C# Http Basic Authentication Bypass

Question

On a C# ASP.NET application, I've managed to bypass basic authentication (by sending the username/password through "Authorization" headers on a HTTPWebRequest) and I finally got the unlocked the target page that is protected by htaccess (located on a different server, basic auth) and sent the stream back to the browser.

The issue appears as soon as the user clicks on a link, the basic auth logon box pops up again. We don't want the user to enter to username/password again.

It seems that I need to be sending something back in the headers to tell the browser what username/password it's using for authorization.

I've tried:

Old "username:password@host" format (insecure, not allowed on IE anymore).
HTTPWebRequest, which gives me the issue described before.

Considerations:

The remote server being accessed is a black box.

Is there a way to achieve this? (It can be done in JavaScript as well).

This is my function for the HttpRequest:

    public void DoWebRequest(String email, String psw, String hostname, 
    int port, String req_method, String webpage)
    {

    String path = hostname + ":" + port + "/" + webpage;
    String userdata = email + ":" + psw;
    System.Text.ASCIIEncoding encoding = new ASCIIEncoding();
    byte[] data = encoding.GetBytes(path);
    byte[] authBytes = Encoding.UTF8.GetBytes(userdata.ToCharArray());
    String req_short_host_temp = hostname;
    String req_short_host = req_short_host_temp.Replace("http://", "");

    Uri uri = new Uri(path);
    HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(uri) as HttpWebRequest;
    req.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.0.3705;)";
    req.Method = req_method;
    req.PreAuthenticate = false;
    req.Headers["Authorization"] = "Basic " + Convert.ToBase64String(authBytes);
    req.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
    req.Headers.Add("Accept-Language: en-us,en;q=0.5");
    req.Headers.Add("Accept-Encoding: gzip,deflate");
    req.Headers.Add("Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7");
    req.KeepAlive = true;
    req.Headers.Add("Keep-Alive: 1000");
    req.ReadWriteTimeout = 320000;
    req.Timeout = 320000;
    req.Host = req_short_host;
    req.AllowAutoRedirect = true;

    req.ContentType = "application/x-www-form-urlencoded";
    req.Headers.GetType().InvokeMember("ChangeInternal", BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.InvokeMethod, null, req.Headers, new object[] { "Host", req_short_host });

    var headers = new MyHeaderCollection();
    req.Headers = headers;
    headers.Set("Host", req_short_host);

    StreamWriter sw = new StreamWriter(req.GetRequestStream());
    sw.Write("/" + "?user=" + email + "&password=" + psw);
    sw.Close();

    HttpWebResponse response = (HttpWebResponse)req.GetResponse();
    StreamReader reader = new StreamReader(response.GetResponseStream());
    string tmp = reader.ReadToEnd();

    foreach (Cookie cook in response.Cookies)
    {
        tmp += "\n" + cook.Name + ": " + cook.Value;
    }

    Response.Write(tmp);
    Response.End();

}

Do you know any way to achieve this? I'd tried with a cookie but it didn't persist through the html. — pacolive

Stephan B Stephan B · Accepted Answer · 2011-11-22T14:39:30

Don't know about javascript, but there is no way in c# to do this I believe. You may filter all user interaction so the browser never accesses the other server directly. To do this, rewrite all urls in content to point to your script (reverse proxy).

C# Http Basic Authentication Bypass

1 Answers