What are Intruders?
One of the two most publicized threats to security is the intruder (the other is viruses), generally referred to as a hacker or cracker. There are three classes of intruders found:
Masquerader: An individual who is not authorized to use the computer and who penetrates a system’s access controls to exploit a legitimate user’s account. The masquerader is likely to be an outsider.
Misfeasor: A legitimate user who accesses data, programs, or resources for which such access is not authorized, or who is authorized for such access but misuses his or her privileges. The misfeasor generally is an insider.
Clandestine user: An individual who seizes supervisory control of the system and uses this control to evade auditing and access controls or to suppress audit collection. The clandestine user can be either an outsider or an insider.
Intruder attacks range from the benign to the serious. At the benign end of the scale, there are many people who simply wish to explore internets and see what is out there. At the serious end are individuals who are attempting to read privileged data, perform unauthorized modifications to data, or disrupt the system.