A botnet is a special kind of network that cybercriminals build up, one compromised system at a time. Hackers create botnets by successfully attacking your computer or other device and turning it into a "zombie computer" by leaving a small program called a “bot” on it after a successful virus or malware attack. Once the bot is on your system, it’s no longer your system; it’s under the control of the hacker. After you’ve lost control like this (or been “botted” as security people say), the cybercriminal can use your system to send spam and phishing messages, host pornography, or even attack other computers. But while your computer or device may be powerful enough for what you need, by itself it’s not enough for the big business of cybercriminals. So they take compromised systems and build them into a vast, powerful network of systems at their command. This network taken as a whole is called a botnet: a network of botted systems. Botnets are one of the biggest sources of money for hackers and greatest dangers for the Internet. Anti-malware helps protect you and the Internet by protecting against virus and malware attacks in the first place, and removing bots if they get on your system.

  • The countries that had the most reported infections related to the Esthost botnet are the United States, Italy, India, the UK, Germany, France, China, Spain, Canada, and Australia.
  • Esthost wasn’t the only botnet taken down in 2011. The Coreflood botnet had 2 million infected computers at the time of its takedown. Rustock, meanwhile, had 1 million infected computers.

The term “bot” comes from the word “robot.” You can think of a bot on your system as a small virtual robot that responds to its master’s commands (in this case, the cybercriminal).

Because a botnet is made up of a network of computers, large botnets span the globe and give cybercriminals a staggering amount of computing power to use however they want. The largest botnet discovered todate, the DNSChanger botnet taken down in Operation Ghost Click, networked 4 million systems around the world.

Cybercriminals treat botnets like giant supercomputers, using the harnessed resources for themselves or renting it out to others. Sometimes criminals will even sell entire botnets to one another.

With the power of a botnet at their disposal, cybercriminals can use it to send millions of pieces of spam in a short period of time. They can use it to bring almost any website down by telling all the systems in the botnet to flood the victim site with network requests. And they can use it to expand the botnet by using botted systems to plant bots in other systems after successful virus or malware attacks.

Botnets are hard to eradicate. Successfully getting rid of a botnet requires Internet security companies and law enforcement around the world to spend years tracking down the people that control them and moving in unison to take them down. It also requires everyone who connects to the Internet to work to not be a part of the botnet problem.

Don’t help the cybercriminals by letting them add your systems to their supercomputing botnet. Run up-to-date antivirus and anti-malware on all your computers and devices.

Think you’ve been hit by a bot or botnet?

Trend Micro recommends the following product to help you regain control of your system:



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For more information, check out any or all of the following sites:
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