Distributed Denial of Service (DDoS) attacks are made possible by the many unprotected systems connected to the Internet. While broadband users are the favorite targets, even dial-up users can be unwitting participants. Various studies have demonstrated that any vulnerable system can be compromised within as little as 5 minutes online.

Once compromised, the infected system (singularly referred to as a Zombie) joins with other similarly infected system in what is known as a botnet. These botnets are then used for a variety of criminal purposes – all of which pose serious risk to the infected user as well as the entire Internet community. And while some may not care about the risk to the Internet as a whole, remember that many of today’s threats include keylogging capabilities. Of special interest to the attackers are any personal financial details – which are then used for everything from credit card theft to outright identity theft. In short, it’s not just your computer at risk – it’s your wallet.

While it may be tempting to think it cannot happen to you, think again. Malicious code has evolved far beyond the childish pranks of yesteryear. Today's attackers are serious criminals, in it for the money, and they need as many systems under their control as they can get. If your computer isn't properly protected, it's not a matter of whether it's part of a botnet inasmuch as it's a matter of how long and how bad.

Antivirus software is a must, but it is simply not enough. Whether you connect via dial-up, cable, satellite or DSL, and regardless of your ISP, get and use a personal firewall. If you don't have one, several free firewalls, used properly, can offer excellent protection:

• Kerio Personal Firewall
• Sygate Personal Firewall
• ZoneAlarm

See Computer Safety Tips for additional advice on securing your home PC.