Black Hat: How to create a massive DDoS botnet using cheap online ads
“To scale [the botnet] up you need to get a lot of browsers running it,” he says.
The researchers paid the ad network to distribute their ad and within 18 hours it was generating 8.1 million requests to the server coming in fast enough to take it down. That was using HTTP requests six at a time without using the FTP bypass, Grossman says. Since the users whose browsers were enlisted to the botnet were unwitting, they didn’t want to make any changes to the browsers, he says.
The upside for attackers is that the botnet is random with no command-and-control server that defenders could take down. Grossman says he is uncertain whether it would be possible forensically to track down the ad at the center of such a botnet and ultimately track it to the individuals who bought the ad. “You could be tracked by who paid for the guilty ad,” he says.