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The Proactive Approach

Proactive security risk management has many advantages over a reactive approach. Instead of waiting for bad things to happen and then responding to them afterwards, you minimize the possibility of the bad things ever occurring in the first place. You make plans to protect your organization's important assets by implementing controls that reduce the risk of vulnerabilities being exploited by malicious software, attackers, or accidental misuse. An analogy may help to illustrate this idea. Influenza is a deadly respiratory disease that infects millions of people in the United States alone each year. Of those, over 100,000 must be treated in hospitals, and about 36,000 die. You could choose to deal with the threat of the disease by waiting to see if you get infected and then taking medicine to treat the symptoms if you do become ill. Alternatively, you could choose to get vaccinated before the influenza season begins.

Organizations should not, of course, completely forsake incident response. An effective proactive approach can help organizations to significantly reduce the number of security incidents that arise in the future, but it is not likely that such problems will completely disappear. Therefore, organizations should continue to improve their incident response processes while simultaneously developing long-term proactive approaches.

Later sections in this chapter, and the remaining chapters of this guide, will examine proactive security risk management in detail. Each of the security risk management methodologies shares some common high-level procedures:

1. Identify business assets.
2. Determine what damage an attack against an asset could cause to the organization.
3. Identify the security vulnerabilities that the attack could exploit.
4. Determine how to minimize the risk of attack by implementing appropriate controls.

Approaches to Risk Prioritization

The terms risk management and risk assessment are used frequently throughout this guide, and, although related, they are not interchangeable. The Microsoft security risk management process defines risk management as the overall effort to manage risk to an acceptable level across the business. Risk assessment is defined as the process to identify and prioritize risks to the business.

There are many different methodologies for prioritizing or assessing risks, but most are based on one of two approaches or a combination of the two: quantitative risk management or qualitative risk management. Refer to the list of resources in the "More Information" section at the end of Chapter 1, "Introduction to the Security Risk Management Guide," for links to some other risk assessment methodologies. The next few sections of this chapter are a summary and comparison of quantitative risk assessment and qualitative risk assessment, followed by a brief description of the Microsoft security risk management process so that you can see how it combines aspects of both approaches.

Quantitative Risk Assessment

In quantitative risk assessments, the goal is to try to calculate objective numeric values for each of the components gathered during the risk assessment and cost - benefit analysis. For example, you estimate the true value of each business asset in terms of what it would cost to replace it, what it would cost in terms of lost productivity, what it would cost in terms of brand reputation, and other direct and indirect business values. You endeavor to use the same objectivity when computing asset exposure, cost of controls, and all of the other values that you identify during the risk management process.

Note   This section is intended to show at a high level some of the steps involved in quantitative risk assessments; it is not a prescriptive guide for using that approach in security risk management projects.

There are some significant weaknesses inherent in this approach that are not easily overcome. First, there is no formal and rigorous way to effectively calculate values for assets and controls. In other words, while it may appear to give you more detail, the financial values actually obscure the fact that the numbers are based on estimates. How can you precisely and accurately calculate the impact that a highly public security incident might have on your brand? If it is available you can examine historical data, but quite often it is not.

Second, organizations that have tried to meticulously apply all aspects of quantitative risk management have found the process to be extremely costly. Such projects usually take a very long time to complete their first full cycle, and they usually involve a lot of staff members arguing over the details of how specific fiscal values were calculated. Third, for organizations with high value assets, the cost of exposure may be so high that you would spend an exceedingly large amount of money to mitigate any risks to which you were exposed. This is not realistic, though; an organization would not spend its entire budget to protect a single asset, or even its top five assets.

Details of the Quantitative Approach

At this point, it may be helpful to gain a general understanding of both the advantages and drawbacks of quantitative risk assessments. The rest of this section looks at some of the factors and values that are typically evaluated during a quantitative risk assessment such as asset valuation; costing controls; determining Return On Security Investment (ROSI); and calculating values for Single Loss Expectancy (SLE), Annual Rate of Occurrence (ARO), and Annual Loss Expectancy (ALE). This is by no means a comprehensive examination of all aspects of quantitative risk assessment, merely a brief examination of some of the details of that approach so that you can see that the numbers that form the foundation of all the calculations are themselves subjective.

Valuing Assets

Determining the monetary value of an asset is an important part of security risk management. Business managers often rely on the value of an asset to guide them in determining how much money and time they should spend securing it. Many organizations maintain a list of asset values (AVs) as part of their business continuity plans. Note how the numbers calculated are actually subjective estimates, though: No objective tools or methods for determining the value of an asset exist. To assign a value to an asset, calculate the following three primary factors:

• The overall value of the asset to your organization. Calculate or estimate the asset's value in direct financial terms. Consider a simplified example of the impact of temporary disruption of an e-commerce Web site that normally runs seven days a week, 24 hours a day, generating an average of $2,000 per hour in revenue from customer orders. You can state with confidence that the annual value of the Web site in terms of sales revenue is $17,520,000.
• The immediate financial impact of losing the asset. If you deliberately simplify the example and assume that the Web site generates a constant rate per hour, and the same Web site becomes unavailable for six hours, the calculated exposure is .000685 percent per year. By multiplying this exposure percentage by the annual value of the asset, you can predict that the directly attributable losses in this case would be $12,000. In reality, most e-commerce Web sites generate revenue at a wide range of rates depending upon the time of day, the day of the week, the season, marketing campaigns, and other factors. Additionally, some customers may find an alternative Web site that they prefer to the original, so the Web site may have some permanent loss of users. Calculating the revenue loss is actually quite complex if you want to be precise and consider all potential types of loss.
• The indirect business impact of losing the asset. In this example, the company estimates that it would spend $10,000 on advertising to counteract the negative publicity from such an incident. Additionally, the company also estimates a loss of .01 of 1 percent of annual sales, or $17,520. By combining the extra advertising expenses and the loss in annual sales revenue, you can predict a total of $27,520 in indirect losses in this case.

