Paypal Bug Bounty #31 - Mail Encoding Web Vulnerability

Type vulnerlab
Reporter Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (
Modified 2013-04-03T00:00:00


                                            Document Title:
Paypal Bug Bounty #31 - Mail Encoding Web Vulnerability

References (Source):

PayPal Security UID:  erc849qoz

Release Date:

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 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: []

Abstract Advisory Information:
The Vulnerability Laboratory Research Team discovered a persistent web vulnerability in the official PayPal Community Forum website application.

Vulnerability Disclosure Timeline:
2012-09-23:	Researcher Notification & Coordination
2012-09-25:	Vendor Notification
2012-10-01:	Vendor Response/Feedback
2013-03-26:	Vendor Fix/Patch
2012-04-04:	Public Disclosure

Discovery Status:

Affected Product(s):
PayPal Inc
Product: Community (Forums) 2012 Q3

Exploitation Technique:

Severity Level:

Technical Details & Description:
A persistent web vulnerabilities is detected in the official PayPal Community Forum website application.

The vulnerability is located in the not secure parsed Problem Reporter module when processing to request 
a manipulated message body or title parameter. The vulnerability affects the outgoing forum.paypal mail 
service of the community and allows the execution of persistent script code. 

Successful exploitation of the vulnerabilities result in persistent phishing mails, persistent session 
hijacking attacks and persistent mail web context manipulation via paypal.

Vulnerable Section(s):
				[+] PayPal Community (Forum) - Problem Reporter
Vulnerable Module(s):
				[+] Problem Reporter of the Community & Forum
Vulnerable Parameter(s):
				[+] Message Body & Title
Affected Module(s):
				[+] Notification Mail - Forum Administrator

Proof of Concept (PoC):
The persistent vulnerability can be exploited by remote attacker without privileged user account & with low or medium 
required user interaction. For demonstration or reproduce ...

Review:  Notification Mail - Message Body & Title

ID: (KMM65736123V9119L0KM) :ppk1


Solution - Fix & Patch:
The vulnerability can be patched by parsing the vulnerable message values.
Parse the outgoing mails message body & title or maybe the full template with all later available values.

2013-03-26:	Vendor Fix/Patch by PayPal Inc

Security Risk:
The security risk of the two persistent input validation vulnerability is estimated as high(-).
The vulnerability did not affect the user or customer it affects directly the forum admin or moderators.

Credits & Authors:
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (

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