If you connect NT systems to the internet, TURN OFF SERVER SHARING!
I had posted previously my belief that SMB security is broke, since even
administrative shares allow access as a valid user using only plain text
UIDs in the SMB/NetBios messages.
The following link is an Article in Dec 16 (Monday) Information week
talks of an undisclosed hack and exploit programs which will be
to access any file in an NT system until NT has Kerberos.