3.2 Risk Assessment
The first step in improving the
security of your system is to answer these basic questions:
What am I trying to protect and how much is it worth to me? What do I need to protect against? How much time, effort, and money am I willing to expend to obtain
adequate protection?
These questions form the basis of the process known as
risk assessment. Risk assessment is a very
important part of the computer security process. You cannot formulate
protections if you do not know what you are protecting and what you
are protecting those things against! After you know your risks, you
can then plan the policies and techniques that you need to implement
to reduce those risks.
For example, if there is a risk of a power failure and if
availability of your equipment is important to you, you can reduce
this risk by installing an uninterruptable power supply
(UPS).
3.2.1 Steps in Risk Assessment
Risk assessment involves three key steps:
Identifying assets and their value Identifying threats Calculating risks
There are many ways to go about this process. One method with which
we have had great success is a series of in-house workshops. Invite a
broad cross-section of knowledgeable
users, managers, and
executives from throughout your organization. Over the course of a
series of meetings, compose your lists of assets and threats. Not
only does this process help to build a more complete set of lists, it
also helps to increase awareness of security in everyone who attends.
An actuarial approach is more complex than necessary for protecting a
home computer system or very small company. Likewise, the procedures
that we present here are insufficient for a large company, a
government agency, or a major university. In cases such as these,
many companies turn to outside consulting firms with expertise in
risk assessment, some of which use specialized software to do
assessments.
3.2.1.1 Identifying assets
Draw up a list of
items you need to protect. This list should be based on your business
plan and common sense. The process may require knowledge of
applicable law, a complete understanding of your facilities, and
knowledge of your
insurance coverage.
Items to protect include tangibles (disk drives, monitors, network
cables, backup media, manuals, etc.) and intangibles (ability to
continue processing, your customer list, public image, reputation in
your industry, access to your computer, your
system's root password, etc.).
The list should include everything that you consider to be of value.
To determine if something is valuable, consider what the loss or
damage of the item might cost in terms of lost revenue, lost time, or
the cost of repair or replacement.
Some of the items that should probably be in your asset list include:
- Tangibles
-
- Intangibles
-
Safety and health of personnel Privacy of users Personnel passwords Public image and reputation Customer/client goodwill Processing availability Configuration information
You should take a larger view of these and related items rather than
simply considering the computer aspects. If you are concerned about
someone reading your internal financial reports, you should be
concerned regardless of whether they read them from a discarded
printout or snoop on your email.
3.2.1.2 Identifying threats
The next step is to determine a
list of threats to your assets. Some of these threats will be
environmental, and include fire, earthquake, explosion, and flood.
They should also include very rare but possible events such as
structural failure in your building, or the discovery of asbestos in
your computer room that requires you to vacate the building for a
prolonged time. Other threats come from
personnel and from outsiders.
We list some examples here:
Illness of key people Simultaneous illness of many personnel (e.g., flu epidemic) Loss (resignation/termination/death) of key personnel Loss of phone/network services Loss of utilities (phone, water, electricity) for a short time Loss of utilities (phone, water, electricity) for a prolonged time Lightning strike Flood Theft of disks or tapes Theft of key person's laptop computer Theft of key person's home computer Introduction of a virus Bankruptcy of a key vendor or service provider Hardware failure Bugs in software Subverted employees Subverted third-party personnel (e.g., vendor maintenance) Labor unrest Political terrorism Random "hackers" getting into your
machines Users posting inflammatory or proprietary information on the Web
3.2.2 Review Your Risks
Risk assessment should not be done only once and then forgotten.
Instead, you should update your assessment periodically. In addition,
the threat assessment portion should be redone whenever you have a
significant change in operation or structure. Thus, if you
reorganize, move to a new building, switch vendors, or undergo other
major changes, you should reassess the threats and potential
losses.
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