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Paypal Bug Bounty #14 - Persistent Payment Mail Encoding Vulnerability
From: Vulnerability Lab <research () vulnerability-lab com>
Date: Wed, 20 Nov 2013 05:08:31 +0100
Paypal Inc BB #14 - Persistent Payment Mail Vulnerability
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.
(Copy of the Homepage: www.paypal.com) [http://en.wikipedia.org/wiki/PayPal]
Abstract Advisory Information:
The Vulnerability Laboratory Research Team discovered a Web Vulnerability in the official Paypal ecommerce website
Vulnerability Disclosure Timeline:
2012-07-07: Researcher Notification & Coordination (Benjamin Kunz Mejri)
2012-07-10: Vendor Notification (PayPal Site Security Team - Bug Bounty Program)
2013-03-07: Vendor Response/Feedback (PayPal Site Security Team - Bug Bounty Program)
2012-11-01: Vendor Fix/Patch (PayPal Inc Developer Team - Bug Bounty Reward $$$)
2012-11-20: Public Disclosure (Vulnerability Laboratory)
Technical Details & Description:
A persistent input validation vulnerability has been discovered in the official Paypal Inc website content management
system & API.
The bug allows remote attackers to inject own malicious script codes to the application-side of the paypal
The vulnerability is located in the vulnerable `From` value of the Unclaimed Payments > Phone Payments (unconfirmed
phone numbers) module.
The script code execute occurs in the important `Phone Payments` request list of the verify a receiver via phonenumber
The security risk of the persistent web vulnerabilities in the payments module is estimated as high with a cvss (common
scoring system) count of 5.1(+)|(-)5.2.
The vulnerability can be exploited by remote attackers with low user inter action and low privileged paypal
Successful exploitation of the vulnerability results in session hijacking (customers), account steal via persistent
persistent phishing or persistent manipulation of module- or connected module context.
[+] Customer/Pro/Seller Accounts
[+] Unclaimed Payments
[+] Phone Payments
Proof of Concept (PoC):
The persistent input validation web vulnerability can be exploited by remote attackers with low privileged paypal
& low user inter action. For security demonstration or to reproduce the vulnerability follow the provided information
PoC: Money Request Mail Notification
<tbody><tr class="tableRowLightBlue"><td class="tableCellRegularSmall" colspan="2"><span class="emphasis">
To</span></td><td> <span class="emphasis">From</span></td><td class="tableCellRegularSmall"><span class="emphasis">
Amount</span> </td><td class="tableCellRegularSmall"> <span class="emphasis">Date Sent</span></td>
<td class="tableCellRegularSmall"> <span class="emphasis">Status</span></td></tr><tr><td class="tableCellRegularSmall">
<input name="phone_id" value="YbLGqPsRLZzdGAWnePuHErCuqMFSQXIxVdN33JaVMbXUnWvlp5_5H7Ju8R6LaZplCo7kApCTs3TNf0ol"
</td><td class="tableCellRegularSmall"> 408-678-0945</td><td class="tableCellRegularSmall"> Danh Nguyen's Test
<td class="tableCellRegularSmall">$1333337.00 USD </td><td class="tableCellRegularSmall"> Dec 3, 2010</td>
<td class="tableCellRegularSmall"> Pending</td></tr><tr><td class="tableCellRegularSmall">
<input name="phone_id" value="32vLCA4HtsQRr2cQEYpHcCf5wYT0V0kKrp4JnOSqkl78hb2qEUj3A8WvEssI1RqiRTyx3VM8chWSogB0"
<td class="tableCellRegularSmall"> 408-983-5678</td>
<td class="tableCellRegularSmall"> "><[PERSISTENT INJECTED SCRIPT CODE!]"> <</td><td
class="tableCellRegularSmall">$50.00 USD </td><td
POC URL1: https://www.paypal.com/us/cgi-bin/webscr?cmd=_unconfirmed-payments
POC URL2: https://www.sandbox.paypal.com/us/cgi-bin/webscr?cmd=_unconfirmed-payments
Solution - Fix & Patch:
The vulnerability can be patched by a secure encode and parse of the vulnerable From (phone_id) application value.
Step 1: Encode and restrict the vulnerable input fields
Step 2: Parse & filter the stored context when processing to reload as affected output
The security risk of the persistent script code inject vulnerability is estimated as high(-).
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.
Lab or its suppliers are not liable in any case of damage, including direct, indirect, incidental, consequential loss
profits or special damages, even if Vulnerability-Lab or its suppliers have been advised of the possibility of such
states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing
may not apply. We do not approve or encourage anybody to break any vendor licenses, policies, deface websites, hack
or trade with fraud/stolen material.
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- Paypal Bug Bounty #14 - Persistent Payment Mail Encoding Vulnerability Vulnerability Lab (Nov 20)