用这种方式导出Excel，会提示不安全，怎么处理？

ExportExcel Code
        public FileResult ExportExcel()
        {
            var sbHtml = new StringBuilder();
            sbHtml.Append("<table border='1' cellspacing='0' cellpadding='0'>");
            sbHtml.Append("<tr>");
            var lstTitle = new List<string> { "编号", "姓名", "年龄", "创建时间" };
            foreach (var item in lstTitle)
            {
                sbHtml.AppendFormat("<td style='font-size: 14px;text-align:center;background-color: #DCE0E2; font-weight:bold;' height='25'>{0}</td>", item);
            }
            sbHtml.Append("</tr>");

            for (int i = 0; i < 1000; i++)
            {
                sbHtml.Append("<tr>");
                sbHtml.AppendFormat("<td style='font-size: 12px;height:20px;'>{0}</td>", i);
                sbHtml.AppendFormat("<td style='font-size: 12px;height:20px;'>屌丝{0}号</td>", i);
                sbHtml.AppendFormat("<td style='font-size: 12px;height:20px;'>{0}</td>", new Random().Next(20, 30) + i);
                sbHtml.AppendFormat("<td style='font-size: 12px;height:20px;'>{0}</td>", DateTime.Now);
                sbHtml.Append("</tr>");
            }
            sbHtml.Append("</table>");

            //第一种:使用FileContentResult
            byte[] fileContents = Encoding.Default.GetBytes(sbHtml.ToString());
            return File(fileContents, "application/ms-excel", "fileContents.xls");

            //第二种:使用FileStreamResult
            var fileStream = new MemoryStream(fileContents);
            return File(fileStream, "application/ms-excel", "fileStream.xls");

            //第三种:使用FilePathResult
            //服务器上首先必须要有这个Excel文件,然会通过Server.MapPath获取路径返回.
            var fileName = Server.MapPath("~/Files/fileName.xls");
            return File(fileName, "application/ms-excel", "fileName.xls");
        }