store. The transmission of valuable information, such as electronic receipts, purchaseorders, payment data, and order confirmations, has drastically increased the need forsecurity and new automatic methods to deal with security threats.Data security measures date back to the time of the Roman Empire, when Julius Caesarcoded information to prevent enemies from reading secret war and defense plans carried by his Roman legions. Many modern electronic security techniques were developed for wartime use. The U.S. Department of Defense was the main driving force behind early securityrequirements and more recent advances. In the late 1970s, the Defense Department formeda committee to develop computer security guidelines for handling classified informationon computers. The result of that committee’s work was Trusted Computer SystemEvaluation Criteria, known in defense circles as the “Orange Book” because its cover wasorange. It spelled out rules for mandatory access control—the separation of confidential,secret, and top secret information—and established criteria for certification levels for computers ranging from D (not trusted to handle multiple levels of classified documents at once)to A1 (the most trustworthy level).This early security work has been helpful because it provided a basis for electroniccommerce security research. This research today provides commercial security productsand practical security techniques. This early work also helped current security efforts by
developing formal approaches to security analysis and evaluation, including the explicit
evaluation and management of risk.
Computer Security and Risk Management
Computer security is the protection of assets from unauthorized access, use, alteration, or
destruction. There are two general types of security: physical and logical. Physical security
includes tangible protection devices, such as alarms, guards, fireproof doors, security fences,
safes or vaults, and bombproof buildings. Protection of assets using nonphysical means is
called logical security. Any act or object that poses a danger to computer assets is known
as a threat.
Countermeasure is the general name for a procedure, either physical or logical, that
recognizes, reduces, or eliminates a threat. The extent and expense of countermeasures can
vary, depending on the importance of the asset at risk. Threats that are deemed low risk and
unlikely to occur can be ignored when the cost to protect against the threat exceeds the
value of the protected asset. For example, it would make sense to protect from tornadoes
a computer network in Oklahoma, where there is significant and regular tornado activity.
However, a similar network located in Maine would not require the same protection,
because tornadoes are extremely rare in Maine. The risk management model shown in
Figure 10-1 illustrates four general actions that an organization could take, depending on
the impact (cost) and the probability of the physical threat. In this model, a tornado in
Oklahoma would be in quadrant II, whereas a tornado in Maine would be in quadrant IV.
plans carried
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