I've spent a good bit of time these past 10 days at work battling the MS Blaster and W32.Welchia worms. These have some interesting characteristics:

The worms don't announce themselves before infecting a computer.
They burrow unseen through low-level operating system vulnerabilities. They don't require explicit permission to attack.
They're quick to find other vulnerable systems and spread rapidly.
They don't "kill" your computer outright, but usurp it for their purposes, diverting most of the computing resources to spreading.
MS Blaster spreads lies about Microsoft.
Both were anticipated well before they were launched on the Internet; Microsoft made the "cure" available to everyone for free.
Appropriately patched computers are not vulnerable to infection.

Can you see some spiritual parallels with sin in your life as part of the community of humans?