What is the main objective of Host-Based Attacks?

The main objective of host-based attacks is to disrupt the functionalities of a single host. These types of attacks focus on individual computers or devices rather than a network as a whole. By compromising a specific host, an attacker can interfere with its operations, manipulate its data, or exploit its resources. This can include actions such as installing malicious software, altering system configurations, or causing system crashes, all of which directly affect the affected host's performance and availability.

In contrast, other objectives listed involve different strategies; targeting a network of computers would indicate a broader, network-based attack, while gaining access to sensitive data across multiple devices suggests an intention to harvest data through more extensive exploitation. Denial-of-service attacks, while they can affect a single machine, generally aim to overwhelm a system, rendering it unavailable to users rather than disrupting its functionalities in a more focused manner. Thus, option B precisely encapsulates the essence of host-based attacks.