Information Security

Principles and Practice

Mark Stamp

• Publisher: Wiley
• Year: 2021
• ISBN:
  9781119505884
• Edition: 3
• Topic: Informatica
• Subtopic: Sicurezza informatica

Provides systematic guidance on meeting the information security challenges of the 21 st century, featuring newly revised material throughout

Information Security: Principles and Practice is the must-have book for students, instructors, and early-stage professionals alike. Author Mark Stamp provides clear, accessible, and accurate information on the four critical components of information security: cryptography, access control, security protocols, and software. Readers are provided with a wealth of real-world examples that clarify complex topics, highlight important security issues, and demonstrate effective methods and strategies for protecting the confidentiality and integrity of data.

Fully revised and updated, the third edition of Information Security features a brand-new chapter on network security basics and expanded coverage of cross-site scripting (XSS) attacks, Stuxnet and other malware, the SSH protocol, secure software development, and security protocols. Fresh examples illustrate the Rivest-Shamir-Adleman (RSA) cryptosystem, Elliptic-curve cryptography (ECC), and hash functions based on bitcoin and blockchains. Updated problem sets, figures, tables, and graphs help readers develop a working knowledge of classic cryptosystems, symmetric and public key cryptography, cryptanalysis, simple authentication protocols, intrusion and malware detection systems, and more. Presenting a highly practical approach to information security, this popular textbook:

• Provides up-to-date coverage of the rapidly evolving field of information security
• Explains session keys, perfect forward secrecy, timestamps, SSH, SSL, IPSec, Kerberos, WEP, GSM, and other authentication protocols
• Addresses access control techniques including authentication and authorization, ACLs and capabilities, and multilevel security and compartments
• Discusses software tools used for malware detection, digital rights management, and operating systems security
• Includes an instructor's solution manual, PowerPoint slides, lecture videos, and additional teaching resources

Information Security: Principles and Practice, Third Edition is the perfect textbook for advanced undergraduate and graduate students in all Computer Science programs, and remains essential reading for professionals working in industrial or government security. To request supplementary materials, please contact [email protected] and visit the author-maintained website for more: https://www.cs.sjsu.edu/~stamp/infosec/.

Chapter 1
Introductions

“Begin at the beginning,” the King said, very gravely, “and go on till you come to the end: then stop.”

—Lewis Carroll, Alice in Wonderland

1.1 The Cast of Characters

Following tradition, Alice and Bob, are the good guys. Alice and Bob, who are pictured in Figure 1.1 (a) and (b), respectively, generally try to do the right thing. Occasionally, we'll require an additional good guy or two, such as Charlie or Dave. A recurring theme of this book is that stick people often make dumb mistakes, just like real people.

Figure 1.1 The main actors

Trudy, pictured in Figure 1.1 (c), is our generic bad guy who is trying to attack the system in some way. Some authors employ a team of bad guys where the name implies the particular nefarious activity. In such usage, Trudy is an “intruder,” Eve is an “eavesdropper,” and so on. To simplify things, we'll let Trudy be our all‐purpose bad guy, although Eve might make a brief cameo appearance. Just like the bad guys in classic Hollywood Westerns, our bad guys always wear a black hat.

Alice, Bob, Trudy, and the rest of the gang need not be humans. For example, one of many possible permutations would have Alice as a laptop, Bob a server, and Trudy a human.

1.2 Alice's Online Bank

Suppose that Alice starts an online banking business, appropriately named Alice's Online Bank,¹ or AOB. What are Alice's information security concerns? If Bob is Alice's customer, what are his information security concerns? Are Bob's concerns the same as Alice's? If we look at AOB from Trudy's perspective, what security vulnerabilities might we see?

First, let's consider the traditional triumvirate of confidentiality, integrity, and availability, or CIA,² in the context of Alice's Bank. Then we'll point out some of the many other possible security concerns.

1.2.1 Confidentiality, Integrity, and Availability

Confidentiality deals with preventing unauthorized reading of information. AOB probably wouldn't care much about the confidentiality of the information it deals with, except for the fact that its customers certainly do. For example, Bob doesn't want Trudy to know how much money he has in his savings account. Alice's Bank would also face legal problems if it failed to protect the confidentiality of such information.

