documentation.md

A .NET Core middleware for injecting the Owasp recommended HTTP Headers for increased security.

Licence Used

See the contents of the LICENSE file for details

Description

A collection of ASP.NET Core middleware classes designed to increase web application security by adopting the recommended OWASP settings.

Secure Headers

The SecureHeadersMiddleware is used to inject the HTTP headers recommended by the OWASP Secure Headers project into all responses generated by the ASP.NET Core pipeline.

Usage

Add a reference to the NuGet package to your project

dotnet add package OwaspHeaders.Core

Configuration

For both versions 1.x and 2.x, a secureHeaderSettings.json file was used. However, from version 3.x onwards, a build-time builder pattern is now used for configuring the secure headers.

Please see the following sections for how to configure the OwaspHeaders.Core middlware.

Configuration since Version 3.x

Version 3.x and higher of OwaspHaders.Core no longer uses the secureHeaderSettings.json file as this is a runtime dependency. It now uses the builder pattern to set up the header information, which is a compile time dependency.

In your Startup class, add a using statement for the OwaspHeaders.Core middleware

using OwaspHeaders.Core.Extensions;

Then in the Configure method, add the following

app.UseSecureHeadersMiddleware(SecureHeadersMiddlewareExtensions.BuildDefaultConfiguration());

This will use the default configuration for the OwaspHeaders.Core middleware. The method (found in /src/Extensions/SecureHeadersMiddlewareExtensions.cs) looks like this:

public static SecureHeadersMiddlewareConfiguration BuildDefaultConfiguration()
{
    return SecureHeadersMiddlewareBuilder
        .CreateBuilder()
        .UseHsts()
        .UseXFrameOptions()
        .UseXSSProtection()
        .UseContentTypeOptions()
        .UseContentDefaultSecurityPolicy()
        .UsePermittedCrossDomainPolicies()
        .UseReferrerPolicy()
        .Build();
}

In order to use a custom configuration, follow the same pattern (perhaps creating your own extension method to encapsulate it):

public static SecureHeadersMiddlewareConfiguration CustomConfiguration()
{
    return SecureHeadersMiddlewareBuilder
        .CreateBuilder()
        .UseHsts(1200, false)
        .UseXSSProtection(XssMode.oneReport, "https://reporturi.com/some-report-url")
        .UseContentDefaultSecurityPolicy()
        .UsePermittedCrossDomainPolicies(XPermittedCrossDomainOptionValue.masterOnly)
        .UseReferrerPolicy(ReferrerPolicyOptions.sameOrigin)
        .Build();
}

Then consume it in the following manner:

app.UseSecureHeadersMiddleware(CustomSecureHeaderExtensions.CustomConfiguration());

Configuration in Version 2.x

In the constructor for the Startup class, add a reference to a secureHeaderSettings.json

public Startup(IHostingEnvironment env)
{
    var builder = new ConfigurationBuilder()
    .SetBasePath(env.ContentRootPath)
    .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
    .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
    .AddJsonFile("secureHeaderSettings.json", optional:true, reloadOnChange: true)
    .AddEnvironmentVariables();
    Configuration = builder.Build();
}

The contents of the secureHeaderSettings.json file take the following format:

{
    "SecureHeadersMiddlewareConfiguration": {
        "UseHsts": "true",
        "HstsConfiguration": {
            "MaxAge": 42,
            "IncludeSubDomains": "true"
        },
        "UseHpkp": "true",
        "HPKPConfiguration" :{
            "PinSha256" : [
                "e927fad33f9eb96126896413502a1034be0ca379dec377fb891feb9ebc720e47"
                ],
            "MaxAge": 3,
            "IncludeSubDomains": "true",
            "ReportUri": "https://github.com/GaProgMan/OwaspHeaders.Core"
        },
        "UseXFrameOptions": "true",
        "XFrameOptionsConfiguration": {
            "OptionValue": "allowfrom",
            "AllowFromDomain": "com.gaprogman.dotnetcore"
        },
        "UseXssProtection": "true",
        "XssConfiguration": {
            "XssSetting": "oneReport",
            "ReportUri": "https://github.com/GaProgMan/OwaspHeaders.Core"
        },
        "UseXContentTypeOptions": "true",
        "UseContentSecurityPolicy": "true",
        "ContentSecurityPolicyConfiguration": {
            "BlockAllMixedContent": "true",
            "UpgradeInsecureRequests": "true"
        }
    }
}

(the above file is provided for illustration purposes)

Load the contents of the secureHeaderSettings.json into an instance of the SecureHeadersMiddlewareConfiguration in the Startup class' ConfigureServices method.

public void ConfigureServices(IServiceCollection services)
{
    // Add framework services
    // Add functionality to inject IOptions<T>
    services.AddOptions();

    // Add our Config object so it can be injected
    services.Configure<SecureHeadersMiddlewareConfiguration>(Configuration.GetSection("SecureHeadersMiddlewareConfiguration"));
}

Add the SecureHeadersMiddleware into the ASP.NET Core pipeline, in the Startup class' Configure method.

public void Configure(IApplicationBuilder app, IHostingEnvironment env,
    IOptions<SecureHeadersMiddlewareConfiguration> secureHeaderSettings)
{
    // Add SecureHeadersMiddleware to the pipeline
    app.UseSecureHeadersMiddleware(secureHeaderSettings.Value);
}

Testing the Middleware

Run the application, request one of the pages that it serves and view the headers for the page.

This can be done in Google Chrome, using the Dev tools and checking the network tab.

Shown above in the Response Headers section of the Values response.

Development Logs

This repository forms the basis for a series of blog posts that I have written on the topic of ASP.NET Core middleware.

If you would like to read about how I have developed the code in this repository, please see the first in the blog post series entitled: ".NET Core Middleware – OWASP Headers Part 1"