Schneier on Security:

Professional pilot Ron Rapp has written a fascinating article on a 2014 Gulfstream plane that crashed on takeoff. The accident was 100% human error and entirely preventable – the pilots ignored procedures and checklists and warning signs again and again. Rapp uses it as example of what systems theorists call the “normalization of deviance.”

The point is that normalization of deviance is a gradual process that leads to a situation where unacceptable practices or standards become acceptable, and flagrant violations of procedure become normal – despite that fact that everyone involved knows better.

I think this is a useful term for IT security professionals. I have long said that the fundamental problems in computer security are not about technology; instead, they’re about using technology. We have lots of technical tools at our disposal, and if technology alone could secure networks we’d all be in great shape. But, of course, it can’t. Security is fundamentally a human problem, and there are people involved in security every step of the way.

I have seen this personally many times, you can be sloppy several hundred/thousand/whatever times, and it doesn’t bite you, so you come to believe that being sloppy has no risk, and then boom out of “nowhere” a failure. When you look back and analyze the failure you will find that this complacency for the new normal of sloppy behavior is the root cause.