A demilitarized zone (DMZ) is a network segment that is separated from the internal network and the external network, such as the internet, by firewalls or other security devices. A DMZ provides an extra layer of security for the organization’s internal network by isolating the servers and services that need to be accessible to external users, such as a file server, from the rest of the network. A DMZ also prevents external users from accessing the internal network directly, as they have to go through two firewalls to reach it. Therefore, setting up a DMZ is an IS auditor’s best recommendation to protect anorganization from attacks when its file server needs to be accessible to external users12.

The other possible options are:

Enforce a secure tunnel connection: This means that the organization requires external users to establish a secure and encrypted connection, such as a virtual private network (VPN), to access its file server. This can provide some level of security and privacy for the data transmission, but it does not protect the file server or the internal network from attacks if the connection is compromised or if the external users are malicious. Therefore, enforcing asecuretunnel connection is not an IS auditor’s best recommendation to protect an organization from attacks when its file server needs to be accessible to external users3.

Enhance internal firewalls: This means that the organization improves the security and performance of its internal firewalls, which are devices that filter and control the network traffic between different segments of the network. This can provide some level of protection for the internal network from unauthorized or malicious access, but it does not protect the file server or the external network from attacks if the file server is exposed to the internet or if the external network is compromised. Therefore, enhancing internal firewalls is not an IS auditor’s best recommendation to protect an organization from attacks when its file server needs to be accessible to external users4.

Implement a secure protocol: This means that the organization uses a secure and standardized protocol, such as Secure File Transfer Protocol (SFTP) or Secure Shell (SSH), to transfer files between its file server and external users. This can provide some level of security and integrity for the data transmission, but it does not protect the file server or the internal network from attacks if the protocol is exploited or if the external users are malicious. Therefore, implementing a secure protocol is not an IS auditor’s best recommendation to protect an organization from attacks when its file server needs to be accessible to external users5. References: 1: What Is a DMZ Network and Why Would You Use It? | Fortinet 2: Demilitarised zone (DMZ) | Cyber.gov.au 3: What Is VPN Tunneling? | Fortinet 4: Firewall - Wikipedia 5: Secure Shell - Wikipedia