From Webopedia, NetBIOS is "short for Network Basic Input Output System, an application programming interface (API) that augments the DOS BIOS by adding special functions for local-area networks (LANs). Almost all LANs for PCs are based on the NetBIOS. Some LAN manufacturers have even extended it, adding additional network capabilities. NetBIOS relies on a message format called Server Message Block (SMB)."
NetBIOS is primarily used for file and printer sharing within Microsoft Windows networks. It can reveal system names and workgroup names within your network, and if you create "open shares" it can leave your data vulnerable to attack.
I'm not sure how the information about NetBIOS would be useful for marketing, but it can help an attacker learn more about your network. A good Web source on NetBIOS and it's problems can be found at http://cable-dsl.home.att.net/netbios.htm.
For more information on this topic, visit these other SearchSecurity resources:
Security Policies Tip: Security checklist for system administrators
Security Policies Tip: Beware the guest
Best Web Links: Securing Microsoft Products/Platforms
This was first published in March 2002