What is the BEST method to prevent the exploitation of the SMB network protocol?

Choosing to configure the perimeter firewall to deny inbound external connections to SMB ports is the best method to prevent the exploitation of the SMB network protocol. The Server Message Block (SMB) protocol has a history of vulnerabilities that attackers can exploit, particularly if SMB traffic is exposed to external networks. By blocking SMB traffic from external sources at the firewall level, organizations can significantly reduce the attack surface, making it much more difficult for malicious actors to reach SMB services on internal networks where they could exploit these vulnerabilities.

While monitoring and ensuring endpoint detection systems are in place, restricting access to shared network folders, and maintaining regular updates are all important security practices, they do not address the risk of external exploitation as directly as a perimeter firewall configuration. The primary protective measure here focuses on controlling traffic before it can enter the internal network, thus serving as a first line of defense. By preventing external access to SMB ports entirely, the risk of attacks such as the ones seen with ransomware infections and data breaches is greatly diminished. This approach effectively mitigates potential threats before they can affect the organization.