The disclosure of LAN traffic occurs when someone who is unauthorized reads, or otherwise obtains, information as it is moved through the LAN. LAN traffic can be compromised by listening and capturing traffic transmitted over the LAN transport media (tapping into a network cable, listening to traffic transmitted over the air, misusing a provided network connection by attaching an analysis device, etc.).

Many users realize the importance of confidential information when it is stored on their workstations or servers; however, it is also important to maintain that confidentiality as the information travels through the LAN. Information that can be compromised in this way includes system and user names, passwords, electronic mail messages, application data, etc.

For example, even though passwords may be in an encrypted form when stored on a system, they can be captured in plaintext as they are sent from a workstation or PC to a file server. Electronic mail message files, which usually have very strict access rights when stored on a system, are often sent in plaintext across a wire, making them an easy target for capturing.

The compromise of LAN traffic can occur by exploiting the following types of vulnerabilities:

• Inadequate physical protection of LAN devices and medium
• Transmitting plaintext data using broadcast protocols
• Transmitting plaintext data (unencrypted) over the LAN medium