Shields Up!: Botnets

Today let’s take a look at botnets. This is the tool of choice for spammers everywhere. A botnet is a collection of computers, known as zombies, that have been infected by malware. The malware enables the criminal in charge of the group, also known as the bot master, to control all the infected computers remotely. Botnets are used to send spam, conduct DDoS attacks and distribute even more malware. They range in size from tens of thousands to millions of zombies.

A botnet begins its life as a single or group of servers sending out malware. As more and more computers become infected with the malicious software, the botnet grows. Large botnets are capable of sending out billions of spam messages a day. Most advertise fake pharmaceuticals or porn sites. The infected computers are programmed to contact the control server at specific times to receive updates or new instructions.

Botnets are big business. They can generate huge profits through even a tiny response rate to the spam they send out. Another way criminals make money from botnets is to rent them out to other criminals, usually spammers. Botnets also compete with each other and it’s not unusual for botnets to steal zombies from each others.

Here’s a look at some of the most well known botnets, how large they are, and how much spam they are capable of sending per day:

When the black hat ISP McColo was shut down late last year, spam plummeted because many major botnets such as Srizbi and Rustock had been hosted there and were knocked off line. Unfortunately the good times didn’t last – the bot masters found new homes fairly quickly in places like Romania and Estonia.

Your computer could be part of a botnet and you’d never even know it, that is, unless you had the misfortune of being infected by the botnet behind the recent DDoS attacks here in the U.S. and in South Korea. The malware used by that botnet is programmed to encrypt or erase all the data on the systems it infects. It’s a new twist to an old crime.

To protect yourself, click wisely. Be careful about clicking masked URLs, banner ads, and pop ups. Avoid any that try and tell you you’ve won a hot electronic item or laptop and ones that claim your computer is infected or has registry issues. Don’t click links you get in emails from strangers claiming to have exclusive footage of recent headlines or celebrity scandals.

If you’re into social networking, be careful what apps you install on your MySpace and Facebook profiles and don’t automatically follow people who follow you on Twitter. If you find yourself on an unfamiliar site that wants you to download a codec, video player, “software update” or any other kind of program, shut down your browser. Remember, common sense is a scammers worst enemy!