What is the term for malicious code that operates without the user's knowledge?

Malware is a broad term that encompasses any malicious software designed to disrupt, damage, or gain unauthorized access to computer systems. This category includes various forms of harmful code, one of which is designed to operate without the user's knowledge. Because malware can take on many different forms—such as viruses, worms, trojans, ransomware, and spyware—classifying it under the umbrella of malware allows for the recognition of its harmful nature across different types of malicious code.

While other options represent specific categories or types of malware, they do not fully encapsulate the broader concept of malicious software. For instance, a virus specifically refers to code that attaches itself to other programs, replicates itself, and spreads. A trojan appears to be a legitimate application but serves malicious purposes in the background, and spyware is a type of malware that specifically gathers information from a user's computer without their consent. However, not all viruses, trojans, or spyware cover the full spectrum of malicious behavior that malware encompasses, making the broad term of malware the best descriptor for code that acts without user awareness.