This chapter is from the book
This chapter is from the book
This chapter is from the book
1.8 Exercises
Distinguish among vulnerability, threat, and control.
Theft usually results in some kind of harm. For example, if someone steals your car, you may suffer financial loss, inconvenience (by losing your mode of transportation), and emotional upset (because of invasion of your personal property and space). List three kinds of harm a company might experience from theft of computer equipment.
List at least three kinds of harm a company could experience from electronic espionage or unauthorized viewing of confidential company materials.
List at least three kinds of damage a company could suffer when the integrity of a program or company data is compromised.
List at least three kinds of harm a company could encounter from loss of service, that is, failure of availability. List the product or capability to which access is lost, and explain how this loss hurts the company. How does the nature of harm differ depending on the nature of the company (for example, a hospital versus a restaurant)?
Describe a situation in which you have experienced harm as a consequence of a failure of computer security. Was the failure malicious or not? Did the attack target you specifically, or was it general and you were the unfortunate victim? If you haven’t personally experienced harm, describe a situation in which you could imagine yourself being harmed.
Describe two examples of vulnerabilities in automobiles for which auto manufacturers have instituted controls. Tell why you think these controls are effective, somewhat effective, or ineffective.
One control against accidental software deletion is to save all old versions of a program. Of course, this control is expensive in terms of cost of storage, not to mention difficult to implement. Suggest a less-costly control against accidental software deletion. Is your control effective against all possible causes of software deletion? If not, what threats does it not cover?
On your personal computer, who can install programs? Who can change operating system data? Who can replace portions of the operating system? Can any of these actions be performed remotely?
What is to you the most important thing—app, data item, capability—of your smartphone? What steps have you taken to secure against the loss of that thing?
Suppose a program to print paychecks secretly leaks a list of names of employees earning more than a certain amount each month. What controls could be instituted to limit the vulnerability of this leakage?
Preserving confidentiality, integrity, and availability of data is a restatement of the concern over the three harms of interception, modification, and interruption. How do the first three concepts relate to the second three? That is, is any of the three harms equivalent to one or more of the first three concepts? Is one of the three concepts encompassed by one or more of the three harms?
Do you think attempting to break into (that is, obtain access to or use of) a computing system without authorization should be illegal? Why or why not?
Describe an example (other than the ones mentioned in this chapter) of data whose confidentiality has a short timeliness, say, a day or less. Describe an example of data whose confidentiality has a timeliness of more than a year.
(a) Cite a situation in which preventing harm is an appropriate computer security objective. (b) Cite a situation in which moderating or minimizing harm is an appropriate computer security objective. When is (a) more appropriate; when is (b) more appropriate? That is, what external factors would make one preferable to the other?
Do you currently use any computer security control measures? If so, what? Against what attacks are you trying to protect?
Describe an example in which absolute denial of service to a user (that is, the user gets no response from the computer) is a serious problem to that user. Describe another example where 10% denial of service to a user (that is, the user’s computation progresses, but at a rate 10% slower than normal) is a serious problem to that user. Could access by unauthorized people to a computing system result in a 10% denial of service to the legitimate users? How?
When you say that software is of high quality, what do you mean? How does security fit in your definition of quality? For example, can an application be insecure and still be “good”? Explain your answer.
Developers often think of software quality in terms of faults and failures. Faults are problems (for example, loops that never terminate or misplaced commas in statements) that developers can see by looking at the code. Failures are problems, such as a system crash or the invocation of the wrong function, that are visible to the user. Thus, faults can exist in programs but never become failures because the conditions under which a fault becomes a failure are never reached. How do software vulnerabilities fit into this scheme of faults and failures? Is every fault a vulnerability? Is every vulnerability a fault?
Consider a program to display on your website your city’s current time and temperature. Who might want to attack your program? What types of harm might they want to cause? What kinds of vulnerabilities might they exploit to cause harm?
Consider a program that allows consumers to order products from the web. Who might want to attack the program? What types of harm might they want to cause? What kinds of vulnerabilities might they exploit to cause harm?
Consider a program to accept and tabulate votes in an election. Who might want to attack the program? What types of harm might they want to cause? What kinds of vulnerabilities might they exploit to cause harm?
Consider a program that allows a surgeon in one city to assist in an operation on a patient in another city via an internet connection. Who might want to attack the program? What types of harm might they want to cause? What kinds of vulnerabilities might they exploit to cause harm?