mitigations.md

Mitigation Strategies Analysis for go-chi/chi

Mitigation Strategy: Explicit Route Ordering and Testing (Chi-Specific)

• Description:

  1. Chi Route Analysis: Analyze all routes defined using chi.Router. Identify potential overlaps or ambiguities specifically considering chi's routing mechanisms. Pay close attention to how chi handles wildcards ({param}), regular expressions, and nested routers.
  2. Chi-Aware Prioritization: Reorder route definitions, leveraging chi's behavior of processing routes in the order they are registered. More specific chi routes (e.g., those with more static segments) should always precede more general ones (e.g., those with multiple wildcards).
  3. Chi-Specific Test Cases: Create test cases that target chi's routing logic. This includes:
     • Wildcard Variations: Test different values for wildcard parameters, including empty strings, special characters, and long strings.
     • Regular Expression Matching: If using regular expressions in routes, thoroughly test the regex patterns to ensure they match only the intended inputs.
     • Nested Router Interactions: If using nested routers (chi.Mux), test how routes defined in different routers interact.
     • Chi Context Values: Verify that chi.RouteContext is populated correctly with the expected URL parameters in each handler.
  4. httptest with Chi: Use Go's net/http/httptest package to create HTTP requests and send them directly to your chi router instance. This ensures you are testing chi's routing logic in isolation.
  5. Automated Chi-Focused Tests: Integrate these chi-specific tests into your CI pipeline.

• Threats Mitigated:

  • Chi-Specific Route Hijacking (High Severity): An attacker crafts a request that exploits chi's routing logic to bypass intended access controls.
  • Unexpected Chi Handler Execution (Medium Severity): Ambiguous routes, as interpreted by chi, lead to the wrong handler being executed.
  • Chi Context Parameter Injection (Medium Severity): An attacker manipulates URL parameters to inject unexpected values into chi.RouteContext, potentially leading to vulnerabilities in handlers that rely on those parameters.

• Impact:

  • Chi-Specific Route Hijacking: Risk significantly reduced. Explicit ordering and chi-focused testing make it much harder to exploit chi's routing nuances.
  • Unexpected Chi Handler Execution: Risk significantly reduced. Testing ensures the correct chi handler is invoked.
  • Chi Context Parameter Injection: Risk reduced. Testing verifies that chi.RouteContext is populated correctly and that handlers properly validate and sanitize these parameters.

• Currently Implemented:

  • Example: Basic route ordering is implemented, but tests don't specifically target chi's wildcard handling or nested router interactions.

• Missing Implementation:

  • Example: Comprehensive testing for chi's regular expression routing is missing. Tests don't verify the contents of chi.RouteContext in all handlers.

Mitigation Strategy: Secure Chi Middleware Configuration and Ordering

• Description:

  1. Chi Middleware Audit: List all middleware used with your chi router. Document the purpose of each middleware and how it interacts with chi's request lifecycle.
  2. Chi-Specific Ordering: Ensure middleware is ordered correctly within the chi router's context. Understand how chi executes middleware relative to routing and sub-routers. Authentication middleware should always be registered before authorization middleware within the chi router.
  3. Chi Context Awareness: If middleware interacts with chi.RouteContext (e.g., to access URL parameters), ensure it does so securely. Validate and sanitize any data retrieved from the context.
  4. "Fail Closed" with Chi: Design authorization middleware that is specifically integrated with chi to "fail closed." If the middleware, using chi's context and routing information, cannot definitively determine authorization, it should deny access.
  5. Chi-Specific Middleware Testing: Create tests that specifically verify the behavior of middleware within the context of a chi router. Use httptest to send requests through your chi router and assert the expected behavior of the middleware chain.
  6. Chi Sub-Router Middleware: If using chi's sub-routers, carefully consider the placement of middleware. Middleware registered on a parent router will apply to all sub-routers unless overridden.

• Threats Mitigated:

  • Chi-Related Authentication Bypass (Critical Severity): Incorrectly configured or ordered authentication middleware within chi allows bypass.
  • Chi-Related Authorization Bypass (Critical Severity): Flaws in authorization middleware, specifically in how it interacts with chi's routing and context, allow unauthorized access.
  • Chi Context Manipulation (High Severity): Middleware improperly modifies chi.RouteContext, potentially leading to vulnerabilities in downstream handlers.

