mitigations.md

Mitigation Strategies Analysis for dotnet/aspnetcore

Mitigation Strategy: Robust Input Validation using ASP.NET Core Features

• Description:

  1. Leverage ASP.NET Core Validation Attributes: Utilize Data Annotation attributes provided by System.ComponentModel.DataAnnotations directly within your ViewModels, DTOs, or Razor Page models. Examples include [Required], [StringLength], [Range], [EmailAddress], [RegularExpression]. These attributes are natively understood by ASP.NET Core model binding and validation pipeline.
  2. Integrate FluentValidation: For more complex and decoupled validation logic, integrate the FluentValidation library into your ASP.NET Core application. Define validators as separate classes inheriting from AbstractValidator<T> and register them with ASP.NET Core's Dependency Injection container. ASP.NET Core provides seamless integration with FluentValidation.
  3. Utilize ModelState.IsValid: In your ASP.NET Core controllers or Razor Page handlers, always check ModelState.IsValid after model binding occurs. This property reflects the outcome of the validation process based on the configured validation attributes or FluentValidation rules.
  4. Add Model Errors Manually: If you need to perform custom validation logic within your controller actions or Razor Page handlers that cannot be expressed through attributes or FluentValidation, manually add errors to the ModelState using ModelState.AddModelError(). This ensures these custom errors are also considered during validation checks.
  5. Return ValidationProblemDetails for APIs: For API endpoints, when ModelState.IsValid is false, return a ValidationProblemDetails response (using BadRequest(ModelState) or ControllerBase.ValidationProblem()). This response format is the standard ASP.NET Core way to communicate validation errors to API clients, providing structured error information.

• Threats Mitigated:

  • SQL Injection (High Severity): Prevents injection by ensuring data passed to database queries (often via EF Core) is validated and conforms to expected types and formats.
  • Cross-Site Scripting (XSS) (High Severity): Reduces XSS by validating input intended for display, ensuring only safe characters are accepted or by triggering validation errors for potentially malicious input.
  • Command Injection (High Severity): Prevents command injection by validating input used in system commands, ensuring it adheres to expected patterns and constraints.
  • Path Traversal (Medium Severity): Mitigates path traversal by validating file paths, ensuring they conform to expected formats and do not contain malicious path components.
  • Denial of Service (DoS) (Medium Severity): Helps prevent DoS by rejecting invalid or excessively large input early in the ASP.NET Core request pipeline, reducing resource consumption on invalid requests.
  • Business Logic Errors (Medium Severity): Reduces business logic errors by ensuring data conforms to expected business rules, preventing unexpected application states and behaviors.

• Impact:

  • SQL Injection: High - Significantly reduces SQL injection risk when validation is applied to all data used in database queries within ASP.NET Core application.
  • XSS: High - Reduces XSS risk by validating user input processed by ASP.NET Core Razor views or API responses.
  • Command Injection: High - Prevents command injection when input used in system commands is validated within ASP.NET Core application logic.
  • Path Traversal: Medium - Reduces path traversal risk when file paths are processed and validated within ASP.NET Core application.
  • DoS: Medium - Contributes to DoS mitigation by rejecting invalid requests early in the ASP.NET Core pipeline.
  • Business Logic Errors: Medium - Improves application robustness by enforcing data integrity within ASP.NET Core application logic.

• Currently Implemented:

  • Partially Implemented: Basic Data Annotation validation is used in many ViewModels and Razor Page models across the ASP.NET Core application (/Models, /Pages).

• Missing Implementation:

  • FluentValidation Integration: FluentValidation is not consistently used for complex validation rules within the ASP.NET Core application, leading to less maintainable and potentially less robust validation logic.
  • API Input Validation Consistency: Input validation in ASP.NET Core API controllers (/Controllers/Api) is less consistent and could benefit from more structured validation using Data Annotations or FluentValidation and returning ValidationProblemDetails.
  • Custom Validation Rules as Reusable Components: Custom validation logic within the ASP.NET Core application is not always implemented as reusable validation attributes or FluentValidation rules, leading to potential duplication and inconsistencies.

