The Internet made popular by the World Wide Web has resulted in the physical connection of hundreds of millions of computers around the World and beyond. With such massive connectivity comes the increasing risk of accidental and malicious hazards to data, software, hardware and even human life. The objectives of computer and network security are as simple as they are contradictory. We all want perfect confidentiality of our own personal information, exacting integrity in the data we access and unlimited availability to all information we want to access. It is unlikely that any OS can be made completely secure and it is beyond current technology to prove that a computer system is unbreakable.
Security is an afterthought in most system architectures.
OS designers and applications programmers do not place sufficient concern on the possibilities of malicious attacks. Implementing Security measures is costly and the effectiveness is unprovable. Since we cannot perform algebraic analysis on real computer systems to prove they are secure, we are limited to testing by trial and error. The vast majority of malicious attacks take advantage of human error. Using simplistic passwords, not changing passwords, writing down passwords, using the same password for multiple purposes, not implementing or updating virus detection software, opening anonymous email attachments, allowing automatic downloads, not checking data media and leaving directories shared on a network are a few examples of bad security practices.