Which of the following are common types of malware?

The identification of common types of malware includes viruses, worms, trojans, ransomware, and spyware, making this choice the most accurate. Each of these represents distinct malicious software designed to harm, exploit, or otherwise compromise information systems.

Viruses attach themselves to legitimate files and programs, infecting other files when executed. Worms can replicate themselves and spread independently across networks, often exploiting vulnerabilities in other connected systems. Trojans masquerade as legitimate software to deceive users into installing them, facilitating unauthorized access or damage. Ransomware is particularly damaging as it encrypts files on a victim's system, demanding ransom for decryption. Spyware secretly monitors user activity, gathering sensitive information without the user’s consent.

The other options represent different categories or technologies that do not fit the definition of malware. Firewalls, VPNs, and proxy servers are security tools designed to protect and manage network traffic. Adware and phishing pertain to advertising and social engineering tactics rather than being types of malware. Brute force attacks are methods for unauthorized access rather than malware types. Lastly, encryption tools and backup software are protective and preventive measures, not classified as malware.