Security experts such as Patrick Morley, CEO of enterprise security firm Bit9 say that attacks are on the rise. Morley came to visit me last week in San Francisco after giving an educational seminar about how to stop malware. He predicts that security will move toward so-called white listing, the practice of defining the software that IT departments will let run on computers and mobile devices. Bit9 has created a global registry of known "good software" and offers a product that acts as a sentry, only letting employees download applications that aren't dangerous.

This works in reverse of the way many anti-virus software programs work. Those programs scan for code that's known to be bad. The problem, says Morley, is that at this point there are more bad viruses than there are safe software applications on the market.

"We're all looking for bad but we know what good is," said Cisco's chief security officer John Stewart, when I interviewed him in March. Software vendors all know what they publish and the idea is to create a comprehensive list of that software so that everything else is questioned. "I think it's high time that we continue to look for things that are potentially more effective," said Stewart.

On a clean system, all of the images on this page will show up. If it's infected, some will be missing. The site includes simple instructions on how to interpret the results and how to remediate an infected system. Run it on your PC. Better yet, run it on your mother's PC and your kids' PCs.

Conficker still remains something of a mystery. Experts have no real idea of who is behind it or what it was intended to do, says Tom Cross, manager of X-Force Research at IBM Internet Security Systems who has worked closely with the Conficker Working Group. Despite the fears of security experts, the bots infected with the worm were never used to mount any sort of serious attack. What remains unknown is whether the infection was some sort of elaborate rehearsal for a future attack or if the vigilance of the computer security community prevented something worse from happening.

Contrary to widespread reports that seem to have originated in the South Korean government, little evidence has come to light to suggest that North Korea is behind the attack. That's not to say the North Koreans don't have something to do with it, just that the evidence is lacking.

But whoever is behind this, it is disturbing to learn that a number of government agencies are still vulnerable even to a relatively unsophisticated attack, one that most Web-savvy businesses have long since learned to deal with.