Hey, I got good news for you. Another taxonomy coming up, list that you have to keep track of. But pretty soon we'll be running out of lists. So, do hang with me. Now listen, it turns out that there are really three primary types of threats that we deal with on the internet and in computing. In a minute, I'll tell you there may be a fourth. But let's start with the first three. And threat really is something bad that can happen to an asset. An asset is the thing you care about: your computing, your network your software, your infrastructure, your data, your customer lists, your source code. Things you care about. Something bad can happen to that as a result of some sort of malicious attack. We call that a threat. Notice, the English word threat is something that I would use with you as some way of causing you to think that some future action might happen in a bit like I'm going to threaten you. This is a little different. Think of threat more as a technical term that just describes a set of possible conditions that can cause something bad to an asset. So, let's take the first three. First one is called confidentiality and that's where secrets are given up. There's leaks of information. If you live here in the United States, then you know we've had issues in our government with a lot of things leaking and with election-related leaking. And well, it can be very damaging when information that was intended to be secret is leaked. Think about a conversation you may have had with a friend. You may have said some things that you don't want everyone to know about. But if I had a secret listener and I was able to capture what you said and then I push on the internet, you're not going to like that. The property of preventing that is called privacy. So, when we have privacy properties, then we worry less about confidentiality or disclosure problems. That make sense? So, confidentiality is the first threat type. Second is called integrity and that has to do with malicious modification, malicious altering of something. That's where I go in, instead of reading and stealing your data, I change your system. I alter it. I break it. I infect it. I do something that effects the validity or the integrity of the system. A million examples but obviously malware and viruses are the most common. Malware in a system is an example of an integrity threat. So, that's our second one. Third one is called availability, and you might think of it also is denial of service. That's where a hacker, a malicious actor, somebody takes steps to block legitimate access to some resource like the network. I can see your network's hooked up to a internet service provider pipe through a router and the internet service provider takes you out to the internet. Your network, ISP, internet, got that? And then somebody out on the internet decides, hey I want to make it difficult for you to connect to the internet. So, what I'm I going to do? I'm going to make this link real busy. I'm going to just keep sending stuff to you over and over and over and over again. Create a gigantic traffic jam on your ISP ingress or egress pipe. And, sadly, normal users can't get in because it's too busy creating traffic jam. We call that a denial of service attack. So, the first three when we organize them by the first letters: confidentiality, integrity, availability. It spells CIA and I guess, you know, in the US, there's like a little joke there that it would be like the CIA. But we call it the CIA model of cybersecurity, the three types of threats. Here's the problem, I think there's a fourth threat type. And I wrote a textbook on this 25 years ago and I put this in there. But the fourth, well, let me tell you, I think it's theft or fraud. And here's the idea. If I steal money, if I steal a service without paying, I could say get on a train and I'm riding on an empty train. And I might be, if I'm in the US, I'm taking a train from New York to Philadelphia. I get on early in the morning. I sit down, the whole train's empty. The conductor comes up and says, "Hello sir, do you have a ticket?" And I say, "I don't have a ticket." He goes, "What you mean, you don't have a ticket?" I say, "I don't have a ticket. I don't have any money but I'm going to get a job in Philadelphia. If I get a job, I'll take the train all the time. Can you let me go?" What does the conductor do? Should the conductor throw you off, leave you on. You are committing fraud. You're stealing service. Now, I hope you let him stay on. Seems like a nicer world if the conductor let you stay on. But set that aside. You can see it's not really a disclosure problem. It's not really integrity. And certainly not denial of service. Nobody's on the train. So, when people steal services without paying, I think it's a fourth threat type. So, sometimes I say fraud is a fourth, and I say CIAF model. But the CIA model is well established in computer security. Either one works but you certainly should recognize that CIA are well developed kind of concepts. Let's test our thinking here a little bit.
