"When a website goes down, it takes time to bring it back up," Gaffan said. "There's no point continuing to fire at that target when it's down. You want to conserve your ammunition and fly under the radar, because the more you fire the greater the chances of someone identifying you as the source of the fire."
The technique also allows the attackers to get better mileage from their resources. "They could hit multiple targets with a single piece of infrastructure as opposed to hitting one target for an hour," Gaffan said.
Part of the reason attackers are sharpening their skills of deception is that defenders are getting better at blunting DDoS attacks. "The Internet as a whole is getting better at responding to these attacks," said Cisco Technical Leader for Threat Research, Craig Williams.
"We've seen DNS amplification shoot through the roof, but I suspect that's going to start dropping with the addition of RPZs that can mitigate queries and people getting better at closing down open resolvers," Williams told CSOonline.
Sign up for Computerworld eNewsletters.