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This chapter is from the book

1.4 What Are You Protecting?

There are essentially five things that you need to protect against.

  1. An intruder reading your confidential data

    An intruder could see your product designs, competitive plans for the future, names and addresses of customers, customers' credit card and bank account information, your bank account numbers and contents, sensitive system data including modem phone numbers, passwords, etc.

    Frequently the greater harm will happen if the intruder makes the data available to others. While a cracker herself knowing about your product design may not be a severe problem, publishing it on the Internet where your competitors can get it is a severe problem. If your customers' credit card numbers are revealed and it becomes publicly known (as has happened to America Online) people will be afraid to do business with you.

  2. An intruder changing your data

    This is perhaps the most scary and damaging intrusion. An intruder can alter designs and data without your people discovering it. This could cause loss of life and very severe liability. What if the formulation of a pharmaceutical company's medicine is changed, the design of an automobile or airplane is changed, or the program operating a factory or patient X-ray or Gamma ray device is changed. Patients' medical records could be altered. Any of these situations could result in death. They also could result in large lawsuits.

    An intruder may not even realize the harm that his actions could do. In a case in Berkeley, California, crackers were in a system that controlled a cyclotron that sometimes was used for cancer treatments. Intruders have caused banks' ATMs to spit out money to no one in particular and made embarrassing changes to agencies' Web pages, including the Central Intelligence Agency's.

  3. An intruder removing your data

    The harm here is self-evident and a good backup program limits the damage that can be done if it is detected.

  4. Denial of Service

    This is when an intruder causes a computer or network to be "less available" or "not available." Less available includes the system slowing down substantially because of intruder-induced loads or rescheduling, fewer modems or ports being available to legitimate users, due to intruders shutting some down, etc. Not available means that the intruder has caused the system to crash or go down.

    An intruder may think it amusing to crash the computer controlling a phone company exchange. Unfortunately, this blocks 911 emergency calls and interrupts the Air Traffic Control System voice and radar circuits between a control tower and remote radio antennas and other control towers. This could cause loss of life. Note that any interference with the operation of an aircraft in the U.S. that causes loss of life is a federal felony that carries the death penalty.

  5. An intruder launching other attacks from your site

    This could result in Denial of Service both due to loss of bandwidth and from other sites blocking your site as "a cracker site." This attack could result in bad publicity and possible legal liability.

Any of these attacks can cause less severe problems, such as the bankruptcy of a company, or firing of a SysAdmin. Certainly, this latter problem is the most severe of all.

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