Securing ASP.NET Core Web API

Securing ASP.NET Core Web API

Securing your ASP.NET Web API is essential to protect sensitive data, prevent unauthorized access, and ensure reliable service. Here’s a comprehensive list of best practices tailored for ASP.NET Core Web APIs:

🔐 Authentication & Authorization

• Use [ApiController]: Automatically handles model validation and returns 400 responses for invalid models.
• Implement JWT Authentication: Secure endpoints using JSON Web Tokens with proper validation parameters:

services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
  .AddJwtBearer(options => {
    options.TokenValidationParameters = new TokenValidationParameters {
      ValidateIssuer = true,
      ValidateAudience = true,
      ValidateLifetime = true,
      ValidateIssuerSigningKey = true,
      ValidIssuer = "your-issuer",
      ValidAudience = "your-audience",
      IssuerSigningKey = new SymmetricSecurityKey(
        Encoding.UTF8.GetBytes("your-secret-key"))
    };
  });
  

• Role-Based Access Control: Use [Authorize(Roles = "Admin")] to restrict access to specific roles.

🛡️ Input Validation & Model Binding

• Use Data Annotations: Validate input using [Required], [Range], [EmailAddress], etc.
• Avoid Overposting: Use DTOs to expose only necessary fields.
• Sanitize Inputs: Prevent injection attacks by validating and sanitizing user input.

🌐 CORS Configuration

Restrict Origins: Configure CORS to allow only trusted domains:

services.AddCors(options => {
  options.AddPolicy("AllowTrustedOrigins", builder =>
    builder.WithOrigins("https://yourdomain.com")
           .AllowAnyHeader()
           .AllowAnyMethod());
});
  

🔒 Transport & Data Protection

• Enforce HTTPS: Redirect all HTTP traffic to HTTPS using middleware.
• Use SSL/TLS: Ensure certificates are valid and up-to-date.
• Protect Sensitive Data: Avoid logging secrets; use ASP.NET Core’s Data Protection API for encryption.

🧠 Rate Limiting & Throttling

• Prevent Abuse: Use middleware or reverse proxies (like NGINX or Azure API Management) to limit request rates and prevent DoS attacks.

🧾 Logging & Monitoring

• Audit Logs: Track access and changes to sensitive endpoints.
• Use Serilog or Application Insights: Monitor performance and detect anomalies.

🧰 Dependency & Configuration Security

• Secure Configuration: Store secrets in environment variables or secure vaults (e.g., Azure Key Vault).
• Keep Dependencies Updated: Regularly patch libraries to avoid known vulnerabilities.

🧪 Testing & Hardening

• Penetration Testing: Simulate attacks to identify weaknesses.
• Security Headers: Add headers like X-Content-Type-Options, X-Frame-Options, and Content-Security-Policy.