Final Answer:
To initiate a denial-of-service attack, a tiny program is downloaded surreptitiously from the attacker's computer to dozens, hundreds, or even thousands of computers all over the world. Based on a command by the attacker or at a preset time, these computers, called zombies, go into action, each sending a simple request for access to the target site again and again.
Step-by-step explanation:
Denial-of-service (DoS) attacks leverage a network of compromised computers, known as zombies, to flood a target system with traffic, rendering it unavailable to legitimate users. These zombies are essentially the unwitting participants in the attack, as the malicious program is downloaded onto their machines without their knowledge. At the command of the attacker or a preset time, these zombies collectively unleash a barrage of requests towards the target site, overwhelming its resources and causing a disruption in service.
The term "zombies" is used to describe these compromised computers because, in the context of a DoS attack, they effectively become automated, mindless agents following the instructions of the attacker. Each zombie independently sends repeated requests to the target site, creating a massive volume of traffic that the target infrastructure struggles to handle. The scale of the attack depends on the number of compromised machines, amplifying its impact. This method allows attackers to harness the combined power of numerous systems distributed globally, making it challenging for defenders to trace and mitigate the attack effectively. The covert nature of this process makes it particularly insidious, as the owners of the compromised machines may be unaware of their involvement in the malicious activity.