mitigations.md

Mitigation Strategies Analysis for gofiber/fiber

Mitigation Strategy: Middleware Configuration and Ordering

Description:

1. Planning: Create a document outlining the purpose of each Fiber middleware, its dependencies, and security implications. Define a clear execution order, prioritizing security-critical Fiber middleware.
2. Implementation: In your Fiber application's setup (e.g., main.go), add Fiber middleware in the planned order. Use Fiber's built-in middleware functions (e.g., app.Use(fiber.Compress()), app.Use(fiber.Cors(config)), app.Use(csrf.New(config))). For custom Fiber middleware, ensure correct placement.
3. Configuration: Configure each Fiber middleware instance with appropriate settings. For fiber.Cors, specify allowed origins, methods, and headers explicitly. For fiber.CSRF, integrate with your templating/frontend. For fiber.Limiter, set appropriate rate limits.
4. Testing: Write integration tests verifying the correct behavior of Fiber middleware. Test scenarios where middleware should block/allow requests (e.g., invalid CSRF token with fiber.CSRF, exceeding rate limit with fiber.Limiter, unauthorized origin with fiber.Cors).
5. Review: Regularly review the Fiber middleware configuration and order, especially after adding new features or updating Fiber or its dependencies.

Threats Mitigated:

• Cross-Site Request Forgery (CSRF) (High Severity): Incorrect or missing fiber.CSRF middleware allows attackers to trick users.
• Cross-Origin Resource Sharing (CORS) Misconfiguration (Medium to High Severity): Overly permissive fiber.Cors settings allow unauthorized access.
• Denial of Service (DoS) (Medium to High Severity): Missing or misconfigured fiber.Compress or fiber.Limiter can lead to DoS.
• Authentication Bypass (Critical Severity): Incorrect Fiber middleware order can bypass authentication.
• Authorization Bypass (Critical Severity): Incorrect Fiber middleware order can bypass authorization.
• Data Leakage (Medium to High Severity): Misconfigured fiber.Recover or custom error handling can expose information.

Impact:

• CSRF: Risk reduced from High to Low (with proper fiber.CSRF implementation).
• CORS Misconfiguration: Risk reduced from Medium/High to Low (with correct fiber.Cors configuration).
• DoS: Risk reduced from Medium/High to Low/Medium (depending on attack and fiber.Compress/fiber.Limiter configuration).
• Authentication/Authorization Bypass: Risk reduced from Critical to Low (if auth middleware is correctly placed).
• Data Leakage: Risk reduced from Medium/High to Low/Medium (depending on data and fiber.Recover configuration).

Currently Implemented: (Example: fiber.Cors and fiber.CSRF are used, but fiber.Limiter is not. Middleware order is documented in middleware.md.)

Missing Implementation: (Example: fiber.Limiter is missing for all API endpoints. Integration tests for Fiber middleware interactions are incomplete.)

Mitigation Strategy: Error Handling and Information Leakage (Fiber-Specific)

Description:

1. Custom Error Handler: Create a custom error handler function: func myCustomErrorHandler(c *fiber.Ctx, err error) error.
2. Global Configuration: Use app.Config.ErrorHandler = myCustomErrorHandler to set the global Fiber error handler.
3. Error Handling Logic: Inside myCustomErrorHandler:
   • Log the error details (including stack traces, if appropriate) internally. Do not send to the client.
   • Determine an appropriate HTTP status code based on the error type.
   • Return a generic error message to the client via c.Status(...).JSON(...). Never return err.Error() directly. Example: return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": "An unexpected error occurred."})
4. Route-Specific (Optional): Handle errors within route handlers if needed, but never expose internal details.
5. Testing: Write tests that trigger errors and verify responses do not contain sensitive information from Fiber or underlying libraries.

Threats Mitigated:

• Information Disclosure (Medium to High Severity): Exposing internal Fiber error details (stack traces, internal paths) helps attackers.

Impact:

• Information Disclosure: Risk reduced from Medium/High to Low.

Currently Implemented: (Example: A custom error handler is in handlers/errors.go, but doesn't consistently log all details.)

Missing Implementation: (Example: Some routes return raw Fiber error messages. Testing for information leakage is incomplete.)

Mitigation Strategy: Routing and Parameter Handling (Fiber-Specific)

Description:

1. Precise Routes: Define Fiber routes with specific paths and methods. Avoid broad wildcards or regex unless necessary.
2. Parameter Validation: Use Fiber's parsing/validation:

   app.Get("/users/:id", func(c *fiber.Ctx) error {
       id, err := c.ParamsInt("id") // Use Fiber's methods
       if err != nil {
           return c.Status(fiber.StatusBadRequest).SendString("Invalid ID") // Use Fiber's status codes
       }
       // ... use the validated 'id' ...
       return nil
   })

3. Type Conversion: Use Fiber's c.ParamsInt, c.ParamsBool, c.Query, etc., for type conversion.
4. Whitelist (if applicable): If a Fiber parameter has limited valid values, use a whitelist.
5. Sanitization: If using user input in file paths/commands, sanitize thoroughly. Whitelist when possible. This is crucial even with Fiber.
6. Testing: Test with valid and invalid Fiber parameter values to ensure validation works.

Threats Mitigated:

• Parameter Tampering (Medium to High Severity): Attackers modify Fiber route parameters.
• Path Traversal (High Severity): If user input constructs file paths (even with Fiber routing), attackers can access unintended files.
• Command Injection (Critical Severity): If user input is in commands (even indirectly via Fiber), attackers can execute arbitrary commands.

Impact:

• Parameter Tampering: Risk reduced from Medium/High to Low (with Fiber's validation).
• Path Traversal: Risk reduced from High to Low (with sanitization/whitelisting – Fiber alone doesn't prevent this).
• Command Injection: Risk reduced from Critical to Low (with sanitization/whitelisting – Fiber alone doesn't prevent this).

Currently Implemented: (Example: Basic Fiber parameter validation is used, but sanitization for file paths is missing in one handler.)

Missing Implementation: (Example: /files/:filename doesn't sanitize filename, risking path traversal – even with Fiber's routing.)

Mitigation Strategy: Session Management (Fiber-Specific)

Description:

1. Secure Store: Use Fiber's session middleware with a secure backend (Redis, database). Do not use the default in-memory store in production.
2. Configuration: Configure Fiber's session middleware:
   • Cookie.Secure = true (HTTPS only)
   • Cookie.HttpOnly = true (prevent JS access)
   • Cookie.SameSite = fiber.SameSiteStrictMode (restrict cross-origin)
   • Expiration: Set a reasonable expiration.
3. Session ID: Fiber's default session ID generation should be cryptographically strong; verify.
4. Invalidation: On logout, explicitly invalidate the session: session.Destroy().
5. Testing: Test Fiber session creation, expiration, invalidation, concurrent sessions, and access after logout.

Threats Mitigated:

• Session Hijacking (High Severity): Attackers steal Fiber session cookies.
• Session Fixation (High Severity): Attackers set a known Fiber session ID.
• Cross-Site Scripting (XSS) (High Severity): If Fiber session cookies aren't HttpOnly, they can be stolen via XSS.

Impact:

• Session Hijacking/Fixation: Risk reduced from High to Low (with proper Fiber session configuration).
• XSS (session cookies): Risk reduced from High to Low (with HttpOnly).

Currently Implemented: (Example: Fiber's session middleware uses Redis. Secure, HttpOnly, SameSite are set. Sessions expire after 30 minutes.)

Missing Implementation: (Example: No automated tests verify Fiber session security attributes.)