Xenon is a leading real estate firm located in Australia.

In the scenario described, the employee performed a Network Sniffing attack. This type of attack involves capturing and analyzing packets traveling through a network. Since the admin discovered that confidential emails related to the tender were captured and that an open switch port was used to connect to the network, it indicates that the data was intercepted as it traveled across the network, which is characteristic of a sniffing attack. Network sniffing can be either passive or active; however, the scenario suggests a passive approach where the packets were monitored and captured without altering the network traffic.

References: The Certified Network Defender (CND) course by EC-Council includes topics on various network attacks, including sniffing. It teaches how sniffing can be used to capture sensitive information like email conversations if proper security controls, such as closing unused switch ports, are not in place1. Additionally, network scanning and monitoring tools that can detect such unauthorized connections and activities are also covered in the CND curriculum1.