Botnets – they're dangerous, deceptive, and very difficult to detect and deal with.
What's more, according to recent surveys, the botnet threat is growing…rapidly.
Experts say it's imperative that enterprises and consumers become aware of the acute and growing dangers posed by botnets, and take decisive and effective steps to counter them before it's too late. But that's easier said than done as botnets are insidious, and use stealth as a key weapon.
So what's a bot?
Botnets are networks of "bots" – short for robots. But these aren't the mechanical humanoids of science fiction; they're computers – large networks of captured and compromised computers.
After being commandeered, these machines may be used for a range of nefarious purposes, including scanning networks for other vulnerable systems, launching denial of service (DoS) attacks against a specified target, sending spam e-mails, and keystroke logging as a prelude to ID or password theft.
Botnets are generally created through spam e-mails or adware that leaves behind a software agent, also sometimes called a 'bot'.
When unsuspecting users click on a link, or open the delinquent e-mail, it downloads a software agent that turns their computers into botnet clients.
Captured – or "botted" – machines can be controlled remotely by the malware creator – referred to as the bot master or bot herder
If additional software has to be downloaded to complete the capture process, the bot would first do that, explains Jim Lippard director of information security operations at Florham Park, N.J.–based network services provider Global Crossing, in a podcast. "It may use any mechanism – FTP, TFTP, HTTP – to install the software."
Global Crossing's customers include more than 35 percent of the Fortune 500, as well as 700 carriers, mobile operators and ISPs.
The next thing the bot does is call home.
It would "usually do a domain name server (DNS) lookup on a particular name used by the miscreant for that botnet. Then it will find the host for that name, and connect to it using standard Internet Relay Chat (IRC) protocol," Lippard says.
The larger a botnet, the more formidable the attack it can launch.
For instance, when a botnet containing tens of thousands of captured machines is used to launch a denial of service attack, the consequences can be serious and irreparable.
There's the well publicized case of the botnet created by Christopher Maxwell that installed adware on vulnerable machines.