Impossible is impossible!

Sometimes when you plan for a security event, it would be expected that the thing you're doing will be making some outcome (something bad probably) impossible. The goal of the security group is to keep the bad guys out, or keep the data in, or keep the servers patched, or find all the security bugs in the code. One way to look at this is security is often in the business of preventing things from happening, such as making data exfiltration impossible. I'm here to tell you it's impossible to make something impossible.

As you think about that statement for a bit, let me explain what's happening here, and how we're going to tie this back to security, business needs, and some common sense. We've all heard of the 80/20 rule, one of the forms is that the last 20% of the features are 80% of the cost. It's a bit more nuanced than that if you really think about it. If your goal is impossible it would be more accurate to say 1% of the features are 2000% of the cost. What's really being described here is a curve that looks like this

You can't make it to 100%, no matter how much you spend. This of course means there's no point in trying, but more importantly you have to realize you can't get to 100%. If you're smart you'll put your feature set somewhere around 80%, anything above that is probably a waste of money. If you're really clever there is some sort of best place to be investing resources, that's where you really want to be. 80% is probably a solid first pass though, and it's an easy number to remember.

The important thing to remember is that 100% is impossible. The curve never reaches 100%. Ever.

The thinking behind this came about while I was discussing DRM with someone. No matter what sort of DRM gets built, someone will break it. DRM is built by a person which means, by definition, a smarter person can break it. It can't be 100%, in some cases it's not even 80%. But when a lot of people or groups think about DRM, the goal is to make acquiring the movie or music or whatever 100% impossible. They even go so far as to play the cat and mouse game constantly. Every time a researcher manages to break the DRM, they fix it, the researcher breaks it, they fix it, continue this forever.

Here's the question about the above graph though. Where is the break even point? Every project has a point of diminishing returns. A lot of security projects forget that if the cost of what you're doing is greater than the cost of the thing you're trying to protect, you're wasting resources. Never forget that there is such a thing as negative value. Doing things that don't matter often create negative value.

This is easiest to explain in the context of ransomware. If you're spending $2000 to protect yourself from a ransomware invasion that will cost $300, that's a bad investment. As crime inc. continues to evolve I imagine they will keep a lot of this in mind, if they can keep their damage low, there won't be a ton of incentive for security spending, which helps them grow their business. That's a topic for another day though.

The summary of all this is that perfect security doesn't exist. It might never exist (never say never though). You have to accept good enough security. And more often than not, good enough is close enough to perfect that it gets the job done.

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