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       One-on-one meetings

       Interviews

       Scenarios

       Delphi technique

      Determining which mechanism to employ is based on the culture of the organization and the types of risks and assets involved. It is common for several methods to be employed simultaneously and their results compared and contrasted in the final risk analysis report to upper management. Two of these that you need to be more aware of are scenarios and the Delphi technique.

      Scenarios

      The basic process for all these mechanisms involves the creation of scenarios. A scenario is a written description of a single major threat. The description focuses on how a threat would be instigated and what effects its occurrence could have on the organization, the IT infrastructure, and specific assets. Generally, the scenarios are limited to one page of text to keep them manageable. For each scenario, several safeguards are described that would completely or partially protect against the major threat discussed in the scenario. The analysis participants then assign to the scenario a threat level, a loss potential, and the advantages of each safeguard. These assignments can be simple—such as High, Medium, and Low, or a basic number scale of 1 to 10—or they can be detailed essay responses. The responses from all participants are then compiled into a single report that is presented to upper management. For examples of reference ratings and levels, please see Tables D-3, D-4, D-5, D-6, and E-4 in NIST SP 800-30 Rev.1:

       csrc.nist.gov/publications/detail/sp/800-30/rev-1/final

      The usefulness and validity of a qualitative risk analysis improves as the number and diversity of the participants in the evaluation increases. Whenever possible, include one or more people from each level of the organizational hierarchy, from upper management to end user. It is also important to include a cross-section from each major department, division, office, or branch.

      Delphi Technique

The Delphi technique is probably the primary mechanism on the previous list that is not immediately recognizable and understood. The Delphi technique is simply an anonymous feedback-and-response process used to enable a group to reach an anonymous consensus. Its primary purpose is to elicit honest and uninfluenced responses from all participants. The participants are usually gathered into a single meeting room. To each request for feedback, each participant writes down their response on paper or through digital messaging services anonymously. The results are compiled and presented to the group for evaluation. The process is repeated until a consensus is reached. The goal or purpose of the Delphi technique is to facilitate the evaluation of ideas, concepts, and solutions on their own merit without the discrimination that often occurs based on who the idea comes from.

      Quantitative Risk Analysis

      The quantitative method results in concrete probability indications or a numeric indication of relative risk potential. That means the end result is a report that has dollar figures for levels of risk, potential loss, cost of countermeasures, and value of safeguards. This report is usually fairly easy to understand, especially for anyone with knowledge of spreadsheets and budget reports. Think of quantitative analysis as the act of assigning a quantity to risk—in other words, placing a dollar figure on each asset and threat impact. However, a purely quantitative analysis is not sufficient—not all elements and aspects of the analysis can be accurately quantified because some are qualitative, subjective, or intangible.

      The process of quantitative risk analysis starts with asset valuation and threat identification (which can be performed in any order). This results in asset-threat pairings that need to have estimations of harm potential/severity and frequency/likelihood assigned or determined. This information is then used to calculate various cost functions that are used to evaluate safeguards.

The major steps or phases in quantitative risk analysis are as follows (see Figure 2.3, with terms and concepts defined after this list of steps):

      1 Inventory assets, and assign a value (asset value [AV]).

      2 Research each asset, and produce a list of all possible threats to each individual asset. This results in asset-threat pairings.

      3 For each asset-threat pairing, calculate the exposure factor (EF).

      4 Calculate the single loss expectancy (SLE) for each asset-threat pairing.

      5 Perform a threat analysis to calculate the likelihood of each threat being realized within a single year—that is, the annualized rate of occurrence (ARO).

      6 Derive the overall loss potential per threat by calculating the annualized loss expectancy (ALE).

      7 Research countermeasures for each threat, and then calculate the changes to ARO, EF, and ALE based on an applied countermeasure.

      8 Perform a cost/benefit analysis of each countermeasure for each threat for each asset. Select the most appropriate response to each threat.

FIGURE 2.3 The six major elements of quantitative risk analysis

The cost functions associated with quantitative risk analysis include the following:

       Exposure Factor The exposure factor (EF) represents the percentage of loss that an organization would experience if a specific asset were violated by a realized risk. The EF can also be called the loss potential. In most cases, a realized risk does not result in the total loss of an asset. The EF simply indicates the expected overall asset value loss because of a single realized risk. The EF is usually small for assets that are easily replaceable, such as hardware. It can be very large for assets that are irreplaceable or proprietary, such as product designs or a database of customers. The EF is expressed as a percentage. The EF is determined by using historical internal data, performing statistical analysis, consulting public or subscription risk ledgers/registers, working with consultants, or using a risk management software solution.

       Single-Loss Expectancy The single-loss expectancy (SLE) is the potential loss associated with a single realized threat against a specific asset. It indicates the potential amount of loss an organization would or could experience if an asset were harmed by a specific threat occurring.The SLE is calculated using the following formula:SLE = asset value (AV) * exposure factor (EF)or more simply:SLE = AV * EFThe SLE is expressed in a dollar value. For example, if an asset is valued at $200,000 and it has an EF of 45 percent for a specific threat, then the SLE of the threat for that asset is $90,000. It is not always necessary to calculate an SLE, as the ALE is the most commonly needed value in determining criticality prioritization. Thus, sometimes during risk calculation, SLE may be skipped entirely.

       Annualized Rate of Occurrence The annualized rate of occurrence (ARO) is the expected frequency with which a specific threat or risk will occur (that is, become realized) within a single year. The ARO can range from a value of 0.0 (zero), indicating that the threat or risk will never be realized, to a very large number, indicating that the threat or risk occurs often. Calculating the ARO can be complicated. It can be derived by reviewing historical internal data, performing statistical analysis, consulting public or subscription risk ledgers/registers, working with consultants, or using a risk management software solution. The ARO for some threats or risks is calculated by multiplying the likelihood of a single occurrence by the number of users who could initiate the threat. ARO is also known as a probability determination. Here's an example: the ARO of an earthquake in Tulsa may be .00001, whereas the ARO of an earthquake in San Francisco may be .03 (for a 6.7+ magnitude), or you can compare the ARO of an earthquake in Tulsa of .00001 to the ARO of an email virus in

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