The local administrator account for a company's VPN appliance was unexpectedly used to log in to the remote management interface. Which of the following would have most likely prevented this from happening?

Changing the default password would most likely have prevented this incident. Default passwords are widely known and often exploited by attackers. If the local administrator account still had its factory-set default password, an attacker could easily guess it and gain unauthorized access to the VPN appliance's management interface. While using least privilege is a good security practice, it primarily restricts what an account can do once logged in, not necessarily preventing the login itself if the credentials are compromised. Assigning individual user IDs is also a strong security measure, but if the local administrator account (which is often a default, shared account) was the one compromised, individual IDs wouldn't directly address that specific vulnerability. Reviewing logs more frequently is reactive; it helps detect an incident after it has occurred, rather than preventing it.