Title: ====== PayPal Bug Bounty #45 BillSafe - Remote Auth Bypass Session Web Vulnerability Date: ===== 2013-04-30 References: =========== http://www.vulnerability-lab.com/get_content.php?id=804 http://www.vulnerability-lab.com/dev/?p=665 PayPal Security UID: og1eb1mgi PayPal Inc Bug Bounty: 5000$ (USD) VL-ID: ===== 804 Common Vulnerability Scoring System: ==================================== 8.6 Introduction: ============= Als spezialisierte Factoringgesellschaft für die Abwicklung von Rechnungskauf-Zahlungen im Internet wurde die BillSAFE GmbH 2008 durch die Altgesellschafter der mediafinanz AG gegründet. Das Management der BillSAFE GmbH besteht ausnahmslos aus Risikomanagement-Experten mit jahrelanger Erfahrung aus der Betreuung von namhaften Online-Shops und Versandhandelsunternehmen. 2009 erfolgte die reguläre Inbetriebnahme des Services mit der Anbindung der ersten 100 Online-Shops. 2010 beteiligte sich die eBay Tochter PayPal im Rahmen einer strategischen Partnerschaft an der BillSAFE GmbH. 2011 wurde ein neuer Unternehmensstandort auf dem eBay Campus in Berlin Dreilinden eröffnet, um die enge operative Zusammenarbeit mit PayPal weiter zu intensivieren. Seit Dezember 2011 ist die BillSAFE GmbH ein 100%iges PayPal Unternehmen und Teil der eBay Firmengruppe. Die von BillSAFE angebotenen Produkte bündeln die Erfahrung aus der Abwicklung von mehreren hundert Millionen E-Commerce Transaktionen durch PayPal mit der Expertise in der Bearbeitung von mehreren Millionen Inkassofällen durch die mediafinanz AG. (Copy of the Vendor Homepage: http://www.billsafe.de/company/about ) Abstract: ========= The Vulnerabilitly Laboratory Research Team discovered a auth bypass vulnerability in Paypals Billsafe online payment service web application. Report-Timeline: ================ 2013-01-27: Researcher Notification & Coordination 2013-01-28: Vendor Notification 2013-02-12: Vendor Response/Feedback 2013-04-03: Vendor Fix/Patch 2013-04-30: Public Disclosure Status: ======== Published Affected Products: ================== PayPal Inc Product: BillSafe - Online Payment Service 2013 Q1 Exploitation-Technique: ======================= Remote Severity: ========= Critical Details: ======== A auth bypass web session vulnerability is detected in Paypals Billsafe online payment service web application. The vulnerability typus allows an attacker to bypass the first login user session auth and change passwords and emails of billsafe web application accounts. The application is processing to request after a account activation plain passwords without any kind of token protection mechanism. The vulnerability is located in the first login section of the billsafe website when processing to load (after the activation) manipulated user/email/pass context. Remote attackers can manipulate accounts by live tampering the activation session link request. When the remote attacker is tampering the session live, he only needs to exchange the plain requested values (name/email/pass) with the earlier valid requested values. After changing the vulnerable values the attacker only needs to send the same request again to reset any billsafe client application account. Exploitation of the vulnerability requires no privileged application user account and no user interaction. Successful exploitation of the vulnerability results in account compromise, account manipulation and account theaft. Vulnerable Service(s): [+] PayPal Inc - BillSafe Vulnerable Module(s): [+] Account - First Login Vulnerable Parameter(s): [+] eMail [+] password Affected Module(s): [+] Account System Proof of Concept: ================= The auth bypass vulnerability can be exploited by remote attackers without required user interaction or privileged application user account. For demonstration or reproduce ... Requirement(s): [+] Browser (Mozilla) [+] Tamper Data - Addon [+] A secound valid registration session change values Registration(s): http://client.billsafe.de/login/register/id/aa3a863357fe6acb0fe16f7cce1a46d135235 Host=client.billsafe.de User-Agent=Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20100101 Firefox/17.0 Accept=text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language=de-de,de;q=0.8,en-us;q=0.5,en;q=0.3 Accept-Encoding=gzip, deflate DNT=1 Connection=keep-alive Referer=http://client.billsafe.de/login/first-login/ Cookie=__utma=22145316.759281629.1356643963.1356643963.1356653145.2; __utmc=22145316; __utmz=22145316.1356643963.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=billsafe%20paypal; PHPSESSID=mdkgkm8j91n4d57hdl8c9bjqo6; __utmb=22145316.96.9.1356654870355 Cache-Control=max-age=0 Content-Type=application/x-www-form-urlencoded Content-Length=92 POSTDATA=clientId=35235&password=benjamin337&email=bkm%40vulnerability-lab.com&integration=prepared Reference(s): http://client.billsafe.de/login/first-login/ Manually steps to reproduce ... 1. Start your web browser and open up the billsafe website 2. Register an user account via the main registration form 3. Go to your postbox and copy the link with the session 4. Open the browser, start tamper data and load the request (mail link) of the login register id 5. The tamper will show you the plain context which can be changed to your own values 6. Hold the request and change the values to your own new email account or password 7. Reload the page, change to your own new password, load the mail 8. Registration successful. You can now login with the account details of any other user. Solution: ========= 2013-04-03: Vendor Fix/Patch by PayPal Inc coordinated via the PayPal Site Security Team Coordination: Security Case Manager (Jack) Risk: ===== The security risk of the auth bypass session web vulnerability is estimated as critical. 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. 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. 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