The point of IT security is not to keep everything locked up. The reason we often think about security like that may be our day-to-day concepts of security. For example, maximum security prisons where particularly dangerous criminals are being kept. Keeping them locked up may be a comforting idea. However, we would probably squirm at the thought of maximum-security supermarkets, where only prescreened customers could get in for a limited. A high level of security is good but obviously it doesn’t work for all aspects of our society. Security needs to be flexible. We need a clearer understanding of what security is. Here are five theses on security that describe that.
Thesis 1: “Security Is the Ability to Mitigate the Negative Impact of a System Breach”
The consequence is that understanding what these impacts could be is the first step, not finding out what security tools can do and how many different types of mitigation you can pile onto the solution. Understanding potential negative impacts comes before thinking about how to mitigate them. If there are no or only small potential negative impacts of a system consequently no or little mitigation is necessary in order for the system to be secure.
Thesis 2: “Mitigation Always Has a Cost”
Security never comes for free. It may come at a low cost and the cost may be decreasing for certain types of mitigation over time, but it is never free. What’s more is that much of security costs are hidden.
There are three primary types of mitigation costs: economic cost, utility cost and time cost. The economic cost is capital and operational costs associated with mitigation. These include salary for security personnel, licenses and training. Usually, they are well understood and acknowledged and will be on budgets.
Utility costs arise when a solutions utility is reduced due to a mitigation effort. This is the case when a user is restricted in accessing certain types of information due to their role. A developer may want to use production data because it is easier or wants to perform certain system functions that he or she might otherwise need someone else to do. Full utility is only achieved with full admin rights, reducing those privileges as part of a security effort reduces utility.
Time costs arise when a mitigation effort increases the time spent to achieve an objective. For example, two factor authentication or the use of CAPTCHA are well known examples of time costs but approval flows for gaining access and authorizations in a system are other examples of time costs.
Only the first type is typically considered when thinking about security costs, but the others may exceed the economic costs. This means that security carry large unknown costs that need to be managed.
Thesis 3: “You Can Never Achieve 100% Mitigation with Higher Than 0% Utility”
The only 100% secure solution is to unplug the server, which of course renders it useless. It only becomes useful when you plug it in but then it has a theoretical vulnerability. If the discussion is only centered around how to achieve 100% protection any use is futile. The consequence of this is that the discussion needs to turn to the degree of protection. Nothing is easier than dreaming up a scenario that would render current or planned mitigation futile but how likely is that. We need to conceptualize breaches as happening with a certain probability under a proposed set of mitigations.
Thesis 4: “Marginal Risk Reduction of Mitigation Efforts Approach Zero”
The addition of each new mitigation effort needs to be held up against the additional reduction in the probability of a system breach or risk. The additional reduction of risk provided by a mitigation effort is the marginal risk reduction. When the marginal risk reduction approaches zero, additional mitigation should be carefully considered. Let us look at an example: If a service has no authentication the risk of a breach is maximal. Providing basic authentication is a common mitigation effort that will reduce risk significantly. Adding a second may provide a non-trivial reduction in risk but smaller than the first mitigation. Adding a third factor offers only a low marginal reduction in risk. Adding a fourth clearly approaches zero marginal reduction in risk. For some cases like nuclear attack, it may be warranted; for watching funny dog videos, maybe not.
Thesis 5: “The Job at Hand Is Not Just to Secure but to Balance Security and Utility”
Given that mitigation always has a cost, and the marginal risk reduction of additional mitigation efforts approaches zero, we need to reconsider the purpose of security. The purpose of security should therefore be reconceptualized from optimal protection to one of achieving the optimal balance between risk reduction, cost and utility. Finding that balance starts by understanding the nature and severity of the negative impacts of a system breach. While costs of mitigation continue to drop due to technological advances the full spectrum of costs should be considered. Preventing access to nuclear launch naturally needs top level security, but a blog about pink teddy bears does not. For every component we have in the cloud we need to make this analysis in order to achieve the right balance, not to live with too high risk and not spend unnecessarily to reduce an already low risk. At the same time we need to keep our eyes on how mitigation efforts impact the utility of the system so as not to unnecessarily reduce the usefulness.
Danish 
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