Revenues:
Lost sales due to business interruption form a substantial part of a cyber incident’s costs. These can be estimated by multiplying average daily revenue by number of days expected outage. Some cyber incidents can take business critical systems out for months.
Headcount:
Restitution costs are proportional on the size of the IT estate. It is not uncommon for a company to replace all its software and PCs post breach to ensure they are restarting with a clean system. The number of PCs in a company is proportional to the number of employees, adjusted for the blue to white collar ratio.
Customers:
In the USA and Europe, companies that suffer data breaches are likely to suffer fines from the regulator linked to the number of customer records breached. But even excluding these regulatory fines, there are other costs that scale up relative to the number of customers a company has. Customers need to be formally notified that their data has been exposed and the dark web monitored to see where this data is surfacing. Often an external call centre needs to be engaged to handle all the concerned calls from clients. These costs are all proportional to the size of the customer base.