Integrity deals with preventing, or at least detecting, unauthorized “writing” (i.e., changes to data). Alice's Bank must protect the integrity of account information to prevent Trudy from, say, increasing the balance in her account or changing the balance in Bob's account. Note that confidentiality and integrity are not the same thing. For example, even if Trudy cannot read the data, she might be able to modify it, which, if undetected, would destroy its integrity. In this case, Trudy might not know what changes she had made to the data (since she can't read it), but she might not care—sometimes just causing trouble is good enough for Trudy.

Denial of service, or DoS, attacks are a relatively recent concern. Such attacks try to reduce access to information. As a result of the rise in DoS attacks, data availability has become a fundamental issue in information security. Availability is a concern for both Alice's Bank and Bob—if AOB's website is unavailable, then Alice can't make money from customer transactions and Bob can't get his business done. Bob might then take his business elsewhere. If Trudy has a grudge against Alice, or if she just wants to be malicious, she might attempt a denial of service attack on AOB.

1.2.2 Beyond CIA

Confidentiality, integrity, and availability are only the beginning of the information security story. Beginning at the beginning, consider the situation when AOB's customer Bob logs on to his computer. How does Bob's computer determine that “Bob” is really Bob and not Trudy? And when Bob logs into his account at Alice's Online Bank, how does AOB know that “Bob” is really Bob, and not Trudy? Although these two authentication problems appear to be similar on the surface, under the covers they are almost completely different.

Authentication on a standalone computer often requires that Bob's password be verified. To do so securely, some clever techniques from the field of cryptography are required. On the other hand, authentication over a network is open to many kinds of attacks that are not usually relevant on a standalone computer. Potentially, the messages sent over a network can be viewed by Trudy. To make matters worse, Trudy might be able to intercept messages, alter messages, and insert messages of her own making. If so, Trudy can simply replay Bob's old messages in an effort to, say, convince AOB that she is really Bob. As a result, authentication over a network requires careful attention to protocol, that is, the composition and ordering of the exchanged messages. Cryptography also plays a critical role in security protocols.

Once Bob has been authenticated by AOB, then Alice must enforce restrictions on Bob's actions. For example, Bob can't look at Charlie's account balance or install new accounting software on the AOB system. However, Sam, the AOB system administrator, can install new software. Enforcing such restrictions falls under the broad rubric of authorization. Note that authorization places restrictions on the actions of authenticated users. Since authentication and authorization both deal with issues of access to various computing and network resources, we'll lump them together under the clever title of access control.

All of the information security mechanisms discussed so far are implemented in software. And, if you think about it, other than the hardware, is there anything that is not software in a modern computing system? Today, software systems tend to be large, complex, and rife with bugs. A software bug is not just an annoyance, it is a potential security issue, since it may cause the system to misbehave. Of course, Trudy loves misbehavior.

What software flaws are security issues, and how are they exploited? How can AOB be sure that its software is behaving correctly? How can AOB's software developers reduce (or, ideally, eliminate) security flaws in their software? We'll examine these software development‐related questions (and much more) in this book.

Although bugs can (and do) give rise to security flaws, these problems are created unintentionally by well‐meaning developers. On the other hand, some software is written with the intent of doing evil. Examples of such malicious software, or malware, includes the all‐too‐familiar computer viruses and worms that plague the Internet today. How do these nasty beasts do what they do, and what can Alice's Online Bank do to limit their damage? What can Trudy do to increase the nastiness of such pests? We'll consider these and related questions.

Of course, Bob has many software concerns, too. For example, when Bob enters his password on his computer, how does he know that his password has not been captured and sent to Trudy? If Bob conducts a transaction at www.alicesonlinebank.com , how does he know that the transaction he sees on his screen is the same transaction that actually goes to the bank? That is, how can Bob be confident that his software (not to mention the network) is behaving as it should, instead of as Trudy would like it to behave? We'll consider these sorts of questions as well.

1.3 About This Book

Lampson [69] believes that real‐world security boils down to the following:

• Specification/policy — What is the system supposed to do?
• Implementation/mechanism — How does it do it?
• Correctness/assurance — Does it really work?

Your humble author would humbly³ add a fourth category:

• Human nature — Can the system survive “clever” users?

The focus of this book is primarily on the implementation/mechanism front. Your self‐assured author assures you that this is appropriate, nay essential...