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PayPal Inc Bug Bounty #61 - Persistent Mail Encoding Vulnerability
From: Vulnerability Lab <research () vulnerability-lab com>
Date: Thu, 17 Oct 2013 14:07:41 +0200
PayPal Inc Bug Bounty #61 - Persistent Mail Encoding Vulnerability
PayPal Security UID: bzbe1he
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 Vendor Homepage: www.paypal.com) [http://en.wikipedia.org/wiki/PayPal]
Abstract Advisory Information:
The Vulnerability Laboratory Research Team discovered in the official PayPal Inc (Ebay) MainStreet finance service
Vulnerability Disclosure Timeline:
2013-01-28: Researcher Notification & Coordination (Benjamin Kunz Mejri)
2013-01-31: Vendor Notification (PayPal Site Security Team - Bug Bounty Program)
2013-10-12: Vendor Response/Feedback (PayPal Site Security Team - Bug Bounty Program)
2013-10-15: Vendor Fix/Patch (PayPal Developer Team)
2013-10-16: Public Disclosure (Vulnerability Laboratory)
Product: MainStreet - Ebay Paypal Marketing Service 2013 Q1
Technical Details & Description:
A persistent mail encoding web vulnerability is detected in the official PayPal Inc (Ebay) MainStreet Finance Service
The vulnerability allows to send via POST method malicious mails to customers with own injected persistent script code.
The persistent input validation mail encoding vulnerability is located in the paypal mainstreet service application.
can inject malicious script codes via POST method request in the profile name value. The remote attacker can send the
request with the `Send to Friends` function to exploit paypal customer accounts. The script code executes in the mail
response of the
feedback and send to friends function.
Exploitation of the vulnerability requires no privileged application user account and low or medium user interaction.
Successful exploitation of the vulnerability results in persistent phishing , persistent session hijacking and
mail context manipulation.
[+] PayPal Inc - MainStreet (also Ebay)
[+] Send to Friends
[+] Name (Sender: Friend)
[+] Notification Mail (Web Server) [DL-BML-MerchantPortalFeedback () ebay com]
Proof of Concept (PoC):
The vulnerability can be exploited by remote attackers with low privileged application user account and low or medium
required user interaction.
For demonstration or reproduce ...
Review: x has forwarded a page to you from eBay Inc. PayPal Main Street
<h1 style="font-family:Arial,Helvetica,sans-serif; font-size:18px;">
<a href="http://www.ebaymainstreet.com/forward/emailref?path=%3Cfront%3E" title="eBay Inc. Main Street"><img
src="http://www.ebaymainstreet.com/sites/default/files/ebay_mainstreet_logo.png" alt=""> eBay Inc. Main Street</a></h1>
<td style="font-family:Arial,Helvetica,sans-serif; font-size:12px;">
<a href="mailto:01x445 () gmail com">>"<>;%20%20%20%20>
"<[PERSISTENT INJECTED SCRIPT CODE!])<" <="" a=""> thought you would like to see this page from the eBay Inc. Main
Street web site.
<p>Message from Sender</p><p><my message :O)<</p>
The security risk of the persistent mail encoding input validation web vulnerability is estimated as medium(+).
Credits & Authors:
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (bkm () vulnerability-lab com)
Disclaimer & Information:
The information provided in this advisory is provided as it is without any warranty. Vulnerability Lab disclaims all
either expressed or implied, including the warranties of merchantability and capability for a particular purpose.
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