by adam on October 7, 2014
There’s a recurring theme in data breach stories:
The risks were clear to computer experts inside $organization: The organization, they warned for years, might be easy prey for hackers.
But despite alarms as far back as 2008, $organization was slow to raise its defenses, according to former employees.
The particular quote is from “Ex-Employees Say Home Depot Left Data Vulnerable,” but you can find similar statements about healthcare.gov, Target, and most other breaches. It’s worth taking apart these claims a little bit, and asking what we can do about them.
This is a longish blog post, so the summary is: these claims are true, irrelevant, and a distraction from engineering more secure organizations.
I told you so?
First, these claims are true. Doubtless, in every organization of any size, there were people advocating all sorts of improvements, not all of which were funded. Employees who weren’t successful at driving effective change complain that “when they sought new software and training, managers came back with the same response: ‘We sell hammers.’” The “I told you so” isn’t limited to employees, there’s a long list of experts who are willing to wax philisophic about the mote in their neighbors eyes. This often comes in the form of “of course you should have done X.” For example, the Home Depot article includes a quote from Gartner, “Scanning is the easiest part of compliance…There are a lot of services that do this. They hardly cost any money.” I’ll get to that claim later in this article. First, let’s consider the budget items actually enumerated in the article.
In the New York Times article on Home Depot, I see at least four programs listed as if they’re trivial, cheap, and would have prevented the breach:
- Threat intelligence
- Continuous (network) anomaly detection
- Vulnerability scanning
Let’s discuss each in turn.
(1) The claims that even modern, updated anti-virus is trivially bypassed by malware employed by criminals are so common I’m not going to look for a link.
(2) Threat intelligence (and “sharing”) usually means a feed of “observables” or “indicators of compromise.” These usually include hashes of files dropped by intruders, IP addresses and domain names for the “command and control” servers or fake emails which are sent, either containing an exploit, a trojan horse, or a phishing link. This can be useful if your attackers don’t bother to change such things between attacks. The current state of these feeds and their use is such that many attackers don’t really bother to make such changes.
(See also my previous comments on “Don’t share, publish:” we spend so much time on rules for sharing that we don’t share.) However, before saying “everyone should sign up for such services,” “they’ll be a silver bullet,” we should consider what the attackers will do, which is to buy the polymorphism services that more common malware has been using for years. So it is unlikely that threat intelligence would prevent this breach.
(3) Continuous anomaly detection generally only works if you have excellent change management processes, careful network segmentation, and a mostly static business environment. In almost any real network, the level of alarms from such systems are high, and the value of the alarms, incredibly low. (This is a result of the organizations making the systems not wanting to be accused of negligence because their system didn’t “sound the alarm,” and so they alarm on everything.) Most organizations who field such things end up ignoring the alarms, dropping the maintenance contracts, and leaving the systems in place to satisfy the PCI auditors.
(4) Vulnerability scanning may be cheap, but like anomaly detectors, they are motivated to “sound the alarm” on everything. Most alarms are not push-button remediation. Even if that feature is offered, there’s a need to test the remediation to see if it breaks anything, to queue it in the aforementioned change management, and to work across some team boundary so the operations team takes action. None of which falls under the rhetoric of “hardly cost any money.”
The Key Question: How to do better?
Any organization exists to deliver something, and usually that something is not cyber security. In Home Depot’s case, they exist to deliver building supplies at low cost. So how should Home Depot’s management make decisions about where to invest?
Security decisions are like a lot of other decisions in business. There’s insufficient information, people who may be acting deceitful, and the stakes are high. But unlike a lot of other decisions, figuring out if you made the right one is hard. Managers make a lot of decisions, and the relationship between those decisions and the security outcomes is hard to understand.
The trouble is, in security, we like to hide our decisions, and hide the outcomes of our decisions. As a result, we never learn. And employees keep saying “I told you so” about controls that may or may not help. As I said at BSides Las Vegas, companies are already paying the PR price, they need to move to talking about what happened.
