using the same kithttp.NewServer instance.

Missing Implementation:

• Separate kithttp.NewServer instances (or equivalent for other transports) need to be created for internal endpoints. go-kit/kit server options (e.g., ServerErrorHandler, ServerBefore) should be used to implement security checks within the go-kit/kit framework.

Mitigation Strategy: go-kit/kit Middleware Configuration and Ordering

Description:

1. Middleware Inventory: List all middleware used with go-kit/kit endpoints (e.g., logging, tracing, rate limiting, authentication).
2. go-kit/kit Middleware Ordering: Carefully define the order in which middleware is applied using endpoint.Chain. Ensure that security-critical middleware (authentication, authorization) is executed before other middleware (logging, tracing). Incorrect ordering can create bypass vulnerabilities.

   // Correct ordering: Authentication -> Rate Limiting -> Logging
   chainedEndpoint := endpoint.Chain(
       authMiddleware,
       ratelimitMiddleware,
       loggingMiddleware,
   )(myEndpoint)

3. go-kit/kit Logging Middleware Customization: Customize the go-kit/kit/log integration to ensure sensitive data is never logged. This might involve creating a custom logger that wraps go-kit/kit/log.Logger and implements redaction logic. This is specifically about configuring the logging within the go-kit/kit context.
4. go-kit/kit Rate Limiting Configuration: Use go-kit/kit/ratelimit to configure rate limiting specifically for go-kit/kit endpoints. Choose an appropriate algorithm (token bucket, leaky bucket) and configure the limits based on the endpoint's sensitivity and expected traffic.
5. go-kit/kit Circuit Breaker Configuration: Use and properly configure go-kit/kit/circuitbreaker middleware to prevent cascading failures. Tune the thresholds and timeouts appropriately for your service's dependencies.

Threats Mitigated:

• Authentication Bypass (High Severity): Incorrect middleware ordering can allow unauthenticated requests to bypass security checks.
• Information Disclosure via Logs (Medium Severity): Improperly configured logging middleware can leak sensitive data.
• Denial of Service (DoS) (Medium to High Severity): Misconfigured or missing rate limiting can allow attackers to overwhelm the service.
• Cascading Failures (High Severity): Misconfigured or missing circuit breaker can allow one service failure to take down the entire system.

Impact:

• Authentication Bypass: Risk significantly reduced (from High to Low).
• Information Disclosure via Logs: Risk significantly reduced (from Medium to Low).
• Denial of Service (DoS): Risk reduced (depending on rate limiting configuration).
• Cascading Failures: Risk reduced.

Currently Implemented:

• Basic logging middleware is used. Middleware ordering is not explicitly defined or reviewed. No custom redaction logic is in place for go-kit/kit logging. Rate limiting and circuit breaker are not implemented.

Missing Implementation:

• Explicit middleware ordering needs to be defined and enforced using endpoint.Chain. The go-kit/kit/log integration needs to be customized to prevent sensitive data logging. go-kit/kit/ratelimit and go-kit/kit/circuitbreaker needs to be implemented and configured.

Mitigation Strategy: Secure Handling of go-kit/kit Errors

Description:

1. go-kit/kit Error Response Customization: Use go-kit/kit's error handling mechanisms (e.g., kithttp.ServerErrorEncoder, kitgrpc.ErrorResponseFunc) to customize error responses sent to clients. Avoid returning raw Go errors or internal implementation details.

   // Example using kithttp.ServerErrorEncoder
   server := kithttp.NewServer(
       myEndpoint,
       decodeRequest,
       encodeResponse,
       kithttp.ServerErrorEncoder(func(ctx context.Context, err error, w http.ResponseWriter) {
           // Return a generic error message to the client
           w.WriteHeader(http.StatusInternalServerError)
           w.Write([]byte("An internal error occurred."))
           // Log the detailed error internally
           level.Error(logger).Log("err", err)
       }),
   )

2. Consistent Error Handling within go-kit/kit: Ensure that all go-kit/kit components (endpoints, middleware, transport layers) handle errors consistently. Use go-kit/kit's recommended patterns for error propagation and reporting.
3. Do not expose stack traces: Ensure that stack traces are not exposed to the client.

Threats Mitigated:

• Information Disclosure via Error Messages (Medium Severity): Prevents attackers from gaining insights into the internal workings of the service by analyzing error messages.

Impact:

• Information Disclosure via Error Messages: Risk significantly reduced (from Medium to Low).

Currently Implemented:

• Default go-kit/kit error handling is used. No custom error encoders or response functions are implemented.

Missing Implementation:

• Custom error encoders/response functions (e.g., kithttp.ServerErrorEncoder, kitgrpc.ErrorResponseFunc) need to be implemented to control the format and content of error responses sent to clients.

Mitigation Strategy: Secure Custom go-kit/kit Transports and Encodings

Description:

1. Avoid Custom Implementations (if possible): Prioritize using the built-in transports (HTTP, gRPC) and encodings (JSON, Protobuf) provided by go-kit/kit. These are generally well-tested and maintained.
2. Rigorous Code Review (if custom): If a custom transport or encoding must be implemented, subject the code to extremely thorough code review, focusing on security aspects:
   • Input Validation: Validate all input received from the custom transport or encoding.
   • Buffer Handling: Ensure proper buffer management to prevent buffer overflows or other memory-related vulnerabilities.
   • Error Handling: Handle errors gracefully and avoid leaking sensitive information.
   • Cryptography (if applicable): If the custom transport involves encryption or signing, use well-established cryptographic libraries and follow best practices.
3. Security Testing (if custom): Perform dedicated security testing (e.g., fuzzing) on the custom transport or encoding implementation to identify potential vulnerabilities.

Threats Mitigated:

• Various vulnerabilities depending on the custom implementation (High Severity): Custom transports and encodings can introduce a wide range of vulnerabilities if not implemented securely. This includes injection attacks, buffer overflows, denial-of-service, and more.

Impact:

• Various vulnerabilities: Risk significantly reduced by thorough review and testing (but the risk remains higher than using standard components).

Currently Implemented:

• The project currently uses the standard kithttp transport and JSON encoding.

Missing Implementation:

• No action needed currently, as no custom transports or encodings are used. If custom implementations are added in the future, this mitigation strategy becomes critical.