How to protect
In order to identify weaknesses in the security system that could be exploited by a perpetrator, a vulnerability and associated risk assessment should be conducted. Throughout the assessment process well-established security principles, including security zones and defence in depth, need to be taken into account.
'Security zones' refers to the concept of defining a series of clearly distinct areas to progressively control unauthorized access, separated by single or a set of security controls. 'Defence in depth' refers to using a layered approach to employ different and often redundant security measures to support and complemrnt each other. Thus,if one layer of defence turns out to be inadequate, another layer of defence may nevertheless prevent a full breach. The different layers may be technological,procedural or organizational by nature and work in coordination.
To estimate site vnlnerabilities, scenarios need to be developed in which the existing security controls are measured against one or several threat levels established in the threat analysis for different type of perpetratrators. In practice the main part of the vulnerability analysis is a 'vulnerability workshop' where a modified SWIFTT (Structured What If Technique) approach is used. Key employees, security staff,facility engineers, operational staff and others are invited to a brainstorming exercise preformed in a structured manner to identify potential access modes to critical assets. The analysis itself is based exploring existing controls, together with potential threats and vulnerabilies with access zones and layers of protection that lead progressively towards the assets to be protected. Each layer is systematically reviewed in terms of strengths and weaknesses, but also evaluated against its potential to deter, detect, delay and deny (the so-called 'D scores') the defined perpetrators. An assessment is then made of the system capability and this is matched against the organization's agreed acceptance criteria for the level of protechion required. In that wat a series of credible scenarios is developed and an evaluation can be made of the system's ability to meet stated objectives, and deficiencies can be identified and addressed.
The objective of the risk analysis is to estimate the risk associated with each scenario that has been developed and prioritzed in the vnlnerability analysis. To do this an estimate of the probability of challenge to your organiztion by any given threat must be made. This can be a difficult and demanding task that will often be associated with a great deal of uncertainty. However, it is an essential task if a security system is to be based on risk rather than relying on potential impact. Clearly this would be an unfortunate position for organizations that possess assets that potentially could cause catastrophic impacts if compromised, but where the credible threat to these assets is insignificant.
Thus risk assessment provides the decision maker with an enhanced basis for making a substantiated decision on wherther or not risk-reducing measures should be implemented to assure adequate security of the owner's asset, and provides a foundation for performing cost-effectiveness studies for proposed controls.