Information Security: The Big Picture – Part I

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Information Security:
The Big Picture – Part I
Stephen Fried
Hello, and welcome to Information Security: The Big Picture. My name is Stephen Fried, and over
the course of the next six hours I will be guiding you on a tour of the world of information security.
This course provides an introduction into the area of computer and network security. As more and
more people and companies connect to the Internet, the incidence of hacker attacks, break-ins, and
vandalism continues to increase. With this comes an increasing need for trained professionals to
understand and combat this growing threat. This course will teach you the basics you need to begin
securing your systems against threats from both inside and outside your organization.
The course takes a high-level approach, touching on many different topics in an overview style. The
information here is presented in plain English, not technical jargon, so students from all backgrounds
can understand the material and begin to apply the concepts immediately. Technical concepts (e.g.
communications technology, networking, protocols) are explained thoroughly in an easy-to-
understand manner, allowing even non-technical students to understand these areas. We rely heavily
on real-world examples and common-sense descriptions, enabling students to take their own “real
world” experiences and apply them to the information security arena.
So, without further ado, let’s get started.
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Preface
• Course is designed to give a broad
introduction to information security
• Use of real-world analogies to explain
security concepts

• Will not go into too much technical depth
• Some technical descriptions may be
oversimplified
• Use of sample data – not “real”
As stated before, this course is designed to give the student an introduction to the broad spectrum of topics
that are covered under the umbrella of Information Security. To completely and thoroughly discuss all the
possible topics that could be housed under that term would really take several weeks of in-depth study.
Unfortunately, we only have six hours so we are going to take a more practical approach. We will touch on
a variety of areas, giving explanations of each and diving into a few in more detail, but we will refrain from
diving too deep into any one topic.
As much as possible, I will try to use real-world examples to illustrate different terms and concepts. I have
found, over the years, that many issues in information security are really the same ones that arise in our
everyday lives. By applying those experiences to this new area, I hope to better explain the terms, concepts,
and topics we will be discussing.
This course does not go into a great deal of technical detail. It is designed for people who do not
necessarily have a technical background but need to know more about security. We won’t be discussing
much about bit patterns, dissecting the mathematical algorithms used in cryptography, and we’ll stay pretty
clear of discussion or dissection of hardware and software. That is not to say that the course does not have
technical content, it’s just that I’ve tried to limit it as much as possible.
Which brings me to my next point. Some of the topics we cover are, in actuality, highly technical and to
completely understand them does take a certain amount of technical explanation. So, in order to allow non-
geek regular folks to understand and enjoy the topics I have had to simplify some of the more esoteric
technical details and descriptions. My apologies in advance if my simplification goes a little far. Please
know that it was all for the sake of reaching as wide an audience as possible.
Finally, I use many examples of sample data in this course – Social Security numbers, network addresses,
people and company names, etc. I have tried my best to make as much of this up as possible. Any
resemblance between the example data and any persons, companies, or groups, living or dead, is purely
coincidental.
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Agenda
•
General Security Introduction
• Telecommunications Fundamentals
•Network Fundamentals
•Network Security
• World Wide Web Security
• Information Secrecy & Privacy
• Identification and Access Control
• Programmatic Security
•Conclusion
Our first topic is a General Security Introduction.
In this section we introduce you to some basic terms, concepts, and definitions you will need to begin
understanding information security.
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What Is “Security”?
• “Freedom from risk or danger”*
• The application of safeguards to
prevent loss
• A subjective measurement of
preparedness for risk
•A
feeling
of safety
*The American Heritage Dictionary of the English Language

