An event is defined as an attempt, successful or unsuccessful, to gain unauthorized access to, disrupt or misuse an Information System or information stored on such Information System.
An incident is defined as a breach of a system's security policy in order to affect its integrity or availability and/or the unauthorised access or attempted access to a system or systems.

Explanation
Implementing 802.1X would have best prevented this avenue of attack. 802.1X is a standard that provides port-based network access control (PNAC), which means that it authenticates devices before allowing them to access network resources through a physical or wireless port. 802.1X can prevent unauthorized devices from obtaining valid IP addresses or accessing sensitive data by requiring them to provide credentials, such as a username and password, a certificate, or a token. 802.1X can also dynamically assign VLANs or firewall rules based on the device identity or role.