GhostMail - (Status Message) Persistent Web Vulnerability

Document Title:
===============
GhostMail - (Status Message) Persistent Web Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1470


Release Date:
=============
2018-06-27


Vulnerability Laboratory ID (VL-ID):
====================================
1470


Common Vulnerability Scoring System:
====================================
4


Vulnerability Class:
====================
Script Code Injection


Current Estimated Price:
========================
1.000€ - 2.000€


Product & Service Introduction:
===============================
Sign up to military grade encrypted GhostMail and enjoy instant free and secure email & chat. No download or installs needed.
GhostMail is your new secure email & chat platform, with great features like self destruction, two factor login and much more...
Join free today and start enforcing your privacy and online rights.

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


Abstract Advisory Information:
==============================
The vulnerability laboratory core research team discovered an application-side vulnerability in the official GhostMail chat online service web-application.


Vulnerability Disclosure Timeline:
==================================
2018-06-27: Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
GhostCom Ltd.
Product: GhostMail (Chat) - Web Application (Online Service) 2015 Q2


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


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


Authentication Type:
====================
Restricted authentication (user/moderator) - User privileges


User Interaction:
=================
Low User Interaction


Disclosure Type:
================
Bug Bounty Program


Technical Details & Description:
================================
An application-side html injection web vulnerability has been discovered in the official GhostMail chat web-application.
The vulnerability allows to inject unauthorized malicious script codes on the application-side of the affected module.

The issue exists in chat status of the application and is remotly exploitable against other ghostmail user accounts.
The request method to inject is POST and the attack vector is located on the application-side of the affected online 
service web-application. The encoding of the status message in the chat client is broken. Local and remote attackers 
can use the lack of validation to perform html injection attacks to compromise user/moderator/admin session data.

The security risk of the html injection web vulnerability is estimated as medium with a cvss count of 4.0.
Exploitation of the issue requires a low privileged web-application user account and no direct user interaction. 
Successful exploitation of the application-side vulnerability results in session hijacking, persistent phishing, 
persistent external redirects and persistent manipulation affected or connected module context.

Vulnerable Domain(s):
[+] Ghostmail.com

Vulnerable Module(s):
[+] Status Message

Vulnerable Parameter(s):
[+] Status message body context


Proof of Concept (PoC):
=======================
The html injection web vulnerability can be exploited by local and remote attackers with low user interaction and low privileged application user account.
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. Register an account and login to the ghostmail application
2. Move to the chat status contents
3. Close the tag of title with double quote "
4. Now, add a new malicious content as payload in the status title  for the chat
5. Start to chat and in the same moment the execution of the script code occurs at both party sides of the client
6. Successful reproduce of the vulnerability!

Note: There is no filter validation or mechanism in place to prevent an execution within the ghostmail web-application.

Reference(s):
https://www.ghostmail.com/


Solution - Fix & Patch:
=======================
The vulnerability can be patched by a parse and encode of the vulnerable status mesage in the ghostmail chat client.
The issue has been reported in 2016 Q4 (2016-10-01) and was finally resolved in 2017 Q3 - Q4 by the ghostmail developer team.


Security Risk:
==============
The security risk of the application-side input validation web vulnerability in the chat module is estimated as medium (CVSS 4.0).


Credits & Authors:
==================
Vulnerability-Lab [[email protected]] - https://www.vulnerability-lab.com/show.php?user=Vulnerability-Lab


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