Consider a system that generates 10 million audit records per day.Assume that, on

Buffer-overflow attacks can be avoided by adopting a better programming methodology or by using special hardware support. Discuss these solutions.

A password may become known to other users in a variety of ways. Is there a simple method for detecting that such an event has occurred? Explain your answer.

What is the purpose of using a salt along with the user-provided password? Where should the salt be stored, and how should it be used?

The list of all passwords is kept within the operating system. Thus, if a user manages to read this list, password protection is no longer provided. Suggest a scheme that will avoid this problem. (Hint: Use different internal and external representations.)

An experimental addition to UNIX allows a user to connect a watchdog program to a file. The watchdog is invoked whenever a program requests access to the file. The watchdog then either grants or denies access to the file. Discuss two pros and two cons of using watchdogs for security.

The UNIX program COPS scans a given system for possible security holes and alerts the user to possible problems. What are two potential hazards of using such a system for security? How can these problems be limited or eliminated?

Discuss a means by which managers of systems connected to the Internet could design their systems to limit or eliminate the damage done by worms. What are the drawbacks of making the change that you suggest?

Argue for or against the judicial sentence handed down against Robert Morris, Jr., for his creation and execution of the Internet worm discussed in Section 15.3.1.

Make a list of six security concerns for a banks computer system. For each item on your list, state whether this concern relates to physical, human, or operating-system security.

What are two advantages of encrypting data stored in the computer system?

What commonly used computer programs are prone to man-in-themiddle attacks? Discuss solutions for preventing this form of attack.

Compare symmetric and asymmetric encryption schemes, and discuss the circumstances under which a distributed system would use one or the other.

Why doesnt Dkd,N(Eke,N(m)) provide authentication of the sender? To what uses can such an encryption be put?

Discuss how the asymmetric encryption algorithm can be used to achieve the following goals. a. Authentication: the receiver knows that only the sender could have generated the message. b. Secrecy: only the receiver can decrypt the message. c. Authentication and secrecy: only the receiver can decrypt the message, and the receiver knows that only the sender could have generated the message.

Consider a system that generates 10 million audit records per day. Assume that, on average, there are 10 attacks per day on this system and each attack is reflected in 20 records. If the intrusion-detection system has a true-alarm rate of 0.6 and a false-alarm rate of 0.0005, what percentage of alarms generated by the system correspond to real intrusions?