They must now become educated users aware of the risks they have opened their systems up to. The perpetrators used open systems to choreograph a wide scale massive attack directed at the servers of these companies. The enablers of this type of attack were users who have left their systems unprotected. Internet security is no longer just the concern of large companies. Now users like you and I must actively protect our own systems against people with malicious intent in mind.
Internet security is a part of a larger security issue known as network security.
To understand Internet security, one must also understand network security on the whole. A fundamental of network security is the fact that the network is only as secure as its weakest node, or in this case, weakest computer. The Internet has millions of computers connected to it at any point in time. Following the rule of network security, the Internet is only as secure as the most insecure computer connected to it. The repercussions this has on networks inside businesses is that any network inside a company is only as secure as its connection to the Internet.