Mitigation Strategy: Anti-Forgery Tokens using ASP.NET Core Anti-Forgery System

• Description:

  1. Ensure Anti-Forgery Service is Registered: Verify that services.AddAntiforgery() is present in the ConfigureServices method of your ASP.NET Core Startup.cs file. This registers the necessary services for ASP.NET Core's anti-forgery system. (This is usually default in project templates).
  2. Generate Tokens in Razor Forms with @Html.AntiForgeryToken(): In your Razor Pages or MVC Views within your ASP.NET Core application, use the @Html.AntiForgeryToken() helper method inside <form> tags that perform state-changing operations (POST, PUT, DELETE). This ASP.NET Core helper automatically generates and injects the anti-forgery token into the form as a hidden input field.
  3. Validate Tokens on Server-Side with [ValidateAntiForgeryToken]: For ASP.NET Core Razor Page handlers or MVC controller actions that handle form submissions, apply the [ValidateAntiForgeryToken] attribute. This ASP.NET Core attribute automatically validates the incoming anti-forgery token against the token stored in the user's cookie by the ASP.NET Core framework.
  4. Handle AJAX/JavaScript Requests with Custom Token Retrieval (ASP.NET Core): For AJAX or JavaScript-driven requests in your ASP.NET Core application that modify state, you need to manually retrieve the anti-forgery token. You can obtain it from a cookie set by ASP.NET Core or render it into the page and access it via JavaScript. Include this token as a header (e.g., RequestVerificationToken) in your AJAX requests. On the server-side ASP.NET Core action, still use [ValidateAntiForgeryToken].
  5. Exclude Safe Methods from Validation (ASP.NET Core): Do not apply the [ValidateAntiForgeryToken] attribute to ASP.NET Core actions that only handle safe HTTP methods (GET, HEAD, OPTIONS, TRACE) as these should not modify server-side state and do not require CSRF protection.

• Threats Mitigated:

  • Cross-Site Request Forgery (CSRF) (High Severity): ASP.NET Core's anti-forgery system is designed specifically to prevent CSRF attacks, ensuring that requests modifying state originate from your application and not from malicious cross-site origins.

• Impact:

  • CSRF: High - Effectively prevents CSRF attacks in ASP.NET Core applications when implemented correctly for all state-changing operations.

• Currently Implemented:

  • Partially Implemented: @Html.AntiForgeryToken() is used in many forms within Razor Pages and MVC Views in the ASP.NET Core application (/Pages, /Views). [ValidateAntiForgeryToken] attribute is applied to some, but not all, POST handlers and controller actions within the ASP.NET Core application.

• Missing Implementation:

  • Consistent [ValidateAntiForgeryToken] Application in ASP.NET Core: The [ValidateAntiForgeryToken] attribute is not consistently applied to all relevant POST, PUT, and DELETE handlers and controller actions within the ASP.NET Core application, leaving some state-changing endpoints potentially vulnerable to CSRF.
  • AJAX/JavaScript CSRF Protection in ASP.NET Core: Handling of anti-forgery tokens for AJAX/JavaScript requests within the ASP.NET Core application is not fully implemented. API endpoints and JavaScript-driven forms in ASP.NET Core are potentially vulnerable to CSRF.
  • API Endpoint CSRF Protection (ASP.NET Core): API endpoints in the ASP.NET Core application that accept state-changing requests are not consistently protected against CSRF. Consider alternative CSRF protection mechanisms for APIs within ASP.NET Core if cookie-based tokens are not suitable (e.g., Synchronizer Token Pattern with custom header, potentially using ASP.NET Core's anti-forgery services to generate and validate these tokens).

Mitigation Strategy: HTTPS Redirection Middleware in ASP.NET Core

• Description:

  1. Add UseHttpsRedirection() Middleware in Startup.cs: Ensure the UseHttpsRedirection() middleware is added to the ASP.NET Core request pipeline within the Configure method of your Startup.cs file. This is the primary step to enable HTTPS redirection in ASP.NET Core.
  2. Configure HttpsRedirectionOptions (ASP.NET Core): Optionally customize the HTTPS redirection behavior using HttpsRedirectionOptions within the UseHttpsRedirection() middleware configuration in Startup.cs. You can configure:
     • RedirectStatusCode: Set the HTTP status code for redirection (default is 307). Consider 301 for permanent HTTPS migration.
     • HttpsPort: Specify a non-default HTTPS port if needed.
  3. Production HTTPS Configuration (ASP.NET Core Deployment): Ensure your ASP.NET Core application is deployed to a production environment where HTTPS is properly configured on the web server (e.g., IIS, Nginx, Apache) and that the application is accessible via HTTPS. The ASP.NET Core HTTPS Redirection Middleware will then automatically redirect HTTP requests to HTTPS.
  4. Development HTTPS Setup (ASP.NET Core Development): For local ASP.NET Core development, configure Kestrel to listen on HTTPS or temporarily disable HTTPS redirection if you lack a valid SSL certificate for localhost. ASP.NET Core project templates often include HTTPS configuration for development environments.

