Deutsche Bahn Ticket Vending Machine Local Kiosk – Privilege Escalation

Exploit Database
124 阅读

作者： Vulnerability-Lab

日期： 2019-12-19
类别：
- webapps
平台：
- hardware
来源：https://www.exploit-db.com/exploits/47796/

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# Exploit Title: Deutsche Bahn Ticket Vending Machine Local Kiosk - Privilege Escalation

# Date: 2019-12-18

# Exploit Author: Vulnerability-Lab

# Vendor Homepage: https://www.bahn.de/db_vertrieb/view/leistungen/automaten-fahrkartenentwerter.shtml

# Tested on: Windows XP

Document Title:

===============

Deutsche Bahn Ticket Vending Machine- Local Kiosk Privilege Escalation Vulnerability

References (Source):

====================

https://www.vulnerability-lab.com/get_content.php?id=2191

Vulnerability Magazine:

https://www.vulnerability-db.com/?q=articles/2019/12/13/zero-day-vulnerability-deutsche-bahn-ticket-machine-series-system-uncovered

Release Date:

=============

2019-12-14

Vulnerability Laboratory ID (VL-ID):

====================================

2191

Common Vulnerability Scoring System:

====================================

6.4

Vulnerability Class:

====================

Privilege Escalation

Product & Service Introduction:

===============================

Customers can buy tickets at our ticket machines at any time, regardless

of opening hours. Thus, the vending machine also

secures sales in rural areas.

- innovatively designed user guidance

- Real-time timetable information for rail traffic

- traveler information

- ticket paper supply

- free fault hotline: 0800 2886644

- Professional and contemporary maintenance

The ticket vending machine can also be configured according to

individual requirements. The housing can be designed as desired.

Customers can purchase their tickets with different means of payment.

User guidance is available in different languages.

(Copy of the Homepage:

https://www.bahn.de/db_vertrieb/view/leistungen/automaten-fahrkartenentwerter.shtml

)

Abstract Advisory Information:

==============================

The vulnerability laboratory core research team discovered a local kiosk

privilege escalation vulnerability in the deutsche bahn ticket vending

machine series with windows xp.

Vulnerability Disclosure Timeline:

==================================

2019-12-14: Public Disclosure (Vulnerability Laboratory)

Discovery Status:

=================

Published

Exploitation Technique:

=======================

Local

Severity Level:

===============

Medium

Authentication Type:

====================

No authentication (guest)

User Interaction:

=================

No User Interaction

Disclosure Type:

================

Responsible Disclosure Program

Technical Details & Description:

================================

A kiosk mode escalation vulnerability has been discovered in the

official deutsche bahn ticket vending machine series for windows.

The security vulnerability allows local attackers to bypass the kiosk

mode to compromise the local file system and applications.

It is possible for local attackers to break out of the kiosk mode of the

Deutsche Bahn vending machine application if

the Password Agent (PasswordAgent.exe) of the system receives a timeout

or has a runtime error in the program

itself in the background. These errors can occur due to aborted

sessions, unclean logout or common errors when

using the application at system level.

In the event of a local error, attackers can bring the error message to

the foreground by pressing the number field - Cancel

during a transaction. After the error message becomes visible, the

attacker can click on a link of the error message where you

can normally see what the error report contains. The attacker will then

be redirected to a form in the error message, where he

can search for errors in a collection of microsoft articles via "Submit

/ Dont' Submit" or another link on the online path. There

the attacker clicks on it and receives the web browser. From the web

browser, the attacker retrieves the options menu and can access

the local system directory and has then the ability to compromise the

ticket vending machine with windows xp.

The error message is normally on those devices deactivated through a

hardening process of the servce provider. In that special case

the exception handling of windows was not deactivated or set to the

background, which allows the attacker to move through to other

options to finally access the file system via browser.

The ticket vending machine vulnerability requires no user interaction

and can only be exploited by local attackers with physical

device access. No keyboard or front loader opening required.

Vulnerable System(s):

[+] Windows XP

Affected Component(s):

[+] Exception Handling (Error Message Content)

Proof of Concept (PoC):

=======================

The local vulnerability can be exploited by local attackers with

physical device access without user interaction.

For security demonstration or to reproduce the vulnerability follow the

provided information and steps below to continue.

PoC: Sheet

PasswordAgent.exe := Unexpected Error (Background) - Runtime/Session/Timeout

=> Transaction Application => Cancel := Unexpected Error (Background) -

Runtime/Session/Timeout (Front)

=> Click Error Report => Click Search Collection => Web Browser => Local

File System => PWND!

What are attackers able to do when the file system of the vending

machine is accessable thus way?

1. Inject of local malware to the ticket machine (editor / debugger /

cmd / ps - exp. ransomware/malware)

2. Local manipulation for skimming devices to assist (transmit prepares)

2. Phishing of local credentials from screen via system (db browser

application)

3. Intercept or manipulation to access card information (local file

system - sniff/extract)

4. Crash or freeze the computer system (exp. kill of process / loop script)

5. Scare or joké activities (exp. html / js to front screens with web

browser or by a new window process)

Refernece(s):

https://www.vulnerability-db.com/sites/default/files//newscenter-gallery/IMG_6457.JPG

https://www.vulnerability-db.com/sites/default/files//newscenter-gallery/IMG_6458.JPG

https://www.vulnerability-db.com/sites/default/files//newscenter-gallery/IMG_6460.JPG

Solution - Fix & Patch:

=======================

There are now several problems related to system hardening that can be

resolved:

1. It should not be possible for users with system user rights to use

the web browsers

2. The error message menu can be deactivated or completely modified

3. Some functions in menus can be deactivated by hardening (browser,

messages & Co.)

4. Check that all other tasks are always running in the background or

are being moved there permanently

5. The deutsche bahn vending machine application and user interface

should be shut down in the event of persistent errors in the foreground

6. The activities of the testing has been logged but did not triggered

any alert for defense purpose

Deutsche Bahn: Patch Rollout in Progress

https://www.vulnerability-db.com/sites/default/files//newscenter-gallery/073915298_0.png

https://www.vulnerability-db.com/sites/default/files//newscenter-gallery/dbatm78235.png

Security Risk:

==============

The security risk of the local ticket vending machine system

vulnerability is estimated as high.The bug to escalate can be easily

exploited by local interaction with the touch display to access the file

system.

Credits & Authors:

==================

Benjamin K.M. -

https://www.vulnerability-lab.com/show.php?user=Benjamin+K.M.

Disclaimer & Information:

=========================

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