With that information, we can do better at evaluating controls, and moving from opinions about what works (with the attendant “I told you so”) to evidence about effective investments in security.
by adam on September 29, 2014
My thanks to the judges, most especially to Gastón Hillar for the constructive criticism that “Unluckily, the author has chosen to focus on modeling and didn’t include code samples in the book. Code samples would have been very useful to make the subject clearer for developers who must imagine in their own lines of code how some of the attacks are performed.” He also says “Overall, this is an excellent volume that should be examined by most developers concerned with issues of security.” The full review is at “Jolt Finalist: Threat Modeling.”
by adam on August 27, 2014
All through the week of BSides/BlackHat/Defcon, people came up to me to tell me that they enjoyed my BSides Las Vegas talk. (Slides, video). It got some press coverage, including an article by Jon Evans of TechCrunch, “Notes From Crazytown, Day One: The Business Of Fear.” Mr. Evans raises an interesting point: “the computer security industry is not in the business of openness, it is in the business of fear.” I’ve learned to be happy when people surface reasons that what I’m saying won’t work, because it gives us an opportunity to consider and overcome those objections.
At one level, Mr Evans is correct. Much of the computer security industry is in the business of fear. There are lots of incentives for the industry, many of which take us in wrong directions. (Mr. Evans acknowledges the role of the press in this; I appreciate his forthrightness, and don’t know what to do about that aspect of the problem, beyond pointing out that “company breached” is on its unfortunate way to being the new “dog bites man.”)
But I wasn’t actually asking the industry to change. I was asking professionals to change. And while that may appear to be splitting hairs, there’s an important reason that I ask people to consider issues of efficacy and burnout. That reason is I think we can incentivize people to act in their own long term interest. It’s challenging, and that’s why, after talking to behavior change specialists, I chose to use a set of commitment devices to get people to commit to pushing organizations to disclose more.
I want to be super-clear on my request, because based on feedback, not everyone understood my request. I do not expect everyone who tries to succeed. [#include Yoda joke.] All I’m asking people to do is to push their organizations to do better. To share root cause analyses. Because if we do that, we will make things better.
It’s not about the industry, it’s about the participants. It’s about you and me. And we can do better, and in doing so, we can make things better.
by adam on July 10, 2014
Gabrielle Gianelli has pulled back the curtain on how Etsy threat modeled a new marketing campaign. (“Threat Modeling for Marketing Campaigns.”)
I’m really happy to see this post, and the approach that they’ve taken:
First, we wanted to make our program sustainable through proactive defenses. When we designed the program we tried to bake in rules to make the program less attractive to attackers. However, we didn’t want these rules to introduce roadblocks in the product that made the program less valuable from users’ perspectives, or financially unsustainable from a business perspective.
Gabrielle apologizes several times for not giving more specifics, eg:
I have to admit upfront, I’m being a little ambiguous about what we’ve actually implemented, but I believe it doesn’t really matter since each situation will differ in the particulars.
I think this is almost exactly right. I could probably tell you about the specifics of the inputs into the machine learning algorithms they’re probably using. Not because I’m under NDA to Etsy (I’m not), but because such specifics have a great deal of commonality. More importantly, and here’s where I differ, I believe you don’t want to know those specifics. Those specifics would be very likely to distract you from going from a model (Etsy’s is a good one) to the specifics of your situation. So I would encourage Etsy to keep blogging like this, and to realize they’re at a great level of abstraction.
So go read Threat Modeling for Marketing Campaigns
by adam on June 11, 2014
Stefan Larson talks about “What doctors can learn from each other:”
Different hospitals produce different results on different procedures. Only, patients don’t know that data, making choosing a surgeon a high-stakes guessing game. Stefan Larsson looks at what happens when doctors measure and share their outcomes on hip replacement surgery, for example, to see which techniques are proving the most effective. Could health care get better — and cheaper — if doctors learn from each other in a continuous feedback loop? (Filmed at TED@BCG.)