Determining the SLE

The SLE is the total amount of revenue that is lost from a single occurrence of the risk. It is a monetary amount that is assigned to a single event that represents the company's potential loss amount if a specific threat exploits a vulnerability. (The SLE is similar to the impact of a qualitative risk analysis.) Calculate the SLE by multiplying the asset value by the exposure factor (EF).The exposure factor represents the percentage of loss that a realized threat could have on a certain asset. If a Web farm has an asset value of $150,000, and a fire results in damages worth an estimated 25 percent of its value, then the SLE in this case would be $37,500. This is an oversimplified example, though; other expenses may need to be considered.

Determining the ARO

The ARO is the number of times that you reasonably expect the risk to occur during one year. Making these estimates is very difficult; there is very little actuarial data available. What has been gathered so far appears to be private information held by a few property insurance firms. To estimate the ARO, draw on your past experience and consult security risk management experts and security and business consultants. The ARO is similar to the probability of a qualitative risk analysis, and its range extends from 0 percent (never) to 100 percent (always).

Determining the ALE

The ALE is the total amount of money that your organization will lose in one year if nothing is done to mitigate the risk. Calculate this value by multiplying the SLE by the ARO. The ALE is similar to the relative rank of a qualitative risk analysis.

For example, if a fire at the same company's Web farm results in $37,500 in damages, and the probability, or ARO, of a fire taking place has an ARO value of 0.1 (indicating once in ten years), then the ALE value in this case would be $3,750 ($37,500 x 0.1 = $3,750).

The ALE provides a value that your organization can work with to budget what it will cost to establish controls or safeguards to prevent this type of damage — in this case, $3,750 or less per year — and provide an adequate level of protection. It is important to quantify the real possibility of a risk and how much damage, in monetary terms, the threat may cause in order to be able to know how much can be spent to protect against the potential consequence of the threat.

Determining Cost of Controls

Determining the cost of controls requires accurate estimates on how much acquiring, testing, deploying, operating, and maintaining each control would cost. Such costs would include buying or developing the control solution; deploying and configuring the control solution; maintaining the control solution; communicating new policies or procedures related to the new control to users; training users and IT staff on how to use and support the control; monitoring the control; and contending with the loss of convenience or productivity that the control might impose. For example, to reduce the risk of fire damaging the Web farm, the fictional organization might consider deploying an automated fire suppression system. It would need to hire a contractor to design and install the system and would then need to monitor the system on an ongoing basis. It would also need to check the system periodically and, occasionally, recharge it with whatever chemical retardants the system uses.

ROSI

Estimate the cost of controls by using the following equation:

ALE before control) – (ALE after control) – (annual cost of control) = ROSI

For example, the ALE of the threat of an attacker bringing down a Web server is $12,000, and after the suggested safeguard is implemented, the ALE is valued at $3,000. The annual cost of maintenance and operation of the safeguard is $650, so the ROSI is $8,350 each year as expressed in the following equation: $12,000 - $3,000 - $650 = $8,350.

Results of the Quantitative Risk Analyses

The input items from the quantitative risk analyses provide clearly defined goals and results. The following items generally are derived from the results of the previous steps:

• Assigned monetary values for assets
• A comprehensive list of significant threats
• The probability of each threat occurring
• The loss potential for the company on a per-threat basis over 12 months
• Recommended safeguards, controls, and actions

You have seen for yourself how all of these calculations are based on subjective estimates. Key numbers that provide the basis for the results are not drawn from objective equations or well-defined actuarial datasets but rather from the opinions of those performing the assessment. The AV, SLE, ARO, and cost of controls are all numbers that the participants themselves insert (after much discussion and compromise, typically).

Qualitative Risk Assessment

What differentiates qualitative risk assessment from quantitative risk assessment is that in the former you do not try to assign hard financial values to assets, expected losses, and cost of controls. Instead, you calculate relative values. Risk analysis is usually conducted through a combination of questionnaires and collaborative workshops involving people from a variety of groups within the organization such as information security experts; information technology managers and staff; business asset owners and users; and senior managers. If used, questionnaires are typically distributed a few days to a few weeks ahead of the first workshop. The questionnaires are designed to discover what assets and controls are already deployed, and the information gathered can be very helpful during the workshops that follow. In the workshops participants identify assets and estimate their relative values. Next they try to figure out what threats each asset may be facing, and then they try to imagine what types of vulnerabilities those threats might exploit in the future. The information security experts and the system administrators typically come up with controls to mitigate the risks for the group to consider and the approximate cost of each control. Finally, the results are presented to management for consideration during a cost-benefit analysis.

As you can see, the basic process for qualitative assessments is very similar to what happens in the quantitative approach. The difference is in the details. Comparisons between the value of one asset and another are relative, and participants do not invest a lot of time trying to calculate precise financial numbers for asset valuation. The same is true for calculating the possible impact from a risk being realized and the cost of implementing controls.

The benefits of a qualitative approach are that it overcomes the challenge of calculating accurate figures for asset value, cost of control, and so on, and the process is much less demanding on staff. Qualitative risk management projects can typically start to show significant results within a few weeks, whereas most organizations that choose a quantitative approach see little benefit for months, and sometimes even years, of effort. The drawback of a qualitative approach is that the resulting figures are vague; some Business Decision Makers (BDMs), especially those with finance or accounting backgrounds, may not be comfortable with the relative values determined during a qualitative risk assessment project.