Understanding security risk management: Criticality categories

Security risk management involves a sober assessment of your client's business operations and the relative security risks of each. Once the need for security risk analysis has been recognized by your client, the next step is to establish catageories — such as mission-critical, vital, important and minor — in which to place each operational area. When this is done, it becomes easier to establish priorities for strengthening security measures where they are most needed.

By Susan Snedaker

Once the need for security risk analysis has been recognized by your client, the next step is to establish catageories — such as mission-critical, vital, important and minor — in which to place each operational area. When this is done, it becomes easier to establish priorities for strengthening security measures where they are most needed.

You can develop any category system that works for you but as with all rating systems, be sure the categories are clearly defined and that there is a shared understanding of the proper use and scope of each. Here is one commonly used rating system for assessing criticality:

  • Category 1: Critical Functions—Mission-Critical
  • Category 2: Essential Functions—Vital
  • Category 3: Necessary Functions—Important
  • Category 4: Desirable Functions—Minor

Obviously, your business continuity plan will focus the most time and resources on analyzing the critical functions first, essential functions second. It's possible you will delay dealing with necessary and desirable functions until later stages of your business recovery. Many companies identify these four areas and set timelines for when each of these categories will be functional following a business disruption. Let's look at each category in more detail. You can use these category descriptions as-is or you can tweak them to meet your company's unique needs.


Mission-critical business processes and functions are those that have the greatest impact on your company's operations and potential for recovery. Almost everyone working in a company has an innate understanding of the mission-critical operations within their department. The key is to gather all that data and develop a comprehensive look at your mission-critical processes and functions from an organizational perspective. What are the processes that must be present for your company to do business? These are the mission-critical functions. One way to get people to focus on the mission-critical functions is to ask (whether through questionnaire, interview, or workshops) what the first three to five things people would do in their department following a business disruption once the emergency or imminent threat of a business disruption subsides. This often gives you the clearest view of the mission-critical business functions in each department.

From an IT perspective, the network, system, or application outage that is mission-critical would cause extreme disruption to the business. Such an outage often has serious legal and financial ramifications. This type of outage may threaten the health, well-being, and safety of individuals (hospital systems come to mind).These systems may require significant efforts to restore and these efforts are almost always disruptive to the rest of the business (in the case that any other parts of the business are actually able to function during such an outage).The tolerance for such an outage, whether from the IT system or the function/process it provides, is very low and the recovery time requirement is often described in terms of hours, not days.


Some business functions may fall somewhere between mission-critical and important, so you may choose to use a middle category that we've labeled "vital" or "essential." How can you distinguish between mission-critical and vital? If you can't, you may not need to use this category.

However, you might decide that certain functions are absolutely mission-critical and others are extremely important but should be addressed immediately after the mission-critical functions. Vital functions might include things like payroll, which on the face of it might not be mission-critical in terms of being able to get the business back up and running immediately but which can be vital to the company's ability to function beyond the disaster recovery stage.

From an IT perspective, vital systems might include those that interface with mission critical systems. Again, this distinction may not be helpful for you. If not, don't try to force your systems into this framework; simply don't use this category. You'll end up with just three categories—mission-critical, important, and minor. If that works for you, that's fine. If you use this category, your recovery time requirement might be measured in terms of hours or a day or two.


Important business functions and processes won't stop the business from operating in the near-term but they usually have a longer-term impact if they're missing or disabled. When missing, these kinds of functions and processes cause some disruption to the business. They may have some legal or financial ramifications and they may also be related to access across functional units and across business systems.

From an IT perspective, these systems may include e-mail, Internet access, databases, and other business tools that are used in a support function, whether to support business functions or IT functions. If disabled, these systems take a moderate amount of time and effort (as compared to mission-critical) to restore to a fully functioning state. The recovery time requirement for important business processes often is measured in days or weeks.


Minor business processes are often those that have been developed over time to deal with small, recurring issues or functions. They will not be missed in the near-term and certainly not while business operations are being recovered. They will need to be recovered over the longer-term. Some minor business processes may be lost after a significant disruption and in some cases, that's just fine. Many companies develop numerous processes that should at some point be reviewed, revised, and often discarded, but that rarely occurs during normal business operations due to more demanding work. In some sense, a business disruption can be good for those small business functions and processes as they may be reworked or revised or simply pared down after a disruption. You may use the process of performing your BIA to recommend paring down these minor business functions as well, though your time is better spent focusing on the mission-critical and vital elements. You may make notes about which functions and processes could be pared down outside of the BC/DR planning process and hand this off to the appropriate SMEs for later action. From an IT perspective, these types of system outages cause minor disruptions to the business and they can be easily restored. The recovery time requirement for these types of processes often is measured in weeks or perhaps even months.

Be sure to prompt participants to think about all business processes throughout the year. Some functions and processes occur only during certain times of the year, such as tax season, year end, holidays, and such, and these might be missed during the process. If they're important enough processes, there's a good chance they'll be included, but project management best practices don't rely on luck—they rely on process. Be sure you to ask about any special processes that occur throughout the calendar year that might not immediately come to mind for participants.

Understanding security risk management

  How to perform security risk management
  Criticality categories
  Recovery time requirements

Business Continuity and Disaster Recovery Planning for IT Professionals
Reprinted from Chapter four of
Business Continuity and Disaster Recovery Planning for IT Professionals by Susan Snedaker. Printed with permission from Syngress, a division of Elsevier. Copyright 2007. For more information about this title, please visit www.syngress.com.

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