java - Servlet类中的XSS漏洞问题response.getOutputStream()。write(buffer)

我正在针对模块的代码审核报告修复问题。问题是XSS漏洞。
它已报告语法问题
response.getOutputStream（）。write（buffer）;
如何解决？
我做了足够的家庭作业，发现OWASP建议的ESAPI可以帮助我修复它，但是如何实现呢？问题出在servlet类中吗？
或任何其他api或其他任何可以帮助我修复它的东西？
请分享您的相关经验。

FileOutputStream fos = null;
        FileInputStream fileInuptStream =null;
        BufferedInputStream bufferedInputStream = null;
        ByteArrayOutputStream byteArrayOutputStream =null;
        try{
           ServletContext servletContext = request.getSession().getServletContext();
            File attachmentDir = new File(servletContext.getRealPath("")+File.separator+"Reports" );
            String uploadDir=attachmentDir.getPath();
            if (!attachmentDir.exists()) {
                attachmentDir.mkdirs();
            }

            HSSFWorkbook wb= new HSSFWorkbook();
             AAAA  aaa=new AAAA();
            wb=aaa.getExportXLS(request, response, fileName, wb);
             if(request.getSession().getAttribute("SESSION_AAAAA")!=null){
                    request.getSession().removeAttribute("SESSION_AAAAA");
            }
              fos=new FileOutputStream(uploadDir+File.separator+fileName);
            wb.write(fos);

            File fileXls=new File(uploadDir+File.separator+fileName);
              fileInuptStream = new FileInputStream(fileXls);
              bufferedInputStream = new BufferedInputStream(fileInuptStream);
              byteArrayOutputStream = new ByteArrayOutputStream();
            int start = INT_ZERO;
            int length = ONE_ZERO_TWO_FOUR;
            int offset = MINUS_ONE;
            byte [] buffer = new byte [length];
            while ((offset = bufferedInputStream.read(buffer, start, length)) != -1)
                byteArrayOutputStream.write(buffer, start, offset);


            buffer = byteArrayOutputStream.toByteArray();

            response.setHeader("Expires", "0");
            response.setHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0");
            response.setHeader("Pragma", "public");
            response.setContentType("application/xls");
            response.setHeader("Content-disposition","attachment; filename="+fileName );
            response.setContentLength((int ) fileXls.length());
            response.getOutputStream().write(buffer);  --- REPORTED AT THIS LINE
            response.getOutputStream().flush();

最佳答案

这是一个错误的警告。该Servlet返回的是由Apache POI创建的XLS文件，而不是HTML文档。不可能存在XSS攻击的手段。

但是，此代码非常笨拙且效率低下。它正在扩展的WAR文件夹中创建一个文件（无论何时重新部署WAR都会丢失该文件），然后将其全部内容完全复制到服务器的内存中，而不是直接写入响应。这种笨拙的方法可能使审计工具感到困惑。您应该只将HttpServletResponse#getOutputStream()传递给Workbook#write()。

这是基于到目前为止发布的代码的完整重写：

HSSFWorkbook wb = new HSSFWorkbook();
AAAA aaa = new AAAA();
wb = aaa.getExportXLS(request, response, fileName, wb);
response.setHeader("Expires", "0");
response.setHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0");
response.setHeader("Pragma", "public");
response.setContentType("application/xls");
response.setHeader("Content-disposition", "attachment; filename=" + fileName);
wb.write(response.getOutputStream());