attack-surface.md

Attack Surface Analysis for go-chi/chi

Attack Surface: Route Definition Complexity and Overlap

• Description: Complex or overlapping route definitions in chi can lead to unintended route matching, allowing access to resources or functionalities that should be protected by different routing rules.
• How chi contributes: chi's flexible routing patterns (path parameters, wildcards) enable complex route definitions, increasing the chance of accidental overlaps if not carefully managed.
• Example:
  • Route /users/{id} is intended for user-specific actions.
  • Route /users/admin is intended for admin actions.
  • If /users/admin is defined after /users/{id}, a request to /users/admin might be incorrectly matched by /users/{id} with {id} being "admin", bypassing intended admin-specific routing and potentially access controls.
• Impact: Unauthorized access to resources, bypass of access controls, potential data breaches or privilege escalation.
• Risk Severity: High
• Mitigation Strategies:
  • Carefully design routes with clarity and specificity. Avoid overly broad wildcard routes when more specific patterns are possible.
  • Define more specific routes before more general routes to ensure correct matching precedence.
  • Thoroughly test routing logic with various URL inputs to identify and resolve any unintended overlaps or matching issues.
  • Clearly document route definitions and intended access controls to facilitate review and prevent misconfigurations.

Attack Surface: Path Parameter Injection

• Description: Path parameters extracted by chi from URLs can be injection points if not properly validated and sanitized before use in backend operations (database queries, file system access, etc.).
• How chi contributes: chi's core functionality is to parse and provide access to path parameters, making it a direct conduit for user-supplied input into the application.
• Example:
  • Route /files/{filename} is intended to serve files based on the filename parameter.
  • If the application directly uses the filename parameter to construct a file path without validation, an attacker could use a path traversal payload like ../etc/passwd in the filename to access sensitive files outside the intended directory.
• Impact: SQL injection, command injection, path traversal, local file inclusion, remote code execution (depending on the context of parameter usage).
• Risk Severity: Critical to High
• Mitigation Strategies:
  • Strictly validate path parameters against expected formats and character sets.
  • Sanitize or encode path parameters to neutralize potentially harmful characters or sequences.
  • Use parameterized queries or prepared statements for database interactions to prevent SQL injection.
  • Limit the privileges of the application user to only the necessary resources and operations (Principle of Least Privilege).
  • For file operations, use secure file handling practices, such as whitelisting allowed file paths or using secure file access APIs.

Attack Surface: Middleware Bypass due to Routing Errors

• Description: Incorrect route configuration or misunderstandings about middleware application in chi can lead to middleware being unintentionally bypassed for certain routes, leaving them unprotected.
• How chi contributes: chi's middleware chaining mechanism relies on correct route association. Errors in defining routes or applying middleware to route groups can result in gaps in middleware coverage.
• Example:
  • Authentication middleware is intended to protect all routes under /api/.
  • Due to a typo or misconfiguration in route definition, a specific route like /api/sensitive-data is not correctly included in the middleware group, allowing unauthenticated access.
• Impact: Bypass of authentication, authorization, rate limiting, or other security measures implemented in middleware, leading to unauthorized access or exploitation of vulnerabilities in unprotected endpoints.
• Risk Severity: High
• Mitigation Strategies:
  • Double-check middleware application to ensure it covers all intended routes and route groups.
  • Utilize chi's route grouping and prefixing features to organize routes and apply middleware consistently to entire groups.
  • Implement tests to verify that middleware is correctly applied to all intended routes and that requests to protected routes are indeed processed by the middleware.
  • Conduct code reviews of route definitions and middleware application logic to identify potential misconfigurations.

Attack Surface: Middleware Ordering Vulnerabilities

• Description: Incorrect ordering of middleware in chi's middleware chain can create security vulnerabilities by executing security checks in the wrong sequence (e.g., authorization before authentication).
• How chi contributes: chi allows developers to define the order of middleware execution. Misunderstanding or incorrectly configuring this order can lead to security flaws.
• Example:
  • Middleware chain is configured as: [AuthorizationMiddleware, AuthenticationMiddleware].
  • Authorization middleware checks permissions based on user roles, but AuthenticationMiddleware, which verifies user identity, runs after authorization.
  • An unauthenticated user could potentially trigger authorization checks and, if there are flaws in the authorization logic that don't strictly require authentication, might gain unauthorized access.
• Impact: Bypass of security checks, unauthorized access, privilege escalation, data breaches.
• Risk Severity: High to Critical
• Mitigation Strategies:
  • Carefully plan and implement middleware order based on security logic. Typically, authentication should precede authorization, input validation, and other security checks.
  • Document the intended middleware execution order for clarity and maintainability.
  • Review the middleware chain configuration to ensure logical and secure ordering.

Attack Surface: Vulnerabilities in Custom Middleware

• Description: Security vulnerabilities in custom middleware code developed for chi applications directly increase the application's attack surface.
• How chi contributes: chi encourages the use of middleware for modular request handling, including security logic. If custom middleware is not developed securely, it becomes a vulnerability point within a chi-based application.
• Example:
  • Custom authentication middleware has a logic flaw that allows bypassing authentication under certain conditions (e.g., incorrect token validation, race conditions).
  • Custom authorization middleware is vulnerable to injection attacks if it constructs authorization queries based on unsanitized user input.
• Impact: Bypass of security controls, authentication bypass, authorization bypass, injection vulnerabilities, data breaches, privilege escalation, denial of service (depending on the vulnerability).
• Risk Severity: Critical to High
• Mitigation Strategies:
  • Follow secure coding principles when developing custom middleware.
  • Conduct thorough security code reviews of custom middleware code.
  • Use static and dynamic analysis tools to identify potential vulnerabilities in custom middleware.
  • Include custom middleware in penetration testing efforts to assess its security effectiveness.
  • Leverage established and well-vetted security libraries and patterns when implementing security-related logic in custom middleware (e.g., for authentication, authorization, input validation).