String Theories

Design ❤ Security

June 16, 2015 | 7 Minute Read

To many people design and security are at the opposite ends of the tech spectrum. One deals with the deep complexities of how the machines and code work (or don't work). The other deals with how the very surface of the stack is presented to humans.

The reality is that they’re two sides of the same coin. They require the same type of thinking. They’re both about how people interact with systems, and about what motivates those people, for good or bad.

So, why don’t we work more closely together? Why don’t we learn from each other and use each other’s knowledge, techniques, and tools?

One tool that’s extremely popular in the design world is the persona. Personas are example user profiles. These include names, ages, backgrounds, motivations and aspirations, skills and frustrations. They are created by researching your user base and creating fictional composite profiles that reflect the range of your users.

Personas are used to help designers keep the needs and lives of the range of their users in mind when making decisions. This helps them to meet all their needs.

Design personas often lack any mention of privacy or security concerns. They rarely consider what it would mean for that user to lose access to their account, their personal details, for their business to be compromised.

Nor do they consider attacker-personas: personas for people you don’t want to access your systems.

I’m going to break down 3 recent examples I’ve seen where design and security could’ve worked together better using personas as a tool.

##The sign up form redesign

I recently observed a team redesign their sign up forms. The designers spent a lot of time working with the marketing team to figure out what information needed to be collected, and the best way to collect that information without creating friction for the customer. Versions were iterated over and A/B tested for hours and hours.

The resulting sign up form created a better experience for sign-up, but didn’t make any improvement in the weak security design.

The passwords had no minimum length, and no indication of strength to help users make smart decisions. No-one considered recommending a password management tool to the business customers of the site, despite the risks to their business. No-one talked to the security engineers.

The designers had created personas - but none of the personas mentioned security or privacy requirements. There were no personas for the bad guys. Nothing to help them think like the bad guys and work to thwart them. Here, security could help designers build the right personas to reduce risk to users.

##The Kiwicon talk

People outside the security community think about being compromised as an ‘if’.

The first thing you learn when you first start talking to the security community is that everything is fucked. Everything has holes. Everything is compromised. They don’t tell you this to terrify you; it’s just the baseline truth they work from.

Once you’re working from that baseline truth, it’s not a matter of if you’ll be compromised, but when.

There’s a fundamental difference in the way you approach the problem once you’re thinking ‘when’. When you’re in ‘if’ mode, you think about attacks as something you can prevent. You think you can keep people out if you just build big enough (metaphorical) walls.

Once you’re in ‘when’ mode, you have to start being strategic. The size of the wall doesn’t count; what matters is making the cost:benefit ratio too low. Attackers are humans with motivations.

At Kiwicon, a security conference, one of the speakers discussed this - understanding not only what you have to protect, but who you have to protect it from, and that they’re not an amorphous blob of “EV1L HACK3RS”.

He discussed understanding the difference in motivation and cost for a pro vs a script kiddie. He talked about the tools available to each of them, and what those tools enabled them to do. He talked about how much they time they were willing to spend, given that time equates to money, and how that related to the system you were trying to protect.

Essentially, he was talking about building attacker personas. These personas could then be used to help make strategic decisions about which parts of the systems to focus on defending. This helps to ensure the most effective defences are built with the limited resources available.

Like interface design, once you understand who you’re designing security for, it’s a lot easier to place obstacles in their way. Unlike interface design, security design doesn’t have a well-established practice for this. Here, designers could help security teams build personas to enable more effective defence.

The neat thing? Designers have to build new personas for every product. There are hundreds of different user personas, and each product only deals with the ones relevant to them. Attacker-personas are different. They’re less product-specific, and a good set of attacker-personas could be used to help plan security in many systems.

##The terrible product descended from CERN

Recently, I was linked to a new product: Better Error Pages from The product allows you to enter your brand colours and some details, and gives you a downloadable HTML file for a 404, 503, and maintenance page.

On the surface, it seems like a non-awful idea. Package up a nice, easy way to get a non-ugly error page. Users expect something a bit prettier these days. Everyone has them, and if you don’t, you’ll look bad.

Take a second glance, and it’s a terrible idea from both a design and a security perspective - something security and design personas would have shown in an instant.

For most applications, the majority of your end-users will be non-technical. Your design personas would likely highlight that, when something goes wrong, they feel comforted by professional presentation and clear directions. They don’t need or understand technical jargon.

They’re not interested in the error code on the page. They’re not really interested in your server issues. This is superfluous information. They want to know what to do next.

When you’re trying to break into someone else’s site, information is gold. The security personas would likely have highlighted that they’re interested in knowing where and when things are going wrong, because that’s somewhere they can start digging. There is no good reason to ever show an end-user an HTTP status code on a production site. You never, ever want to give an attacker more information than you need to.

This is a perfect example of cargo-cult programming. We should have them because everyone has them, right? Turns out that back in the early days of the Web, the original CERN httpd web server dumped status codes on a page for machines to read. They were never intended for users to read but people didn’t understand the specs, and so they just copied them. Decades later, they’re still here. In the intervening years, they’ve become beautiful and on-brand.

Our end users don’t want them. We don’t want to give them to attackers. But they still exist, and so do products like’s Error Pages.

Nobody involved in that product, from designers to security folks, sat down and thought about a persona-based design for this: giving the people who need information the right information at the right time, and keeping the stuff we don’t want to share out of reach.

##We should talk

The two disciplines are deeply interlinked. Bad design, especially bad UX, can cause bad security - like the banking apps that don’t let you paste your password in from your password manager, or don’t let you use your browser autocomplete.

Bad security can definitely result in a bad user experience. One of the biggest problems in security is the squishy humans, as Laura Bell would say, and that’s a problem that we need to work together to solve.

We don’t talk enough about how design and security can help each other. Let’s talk.