• Impact:

  • Chi-Related Authentication/Authorization Bypass: Risk significantly reduced by correct ordering, "fail closed" design, and chi-specific testing.
  • Chi Context Manipulation: Risk reduced by validating and sanitizing data retrieved from and written to chi.RouteContext within middleware.

• Currently Implemented:

  • Example: Authentication middleware is registered with the chi router, but authorization middleware is not "fail closed" and doesn't fully utilize chi.RouteContext.

• Missing Implementation:

  • Example: Comprehensive testing of middleware interactions specifically within the chi router is missing. The "fail closed" principle is not consistently applied to authorization middleware integrated with chi.

Mitigation Strategy: Secure Chi Context Value Handling

• Description:

  1. Chi Context Audit: Review all code that interacts with chi.RouteContext and the underlying context.Context.
  2. Avoid Sensitive Data in Chi Context: Never store sensitive data directly in chi.RouteContext or the underlying context.Context.
  3. Typed Keys for Chi Context: Use typed keys (not strings) when storing and retrieving values from the context.Context that is passed through chi. This is a general Go best practice, but it's crucial within chi's middleware and handler chain.
  4. Chi Context Scope Awareness: Understand that data added to the context in one chi middleware will be available to subsequent chi middleware and the handler. Limit the scope and lifetime of data in the context.
  5. Secure Storage with Chi: If you need to associate sensitive data with a request handled by chi, use a secure storage mechanism (e.g., encrypted sessions) and store only a reference (e.g., session ID) in the chi.RouteContext or the underlying context.
  6. Chi Context Validation: Validate and sanitize any data retrieved from chi.RouteContext within your handlers. Do not assume that the data is safe, even if it was added by a trusted middleware.

• Threats Mitigated:

  • Chi Context Information Disclosure (High Severity): Leaking sensitive data stored in chi.RouteContext or the underlying context.
  • Chi Context-Based Session Hijacking (Critical Severity): If session tokens are insecurely stored in the chi context, an attacker could hijack a session.
  • Chi Context Data Tampering (Medium Severity): Mutable data in the chi context could be tampered with, affecting downstream handlers.

• Impact:

  • Chi Context Information Disclosure: Risk significantly reduced by avoiding direct storage of sensitive data.
  • Chi Context-Based Session Hijacking: Risk significantly reduced by using secure session management and storing only references in the chi context.
  • Chi Context Data Tampering: Risk reduced by using typed keys, limiting scope, and validating data retrieved from the chi context.

• Currently Implemented:

  • Example: Typed keys are used for some chi.RouteContext values, but not consistently.

• Missing Implementation:

  • Example: A comprehensive review of all chi.RouteContext usage is needed to ensure no sensitive data is stored directly and that typed keys are used consistently. Handlers do not always validate data retrieved from the context.

Mitigation Strategy: Robust Chi Panic Handling (using chi.Recoverer)

• Description:

  1. chi.Recoverer Integration: Ensure the chi.Recoverer middleware is included in your main chi router's middleware stack. This is crucial for handling panics that occur within chi's routing and handler execution.
  2. chi.Recoverer Configuration: Verify that chi.Recoverer is correctly configured to log panics (including stack traces) to a secure location. The client should never receive the stack trace.
  3. Custom Error Responses (with Chi): While chi.Recoverer provides a default 500 response, you can customize this, but ensure no sensitive information is leaked in the custom response.
  4. Chi-Specific Panic Testing: Write tests that intentionally trigger panics within chi handlers to verify that chi.Recoverer catches them and handles them gracefully.

• Threats Mitigated:

  • Chi-Related Denial of Service (DoS) (High Severity): Unhandled panics within chi handlers or middleware can crash the application.
  • Chi-Related Information Disclosure (Medium Severity): Unhandled panics can leak sensitive information (stack traces) in responses generated by chi.

• Impact:

  • Chi-Related DoS: Risk significantly reduced. chi.Recoverer prevents chi-related panics from crashing the application.
  • Chi-Related Information Disclosure: Risk significantly reduced. chi.Recoverer prevents stack traces from being exposed to clients in responses from chi.

• Currently Implemented:

  • Example: chi.Recoverer is included in the main chi router's middleware stack.

• Missing Implementation:

  • Example: Testing for panic handling specifically within chi handlers is incomplete.