Infections can occur even through legitimate Web sites, botnet delivery mechanisms are becoming more sophisticated and subtle, and users don't have to actually do anything, except load a Web page, in order to enable botnet infections.

Uncovering bot communications is extremely difficult, according to Wenke Lee, an associate professor at GTISC and a leading botnet researcher. "It's very difficult to filter bot traffic at the network edge since it uses http and every enterprise allows http traffic," Lee says.

The GTISC report cites a second quarter 2008 assessment by Panda Labs, which found 10 million bot computers were used to distribute spam and malware over the Internet every day.

Cyberwar

One of the most troubling sections in the report deals with cyberwar: the deliberate use by one nation of computer technology to weaken, cripple or confuse an enemy nation's military, economic and infrastructure assets.