SevDesk 1.1 Persistent Script Insertion

`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 ([email protected]) [www.vulnerability-lab.com]  
  
  
Disclaimer & Information:  
=========================  
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