Groundrules on Complaining About Security

Groundrules on Complaining About Security

In this article, I want to lead into some other articles I’m working on. In those, I’m going to complain about security. But I want those complaints to be thoughtful and within a proper context.

You will hear many of us in security talk about threat models. Adam literally wrote the book on threat models and if you don’t have a copy, you should get one.

Threat models are a way of thinking about security in a somewhat rigorous way. Without some sort of threat model, you’re not really doing security.

Threat models sound complex, but they’re really not. We all do them intuitively all the time, and here’s the basic outline of how to make one. You want answers to these questions:

  1. What are you doing?
  2. What could go wrong?
  3. What are you doing about it?

Among the valuable things in Adam’s book, he talks about these and more, but these three simple questions frame how to talk about security no matter who you are. If you don’t have a threat model, you might be doing something useful, but it’s not really security.

If you are a maker of security, without a threat model you might have a solution in search of a problem. You might also have a stone soup security system, in which you throw a bunch of things in a pot, and while tasty (or secure), isn’t organized. There are many, many stone soup security systems out there.

If you’re going to use a security system, without a threat model you have no way to know if what you’re getting meets your needs.

If you’re challenging a security system, without a threat model, your criticisms may be true but irrelevant.

It is these latter two cases – deciding what security system to you and providing a critique of a security system – that I’m going to focus on, particularly since I’m going to be engaging in challenges, and people selecting a system also need to think about what their own threat model is when selecting a system. If you’re going to use a secuity system, a little bit of thought about what you expect it to do and what you expect it to protect you from is in required.

Let me move a bit away from computer security for a moment; analogies often help.

Let’s look at this statement:

  • Aspirin doesn’t cure cancer.

It’s true. Aspirin doesn’t cure cancer. It doesn’t do half-bad on headaches (with of course, a number of other qualifiers), but it doesn’t cure cancer.

However, if Alice says, “I’m going to go take an aspirin” and Bob says, “Aspirin doesn’t cure cancer,” he has implicitly assumed that her threat model is not:

  • I have a headache
  • I’m going to take an aspirin to cure it

but

  • I have cancer
  • I’m going to take an aspirin to cure it.

Even if Alice actually does have cancer, she might also have a headache. Especially if she has to deal with someone with simplisitic thinking like Bob. This is the sort of headache that got me to write this essay.

Getting back to security, while I was typing the first part of this, a friend and I started on a discussion. We started with wondering if since most front door locks are easily picked, does that mean that they’re just security theatre. The discussion then went into social value of locks (most people are honest, after all), the technological merits of Abloy locks, the expense of getting a good lock for all your doors, the human factors aspects of wanting one key for all your doors, the security problem of weak points from the porch to the windows, and then on to reinforcing hinges and even the front door itself. It was a fun discussion, but it wasn’t a good security discussion, it was security stone soup. The initial question of whether most door locks do anything was the pot of water with a stone in it and we kept adding in garnishes until we ended up with a tasty conversation. However, at no point did we discuss a threat model. We don’t know what we were trying to protect, what threats we were protecting it from, or anything that turns it into a real security discussion.

I think we were talking about a stereotypical threat of a burglar backing up a van to the house and carting off a lot of valuables, but I am just presuming that.

I know of what I speak in this issue of threat models because I’m guilty of it, too. It’s so easy to get caught up in security stone soup that it happened to me while I was writing an essay on threat models and security stone soup.

Now that I have a couple of ground rules in place as a preface, I will complain about security in my next essay.

Blue Hat Report

The other thing I did at Microsoft last week was I participated in Blue Hat. Microsoft invites a selection of interesting researchers to come to Redmond and present a talk to a variety of people within the company. Blue Hat is organized by Kymberlee Price, who works with Andrew Cushman, and they did a great job as hosts.

Thursday was the executive sessions, speakers gave truncated versions of their talks, once in the morning, and once in the afternoon. There were a very senior group of folks in the room, up to people like Jim Allchin, Brian Valentine, and a lot of other names that I recognized, but don’t remember.

Andrew Cushman did a great job of framing the talks, explaining why they were selected, and the reasons that they were important. The audience was engaged, and a couple of times, people turned and asked “Why do we do that?” of the person responsible for a feature that was being (ahem) presented in a new light.

The speakers, myself, and Dan Kaminsky got to have a lunch session with Jim Allchin, and a few other Microsoft folks. Jim talked about new features in upcoming products, and got our thoughts on how Microsoft is doing, and how they could do better.

There’s lots more after the break.

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What Is Phishing

In conversation with a friend, I realized that my essay, “Preserving the Internet Channel Against Phishers” didn’t actually explain the problem. I made the assumption that everyone had the same perception of what it was. (Why didn’t anyone point that out?) So I’ve added the following (after the break), and I think the resultant essay is much improved.

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