API security extensions

Background

🌎 Read more in my blog post: Enforce HTTPS correctly in ASP.NET Core APIs

It's easy to enforce HTTPS (with automatic redirects) in browser apps using the [RequireHttps] attribute. However, the ASP.NET Core docs have this to say about using the attribute in API projects:

Do not use RequireHttpsAttribute on Web APIs that receive sensitive information. RequireHttpsAttribute uses HTTP status codes to redirect browsers from HTTP to HTTPS. API clients may not understand or obey redirects from HTTP to HTTPS. Such clients may send information over HTTP.

Unfortunately there isn't a version of the attribute that closes or rejects the connection without redirecting. You can always enforce HTTPS at the API gateway or reverse proxy layer, but sometimes you want more control.

Usage

Returning an HTTP status code for insecure requests

Use [RequireHttpsOrClose] on controllers or actions to return HTTP code 400 (Bad Request) for insecure requests:

[RequireHttpsOrClose]
public class HomeController

Or, if you want to return a different status code:

[RequireHttpsOrClose(505)]
public class HomeController

Aborting insecure connections

Use the AbortIfNotHttps() middleware if to reject all insecure (HTTP) requests across your entire application.

⚠️ Whenever possible, reject insecure requests at the server or reverse proxy layer. Use this middleware only if you need to enforce this at the ASP.NET Core pipeline level.

Place the middleware at the top of your Configure method:

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.AbortIfNotHttps();

    if (env.IsDevelopment())
    // The rest of your pipeline...
}

Feedback