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Mitigation Strategies Analysis for dotnet/aspnetcore

Mitigation Strategy: Use ViewModels/DTOs and [Bind] Attribute

1. Mitigation Strategy: Use ViewModels/DTOs and [Bind] Attribute

  • Description:

    1. Create ViewModels/DTOs: For each controller action that accepts user input, create a dedicated class (ViewModel or DTO) that contains only the properties expected from the client. Do not use your domain/entity models directly for data binding. This is a core ASP.NET Core MVC pattern.
    2. Use [Bind] (Optional but Recommended): In your controller action, use the [Bind] attribute on the ViewModel/DTO parameter to explicitly specify which properties are allowed to be bound. Example: public IActionResult Create([Bind("Name,Email")] ProductViewModel model). This is an ASP.NET Core-specific attribute.
    3. Use [BindNever]: On properties within your models (even ViewModels) that should never be populated from user input (e.g., Id, IsAdmin, CreationDate), apply the [BindNever] attribute. Example: [BindNever] public int Id { get; set; }. This is an ASP.NET Core-specific attribute.
    4. Controller Action Logic: In your controller action, receive the ViewModel/DTO as a parameter. After model validation, map the data from the ViewModel/DTO to your domain/entity model manually.

  • List of Threats Mitigated:

    • Over-Posting/Mass Assignment (High Severity): Attackers can add extra properties to the request payload. ASP.NET Core's model binding, if misused, can be vulnerable.
    • Type Mismatches (Medium Severity): Exploiting ASP.NET Core's model binding with unexpected types.

  • Impact:

    • Over-Posting/Mass Assignment: Risk reduced from High to Low.
    • Type Mismatches: Risk reduced from Medium to Low.

  • Currently Implemented: [Placeholder]

  • Missing Implementation: [Placeholder]

Mitigation Strategy: Validate Model State and Use Data Annotations

2. Mitigation Strategy: Validate Model State and Use Data Annotations

  • Description:

    1. Data Annotations: Use ASP.NET Core's data annotations (e.g., [Required], [StringLength], [EmailAddress], [Range], [RegularExpression]) on the properties of your ViewModels/DTOs. These are part of the System.ComponentModel.DataAnnotations namespace, deeply integrated with ASP.NET Core.
    2. ModelState.IsValid: In every controller action, always check the ModelState.IsValid property (an ASP.NET Core MVC feature) before processing data.
    3. Return Errors: If ModelState.IsValid is false, return the validation errors to the client using ASP.NET Core's built-in mechanisms.
    4. Custom Validation (if needed): Implement the IValidatableObject interface (part of ASP.NET Core's validation system) on your ViewModel/DTO for complex rules.

  • List of Threats Mitigated:

    • Under-Posting (Medium Severity): Attackers omitting required fields, bypassing checks that rely on ASP.NET Core's model binding.
    • Invalid Input (Medium to High Severity): Data violating rules defined via ASP.NET Core's data annotations.
    • Bypassing Business Logic (Medium to High Severity): Circumventing client-side validation, relying on ASP.NET Core's server-side validation.

  • Impact:

    • Under-Posting: Risk reduced from Medium to Low.
    • Invalid Input: Risk reduced from Medium/High to Low.
    • Bypassing Business Logic: Risk reduced from Medium/High to Low.

  • Currently Implemented: [Placeholder]

  • Missing Implementation: [Placeholder]

Mitigation Strategy: Use Attribute Routing and Route Constraints

3. Mitigation Strategy: Use Attribute Routing and Route Constraints

  • Description:

    1. Attribute Routing: Use ASP.NET Core's attribute routing ([Route], [HttpGet], [HttpPost], etc.) on controller actions. This is the recommended routing mechanism in ASP.NET Core.
    2. Specific Route Templates: Define precise route templates.
    3. Route Constraints: Use ASP.NET Core's route constraints (e.g., [HttpGet("users/{id:int}")]) to restrict parameter types. This is a built-in ASP.NET Core feature.
    4. Route Parameter Validation (in Action): Validate route parameters within your controller actions.

  • List of Threats Mitigated:

    • Ambiguous Routes (Medium Severity): Poorly defined routes leading to incorrect action execution, specific to ASP.NET Core's routing system.
    • Route Parameter Tampering (Medium to High Severity): Manipulating route parameters, exploiting weaknesses in ASP.NET Core's routing if not properly secured.

  • Impact:

    • Ambiguous Routes: Risk reduced from Medium to Low.
    • Route Parameter Tampering: Risk reduced from Medium/High to Low.

