Which of the following actions is essential according to the control SI.L1-3.14.4 for organizations to combat malware?

The essential action according to the control SI.L1-3.14.4 for organizations to combat malware is to regularly update malicious code protection mechanisms. Keeping these mechanisms updated is crucial because cyber threats evolve continually; new malware variants are created daily, and existing protection measures can become ineffective if not maintained. Regular updates ensure that the protection mechanisms can recognize and neutralize the latest threats, thereby safeguarding the organization's information systems and sensitive data.

Updating malicious code protection mechanisms can include updating antivirus software, anti-malware programs, and intrusion detection systems. These updates often contain new definitions and information about newly identified malware, which helps in detecting and mitigating potential infections before they can do significant harm.

In contrast, reviewing incident reports is important for understanding past threats but does not directly combat malware. Installing firewalls is beneficial for network protection, yet it does not specifically address the need to defend against malware once it has bypassed network defenses. Permanently blocking external cyber threats is unrealistic, as it would impede legitimate business operations and communications. Each of these other options contributes to overall security measures but does not directly fulfill the specific requirement outlined in SI.L1-3.14.4 regarding the regular updating of malware protection measures.