Hack a network as another guest with "Network Address"

Security lessons force us to use limited users (Standard User) on windows networks.

I found that a user can change his MAC ADDRESS from Control Panel\Network and Internet\Network Connections ------> [adapter] ---rclick---> Properties ------> Configure ------> Advanced ------> Network Address ------> Value.

How can an attacker use this option to do attack as another user and become invisible in network?