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PayPal Inc Bug Bounty #65 China - Redirect Web Vulnerability
From: Vulnerability Lab <research () vulnerability-lab com>
Date: Tue, 19 Nov 2013 04:19:28 +0100
PayPal Inc Bug Bounty #65 China - Redirect Web Vulnerability
PayPal Security UID: rdbeeur
Vulnerability Laboratory ID (VL-ID):
Common Vulnerability Scoring System:
Product & Service Introduction:
PayPal is a global e-commerce business allowing payments and money transfers to be made through the Internet. Online
transfers serve as electronic alternatives to paying with traditional paper methods, such as checks and money orders.
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
spending limit. After that point, PayPal will attempt to take funds for a purchase from funding sources according to a
funding hierarchy. If you set one of the funding sources as Primary, it will default to that, within that level of the
(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
PayPal credit account, PayPal Extras, PayPal SmartConnect, PayPal Extras Master Card or Bill Me Later (if selected as
funding source) (It can bypass the Balance); a verified bank account; other funding sources, such as non-PayPal credit
The recipient of a PayPal transfer can either request a check from PayPal, establish their own PayPal deposit account
a transfer to their bank account.
PayPal is an acquirer, performing payment processing for online vendors, auction sites, and other commercial users, for
charges a fee. It may also charge a fee for receiving money, proportional to the amount received. The fees depend on
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
On October 3, 2002, PayPal became a wholly owned subsidiary of eBay. Its corporate headquarters are in San Jose,
States at eBay s North First Street satellite office campus. The company also has significant operations in Omaha,
Arizona, and Austin, Texas, in the United States, Chennai, Dublin, Kleinmachnow (near Berlin) and Tel Aviv. As of July
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
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
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 redirect web vulnerability in the official chinese (CN) PayPal
Inc web application service.
Vulnerability Disclosure Timeline:
2013-02-03: Researcher Notification & Coordination (中国隐形步行者 -
2013-02-06: Vendor Notification (PayPal Site Security Team - Bug Bounty Program)
2013-05-01: Vendor Response/Feedback (PayPal Site Security Team - Bug Bounty Program)
2013-11-01: Vendor Fix/Patch (PayPal Developer Team)
2013-11-17: Public Disclosure (Vulnerability Laboratory)
Product: [CN] (PP) Web Application - Core 2013 Q1
Technical Details & Description:
A low severity and client-side redirect web vulnerability is detected in the official chinese (CN) PayPal Inc web
The vulnerability allows remote attackers to form malicious links as client-side GET method requests to manipulate a
The vulnerability is located in the login (php) module of the GET method request to the return link `go` parameter.
Remote Attackers can
manipulate the client-side GET method request to redirect the victim via mouse-over to an external malicious
source/website. The issue
is only visible by using the mouse-over a link to open to run the client-side script code. A direct inject via
document.cookie in the go
parameter by not using the echo link is not possible. The security risk of the non-persistent web vulnerability
in the ref go value is estimated as medium with a cvss (common vulnerability scoring system) count of 1.5(+).
The vulnerability can be exploited by remote attackers without privileged application user account and with medium
required user interaction.
Successful exploitation results in client side cross site scripting, client-side session hijacking, client side
phishing or malicious redirects
to external targets/sources.
[+] Login (login.php)
[+] PayPal ReturnTo Button and Login Link
Proof of Concept (PoC):
The client-side vulnerability can be exploited by remote attackers without privileged web-application user account and
required user interaction. For security demonstration or to reproduce the vulnerability follow the information below ...
PoC: Generated Button via ?go= Referer
<a href="####" id="PP_login_btn"><img src="https://www.paypal-biz.com/club/pplogin/login-with-paypal-button.png"
id="PPA_login_button" style="cursor:pointer;display:block;" alt="Log in with PayPal Access"></a>
https://www.paypal-biz.com/[CLUB SERVICE]/[LOGIN]?(GO REF)=[PATH OR URL]
https://www.paypal-biz.com/club/login.php?go=<a href=http://vuln-lab.com>www.vulnerability-lab.com</a><div style="1
After including your context to the go parameter and reloading the wesbite, the link will be directly connected to the
button in the website. By including for example html+js context with a external redirect when processing to mouse-overs
or a hover the button it is possible to redirect. To reproduce you need a tamper tool to manipulate the session live.
Solution - Fix & Patch:
The client side open redirect web vulnerability can be patched by a restriction and parse of the vulnerable go value in
the ref link.
The security risk of the client-side open redirect web vulnerability is estimated as low(+).
Credits & Authors:
Vulnerability Laboratory [Research Team] - 中国隐形步行者 -
中国精英 (CNNVD) < = >[www.vulnerability-lab.com]
Disclaimer & Information:
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may not apply. We do not approve or encourage anybody to break any vendor licenses, policies, deface websites, hack
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- PayPal Inc Bug Bounty #65 China - Redirect Web Vulnerability Vulnerability Lab (Nov 19)