Which of the following are based on malicious code? Each correct answer represents a complete solution. Choose two.

A Denial-of-Service attack is a network-level availability attack that typically floods a target with traffic - it does not inherently require malicious code to be installed or executed on the victim's system.

Biometrics is an authentication technology that uses physical or behavioral characteristics such as fingerprints or retina scans to verify identity, and has no relation to malicious code.

A Trojan horse is malicious code that disguises itself as legitimate software to deceive users into executing it, making it a direct and classic example of malware. Unlike viruses or worms, it relies on social engineering to run but is fundamentally defined by its malicious code payload.

A worm is self-replicating malicious code that propagates across networks and systems without requiring user interaction, classifying it by definition as malicious code and a core category of malware.