ANSI Cyberrisk Calculation Guide
In a nutshell, the guide advocates that organizations calculate cyber security risks and costs by asking questions of every organizational discipline that might be affected: legal, compliance, business operations, IT, external communications, crisis management, and risk management/insurance. The idea is to involve everyone who might be affected by a security breach and collect data on the potential risks and costs.
Once all of the involved parties have weighed in, the guide offers a mathematical formula for calculating financial risk: Essentially, it is a product of the frequency of an event multiplied by its severity, multiplied by the likelihood of its occurrence. If risk can be transferred to other organizations, that part of the risk can be subtracted from the net financial risk.
Guide is here.