attack-surface.md

Attack Surface Analysis for gorilla/mux

Attack Surface: Overly Permissive Routes

• Description: Routes defined with broad patterns that unintentionally expose handlers to unexpected inputs or HTTP methods.
  • How mux Contributes: mux's flexible routing capabilities make it easy to create overly general routes if not used carefully. This is the core function of mux.
  • Example: A route /api/{resource}/{id} without restrictions on {resource} could expose internal APIs. /admin/{anything...} without authentication.
  • Impact: Unauthorized access to sensitive data or functionality, potential for remote code execution (RCE) if the handler is vulnerable.
  • Risk Severity: High to Critical.
  • Mitigation Strategies:
    • Specificity: Define routes as specifically as possible.
    • Method Restriction: Use mux.Methods() to restrict HTTP methods.
    • Input Validation: Rigorous input validation within each handler.
    • Regular Audits: Regularly review route configurations.
    • Least Privilege: Handlers should operate with least privilege.

Attack Surface: Incorrect Path Variable Handling

• Description: Failure to sanitize or validate path variables extracted by mux.Vars(r).
  • How mux Contributes: mux provides the Vars() function to extract path variables without sanitization or validation. This is a direct feature of mux.
  • Example: /users/{id} used directly in a SQL query (SQLi) or file access (path traversal).
  • Impact: SQL injection, path traversal, potentially RCE or data breaches.
  • Risk Severity: High to Critical.
  • Mitigation Strategies:
    • Sanitization: Always sanitize path variables.
    • Validation: Validate path variable format and range.
    • Parameterized Queries: Use parameterized queries or ORMs (SQLi prevention).
    • Safe File Access: Prevent path traversal.
    • Type Conversion: Convert to the appropriate data type.

Attack Surface: Regular Expression Denial of Service (ReDoS)

• Description: Using vulnerable regular expressions in route definitions (within mux) for matching.
  • How mux Contributes: mux directly uses regular expressions for route matching, making this a mux-specific attack vector.
  • Example: /products/{name:.*[a-z]+.*} with malicious input causing backtracking.
  • Impact: Denial of service (DoS).
  • Risk Severity: High.
  • Mitigation Strategies:
    • Regex Review: Carefully review and test all regexes.
    • Avoid Complexity: Avoid overly complex regex patterns.
    • Regex Analysis Tools: Use tools to detect ReDoS vulnerabilities.
    • Input Length Limits: Limit input length.
    • Timeouts: Implement request timeouts.
    • Alternative Matching: Consider simpler matching if possible.

Attack Surface: Unintended Route Overlap

• Description: Multiple routes unintentionally matching the same request.
  • How mux Contributes: mux's routing logic and precedence rules, if misconfigured, can lead to this overlap. This is inherent to how mux handles route matching.
  • Example: /users/{id} and /users/profile both potentially matching /users/profile.
  • Impact: Execution of the wrong handler, leading to incorrect data, unauthorized access, or unexpected behavior.
  • Risk Severity: High (depending on the consequences).
  • Mitigation Strategies:
    • Careful Design: Plan routes to avoid overlaps.
    • mux.Walk: Use mux.Walk to inspect routes.
    • Testing: Thoroughly test with various request patterns.
    • Route Ordering: Register specific routes first.
    • Explicit Matching: Use more explicit criteria.