Measuring and sharing outcomes of procedures? I’m sure our anti-virus software makes that unnecessary.
But you should watch the talk anyway — maybe someday you’ll need a new hip, and you’ll want to be able to confidently question the doctors draining you of evil humors.
by adam on May 1, 2014
I’m planning to be on the East Coast from June 16-27, giving threat modeling book talks. (My very popular “Threat Modeling Lessons from Star Wars.”) I’m reaching out to find venues which would like me to come by and speak.
My plan is to arrive in Washington DC on the 16th, and end in Boston, flowing generally northwards. We intend to nail down a schedule on May 15th, so please be in touch by then.
If you are along that path, and would like me to come speak on threat modeling, please let me know by emailing firstname.lastname@example.org. I’m working with Erika of VACreatively to help me organize things.
We look forward to hearing from you and are happy to answer questions you might have.
by adam on April 23, 2014
Today, most presentations on threat modeling talk about each phase of the process. They talk about how to model what you’re building, what can go wrong, and what to do about it. Those tightly coupled processes can be great if you’ve never heard of an approach to threat modeling. But they can add to the challenge for those trying to execute the process. What knowledge and skills can they re-use, and what do they need to replace?
Two of the big ideas in Threat Modeling: Designing for Security are that there’s more than one way to threat model, and that we can and should compose them. We can move beyond every talk covering how to model, how to find problems, and how to fix them. And when we do that, we improve our ability to agilely engage with new approaches, because the cost of experimentation falls.
One such new approach is DIAL: Discovery, Incorrectness, Authorization/Authentication, Limits/Latency. It’s a set of ‘threats’ to reliability, being explored by my colleagues in Microsoft Trustworthy Computing’s Reliability team. DIAL is an interesting complement to security threat modeling, because it starts with a D which (of course) stands for Denial of Service in STRIDE. And that’s sort of neat.
Anyway, the blog posts are worth checking out:
- Reliability vs. resilience
- Categorizing reliability threats to your service
- Reliability-enhancing techniques (Part 1)
- Reliability-enhancing techniques (Part 2)
[Update: inserted "D" in the "starts with a .." sentence. Thanks Mike for pointing out the error!]
by adam on April 21, 2014
It has to be said that no one in the Princess Bride is great at threat modeling. But one scene in particular stands out. It’s while they’re planning to attack the castle and rescue Buttercup:
Westley: I mean, if we only had a wheelbarrow, that would be something.
Inigo: Where we did we put that wheelbarrow the albino had?
Fezzik: Over the albino, I think.
Westley: Well, why didn’t you list that among our assets in the first place?
The trouble here is that Inigo and Fezzik don’t see a wheelbarrow as an asset worth listing. They know about it, but don’t bring it up. This is a predictable and even desirable state. When you model, you discard details that seem irrelevant. If you list absolutely everything, you end up sounding like the rain man, not an engineer.
Knowing what’s important enough to list is challenging. There’s no prescriptive guidance to what assets are worth including. (Because it’s challenging to know what’s a good list, there’s also no clear exit criteria or “gate.”)
Security experts love to complain that others have left things out. If you want to complain, you need to start with a clear definition of what’s an asset, what assets are important enough to list (A $10 wheelbarrow?), and what constitutes a good list. That’s simply easier with the technology that you’re threat modeling, rather worrying about assets.
by adam on April 17, 2014
George Hulme interviewed me for Devops.com, and the article is at “Q&A: Speaking DevOps and Threat Modeling.”
