PayPal Inc Bug Bounty #117 - Session Fixation Vulnerability

[Vulnerability Lab <research@xxxxxxxxxxxxxxxxxxxxx>]

Document Title:
===============
PayPal Inc Bug Bounty #117 - Session Fixation Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1509

EIBBP-31983  (P2)

Video: http://www.vulnerability-lab.com/get_content.php?id=1615

Vulnerability Magazine: 
http://magazine.vulnerability-db.com/?q=articles/2015/10/09/paypal-inc-bug-bounty-117-filter-bypass-remote-session-fixation-vulnerability


Release Date:
=============
2015-10-09


Vulnerability Laboratory ID (VL-ID):
====================================
1509


Common Vulnerability Scoring System:
====================================
4.3


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.

(Copy of the Homepage: www.paypal.com) [http://en.wikipedia.org/wiki/PayPal]


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Core Research Team discovered a session fixation 
web Vulnerability in the official PayPal Inc (France) online service 
web-application.


Vulnerability Disclosure Timeline:
==================================
2015-06-06: Researcher Notification & Coordination (Hadji Samir - Evolution 
Security GmbH)
2015-06-08: Vendor Notification (PayPal Inc - Security & Bug Bounty Team)
2015-07-04: Vendor Response/Feedback (PayPal Inc - Security & Bug Bounty Team)
2015-09-30: Vendor Fix/Patch (PayPal Inc - Developer Team)
2015-10-08: Security Reward (PayPal Inc - Bug Bounty Team) [3.000$]
2015-10-09: Public Disclosure (Vulnerability Laboratory)


Discovery Status:
=================
Published


Affected Product(s):
====================
PayPal Inc
Product: PayPal - Online Service Web Application 2015 Q2


Exploitation Technique:
=======================
Remote


Severity Level:
===============
Medium


Technical Details & Description:
================================
A session fixation web vulnerability has been discovered in the official PayPal 
Inc online service web-application. 
The vulnerability allows remote attackers to manipulate user session 
information to takeover the data for malicious purpose.

Data enters a web application through an untrusted source, most frequently an 
HTTP request. The data is included in an HTTP response 
header sent to a web user without being validated for malicious characters. 
HTTP response splitting is a means to an end, not an end 
in itself. At its root, the attack is straightforward: an attacker passes 
malicious data to a vulnerable application, and the application 
includes the data in an HTTP response header. To mount a successful exploit, 
the application must allow input that contains CR (carriage 
return, also given by %0d or /r) characters into the header AND the underlying 
platform must be vulnerable to the injection of such characters. 
These characters not only give attackers control of the remaining headers and 
body of the response the application intends to send, but also 
allow them to create additional responses entirely under their control. On the 
french paypal webpage for instance there is a vulnerability where 
an attacker can copy and overwrite a victims session ID and use the false ID to 
perform actions like session manipulation and cookie compromise. 
The vulnerability can be exploited by a successful manipulated GET method 
request through the France paypal online service web-application.

The security risk of the unencrypted session fixation issue is estimated as 
medium with a cvss (common vulnerability scoring system) count of 4.3. 
Exploitation of the vulnerability requires no privilege web-application user 
account with low user interaction. Successful exploitation of the 
vulnerability results in manipulation of user session information and 
information disclosure.

Request Method(s):
                                [+] GET

Vulnerable Module(s):
                                [+] /cgi-bin/aao.com/  

Vulnerable Value(s):
                                [+] error page (redirect 302)


Proof of Concept (PoC):
=======================
The vulnerability can be exploited by attackers with restricted physical device 
access and without user interaction. 
For security demonstration or to reproduce the vulnerability follow the 
provided information and steps below to continue.

String Bypass: %0d

https://www.paypal.com/fr/cgi-bin///aao.com//%0dSet-Cookie:HaC80bwXscjqZ7KM6VOxULOB534=6RhGQapRfYgjamJv09KeTBVtJKw9oNcq8mnJDC_2H0t3denjeUdz8DnNpFn7iFUNVfPsPRu99_xUmvNcx_OaToy5En6pvysvcdCKmtdPawmYtupbEAVo4txChxNXlGdPmsWHB0;
 Domain=.paypal.com; Path=/;Expires=Mon, 08 Jun 2020 18:53:07 GMT; HttpOnly; 
Secure
Note: https://www.paypal.com/fr/cgi-bin///aao.com//    rerror page so will 
redirect to paypalproject.com > so any error page will redirect to paypalproject

Reference(s):
https://www.paypal.com/fr/cgi-bin/


Solution - Fix & Patch:
=======================
2015-09-30: Vendor Fix/Patch (PayPal Inc - Developer Team)


Security Risk:
==============
The security risk of the session fixation and filter bypass web vulnerability 
in the paypal framework is estimated as medium. (CVSS 4.3)


Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Hadji Samir 
(samir@xxxxxxxxxxxxxxxxx)  
[http://www.vulnerability-lab.com/show.php?user=Hadji%20Samir]


Disclaimer & Information:
=========================
The information provided in this advisory is provided as it is without any 
warranty. Vulnerability Lab disclaims all warranties, either expressed 
or implied, including the warranties of merchantability and capability for a 
particular purpose. Vulnerability-Lab or its suppliers are not liable 
in any case of damage, including direct, indirect, incidental, consequential 
loss of business profits or special damages, even if Vulnerability-Lab 
or its suppliers have been advised of the possibility of such damages. Some 
states do not allow the exclusion or limitation of liability for 
consequential or incidental damages so the foregoing limitation may not apply. 
We do not approve or encourage anybody to break any vendor licenses, 
policies, deface websites, hack into databases or trade with fraud/stolen 
material.

Domains:    www.vulnerability-lab.com           - www.vuln-lab.com              
                        - www.evolution-sec.com
Contact:    admin@xxxxxxxxxxxxxxxxxxxxx         - 
research@xxxxxxxxxxxxxxxxxxxxx                        - admin@xxxxxxxxxxxxxxxxx
Section:    magazine.vulnerability-db.com       - 
vulnerability-lab.com/contact.php                     - 
evolution-sec.com/contact
Social:     twitter.com/#!/vuln_lab             - facebook.com/VulnerabilityLab 
                        - youtube.com/user/vulnerability0lab
Feeds:      vulnerability-lab.com/rss/rss.php   - 
vulnerability-lab.com/rss/rss_upcoming.php            - 
vulnerability-lab.com/rss/rss_news.php
Programs:   vulnerability-lab.com/submit.php    - 
vulnerability-lab.com/list-of-bug-bounty-programs.php - 
vulnerability-lab.com/register/

Any modified copy or reproduction, including partially usages, of this file 
requires authorization from Vulnerability Laboratory. Permission to 
electronically redistribute this alert in its unmodified form is granted. All 
other rights, including the use of other media, are reserved by 
Vulnerability-Lab Research Team or its suppliers. All pictures, texts, 
advisories, source code, videos and other information on this website 
is trademark of vulnerability-lab team & the specific authors or managers. To 
record, list (feed), modify, use or edit our material contact 
(admin@xxxxxxxxxxxxxxxxxxxxx or research@xxxxxxxxxxxxxxxxxxxxx) to get a 
permission.

                                Copyright © 2015 | Vulnerability Laboratory - 
[Evolution Security GmbH]™



-- 
VULNERABILITY LABORATORY - RESEARCH TEAM
SERVICE: www.vulnerability-lab.com
CONTACT: research@xxxxxxxxxxxxxxxxxxxxx
PGP KEY: 
http://www.vulnerability-lab.com/keys/admin@xxxxxxxxxxxxxxxxxxxxx%280x198E9928%29.txt