SevDesk v1.1 iOS - Persistent Dashboard Vulnerability

[Vulnerability Lab <research@xxxxxxxxxxxxxxxxxxxxx>]

Document Title:
===============
SevDesk v1.1 iOS - Persistent Dashboard Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1311


Release Date:
=============
2015-04-23


Vulnerability Laboratory ID (VL-ID):
====================================
1311


Common Vulnerability Scoring System:
====================================
4.2


Product & Service Introduction:
===============================
Official app for mobile use of sevDesk. A product of SEVENIT GmbH. 

Daily Backup
256bit SSL encryption
TÜV certified data center

Free version
No hidden costs
No minimum contract term

iPhone App
Runs in any browser
No installation required on the PC

Easy to use
Reduced to the essentials
Automated, where it is only possible

(Copy of the Vendor Homepage: https://sevdesk.de/ )


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Research Team discovered multiple vulnerabilities 
in the official SEVENIT GmbH SevDesk mobile application (api).


Vulnerability Disclosure Timeline:
==================================
2014-09-01:     Researcher Notification & Coordination (Benjamin Kunz Mejri)
2014-09-02:     Vendor Notification (SevDesk Developer Team)
2015-04-23:     Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
SevenIT
Product: SevDesk - iOS Mobile Web Application (API) 1.1


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


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


Technical Details & Description:
================================
A persistent input validation web vulnerability has been discovered in the 
official SEVENIT Software GmbH sevDesk v1.1 iOS mobile web-application (api).
The vulnerability allows remote attackers or low privileged user account to 
inject own malicious script codes to the application-side of the vulnerable 
web-application module or service.

The security vulnerability is located in the `firstname` values of the main 
sevDesk `Dasboard` application module & api. Remote attackers are able to 
inject 
own script codes to the mobile dashboard through the api by manipulation of the 
registration information in the client.

The execution of the script code occurs after the inject on the 
application-side in the main mobile dashboard status list. If the test user 
account apply for 
any changes in the account profile the activity becomes visible. In the context 
were the information and details becomes visible is the location were the 
execution of the persistent injected script code takes place. The attack vector 
is persistent and the request method to inject the code is POST. 

The security risk of the persistent script code inject web vulnerability is 
estimated as medium with a cvss (common vulnerability scoring system) count of 
4.2. 
Exploitation of the persistent input validation web vulnerability requires a 
low privileged sevdesk user account with restricted access and low user 
interaction. 
Successful exploitation of the vulnerability results in session hijacking, 
persistent phishing, persistent external redirects to malicious source and 
persistent 
manipulation of affected or connected application modules (api).

Request Method(s):
                                [+] POST

Vulnerable Application(s):
                                [+] sevDesk v1.1 iOS

Vulnerable Module(s):
                                [+] Registration to SevDesk

Vulnerable Parameter(s):
                                [+] firstname (display name)

Affected Module(s):
                                [+] Dasboard Index Status List


Proof of Concept (PoC):
=======================
The persistent input validation web vulnerability can be exploited by remote 
attackers with low privileged application user account and low user interaction.
For security demonstration or to reproduce the security vulnerability follow 
the provided information and steps below to continue.

1. Install the application to your iOS device (ipad iphone)
2. Register an new account 
3. Include as name value your own malicious script code payload
4. Save the settings and open the Dasboard status listing
Note: After the save the context gets discplayed by the mobile app api through 
the web database
5. The script code execution occurs in the main status messages
6. Successful reproduce of the security vulnerability in the mobile iOS 
application!


Picture(s):
                        ../1.png
                        ../2.png
                        ../3.png


Solution - Fix & Patch:
=======================
The issue can be patched by a secure parse and encode of the user credentials 
on registration through the mobile application api.
Restrict the user input to register and parse also the status listing in the 
main dasboard which becomes visible after the malicious changes.


Security Risk:
==============
The security risk of the persistent mobile web vulnerability in the api is 
estimated as medium. (CVSS 4.2)


Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri 
(bkm@xxxxxxxxxxxxxxxxx) [www.vulnerability-lab.com]


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