Its obvious that devops is an important trend, andit’s important to understand how to align threat modeling to that world.
by adam on April 15, 2014
A couple of reviewers have commented that they have different perspective on assets. For example, in a review I very much appreciated, Gunnar Peterson says:
I have slightly a different perspective on Shostack’s view on assets. The book goes into different views that launch the threat model, the approach advocated for in the book is very software-centric. I have no quibble on that, especially if you work for a software company. But for a financial institution, a supply chain, a healthcare company, I think it works less well to assume a software first view of the world. Its simpler in those companies to get traction by looking at the assets in play – accounts, confidential data, supplier access, and so on. for one thing, you can engage a wider portion of the organization. For another you have an easier time linking the resultant threats to a business impact.
The TL;DR response is consultants may like asset-centered approaches more than others, and the closer you are to the code, the less helpful they are. Previously, I wrote (page 39):
Focusing on assets appears to be a common-sense approach to threat modeling, to the point where it seems hard to argue with. Unfortunately, much of the time, a discussion of assets does not improve threat modeling. However, the misconception is so common that it’s important to examine why it doesn’t help.
There’s no direct line from assets to threats, and no prescriptive set of steps… That discussion, at best, results in a list of things to look for in your software or operational model, so why not start by creating such a model? Once you have a list of assets, that list is not (ahem) a stepping stone to finding threats; you still need to apply some methodology or approach. Finally, assets may help you prioritize threats, but if that’s your goal, it doesn’t mean you should start with or focus on assets. [Note that this sentence could be more clear as "assets may help you prioritize threats, but that doesn’t mean you should start with, or focus on, assets.']
Let me say a bit more, since this perspective keeps coming up in both reviews and private conversations. Financial institutions are a great example, because, after all, they hold money as an asset which attackers want and that they want to defend, so we can avoid definitional issues. We can over-simplify and say that money is THE asset that the bank has. Also, I’ve done a fair amount of work threat modeling for financial institutions, so I have a basis for discussing how those systems are really built.
So, let’s take a retail bank as an example. (In contrast to an investment bank, a retail bank does most of its business with consumers and businesses, providing things like loans and money management.) The bank has a general ledger (GL) system. It’s often still on a mainframe, and it is the only place where money really moves from one account to another. So we should start threat modeling there, right? Maybe.
Let’s look at the rest of the business. It turns out that there are pretty much two types of systems at the bank: those that touch the GL as a matter of course, and the desktops and laptops that people use to do their day jobs. In other words, pretty much everything that the bank has deployed, from the web front ends that show you your balance through to the inter-bank transfer systems like ACH and credit cards through the systems that calculate taxes have access to the GL. That access is often mediated through several layers of control, protocol translation and the like, but the access is there. Worse, even the systems that you’d hope are read-only (the tax calculators) can often move money around (manage deductions, enforce IRS mandatory withholding, etc). Now, I’m modeling, that is to say simplifying. But in this instance, I don’t think I’m dramatically over-simplifying.
If you go and enumerate everywhere the money is, or everywhere that there’s access to the GL, what you eventually get to (in essence) is a model of the software. It’s more expensive than a software-mainly model because you need to draw in additional people who can explain the business processes, and add a layer of model that covers how money moves.
Now, it may be that if you come in consulting at the senior management level (and I think Gunnar often does), that you start from the money because the senior management folks have no idea how their systems are actually plugged together, and figuring it out requires following the business processes, and reporting will require going back along that path of following the money. So here, I think the difference is one of intended audience: the book is primarily for people building or operating software, not consultants. If we make it accessible, those folks can and should learn to threat model. It’s easier than git.
People building software or systems at a financial institution, a supply chain, or a healthcare company should start from the software they’re building because it’s what they know best. Another way to say this is that they are surrounded by layers of business analysts, architects, project managers, and other folks who translate between the business requirements (including assets) and software and system requirements.
Gunnar and I agree that assets are a great tool to link “the resultant threats to a business impact.” It’s my experience (as a consultant and at my current employer) that the assets come out in risk discussion after you’ve identified a software issue.
So to answer the question: it depends who you are. If you know the software, you should start there.