A system administrator wants to prevent unauthorized users from accessing sensitive company files. Which of the following should be modified to achieve this?

Modifying the Access Control List (ACL) rules is an effective method for preventing unauthorized users from accessing sensitive company files. ACLs are used in various operating systems and networking devices to define who has permission to access certain resources and what level of access they have (read, write, execute, etc.).

By updating the ACL rules, the system administrator can specify which users or groups have access to the sensitive files, ensuring that only authorized personnel can read or modify them. This level of granularity allows for tight control over file permissions and helps maintain the confidentiality and integrity of sensitive data.

In contrast, while updating processes, adjusting firewall rules, and enhancing endpoint protection can enhance overall security, they don't directly control access to files in the same manner. Updating processes might improve how data is handled but does not specifically address access permissions. Firewall rules typically protect networks and services from unauthorized access but do not govern file-level access rights. Endpoint protection, meanwhile, focuses on securing devices from malware and other threats but does not directly manage permissions for sensitive files. Thus, modifying ACL rules is the most targeted approach for the scenario presented.