I suppose the best way to start talking about information security is to examine the term “security” itself.
What is “security?” I looked it up in my handy dictionary and found that the definition of Security is
“freedom from risk or danger.” So, by extension, this would mean that information security would be
the science of keeping information free from risk or danger. Well, that sounds good, and is certainly a
worthy goal, but as we shall see over the span of this course, it is not a very realistic one. Why? Because
in today’s world, particularly in today’s on-line world, you can never be completely free from risk or
danger. There is just too much danger going around. So there will always be some risk. But that means
we can never be secure…..
I guess I am talking in circles here, somewhat intentionally. Let’s start at the beginning. You can never
be completely free from risk. When we get to the section on risk and risk analysis we will see how this
is true. But for now, suffice to say that you can never completely prepare for all the bad things that will
happen. So you have to pick and choose the dangers you want to protect against. You put your energy
into preparing for those that you think are the most threatening and spend less time on those that you
think are more remote. So here we see that security becomes subjective. If you have prepared against
your own personal top ten threats, you feel secure. But, your top threats might be different than someone
else’s top threats. Given your list of preparations, someone else might not feel as secure.
There are no absolutes in security, no quick measurement to say definitively if you are secure or not. So
you can never be sure that you have covered all the bases. But, if you do your homework, define your
goals and threats, and make the proper preparations and install the proper safeguards, you will be more
secure than if you had done nothing. And, in the end, maybe that’s what security is really all about – a
feeling of safety. The notion that you feel better about your efforts to protect yourself and your assets.
Perhaps we’ve started off a bit philosophically. Don’t worry, we’ll get back into the meat of things
quickly, but I wanted to start you out with a feel of what security people face every day. Security is part
art, part science, part technical, part philosophy, and all very interesting.
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The Consequences of
Inadequate Security

• Loss of company assets
• Loss of revenue/market share
• Loss of intellectual property
• Loss of privacy
• Damage to reputation
We will spend the rest of the course talking about the importance of security, risk and threats, and the steps you can take to improve
the security of your organization. However, I believe the best way to start out the course is a brief discussion about the
consequences of bad security. What would happen if you didn’t pay attention to security at all? Perhaps answering this question will
get you in a frame of mind to think seriously about your security efforts.
There are many consequences of bad security, and the list probably varies from organization to organization, but this slide shows
the five major consequences. The first is loss of company assets. This the most obvious, as it deals with real, definable losses–
damage to computers, loss of data, service disruptions on your network, etc. When most people think of security consequences they
think of these types of issues. However, there are other consequences that can be just as damaging, but do not immediately come to
mind.
One of these is loss of revenue or market share. When an attacker comes in and defaces your web site, there will be time and
expenses associated with repairing the damage. Those are the direct losses. However, the organization may also lose money because
customers can’t get to the web site to order the company’s products or services. The longer the site takes to rebuild, the more
potential revenue will be lost. Another indirect loss is market share. Depending on the type of business, a short-term loss is usually
recoverable from a customer service perspective. Customers on the web today are used to short-term outages – annoyed, but used to
it. However, if the outage lasts past a certain comfort level, customers will begin looking elsewhere for competing products. Ifthe
outage is long enough, a serious loss of market share may be the result.
An organization that does not pay proper attention to security can be risking its intellectual property. These represent the
knowledge, experience, and research that the organization has developed, and can sometimes be so valuable to the organization that
dollar figures can not even be placed on it. These are the types of assets that are most worthy of protection, since their loss might
mean irreparable harm to the organization’s product development or financial outlook.
A serious breach in security might mean the loss of privacy for your business or your customers. Privacy, particularly privacy of
customer information, has become quite a hot topic over the past several years. We’ll discuss privacy issues in depth later in the
course, but consumers and employees are coming to expect that their personal and financial information will be secured against
unauthorized disclosure or theft. If an organization does not protect this information heavily and allows it to get in the handsof
attackers, the loss to personal privacy may be irreparable.

Finally, a great deal of e-commerce today is based on trust – trust in the vendor, trust in the vendor’s ability to perform as
advertised, trust that information about yourself and your business will be kept confidential. A successful attack on your network or
web site can cause that trust to be lost. Your organization’s reputation is based partly on the fact that it is perceived to be well run,
treats business partners with respect, and that it takes the due care necessary to protect itself and its customers. As any
businessperson knows, reputation can be as important as the balance sheet to a well-run business. Protecting your systems and
networks helps to protect that reputation.
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Basic Security Management
Confidentiality
Integrity Availability
Information Security is generally said to rest on three fundamental pillars: Confidentiality, Integrity,
and Availability. These three functions are commonly referred to as the C-I-A Triad.
Confidentiality refers to the areas affecting the need to keep information private or secret and to
prevent disclosure of information to those who do not need to see it. Confidentiality can be achieved
through the use of encryption, by selective use of access controls, or by keeping sensitive
information apart from publicly-available information.
Integrity is the notion that information should be complete and unaltered as it is used and that any
changes are made only by authorized people and properly recorded. Altering account balances in a
financial system or modifying log records to hide a computer attack are examples of integrity
attacks.
Availability refers to the need to have information available for use when it is needed and in a form
that is usable. Crashing a computer system or large-scale virus attacks are examples of availability
attacks.
These three elements - Confidentiality, Integrity, and Availability - are often interrelated. For
instance, you can use encryption to handle both confidentiality and integrity issues. Alteration of a
system’s information, generally considered an integrity issue, can also have availability
consequences as well. Or, you may determine that for a particular environment or application, you

