Searching for the Response Header property in MessageSecurityException?

I had a requirement in my code wherein I had to make a webservice call, catch a HTTP 401 exception returned by the service, read a value from the header, add some value in the header and call the service again. Seems not very uncommon to me. My client was a WCF application and service was written in Java. Apparently, the exception that was being thrown on client side was of type System.ServiceModel.Security.MessageSecurityException. I remember I tried for about half an hour to find where the hell is the Response object returned from the server. Here it is,

try
{
    Webservice Call..
}
catch (MessageSecurityException ex)
{
    if (ex.InnerException != null && ex.InnerException is WebException)
    {
        WebException webException = ex.InnerException as WebException;
        string sample = webException.Response.Headers["Sample"];
    }
}

Happy Programming!