PayPal Inc Bug Bounty #53 - Multiple Persistent Vulnerabilities

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

Document Title:
===============
PayPal Inc Bug Bounty #53 - Multiple Persistent Vulnerabilities


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=835


Release Date:
=============
2014-09-29


Vulnerability Laboratory ID (VL-ID):
====================================
835


Common Vulnerability Scoring System:
====================================
4.3


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 two persistent input validation web vulnerabilities in the 
official PayPal Inc GP+ online service web-application.


Vulnerability Disclosure Timeline:
==================================
2014-09-29:     Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
PayPal Inc
Product: GP+ - Application Service 2013 Q1


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


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


Technical Details & Description:
================================
Multiple persistent input validation web vulnerabilities has been discovered in the official PayPal Inc GP+ online 
service web-application.
The vulnerability allows an attacker to inject own malicious script codes to the application side (persistent) of the 
vulnerable module.

The persistent input validation vulnerabilities are located `New page title Add` and `Create a new META-description` 
input values of the 
`Improvement-Plan` module. Remote attacker are able to inject own persistent script codes by generating the 
search-engine-content list.
The attack vector is persistent on the application-side of the vulnerable service and the request method to inject the 
code is POST.

To exploit the persistent bugs the attacker needs to bypass with 2 different ways the validation of the meta tag and 
page titel input fields.

Page Title Input Bypass
In the first example method the attacker can use %20``> to split the request and closes the tag with < >.  All after 
the closed 
ending tag will execute the code. At the end the example should look like ... %20``>+[Random Context]+< >[PERSISTENT 
INJECTED SCRIPT CODE!]

Meta Tag Bypass
In the second example method the attacker needs to match the meta tag word validation by including any random word. 
After the random 
word he includes ><> to close the mask, then he opens with ``< a new (note: meta tags splitted with ,) and can execute 
after the ``<   ``> 
his own script code.  At the end the example should look like ... [Random Word as TAG], ><>``<   ``>< ``><[PERSISTENT 
INJECTED SCRIPT CODE!]<

The security risk of the persistent web vulnerability is estimated as medium with a cvss (common vulnerability scoring 
system) count of 4.3. 
Exploitation of the application-side web vulnerability requires a low privileged web-application user account but only 
low user interaction.
Successful exploitation of the vulnerabilities result in persistent phishing mails, session hijacking, persistent 
external redirect to malicious 
sources and application-side manipulation of affected or connected module context.

Request Method(s):
                                [+] POST

Vulnerable Service(s):
                                [+] Paypal Inc - GP+

Vulnerable Module(s):
                                [+] Improvement-Plan > Create a new page title

Vulnerable Parameter(s):
                                [+] New page title Add (name)
                                [+] Create a new META-description (tag)

Affected Module(s):
                                [+] Preview Improve Page - Listing
                                [+] Meta Tag - Listing


Proof of Concept (PoC):
=======================
The vulnerabilities can be exploited by remote attackers with low privileged application user account and low or medium 
required user interaction. For demonstration or reproduce ...

PoC:
%20">< >"<[PERSISTENT INJECTED SCRIPT CODE!]<
... or
PENTEST INJECTED SCRIPT CODE ><>"<">< "><[PERSISTENT INJECTED SCRIPT CODE!]<


Review: Preview improve page - Listing

Module:         Create a new page title > New page title Add
Affected:       Preview improve page - Listing

<div id="preview-seo-improvement-plan">
<div id="search-engine-content">
<a id="heading" href="#">a</a>
<p>%20">%20">><<<[PERSISTENT INJECTED SCRIPT CODE!]) <</iframe></p>
<a href="#">http://maja.com/impressum.php</a> - <span>in cache</span>
</div></div>



Review: Meta TAG - Listing

Module:         Create a new page title > Create a new META-description
Affected:       Meta TAG - Listing

<div id="notifier">
<p class="notifier-heading">Improve page <input id="page-number" name="page" value="0"> of 1</p>
<p class="notifier-text">Each page should have unique title and META description. Create a title that describes 
in a few words what can be found on this page. The META description is used in the search results. Describe in 1 
or 2 short sentences what this page is about.</p></div>

<div id="preview-seo-improvement-plan">
<div id="search-engine-content">
<a id="heading" href="#">MaJa - Ihr Partner in Fragen Webdesign, Webhosting, Webpromotion, Prasentationen...</a>
<p>hello, merlin, [PENTEST INJECTED SCRIPT CODE!]+ben><>"<   
">><>"<</iframe></p>
<a href="#">http://www.vulnerability-lab.com/[o_O]</a> - <span>in cache</span>
</div></div>


Reference(s):
                https://www.paypal-gpplus.com/en/dashboard/improvement-plan/2729702/step2/


Solution - Fix & Patch:
=======================
The vulnerability can be patched by parsing the web context of the Create a new META-description and New page title Add 
input fields.
Do not forget to seperate parse the vulnerable output listing of the vulnerable values to fix the issue.


Security Risk:
==============
The security risk of the persistent input validation vulnerabilities and filter bypass method are estimated as medium. 
(CVSS 4.3)


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


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