What characterizes a Trojan horse in cybersecurity?

A Trojan horse in cybersecurity is characterized by having both known desired functions and unknown undesired functions. This definition captures the essence of how a Trojan operates: it masquerades as a legitimate software to trick users into downloading and executing it. Once installed, it can provide a seemingly useful service or function while simultaneously carrying out malicious activities in the background, such as stealing sensitive data or creating backdoors into systems.

This dual-faceted nature is what makes Trojans particularly dangerous, as users often believe they are interacting with a safe application when, in reality, it may be compromising their security. In contrast, other options do not adequately describe the complexities of a Trojan horse; they either oversimplify its capabilities or misidentify its function entirely.