Bot software spreads, causes new worries

Bot software sounds a bit like a low-budget horror movie, but it's quietly making trouble and stealing data right now, using millions of PCs worldwide. These malicious pieces of code, often compared to an undercover army of robots, invade a PC and use its computing power to do someone else's dirty work - most often without the PC owner's knowledge. The infected PC, known as a Zombie, becomes another node on a Bot network, typically 2,000 to 10,000 PCs strong, according to Symantec. Unfortunately, a Bot network proves a practical tool for people who want to spread PC viruses and worms, send spam emails, install spyware on PCs, or carry out denial-of-service attacks on particular Web sites.