What is unauthorised access or modification?

Answer 1

System crackers,[2] often high school or university students, attempt to access computing facilities for which they have not been authorized. Cracking a computer's defenses is seen as the ultimate victimless crime. The perception is that nobody is hurt or even endangered by a little stolen machine time. Crackers enjoy the simple challenge of trying to log in, just to see whether it can be done. Most crackers can do their harm without confronting anybody, not even making a sound. In the absence of explicit warnings not to trespass in a system, crackers infer that access is permitted. An underground network of hackers helps pass along secrets of success; as with a jigsaw puzzle, a few isolated pieces joined together may produce a large effect. Others attack for curiosity, personal gain, or self-satisfaction. And still others enjoy causing chaos, loss, or harm. There is no common profile or motivation for these attackers. A person not authorised to use iformation in the computer can get access to information and use the information. Intentional or unjustified access by a person unauthorised by owners or system operators where that person can harm or use information on the system

Answer 2

Simply put a password on the account and encrypt data so if the password is changed the data cannot be read. You can go to Novell and see there security products for authorized access.