Aside from the distributed denial-of-service (DDOS) attacks they launch against one another to disrupt their operations (like the recent DDOS battles between the Storm and Stration botnets), they also are constantly trying to hijack bots from one another. "Stealing is easier than building [out] one," says Danny McPherson, chief research officer for Arbor Networks, who tracks botnet activity.
But the savvier botnets go the extra mile to protect their captor capital: Some actually "secure" the bot machines they have infected so no other botnets can steal them or utilize them, too. They install patches on their bots, for instance, to close the security holes and shut down open ports that are vulnerable to attack. "They are installing defenses to make sure no one else doubly infects the machine," says Paul Mockapetris, chairman and chief scientist of Nominum. "There are instances where a machine is infected, and part of that is defense against another infection."
Patching their bots and shutting out other botnets is no harder than initially recruiting a machine as a bot, security experts say. "It would be trivial for a bot to compromise a machine and apply Microsoft's recommended workarounds to prevent re-infection," says David Maynor, CTO of Errata Security.
The bottom line is the bottom line, of course: The more bots you have, the better chance you have of making money off your spam runs, identity theft efforts, etc. And bots are often used to advertise botnet services, too, touting features such as IP addresses that change every 10 minutes.
"They market their own botnet services through the bots. It's an entire economy," Arbor's McPherson says.
McPherson says bots are more of a commodity now. Part of the problem, he says, is that antivirus and IDS tools only detect about 75 percent of malware, which makes it fairly simple to zombify a consumer's machine.
Meanwhile, as botnets are also ditching their old-school Internet Relay Chat (IRC) channels for HTTP and peer-to-peer communications to be less conspicuous to investigators, it raises the bar for their infighting as well.
"Now they have more sophisticated P2P systems -- and hijacking [one another] may be more difficult," notes Adam O'Donnell, senior research scientist for Cloudmark. Still, "botnet hijacking is a common occurrence."
O'Donnell says when new attack vectors are publicized for popular operating systems, it's easy to build up a botnet using them if the botnet operator gets there first. "If those systems become botted quickly by other parties, then it may become easier for a party just to hijack someone else's network."
It's one incestuous ecosystem. Says Errata Security's Maynor: "Think of bot masters like stock brokers: They are always going to go back and cannibalize their base first."
Kelly Jackson Higgins, Senior Editor, Dark Reading