PDF Converter & Editor 2.1 iOS - File Include Vulnerability

[Vulnerability Lab <research () vulnerability-lab com>]

Document Title:
===============
PDF Converter & Editor 2.1 iOS - File Include Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1480


Release Date:
=============
2015-05-06


Vulnerability Laboratory ID (VL-ID):
====================================
1480


Common Vulnerability Scoring System:
====================================
6.9


Product & Service Introduction:
===============================
Text Editor & PDF Creator is your all-in-one document management solution for iPhone, iPod touch and iPad.
It can catch documents from PC or Mac via USB cable or WIFI, email attachments, Dropbox and box and save 
it on your iPhone, iPod Touch or iPad locally.

(Copy of the Vendor Homepage: https://itunes.apple.com/it/app/text-editor-pdf-creator/id639156936 )


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Core Research Team discovered file include web vulnerability in the official AppzCreative 
- PDF Converter & Text Editor v2.1 iOS mobile web-application.


Vulnerability Disclosure Timeline:
==================================
2015-05-06:     Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
AppzCreative Ltd
Product: PDF Converter & Text Editor - iOS Web Application (Wifi) 2.1


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


Severity Level:
===============
High


Technical Details & Description:
================================
A local file include web vulnerability has been discovered in the official AppzCreative - PDF Converter & Text Editor 
v2.1 iOS mobile web-application.
The local file include web vulnerability allows remote attackers to unauthorized include local file/path requests or 
system specific path commands 
to compromise the mobile web-application.

The web vulnerability is located in the `filename` value of the `submit upload` module. Remote attackers are able to 
inject own files with malicious 
`filename` values in the `file upload` POST method request to compromise the mobile web-application. The local 
file/path include execution occcurs in 
the index file dir listing of the wifi interface. The attacker is able to inject the local file include request by 
usage of the `wifi interface` 
in connection with the vulnerable file upload POST method request. 

Remote attackers are also able to exploit the filename issue in combination with persistent injected script codes to 
execute different malicious 
attack requests. The attack vector is located on the application-side of the wifi service and the request method to 
inject is POST. 

The security risk of the local file include vulnerability is estimated as high with a cvss (common vulnerability 
scoring system) count of 6.9. 
Exploitation of the local file include web vulnerability requires no user interaction or privileged web-application 
user account. 
Successful exploitation of the local file include vulnerability results in mobile application compromise or connected 
device component compromise.

Request Method(s):
                                [+] [POST]

Vulnerable Module(s):
                                [+] Submit (Upload)

Vulnerable Parameter(s):
                                [+] filename

Affected Module(s):
                                [+] Index File Dir Listing (http://localhost:52437/)


Proof of Concept (PoC):
=======================
The local file include web vulnerability can be exploited by remote attackers (network) without privileged application 
user account and without user interaction.
For security demonstration or to reproduce the security vulnerability follow the provided information and steps below 
to continue.

Manual steps to reproduce the vulnerability ...
1. Install the software to your iOS device
2. Start the mobile ios software and activate the web-server
3. Open the wifi interface for file transfers
4. Start a session tamper and upload a random fil
5. Change in the live tamper by interception of the vulnerable value the filename input (lfi payload)
6. Save the input by processing to continue the request
7. The code executes in the main file dir index list of the local web-server (localhost:52437)
8. Open the link with the private folder and attach the file for successful exploitation with the path value
9. Successful reproduce of the vulnerability!


PoC: Upload File (http://localhost:52437/Box/)
<div id="module_main"><bq>Files</bq><p><a href="..">..</a><br>
<a href="<iframe>2.png"><../[LOCAL FILE INCLUDE VULNERABILITY IN FILENAME!]>2.png</a>           (     0.5 Kb, 
2015-04-30 10:58:46 +0000)<br />
</p><form action="" method="post" enctype="multipart/form-data" name="form1" id="form1"><label>upload file<input 
type="file" name="file" id="file" /></label><label><input type="submit" name="button" id="button" value="Submit" 
/></label></form></div></center></body></html></iframe></a></p></div>

--- PoC Session Logs [POST] (LFI - Filename) ---
Status: 200[OK]
POST http://localhost:52437/Box/ 
Load Flags[LOAD_DOCUMENT_URI  LOAD_INITIAL_DOCUMENT_URI  ] Größe des Inhalts[3262] Mime 
Type[application/x-unknown-content-type]
   Request Header:
      Host[localhost:52437]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:37.0) Gecko/20100101 Firefox/37.0]
      Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
      Accept-Language[de,en-US;q=0.7,en;q=0.3]
      Accept-Encoding[gzip, deflate]
      Referer[http://localhost:52437/Box/]
      Connection[keep-alive]
   POST-Daten:
      POST_DATA[-----------------------------321711425710317
Content-Disposition: form-data; name="file"; filename="../[LOCAL FILE INCLUDE VULNERABILITY IN FILENAME!]>2.png"
Content-Type: image/png

Reference(s):
http://localhost:52437/
http://localhost:52437/Box/ 


Solution - Fix & Patch:
=======================
The vulnerability can be patched by a secure validation of the filename value in the upload POST method request. 
Restrict the filename input and 
disallow special chars. Ensure that not multiple file extensions are loaded in the filename value to prevent arbitrary 
file upload attacks.
Encode the output in the file dir index list with the vulnerable name value to prevent application-side script code 
injection attacks.


Security Risk:
==============
The security rsik of the local file include web vulnerability in the filename value of the wifi service is estimated as 
high. (CVSS 6.9)


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


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