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Threat Model Analysis for dart-lang/shelf

Threat: Middleware Authentication Bypass

  • Threat: Middleware Authentication Bypass

    • Description: An attacker crafts a malicious request that bypasses authentication checks implemented in custom middleware. This exploits incorrect middleware ordering, logic flaws, or vulnerabilities in how the middleware interacts with shelf.Request and shelf.Response objects. The attacker might manipulate headers, cookies, or exploit timing issues specific to the middleware's interaction with the Shelf pipeline.
    • Impact: Unauthorized access to protected resources, data breaches, impersonation of legitimate users, and potential for further attacks.
    • Affected Shelf Component: Custom Middleware implementations, specifically those handling authentication. The shelf.Pipeline is directly involved due to the ordering and execution of middleware.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Ensure middleware is ordered correctly within the shelf.Pipeline, with authentication before authorization or data access.
      • Thoroughly test authentication middleware with various attack vectors, focusing on how it handles shelf.Request properties and generates shelf.Response objects.
      • Use secure session management techniques, validating that the middleware correctly handles session tokens within shelf.Request and shelf.Response.

Threat: Handler Hijacking via Routing

  • Threat: Handler Hijacking via Routing

    • Description: An attacker crafts a request URL that, due to overly permissive routing rules defined using shelf.Router, matches an unintended handler. The attacker exploits how shelf.Router matches paths and extracts parameters, potentially leading to unexpected handler execution.
    • Impact: Access to unintended functionality, exposure of sensitive data, triggering of unauthorized actions.
    • Affected Shelf Component: The shelf.Router component and its routing logic. This directly involves how shelf.Router processes shelf.Request objects to determine the appropriate handler.
    • Risk Severity: High
    • Mitigation Strategies:
      • Use precise and restrictive routing rules within shelf.Router. Avoid overly broad regular expressions or wildcard matches.
      • Prefer specific path matching over regular expressions when feasible.
      • Thoroughly test all routing paths defined in shelf.Router, including edge cases and unexpected inputs, to ensure correct handler mapping.

Threat: Malicious Middleware Data Tampering

  • Threat: Malicious Middleware Data Tampering

    • Description: A malicious or compromised third-party middleware modifies shelf.Request or shelf.Response data in an unauthorized way. This could involve injecting malicious content, altering data values, or corrupting data integrity by manipulating the request/response objects passed through the shelf.Pipeline.
    • Impact: Data corruption, execution of malicious code (XSS if response data is tampered with), unauthorized data modification.
    • Affected Shelf Component: Any Middleware in the shelf.Pipeline, particularly third-party middleware. The core issue is the ability of middleware to modify shelf.Request and shelf.Response objects.
    • Risk Severity: High
    • Mitigation Strategies:
      • Thoroughly vet any third-party middleware used, examining its interaction with shelf.Request and shelf.Response.
      • Implement strict input validation and output encoding after all middleware in the shelf.Pipeline has processed the request/response.
      • Regularly update all middleware dependencies.

Threat: Information Disclosure via Error Handling

  • Threat: Information Disclosure via Error Handling

    • Description: An attacker triggers an error within a shelf.Handler or Middleware that results in the application exposing sensitive information in the shelf.Response. This is due to inadequate custom error handling, causing Shelf's default error handling (which may expose details) to be used.
    • Impact: Exposure of sensitive information that can aid attackers, revealing implementation details.
    • Affected Shelf Component: Error handling logic within Handler functions and any custom error handling Middleware. Shelf's default error handling (if not overridden) is a primary concern, specifically how it constructs the shelf.Response in error cases.
    • Risk Severity: High
    • Mitigation Strategies:
      • Implement custom error handling middleware that intercepts exceptions and generates generic shelf.Response objects without sensitive details.
      • Never expose raw exception details or stack traces in the shelf.Response sent to the client in a production environment.
      • Configure a default error handler to catch any unhandled exceptions and return a safe shelf.Response.

Threat: Denial of Service via Request Flooding

  • Threat: Denial of Service via Request Flooding

    • Description: An attacker sends a large number of requests to the shelf.Server, overwhelming server resources. Shelf itself does not provide built-in mechanisms to limit request rates, making the application vulnerable.
    • Impact: Application unavailability, service disruption.
    • Affected Shelf Component: The shelf.Server and all Handler and Middleware components, as they are all involved in processing requests. The lack of built-in rate limiting in shelf.Server is the direct vulnerability.
    • Risk Severity: High
    • Mitigation Strategies:
      • Implement rate limiting middleware to restrict the number of requests processed by shelf.Server from a single IP address or user.
      • Use a reverse proxy or load balancer in front of the shelf.Server to provide additional DoS protection.

Threat: Denial of Service via Large Request Bodies

  • Threat: Denial of Service via Large Request Bodies

    • Description: An attacker sends requests with excessively large request bodies to a shelf.Handler, consuming server resources. Shelf does not provide built-in request body size limits, making handlers vulnerable if they don't implement their own checks.
    • Impact: Application unavailability, service disruption.
    • Affected Shelf Component: Handler functions that process shelf.Request bodies, and any Middleware that interacts with the request body. The lack of built-in limits on shelf.Request body size is the direct vulnerability.
    • Risk Severity: High
    • Mitigation Strategies:
      • Implement middleware to limit the maximum size of the shelf.Request body.
      • Use streaming techniques to process large request bodies in chunks, rather than loading the entire shelf.Request.read() result into memory at once.