Content-Security-Policy: script-src 'self'
X-WebKit-CSP: script-src 'self'
X-Content-Security-Policy: script-src 'self'

 Content-Security-Policy: script-src 'self' https://youcdn.com
X-WebKit-CSP: script-src 'self' https://yourcdn.com
X-Content-Security-Policy: script-src 'self' https://yourcdn.com

 Content-Security-Policy: default-src 'self' https://youcdn.com
X-WebKit-CSP: default-src 'self' https://yourcdn.com
X-Content-Security-Policy: default-src 'self' https://yourcdn.com

using System;
using System.Web;

namespace AntiXssHeaders
{
    public class SecurityHeadersConstants
    {
        public static readonly string XXssProtectionHeader = "X-XSS-Protection";
        public static readonly string XFrameOptionsHeader = "X-Frame-Options";
        public static readonly string XWebKitCspHeader = "X-WebKit-CSP";
        public static readonly string XContentSecurityPolicyHeader = "X-Content-Security-Policy";
        public static readonly string ContentSecurityPolicyHeader = "Content-Security-Policy";
        public static readonly string XContentTypeOptionsHeader = "X-Content-Type-Options";
    }

    public class ContentSecurityPolicyModule : IHttpModule
    {
        public void Dispose()
        { }

        public void Init(HttpApplication app)
        {
            app.BeginRequest += AppBeginRequest;
        }

        void AppBeginRequest(object sender, EventArgs e)
        {
            var app = (HttpApplication)sender;
            var response = app.Context.Response;
            setHeaders(response);
        }

        private static void setHeaders(HttpResponse response)
        {
            response.Headers.Set(SecurityHeadersConstants.XFrameOptionsHeader, "SameOrigin");

            // For IE 8+
            response.Headers.Set(SecurityHeadersConstants.XXssProtectionHeader, "1; mode=block");
            response.Headers.Set(SecurityHeadersConstants.XContentTypeOptionsHeader, "nosniff");

            //todo: Add /Home/Report --> public JsonResult Report() { return Json(true); }

            const string cspValue = "default-src 'self';";
            // For Chrome 16+
            response.Headers.Set(SecurityHeadersConstants.XWebKitCspHeader, cspValue);

            // For Firefox 4+
            response.Headers.Set(SecurityHeadersConstants.XContentSecurityPolicyHeader, cspValue);
            response.Headers.Set(SecurityHeadersConstants.ContentSecurityPolicyHeader, cspValue);
        }
    }
}

//// RegisterGlobalFilters -> filters.Add(new ContentSecurityPolicyFilterAttribute());
public class ContentSecurityPolicyFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        var response = filterContext.HttpContext.Response;
        response.AddHeader("Content-Security-Policy", "script-src 'self'");
        // the rest ...
        base.OnActionExecuting(filterContext);
    }
}