• Threats Mitigated:

  • Man-in-the-Middle (MitM) Attacks (High Severity): ASP.NET Core HTTPS Redirection Middleware helps prevent MitM attacks by enforcing HTTPS, ensuring encrypted communication between the browser and the ASP.NET Core server.
  • Session Hijacking (High Severity): By enforcing HTTPS, ASP.NET Core HTTPS Redirection Middleware protects session cookies from being intercepted over unencrypted HTTP connections, mitigating session hijacking risks.
  • Data Eavesdropping (High Severity): HTTPS enforced by ASP.NET Core HTTPS Redirection Middleware encrypts all data transmitted, preventing eavesdropping and protecting data confidentiality.

• Impact:

  • MitM Attacks: High - Effectively prevents MitM attacks for ASP.NET Core applications by ensuring all communication is encrypted via HTTPS redirection.
  • Session Hijacking: High - Prevents session hijacking in ASP.NET Core applications by protecting session cookies through HTTPS enforcement.
  • Data Eavesdropping: High - Protects data confidentiality for ASP.NET Core applications by encrypting all data transmitted over HTTPS.

• Currently Implemented:

  • Implemented: UseHttpsRedirection() middleware is configured in Startup.cs Configure method (/Startup.cs) in the ASP.NET Core application. HTTPS is configured for the production environment on the web server hosting the ASP.NET Core application.

• Missing Implementation:

  • HTTP Strict Transport Security (HSTS) Middleware (ASP.NET Core): While HTTPS redirection is implemented in the ASP.NET Core application, HSTS middleware (UseHsts()) is not yet enabled in Startup.cs. Adding HSTS in ASP.NET Core would further enhance security by instructing browsers to always use HTTPS for the domain, preventing downgrade attacks and further mitigating MitM risks.

Mitigation Strategy: Parameterized Queries using Entity Framework Core (ASP.NET Core)

• Description:

  1. Utilize Entity Framework Core (EF Core) in ASP.NET Core: Adopt Entity Framework Core as the primary Object-Relational Mapper (ORM) for database interactions within your ASP.NET Core application. EF Core is the recommended data access technology for ASP.NET Core.
  2. Avoid Raw SQL String Concatenation in EF Core: When querying the database using EF Core, strictly avoid constructing raw SQL queries by concatenating user input directly into SQL strings. This practice is highly vulnerable to SQL injection.
  3. Employ LINQ and EF Core Querying Methods: Use LINQ queries or EF Core's querying methods (e.g., dbSet.Where(), dbSet.FindAsync(), dbSet.FromSqlInterpolated()) to build database queries in your ASP.NET Core application. These methods inherently handle parameterization, ensuring safe query construction.
  4. Use FromSqlInterpolated or FromSqlRaw with Parameters (EF Core - for Dynamic Queries): If dynamic query construction is necessary in your ASP.NET Core application, utilize EF Core's FromSqlInterpolated or FromSqlRaw methods, but always provide parameters using string interpolation (for FromSqlInterpolated) or parameter placeholders (for FromSqlRaw). These methods allow for parameterized raw SQL execution within EF Core. Exercise extreme caution and thorough review when using raw SQL, even with parameterization.
  5. Code Reviews and Static Analysis for EF Core Usage: Conduct code reviews specifically focused on EF Core usage within your ASP.NET Core application. Look for potential instances of raw SQL query construction or improper parameter handling. Consider using static analysis tools that can detect potential SQL injection vulnerabilities in EF Core code.

• Threats Mitigated:

  • SQL Injection (High Severity): Using parameterized queries via EF Core is the most effective mitigation against SQL injection vulnerabilities in ASP.NET Core applications that interact with databases.

• Impact:

  • SQL Injection: High - Effectively eliminates SQL injection vulnerabilities in ASP.NET Core applications when EF Core parameterized queries are consistently used for all database interactions.

• Currently Implemented:

  • Implemented: Entity Framework Core is used as the primary ORM throughout the ASP.NET Core application (/Data context, repositories, services). LINQ and EF Core querying methods are generally used for data access.

• Missing Implementation:

  • Raw SQL Usage Audit in ASP.NET Core: A dedicated audit is needed to identify and eliminate any remaining instances of raw SQL queries (FromSqlRaw without parameters or string concatenation) within the ASP.NET Core codebase, particularly in less frequently reviewed sections.
  • Dynamic Query Security Review (EF Core): If dynamic query building is employed using EF Core, a specific security review is necessary to ensure that parameterization is correctly and consistently applied in all dynamic query scenarios and that no injection points exist.
  • Developer Training on Secure EF Core Practices: Ensure all developers working on the ASP.NET Core application are thoroughly trained on secure coding practices for database interactions using EF Core, emphasizing the critical importance of parameterized queries and the risks of raw SQL concatenation.