MSDN Documentation

ASP.NET Core Security

This section provides comprehensive guidance on securing your ASP.NET Core applications. We cover authentication, authorization, data protection, and best practices for building secure web applications.

Authentication

Authentication is the process of verifying the identity of a user or service. ASP.NET Core provides flexible mechanisms for handling authentication.

• Identity: A built-in membership system for managing users, passwords, claims, roles, and tokens.
• Cookies: Storing authentication tickets in browser cookies for session management.
• JWT Bearer Tokens: Used for stateless authentication, common in SPA and API scenarios.
• External Providers: Integrating with OAuth 2.0 and OpenID Connect providers like Google, Facebook, Microsoft, etc.

For more details, refer to the ASP.NET Core Authentication documentation.

Authorization

Authorization determines whether an authenticated user is allowed to perform a specific action or access a resource.

• Role-Based Authorization: Restricting access based on user roles (e.g., Administrator, User).
• Policy-Based Authorization: More granular control based on custom requirements and assertions (e.g., requiring a specific claim, age, or date).
• Resource-Based Authorization: Authorization decisions based on the specific resource being accessed.

Explore ASP.NET Core Authorization concepts.

Data Protection

ASP.NET Core Data Protection API provides a framework for protecting data, such as authentication cookies and view state, from tampering and accidental disclosure.

• Encrypting sensitive data.
• Signing data to ensure integrity.
• Key management and rotation.

Learn more about ASP.NET Core Data Protection.

Common Security Threats and Mitigation

Understanding and mitigating common web application security threats is crucial:

• Cross-Site Scripting (XSS): Prevent by properly encoding output and using anti-XSS libraries.
• SQL Injection: Prevent by using parameterized queries or ORMs (like Entity Framework Core).
• Cross-Site Request Forgery (CSRF): Prevent using anti-forgery tokens.
• HTTPS: Always use HTTPS to encrypt communication.

Further Reading: Authentication

Dive deeper into specific authentication scenarios:

// Example: Configuring cookie authentication
services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
    .AddCookie(options =>
    {
        options.LoginPath = "/Account/Login";
        options.LogoutPath = "/Account/Logout";
    });

// Example: Implementing external login with Google
services.AddAuthentication().AddGoogle(options =>
{
    options.ClientId = Configuration["Authentication:Google:ClientId"];
    options.ClientSecret = Configuration["Authentication:Google:ClientSecret"];
});
            

Further Reading: Authorization

Understanding policy-based authorization:

// Example: Defining a policy
services.AddAuthorization(options =>
{
    options.AddPolicy("RequireAdminRole", policy => policy.RequireRole("Admin"));
    options.AddPolicy("Over21", policy => policy.RequireAssertion(context =>
        context.User.HasClaim(c => c.Type == "Age" && int.Parse(c.Value) >= 21)
    ));
});

// Example: Applying authorization in a controller
[Authorize(Policy = "RequireAdminRole")]
public class AdminController : Controller
{
    // ...
}
            

Further Reading: Data Protection

Using the data protection API:

// Inject IDataProtectionProvider
public class MyService
{
    private readonly IDataProtector _protector;

    public MyService(IDataProtectionProvider provider)
    {
        _protector = provider.CreateProtector("MyScopedPurpose");
    }

    public string ProtectData(string data)
    {
        return _protector.Protect(data);
    }

    public string UnprotectData(string protectedData)
    {
        return _protector.Unprotect(protectedData);
    }
}