NewsBeat

18 NewsBeat May/June 2017 By MATTHEW GREEN Secure computing for journalists o, this is not a stupid question. Actually it's an extremely important question, and judging by some of the responses to this Tweet there are a lot of other people who are confused about the answer. Since I couldn't find a perfect layperson's reference anywhere else, I'm going to devote this post to providing the world's simplest explanation of why, in the threat model of your typical journalist, your desktop machine isn't very safe. And specifically, why you're safer using a modern mobile device — and particularly, an iOS device — than just about any other platform. A brief caveat: I'm a cryptographer, not a software security researcher. However, I've spent the past several years interacting with folks like Charlie and Dan and Thomas. I'm pretty confident that they agree with this advice. What's wrong with my laptop/desktop machine? Sadly, most of the problem is you. If you're like most journalists — and really, most professionals — you spend less than 100% of your time thinking about security. You need to get work done. When you're procrastinating from work, you visit funny sites your friends link you to on Facebook. Then you check your email. If you're a normal and productive user, you probably do a combination of all these things every few minutes, all of which culminates in your downloading some email attachment and (shudder) opening it in Word. N You can't tell journalists "just don't open attachments." They will ignore you. Journos open attachments from strangers for a living. — Eva (@evacide) Now I'm not trying to shame you for this. It's perfectly normal, and indeed it's necessary if you want to get things done. But in the parlance of security professionals, it also means you have a huge attack surface. In English, this means that from the perspective of an attacker there are many different avenues to compromise your machine. Many of these aren't even that sophisticated. Often it's just a matter of catching you during an unguarded moment and convincing you to download an executable file or an infected Office document. A compromised machine means that every piece of software on that machine is also vulnerable. If you don't believe this works, head over to Google and search for "Remote Access Trojans". There's an entire commercial market for these products, each of which allows you to remotely control someone else's computer. These off-the-shelf products aren't very sophisticated: indeed, most require you to trick your victim into downloading and running some executable attachment. Sadly, this works on most people just fine. And this is just the retail stuff. Imagine what a modestly sophisticated attacker can do. I do some of those things on my phone as well. Why is a phone better? Classical (desktop and laptop) operating systems were designed primarily to support application developers. This means they offer a lot of power to your applications. An application like Microsoft Word can typically read and write all the files available to your account. If Word becomes compromised, this is usually enough to hurt you. And in many cases, these applications have components with root (or Administrator) access, which makes them even more dangerous. Modern phone operating systems like Android and iOS were built on a different principle. Rather than trusting apps with much power, each app runs in a "sandbox" that (mainly) limits it to accessing its own files. If the sandbox works, even a malicious application shouldn't be able to reach out to touch other apps' files or permanently modify your system. This approach — combined with other protections such as in-memory code signing, hardware secret storage and routing use of anti-exploitation measures — makes your system vastly harder to compromise. Of course, sandboxing isn't perfect. A compromised or malicious app can always access its own files. More sophisticated exploits can "break out" of the sandbox, typically by exploiting a vulnerability in the operating system. Such vulnerabilities are routinely discovered and occasionally exploited. The defense to this is twofold: (1) first, run a modern, up-to-date OS that receives security patches quickly. And (2) avoid downloading malicious apps. Which brings me to the main point of this post. Buzzfeed editor Miriam Elder asks the following question: Possibly stupid question: is the Signal desktop client as secure as the mobile app? — Miriam Elder (@MiriamElder)

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