  • Currently Implemented: [Placeholder]

  • Missing Implementation: [Placeholder]

Mitigation Strategy: Auto-Validate Anti-Forgery Tokens Globally

4. Mitigation Strategy: Auto-Validate Anti-Forgery Tokens Globally

  • Description:

    1. Global Validation: In Program.cs (or Startup.cs), add the AutoValidateAntiforgeryTokenAttribute (an ASP.NET Core-specific attribute) to the global filter collection. This leverages ASP.NET Core's built-in anti-CSRF protection.
    2. Include Token in Forms: Use @Html.AntiForgeryToken() (an ASP.NET Core Razor helper) in forms.
    3. Include Token in AJAX Requests: Use ASP.NET Core's JavaScript helpers to include the token in AJAX request headers.

  • List of Threats Mitigated:

    • Cross-Site Request Forgery (CSRF) (High Severity): Directly mitigated by ASP.NET Core's anti-forgery token mechanism.

  • Impact:

    • CSRF: Risk reduced from High to Low.

  • Currently Implemented: [Placeholder]

  • Missing Implementation: [Placeholder]

Mitigation Strategy: Use [Authorize] Attribute and Role/Claims-Based Authorization

5. Mitigation Strategy: Use [Authorize] Attribute and Role/Claims-Based Authorization

  • Description:

    1. Authentication: Use an ASP.NET Core authentication mechanism (e.g., Identity, JWT Bearer).
    2. [Authorize] Attribute: Apply the [Authorize] attribute (an ASP.NET Core attribute) to controllers/actions.
    3. Role-Based Authorization: Use [Authorize(Roles = "Admin")] (ASP.NET Core feature).
    4. Claims-Based Authorization: Use ASP.NET Core's claims-based authorization and policies.
    5. Policy-Based Authorization: Define authorization policies using ASP.NET Core's authorization services.

  • List of Threats Mitigated:

    • Unauthenticated Access (High Severity): Prevented by ASP.NET Core's authentication and [Authorize] attribute.
    • Unauthorized Access (High Severity): Prevented by ASP.NET Core's role/claims-based authorization.
    • Privilege Escalation (High Severity): Mitigated by proper use of ASP.NET Core's authorization features.

  • Impact:

    • Unauthenticated Access: Risk reduced from High to Low.
    • Unauthorized Access: Risk reduced from High to Low.
    • Privilege Escalation: Risk reduced from High to Low.

  • Currently Implemented: [Placeholder]

  • Missing Implementation: [Placeholder]

Mitigation Strategy: Secure Key Storage and Data Protection API

6. Mitigation Strategy: Secure Key Storage and Data Protection API

  • Description:

    1. Identify Sensitive Data: Determine data needing protection.
    2. Data Protection API: Use the ASP.NET Core Data Protection API to encrypt and decrypt. This is a core ASP.NET Core feature.
    3. Secure Key Storage: Use a secure key storage provider, integrating with ASP.NET Core's configuration system.
    4. Key Rotation: Configure automatic key rotation within the ASP.NET Core Data Protection system.
    5. Configuration: Use IConfiguration to load secrets.

  • List of Threats Mitigated:

    • Data Breach (High Severity): Mitigated by using ASP.NET Core's Data Protection API for encryption.
    • Key Compromise (High Severity): Addressed by key rotation within the ASP.NET Core Data Protection framework.

  • Impact:

    • Data Breach: Risk reduced from High to Medium/Low.
    • Key Compromise: Risk reduced from High to Medium.

  • Currently Implemented: [Placeholder]

  • Missing Implementation: [Placeholder]

Mitigation Strategy: Set Request Size Limits

7. Mitigation Strategy: Set Request Size Limits

  • Description:

    1. Global Configuration: Configure MaxRequestBodySize in your Program.cs or Startup.cs using Kestrel server options. This is an ASP.NET Core-specific configuration.
    2. Per-Action/Controller Configuration: Use the [RequestSizeLimit] attribute (an ASP.NET Core attribute) on specific actions or controllers.
    3. Disable Request Size Limit (Rarely Needed): Use the [DisableRequestSizeLimit] attribute (an ASP.NET Core attribute).
    4. Handle Large Requests: ASP.NET Core will return a 413 Payload Too Large status code.

  • List of Threats Mitigated:

    • Denial of Service (DoS) (High Severity): Mitigated by configuring request size limits within ASP.NET Core.
    • Resource Exhaustion (Medium Severity): Addressed by limiting request sizes in ASP.NET Core.

  • Impact:

    • DoS: Risk reduced from High to Medium/Low.
    • Resource Exhaustion: Risk reduced from Medium to Low.

  • Currently Implemented: [Placeholder]

  • Missing Implementation: [Placeholder]