private static CookieContainer _cc = new CookieContainer();
    private static CookieContainer CookiesCont
    {
        get
        {
            if (_cc == null)
                _cc = new CookieContainer();

            return _cc;
        }
    }

    public static string Auth(string url = "https://hh.ru/account/login", string user, string pass)
    {
        var wr = (HttpWebRequest)WebRequest.Create("http://hh.ru");
        wr.CookieContainer = CookiesCont;
        wr.UserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36";
        wr.ContentType = "application/x-www-form-urlencoded";
        wr.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";
        wr.Referer = "https://smolensk.hh.ru/account/login?state=mismatch&backurl=https://smolensk.hh.ru/&login=repariofirm@gmail.com";
        wr.KeepAlive = true;
        wr.AllowAutoRedirect = true;

        try
        {
            using (WebResponse response = wr.GetResponse())
            {
                if (!string.IsNullOrEmpty(response.Headers["Set-Cookie"]))
                    sCookies = response.Headers["Set-Cookie"];
            }
        }
        catch (Exception ex)
        {
        }

        var start = sCookies.IndexOf("_xsrf");
        var end = sCookies.IndexOf(';');

        string xsrf = sCookies.Substring(start + 6, end - start - 6);
        string data = string.Format("backUrl:https://hh.ru/&failUrl:/account/login?backurl=/&role=&username:{0}&password:{1}&_xsrf={2}", user, pass, xsrf);

        wr = (HttpWebRequest)HttpWebRequest.Create(url);
        wr.Method = "POST";
        wr.CookieContainer = CookiesCont;
        wr.UserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36";
        wr.ContentType = "application/x-www-form-urlencoded";
        wr.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";
        wr.Referer = "https://smolensk.hh.ru/account/login?state=mismatch&backurl=https://smolensk.hh.ru/&login=repariofirm@gmail.com";
        wr.KeepAlive = true;
        wr.AllowAutoRedirect = true;

        try
        {
            var buffer = Encoding.UTF8.GetBytes(data);
            wr.ContentLength = buffer.Length;

            using (var writer = wr.GetRequestStream())
            {
                writer.Write(buffer, 0, buffer.Length);
            }

            HttpWebResponse response = (HttpWebResponse)wr.GetResponse();
            //Считываем данные из запроса
            using (StreamReader DataRead = new StreamReader(response.GetResponseStream()))
            {
                //Записываем в строку
                return DataRead.ReadToEnd();
            }
        }
        catch (WebException WE)
        {
            //Сообщение об ошибке
            return WE.Message;
        }
    }