Which of the following is NOT a common form of malware?

Firewalls are not classified as malware; rather, they serve as protective mechanisms against it. Firewalls are security systems that monitor and control incoming and outgoing network traffic based on predetermined security rules. Their primary purpose is to establish a barrier between trusted internal networks and untrusted external networks, thereby preventing unauthorized access and potential malicious activities.

In contrast, worms, Trojans, and ransomware are all types of malware that actively seek to exploit computer systems, either by replicating themselves, disguising user actions, or encrypting files and demanding a ransom. Understanding the distinction between these categories is crucial for effective cybersecurity practices, as it highlights the importance of utilizing protective measures such as firewalls alongside knowledge of different malware threats.