The misleading microscopic view

The Guardian lists 10 gross ingredients you didn’t know were in your food, ingredients like arsenic, hair, or silicone breast implant filler. Should we react with nausea and disgust? Of course not. Yummy food is yummy food, neither a just detectable trace of someting (arsenic) nor the source of an ingredient (hair) nor possible other uses of the same ingredient (breast implants) have any noticeble impact. That’s by definition: if a dose of anything has a proven adverse health impact, it will be banned from being used in food. The Guardian‘s list is an example of microscopic properties that don’t matter macroscopically. Yummy food is yummy food.

We commit the same error when, in security, we look just at the software defects and neglect their security impact. All software has defects; we might easily assemble a list of 10, or 100, or 1000 defects you didn’t know were in your programs. This does not mean they’d all matter and need to be removed. A system is secure if it evokes a predictable and controlled incident profile over its lifetime. some software defects in some systems affect this incident profile in such a way that their removal matters. Others are just traces of poison, or issues appearing problematic by analogy. The problem is: we often don’t know which is which.