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List: full-disclosure
Subject: [Full-disclosure] Paypal Bug Bounty #27 - Community Web Vulnerability
From: Vulnerability Lab <research () vulnerability-lab ! com>
Date: 2012-11-28 1:58:34
Message-ID: 50B56FCA.4080106 () vulnerability-lab ! com
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Title:
======
Paypal Bug Bounty #27 - Community Web Vulnerability
Date:
=====
2012-11-24
References:
===========
http://www.vulnerability-lab.com/get_content.php?id=704
VL-ID:
=====
704
Common Vulnerability Scoring System:
====================================
2.1
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:
=========
The Vulnerability Laboratory Research Team discovered a a client side Web Vulnerability and a \
stable error in the official Paypal Community Forum Portal.
Report-Timeline:
================
2012-09-17: Researcher Notification & Coordination
2012-09-18: Vendor Notification
2012-10-19: Vendor Response/Feedback
2012-10-29: Vendor Fix/Patch
2012-11-26: Public Disclosure
Status:
========
Published
Exploitation-Technique:
=======================
Remote
Severity:
=========
Medium
Details:
========
A client side input validation vulnerability and a stable persistent error are detected in the \
official PayPal Community website. The vulnerability is located in the add tags function and \
the bound replace module.attackers can produce posts with permanent errors bye replacing a \
standard value string with > `` < ../ and a string code or path to an existing url. Normally \
it should not be possible to inject script code as foldername and replace it with more script \
code to crash with an unhandled exception. Attackers can inject on client side when the \
exception-handling is bypassed via another validation vulnerability.
Vulnerable Module(s):
[+] add tags
Vulnerable Parameter(s):
[+] rc
Proof of Concept:
=================
The vulnerability can be exploited by remote attackers with medium or high required user inter \
action. For demonstration or reproduce ...
POC:
https://www.paypal-community.com/t5/forums/tagreplacepage/message-scope/core-node/board-id/US-Hot-Topics/user-scope/single/
user-id/4716070/tag-scope/single/tag-id/rc=a%20onload=alert%28%22VL%22%29%20%3C%20%22%3E%3Ciframe%20src=a
%20onload=alert%28%22VL%22%29%20%3Cc%20%22%3E%3C
iframe%20src=a%20onload=alert%28%22VL%22%29%20%3C%20%22%3E%3Ciframe%20src=a%20onload=alert%28%22VL
%22%29%20%3C/timerange/all/tag-visibility-scope/public
--- Error Logs ---
An Unexpected Error has occurred.
Sorry, your request failed. A notification has been sent to the development team for \
investigation. Exception ID: 724C64A6
Please click the Back button on your browser.
Return to my original page
ID: 724C64A6
Session Time: 15:30 - 15:51
Reference(s):
../US-Hot-Topics.htm
../public.html
../all.htm
../424675.htm
Note:
The bug exists but the exception-handling prevents the client side execution with a unhandled \
error and opened automatically a ticket for the dev team. It is very dangerous to allow \
special chars like > " < / ' - in the url itself because it results in multiple different \
errors after a while like you can see on the not sanitized calculated output.
Solution:
=========
The vulnerability and stable error can be patched by parsing the rc parameter request.
It also required to restrict the add tag function with a character mask, own exception-handling \
or filter. The result is the url with not anymore stable contain manipulate script code which \
results in permanent errors or client side script code attacks.
2012-10-29: Vendor Fix/Patch
Risk:
=====
The security risk of the non persistent input validation web vulnerability is estimated as \
low(+)|(-)medium.
Credits:
========
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (bkm@vulnerability-lab.com)
Disclaimer:
===========
The information provided in this advisory is provided as it is without any warranty. \
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Copyright © 2012 | Vulnerability Laboratory
--
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