need to pay less attention to one area or another. A web server that holds catalog or brochure
information for a company may require high availability, but lower confidentiality, since the
information is public anyway. Systems that handle bank wire transfers are usually concerned more
with integrity than confidentiality or availability.
However, in any review of overall security you will need to take all three of these issues into
account.
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How Secure is Secure
Enough? (1)
• Three fundamental questions
–What are you protecting?
–What is it worth to you?
–What is it worth to someone else?
Information security practitioners often wrestle with the problem of determining how much security is
considered “enough” for a particular application. Unfortunately, there is no single correct answer to this
question. The best place to start is by answering what I call the three fundamental questions about
information security:
First, what are you trying to protect? You need to define clearly what is the thing you have that is worth time
and effort and energy to keep it safe from harm. Is it a web site? A business plan? A patented formula? An
accounting system? You need to define as specifically as possible the object that needs protection, and
without knowing this, you can go no further. Many security efforts go awry because they fail to answer this
one basic question.
Second, you need to determine what the object is worth to you. What is the intrinsic value this thing has that
makes it worth protecting? It may be a monetary value. For instance, the amount of revenue an e-commerce
site brings into your company. Or it may be more of a symbolic or subjective value. For instance, the amount
your company’s reputation will suffer if its network gets hacked. In any case, you need to have a good idea
of the value of the object, since that will lead you to determine how much effort you will put into protecting

it. If the object is the cafeteria’s lunch menu for the week, you probably won’t put a lot of effort or money
into protecting it. If, however, the object is the secret formula to your best-selling perfume, that is probably
worth a lot more money to your company and worth putting extra resources into protecting it.
Finally, how valuable the thing might be to someone else. If it is valuable to you, you can bet that there are
others that will be willing to put effort into getting it as well. How much money could your top competitor
make if they got hold of that secret formula? If word leaked out that your system for holding customer credit
card numbers got attacked, would your customers move to your business rival? The value of your
information to others may factor into how much you put into security.
You need to address these three questions early on in your security planning. Until you have answered them
to your satisfaction, do not go any further, because you will be putting money and resources into an ill-
defined goal.
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How Secure is Secure
Enough? (2)
• Dealing with motivations
• Raising the effort bar
• Making yourself less “attractive”
• Security “lifetime”
There are other factors to consider as well when determining how much security is “enough”.
Conventional wisdom has it that you need to make security hard enough to break so that eventually an attacker will give up and go
somewhere else. This is because it may become too expensive for an attacker to continue, or they may fear that additional time spent
risks getting caught, or they may just get bored and go elsewhere. Much of this goes to the motivation of the attacker. Why are they
trying to attack you? What do you have that they want? Unfortunately, the answer may not be so obvious. Sure, you may have
something immediately identifiable like a product or money that they want. But you may be getting attacked because of who you are
(like a government or a big, mean, oppressive multinational corporation). You may be getting attacked because of association with
something you represent, like a particular industry (e.g. fur trading or a tobacco company). Or you may be attacked because your
name popped into the head of the attacker as someone that might be “cool” to break into. The problem is that you may never know

why you are getting hit. Without knowing the motivation, how do you determine how much security to apply?
One of the best strategies is to raise the effort bar, so to speak. You need to apply enough security so that the level of effort required is
greater than you think most attackers will be able to apply. You do this by applying the Defense in Depth strategy we will discuss
shortly. Each layer of defense will hopefully serve to deter the attacker from going further in his attack so that eventually he will give
up without getting to the “prize.” In this way, only the most determined, well funded, and experienced criminals will be able toget
through all your defenses. You may never be able to completely secure your systems against all attacks, as that might be too
expensive or resource intensive. But you can raise the effort level high enough for your own comfort.
You can also make an effort to make yourself less “attractive” to a potential attacker. I know people in my neighborhood that put up
“Beware of Dog” signs even if they don’t have a dog, or put burglar alarm company stickers in their windows even though they don’t
have an alarm, or light up their house like a Christmas tree at night, all in an effort to deter burglars from trying to break into their
house. You can apply the same concept with your systems and networks. Let people (both inside and outside your company) know
you use a strong firewall system, or that you monitor and check all transactions that go through your web site, or that you actively
prosecute attackers. These are the system equivalents of dog signs and flood lights. This may be enough to deter some would-be
attackers from even attempting to break into your systems. Be careful, though. If you brag too much about your defenses you may
actually encourage someone who wants to prove they are better than you.
Finally, you want to make your security efforts commensurate with the useful lifetime of your information. For example, if you are
trying to protect the revenue projections for your next quarter, you only really need to protect them until they are made public.
Devising a system that will protect the secret for the next 50 years will not only be expensive, it may be overkill.
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Who Are The Threats?
• Hackers?
•Vandals?
•Espionage?
• Insiders
When looking at the possible sources that threaten your organization’s systems, you have to look at several
types. The first group is the “hacker.” I use hacker in quotes because the real definition of hacker has changed
so much over the years. By hacker I mean a person that uses computers and networks to inflict damage (either

