PayPal Inc Bug Bounty #113 - Client Side Cross Site Scripting Vulnerability

[Vulnerability Lab <research () vulnerability-lab com>]

Document Title:
===============
PayPal Inc Bug Bounty #113 - Client Side Cross Site Scripting Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1453

Video: http://www.vulnerability-lab.com/get_content.php?id=1454

View: https://www.youtube.com/watch?v=v5egy9V_Bs0


Release Date:
=============
2015-04-18


Vulnerability Laboratory ID (VL-ID):
====================================
1453


Common Vulnerability Scoring System:
====================================
3.4


Product & Service 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.

(Copy of the Homepage: www.paypal.com) [http://en.wikipedia.org/wiki/PayPal]


Abstract Advisory Information:
==============================
An independent Vulnerability Laboratory researcher discovered a client-side cross site scripting web vulnerability in 
the official PayPal Inc online service web-application.


Vulnerability Disclosure Timeline:
==================================
2014-12-30: Researcher Notification & Coordination (Milan A Solanki)
2014-12-31: Vendor Notification (PayPal Inc - Bug Bounty Team)
2015-01-08: Vendor Response/Feedback (PayPal Inc - Bug Bounty Team)
2015-01-15: Vendor Fix/Patch (PayPal Inc - Developer Team)
2015-04-18: Public Disclosure (Vulnerability Laboratory)


Discovery Status:
=================
Published


Affected Product(s):
====================
PayPal Inc
Product: PayPal - Online Service Web Application 2015 Q2


Exploitation Technique:
=======================
Remote


Severity Level:
===============
Medium


Technical Details & Description:
================================
A non persistent cross site scripting web vulnerability has been discovered in the official PayPal Inc online service 
web-application.
The vulnerability allows remote attackers to hijack website customer, moderator or admin sessions data by client-side 
manipulated cross site requests.

The vulnerability is located in the `q` values of the merchant search module. Remote attackers are able to inject own 
script codes to the vulnerable GET method 
request of the merchant search module.  The attack vector of the vulnerability is located on the client-side of the 
paypal online service web-application. 
The request method to inject the script code on client-side is `GET`. The injection point of the issue is the 
vulnerable `q` value in the search engine and 
the script code execution point is located in the results output context page.

The security risk of the non-persistent input validation web vulnerability is estimated as medium with a cvss (common 
vulnerability scoring system) count of 3.4.
Exploitation of the client-side cross site scripting web vulnerability requires low user interaction (click) and no 
privileged application user account. 
Successful exploitation results in client-side account theft by hijacking, client-side phishing, client-side external 
redirects and non-persistent manipulation 
of affected or connected service modules.

Request Method(s):
                                [+] GET

Vulnerable Service(s):
                                [+] PayPal Inc (paypal.com)

Vulnerable Module(s):
                                [+] Merchant Search

Vulnerable Parameter(s):
                                [+] q

Affected Section(s):
                                [+] Merchant Search Results


Proof of Concept (PoC):
=======================
The client-side cross site scripting web vulnerability can be exploited by remote attackers without privileged 
application user account and with low user interaction (click).
For security demonstration or to reproduce the security vulnerability follow the provided information and steps below 
to continue.

PoC: Example
https://www.paypal.com/directory/merchants?q=directory/merchants?q=&q=q=directory/merchants?q=&q=[CROSS SITE SCRIPTING 
VULNERABILITY!]

PoC: Payload(s)
https://www.paypal.com/directory/merchants?q=directory/merchants?q=&q=q=directory/merchants?q=&q=%22%3E%3Cimg%20src=x%20onerror=prompt%28document.domain%29%3E
https://www.paypal.com/directory/merchants?q=directory/merchants?q=&q=q=directory/merchants?q=&q=%22%3E%3Ciframe%20src=x%20onerror=prompt%28document.cookie%29%3E


Reference(s):
https://www.paypal.com/directory/merchants?q=directory/merchants?q=
https://www.paypal.com/directory/merchants?q=directory/merchants?q=&q=q=directory/merchants?q=&q=


Solution - Fix & Patch:
=======================
2015-01-15: Vendor Fix/Patch (PayPal Inc - Developer Team)


Security Risk:
==============
The security risk of the client-side cross site scripting web vulnerability in the `q` merchant search value is 
estimated as medium. (CVSS 3.4)


Credits & Authors:
==================
Milan A Solanki - (milans812 () gmail com) [www.safehacking4mas.blogspot.in]


Disclaimer & Information:
=========================
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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, 
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