Document Title:
===============
Paypal Inc Bug Bounty #16 - Persistent Mail Encoding Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=660


Release Date:
=============
2014-09-18


Vulnerability Laboratory ID (VL-ID):
====================================
660


Common Vulnerability Scoring System:
====================================
3.2


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.
Between December 4ñ9, 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 Advisory Information:
==============================
The Vulnerability Laboratory Research Team discovered a persistent mail encodign web vulnerability in the official PayPal Inc merchant online-service web-application.


Vulnerability Disclosure Timeline:
==================================
2014-09-18:  Public Disclosure (Vulnerability Laboratory)


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


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


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


Technical Details & Description:
================================
A persistent input validation vulnerability is detected in the official Paypal Inc Merchant website application (Customer/Pro/Seller).
The vulnerability allows remote attackers to inject own malicious script codes to compromise the application-side of the online-service. 

The bugs allow remote attackers to implement/inject malicious script code on the application side (persistent) of the paypal merchant web service. 
The vulnerability is located in the `Frage Sie uns > Frage übermitteln` module with the connected vulnerable data listing value. The issue is remote 
exploitable and the request method to inject the malicious payload is POST.


Exploitation of the vulnerability requires a low privileged application user account and low or medium user interaction. Successful exploitation 
of the vulnerability can lead to session hijacking, persistent phishing, persistent external redirects to malicious source and persistent 
manipulation of affected or connected module web context.

Request Method(s):
      [+] POST
Vulnerable Type(s):
      [+] Paypal Merchant Accounts

Vulnerable Site(s):
      [+] Paypal Merchant Technical Support (ppmts.custhelp.com/app/ask)

Vulnerable Module(s):
      [+] Frage Sie uns > Frage übermitteln

Vulnerable Parameter(s):
      [+] data

Affected Section(s):
      [+] Notification Mail - Listing Account


Proof of Concept (PoC):
=======================
The persistent input validation vulnerability can be exploited by remote attackers with low or medium required user inter action. 
For security demonstration or to reproduce the security vulnerability follow the provided information and steps below to continue.

Review:  Notification Mail - Listing Account

<tbody><tr><td colspan="2" bgcolor="#E0E0E0"><b> Fragereferenznummer:120711-000465</b></td></tr>
<tr><td colspan="2"><table cellpadding="0" cellspacing="0" width="100%">
<tbody><tr><td class="label" align="right" nowrap="nowrap" width="250px"><b>Übersicht: </b></td>
<td class="data">">"<[PERSISTENT INJECTED SCRIPT CODE])' <<="" td=""></tr>
<tr><td class="label" align="right" width="250px" nowrap><b>Produktebene 1: </b></td>
<td class="data">Magento</td></tr><tr><td class="label" align="right" width="250px" nowrap><b>Erstellungsdatum: &l

URL: https://ppmts.custhelp.com/app/ask

NOTE: NOT ONLY THE USER IS AFFECTED BY THE NOTIFICATION ALSO THE WATCHER IN THE BACKEND OF THE APPLICATION SERVICE.


Solution - Fix & Patch:
=======================
The vulnerability can be patched by a restriction of the input in the `Frage Stellen` module. To prevent executions it is also required to parse and 
encode the vulnerable `data` value. The issue has been resolved by paypal inc.

Security Risk:
==============
The security risk of the persistent input validation mail encoding vulnerability is estimated as medium.


Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (bkm@evolution-sec.com) [www.vulnerability-lab.com]


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=========================
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