How can malware overload a system and cause a denial of service?

Malware can be used to facilitate a denial-of-service (DoS) attack by hijacking a large number of devices to create a botnet, which is a network of infected "zombie" computers.123

The process typically functions as follows:

• Infection: Attackers use malware—such as Trojan horses disguised as benign files—to compromise numerous devices, including computers, digital video recorders, and other internet-connected hardware.12
• Coordination: Once infected, these devices remain under the control of the attacker without the owners' knowledge.13
• Overwhelming the Target: At a predesignated time, the attacker triggers the botnet to send a massive volume of requests to a specific site or server simultaneously.12

This flood of traffic consumes the target's resources, effectively tying up the system and preventing it from responding to requests from legitimate users. By utilizing a vast network of compromised machines, the attacker can render a site or service inaccessible, causing significant disruption to commercial or government operations.132