So far, you've seen how unintentional threats can cause problems on a LAN. Although these users are utilizing their systems with the most honorable of intentions, they can still cause problems from the simple act of them connecting to the LAN. The next set of threats operate under a completely different set of assumptions.
Intentional LAN-based threats involve malicious actions knowingly and consciously taking place on the LAN. These threats are not accidental; they are purposeful. The method of attack relies upon establishing LAN connectivity to establish the attack. This connectivity can be established a number of different ways:
A contractor, business partner, or the like is given authorization and instructions to connect to the LAN, although they use that access to perform unauthorized and malicious acts.
An outsider is allowed physical access inside the office, although they are not authorized to connect to the LAN (such as a sales guy — physical security important), and use someone else's system by walking up to it.
An outsider isn't authorized to physically enter the space or gain access to the LAN.
An outsider takes advantage of non-Ethernet connectivity to gain access (Wi-Fi, remote dial war dial).
All of these means to establish connectivity are important because they share a common trait. They all bypass the firewalls and other technologies put in place to protect the LAN from outsiders on the Internet. Bypassing these systems leaves ...