Botnet, Wikipedia

A b_____ is a collection of Internet-connected programs communicating with other similar programs in order to perform tasks. This can be as mundane as keeping control of an Internet Relay Chat (IRC) channel, or it could be used to send spam email or participate in distributed denial-of-service attacks. The word b_____ is a combination of the words robot and network. The term is usually used with a negative or malicious connotation.

botnet

In distributed d_____-o_-s______ attacks, multiple systems submit as many requests as possible to a single Internet computer or service, overloading it and preventing it from servicing legitimate requests. An example is an attack on a victim's phone number. The victim is bombarded with phone calls by the bots, attempting to connect to the Internet.

denial-of-service

This example illustrates how a botnet is created and used to send e____ s___. How a botnet works 1.A botnet operator sends out viruses or worms, infecting ordinary users' computers, whose payload is a malicious application—the bot. 2.The bot on the infected PC logs into a particular C&C server. 3.A spammer purchases the services of the botnet from the operator. 4.The spammer provides the spam messages to the operator, who instructs the compromised machines via the control panel on the web server, causing them to send out spam messages.

email spam

Computers can be co-opted into a botnet when they execute m________ s______. This can be accomplished by luring users into making a drive-by download, exploiting web browser vulnerabilities, or by tricking the user into running a T_____ h____ program, which may come from an email attachment. This malware will typically install modules that allow the computer to be commanded and controlled by the botnet's operator. Many computer users are unaware that their computer is infected with bots. Depending on how it is written, a Trojan may then delete itself, or may remain present to update and maintain the modules.

malicious software, Trojan horse