real or threatened) upon your environment. (Editor’s note: some people use the term ‘hacker’ simply to refer to
someone who is interested in computers and in finding out how they work. This is in contrast with the work
‘cracker’, which refers to someone with malicious intent. – JEK) Hackers have certainly gotten a large amount
of press in recent years and for good reason. But they are not necessarily your only threat, nor are they the
biggest.
Vandals are a sub-class of hackers. Whereas hackers may or may not be out to steal or disrupt your information,
more often than not they will attempt to cover their tracks, at least initially. And, if they are really good, you
may never know they have been in your systems. Vandals, on the other hand, are out to do visible damage to
your systems. They will deface your web pages, erase your files, anything they can do to disrupt or damage your
systems. You will know instantly when a vandal has been in your computer.
Hackers and vandals present a real threat to your systems, but for the most part, they may not be out to get you
directly. You are just a symbol or an object to them. However, practitioners of espionage are out to target you
specifically. They will try to get your intellectual property, try to disrupt your operations or communications,
and wreak havoc on your environment. They will be backed by your competitors or by a foreign government,
and in some respects represent the most dangerous of all outside threats. They are generally well financed, well
trained, and have a valuable goal in mind.
Finally, one of the largest threats to any environment is insiders. Studies have repeatedly shown that insiders
represent the largest cause of security incidents year after year. The reasons are obvious. These people are
already in a position of trust, they know their way around the systems, and they know what security controls are
in place and usually how they can be defeated. Whether it is through bribery, disgruntled employees, outsourced
personnel, or someone with personal financial hardship, you need to be as mindful of the security impact of your
insiders as you do of outsiders.
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Who Do You “Trust?”
• System will operate in ways that
can be predicted
• According to specifications

• Only allow authorized activities
• No undocumented features
• Trust vs. Security
Central to all discussions about information security is the concept of trust. In the real world, trust is an
intangible concept that can be difficult to define but is readily understood. You trust someone based on your
experiences with them, their reputation, your preferences, your ability to reach agreements with them, etc.
These are all intangible properties, and there is no real way to measure trust .
Computer and network security also uses the concept of trust and in many of the same ways. However, unlike
real life, trust in the security sense has a precise definition and a set of measurable criteria. In order to have trust
in a system, it must operate in ways that can be predicted, according to specifications, allowing only authorized
activities, and can contain no undocumented information paths or features. Let’s look at each one of those
criteria individually.
The system will operate in ways that can be predicted. If you give input into a computer, given the same
runtime environment, it should give you the exact same output every time. There should be no variation in the
way the system operates. For example, if you install a building card access system, you need to know that every
time a person holds their card up to the reader, the system will give an accurate response. If there is any
variability in the system, if it sometimes allows unauthorized people in or prevents entry to authorized people,
the system is of no use.
The system must run according to specifications. This means that the system must have a formal
specification of its operation and can not deviate from that specification. Like operating in predictable ways,
operating according to specifications eliminates any random elements in the system’s operation.
The system should only allow authorized activities. This means that every action taken by and within the
system must be authorized by the system, and any users must be authorized both for access to the system itself
as well as any activities they may perform while on the system.
There must be no undocumented features in the system. One of the more common causes of security
problems is the discovery of undocumented or hidden features. Once these features are discovered, they can be
used to manipulate the system in unpredictable ways, thus violating the trust of the system.
We should also make a distinction here between “trust” and “security”. As we have seen, trust refers to the
dependability of a system to perform as expected within certain parameters. Security, on the other hand, is the
sum total of issues relating to the confidentiality, integrity, and availability of systems and information. Trust is

an important part of security, but it is only one part.