Security in Computer Applications

Computer security has been an increasing concern for IT professionals for a number of years, yet despite all the efforts, computer systems and networks remain highly vulnerable to attacks of different kinds. Design flaws and security bugs in the underlying software are among the main reasons for this. This lecture addresses the following question: how to create secure software? The lecture starts with a definition of computer security and an explanation of why it is so difficult to achieve. It then introduces the main security principles (like least-privilege, or defense-in-depth) and discusses security in different phases of the software development cycle. The emphasis is put on the implementation part: most common pitfalls and security bugs are listed, followed by advice on best practice for security development. The last part of the lecture covers some miscellaneous issues like the use of cryptography, rules for networking applications, and social engineering threats. This lecture was first given on Thursday, February 24th, 2005 at the Inverted CERN School of Computing 2005. Bibliography and further reading are available at http://cern.ch/Sebastian.Lopienski/Security