Breaking the Security Model of Subgraph OS
I recently traveled to Amsterdam to attend a meeting with Tor Project staff, volunteers, and other members of the wider Tor community. Before trips like this, I prepare a separate travel computer, only bringing with me data and credentials that I might need during my trip. My primary laptop runs Qubes, but this time I decided to install Subgraph OS on my travel laptop. I had only briefly messed with it before, and there’s no better way to learn about a new operating system than by forcing yourself to actually use it for a few days.
Subgraph OS is an “adversary resistant computing platform.” It’s similar to Tails in that it’s based on Debian and all traffic is forced through Tor (that’s changing though: there’s now basic support for clearnet Chromium and OpenVPN). It uses a grsecurity Linux kernel, and many apps run in “oz sandboxes”, a homebrew sandbox solution that protects you even if an attacker manages to exploit a bug in one of these apps. Subgraph OS also includes the Subgraph Firewall, an application firewall similar to Little Snitch for macOS — something that’s pretty awesome, and hasn’t really existed in the Linux ecosystem before. Basically, it’s designed to be an easy-to-use Linux distro that’s extremely secure.
Qubes Tip: Making Yubikey OpenPGP smart cards slightly more usable
Qubes 3.2 has support for USB passthrough. This one feature has made Qubes so much more useful for me. It means that a wide variety of devices — from my laptop’s internal webcam, to plugging in smartphones to transfer data or do Android development — are finally supported. I used to have to use a separate non-Qubes computer for several tasks that I can now more conveniently and securely do within Qubes.
How Qubes makes handling PDFs way safer
Bart Gellman asked me on Twitter how to make PDFs safe to open. This is an excellent question, especially for a Pulitzer-winning surveillance/national security reporter who needs to open documents from random people on the internet, who may be trying to hack him or may be a valuable new source. PDFs, and all other document formats, can be terribly dangerous, and opening a malicious one can let an attacker take over your computer.
He was specifically asking if PDF Redact Tools, a tool that I developed to securely redact documents, could be used in Tails to safely sanitize potentially-malicious PDFs before opening them. Yes you can, but Qubes offers some built-in tools that do a better job of this, in a safer manner, with less hassle, and that’s quicker and easier.
Qubes Tip: Opening links in your preferred AppVM
If you use Qubes like I do, you have many different AppVMs to compartmentalize different programs. You might have one VM for your email client, one for your jabber client, one for your password database. But if you click a link in any of these programs, it sure would be nice if that link opened in the browser VM of your choice. This isn’t all that hard to setup.
Backdoored Linux Mint, and the Perils of Checksums
Someone hacked the website of Linux Mint — which, according to Wikipedia’s traffic analysis report is the 3rd most popular desktop Linux distribution after Ubuntu and Fedora — and replaced links to ISO downloads with a backdoored version of the operating system. This blog post explains the situation.
Usable Crypto Capture the Flag Challenge
Last week, during USENIX’s first Enigma conference, EFF hosted a small Capture the Flag hacking competition. I designed one of the challenges myself, entitled Usable Crypto. It requires you to use PGP as an attacker rather than a defender. It’s on the easy side, as far as CTF challenges go, and I think many people who have absolutely no hacking skills but some fumbling-around-with-PGP skills could beat it without too much trouble. And it might even demonstrate why verifying fingerprints really is rather important.
Hardening Debian for the Desktop Using Grsecurity
I recently built a desktop system that I think is reasonably secure. It’s running Debian sid, also known as “unstable” — though in the Debian desktop world that just means you get to use the newest software. It’s just about as stable as “stable”, and besides, #yolo. It’s also running a grsecurity-patched Linux kernel and PaX, technologies that make Linux way more secure. Grsecurity protects you against memory corruption attacks, such as buffer overflows.
Some Thoughts on Faraday Bags and Operational Security
I recently took a trip to Moscow to interview National Security Agency whistblower Edward Snowden about operational security. In the article I published on The Intercept, I mentioned that I used a faraday bag.
Our first meeting would be in the hotel lobby, and I arrived with all my important electronic gear in tow. I had powered down my smartphone and placed it in a “faraday bag” designed to block all radio emissions.
Why I say Linux instead of GNU/Linux
I’ve been writing a computer security column for the Intercept. In most of my columns I mention Linux. Even when it’s not directly relevant (though it often is), most of my columns are in the form of tutorials, and I’d like my tutorials to be equally useful for Linux users as they are for Windows and Mac users.
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