Chapter 3 - Operating System Protection

Chapter 3 - Operating System Protection

Copyright(c), 1990, 1995 Fred Cohen - All Rights Reserved

Operating systems (OSs) are usually viewed from one of two perspectives. The classical theory of operating systems views them as means for efficiently allocating resources, while a more modern viewpoint sees OSs as a means of abstracting the hardware operation of a machine from the normal user.


1 - Describe each attack and a method for protecting against it:

a) Guessing passwords
b) A virus attack
c) A denial of service attack
d) A time bomb
e) A 'terminal gone awry' attack
f) Electronic mail giving phony operator orders

2 - Describe each defensive theory or technique:

a) The subject/object model
b) Access lists
c) Collusion analysis
d) The security and integrity models
e) The lattice and POset models

3 - Explain the difference between:

a) Policies and models
b) Trusted and untrusted computing bases
c) Viruses and Trojan horses
d) Identification, authentication, and authorization

4 - Describe strengths and weaknesses of:

a) Defense in depth
b) The TSEC
c) Auditing for detecting attacks
d) Proof of OS correctness
e) Testing for OS assurance

5 - Describe the virtues and drawbacks of:

a) Least privilege
b) Economy of mechanism
c) Complete mediation
d) Open design

6 - Describe how and why these are used to assist in OS protection:

a) Multiple states (kernel and user)
b) Virtual memory
c) Privileged instructions
d) Interrupts

7 - Describe:

a) Similarities and differences between database and OS protection
b) The use of privacy locks and keys
c) What a statistical database is and how it differs from other databases
d) Two ways bases can be illicitly released
e) Two defenses against attacks from (d)