protected void ErrorLog_Filtering(object sender, Elmah.ExceptionFilterEventArgs e)
{
    var request = System.Web.HttpContext.Current.Request;
    var auth = request.ServerVariables["HTTP_AUTHORIZATION"];
    if (!String.IsNullOrEmpty(auth))
    {
        var authPattern = new Regex(@"(Authorization|HTTP_AUTHORIZATION):\s*" + auth + @"\s*", RegexOptions.ExplicitCapture);
        request.ServerVariables["ALL_HTTP"] = authPattern.Replace(request.ServerVariables["ALL_HTTP"], String.Empty);
        request.ServerVariables["ALL_RAW"] = authPattern.Replace(request.ServerVariables["ALL_RAW"], String.Empty);
    }
    request.ServerVariables["AUTH_PASSWORD"] = null;
    request.ServerVariables.Remove("AUTH_PASSWORD");
    request.ServerVariables["HTTP_AUTHORIZATION"] = null;
    request.ServerVariables.Remove("HTTP_AUTHORIZATION");
}