At last week's DefCon 12 -- the annual underground hacking confab -- AirDefense again monitored the airwaves looking for hacker habits.

What it found wasn't pretty.

“The types of attacks we're seeing are increasingly more sophisticated than those of years past,” said Richard Rushing, the chief security officer of AirDefense, in a statement. “Last year we noted basic denial of service and spoofing attacks, [but] this year hackers have moved on to what we refer to as level three attacks, where hackers are actually injecting traffic into the network and manipulating data.”

Among the hacks that AirDefense witnessed at DefCon 12 was an injection attack that manipulated images in wireless surfers' browsers and dropped in unrequested forms into pages. The security firm also discovered a new denial-of-service (DoS) attack that modified firmware on network cards to knock people off the network, block data, and gain control of the wireless LAN.