Which of the following best describes cryptojacking?

Cryptojacking is best described as the malicious mining of cryptocurrency using someone else's resources. This practice occurs when an attacker secretly uses the processing power of another user's device or system to mine cryptocurrencies. The attacker often does this without the owner's consent, leading to an increase in resource consumption, which can degrade performance, waste electricity, and incur costs for the victim.

Targeted systems may include personal computers, servers, or cloud resources, and the individuals or organizations affected may not even be aware that their resources are being exploited for cryptomining activities. This behavior highlights the unethical and invasive nature of cryptojacking, as it takes advantage of someone else’s hardware to generate profit for the attacker.

The other choices describe different scenarios in cybersecurity and cloud computing. Unauthorized access to a system refers to breaches where attackers gain access to secure areas without permission. Data theft from cloud services involves the illegal extraction of sensitive information stored in the cloud. Disruption of cloud services through DDoS attacks entails overwhelming a service with excessive traffic to make it unreachable. While these actions are indeed malicious, they do not capture the specific nature of cryptojacking as accurately as the correct answer does.