Against DNSSEC

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All secure crypto on the Internet assumes that the DNS lookup from names to IP addresses are insecure. Securing those DNS lookups therefore enables no meaningful security. DNSSEC does make some attacks against insecure sites harder. But it doesn’t make those attacks infeasible, so sites still need to adopt secure transports like TLS. With TLS properly configured, DNSSEC adds nothing…

Troy Hunt: HTTPS adoption has reached the tipping point

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That’s it – I’m calling it – HTTPS adoption has now reached the moment of critical mass where it’s gathering enough momentum that it will very shortly become “the norm” rather than the exception it so frequently was in the past. In just the last few months, there’s been some really significant things happen that have caused me to make this call, here’s why I think we’re now at that tipping point…

Steer! An Experimental Canvas/Websocket Game

As you may know, I’ve lately found an excuse to play with some new web technologies, and I’ve also taken the opportunity to try to gain a deeper understanding of some less bleeding-edge technologies that I think have some interesting potential. And so it was that, while I was staffing the Three Rings stall at last week’s NCVO conference, I made use of the time that the conference delegates were all off listening to a presentation to throw together a tech demo I call Steer!

Animated GIF from a video, showing a player using their mobile phone to steer a car on a desktop computer screen, all using the web browsers on both devices.
A player uses their mobile phone to steer a car on a desktop computer, using nothing more than a web browser.

As you can see from the GIF above, Steer! is a driving game. The track and your car are displayed in a web browser on a large screen, for example a desktop or laptop computer, television, or tablet, and your mobile phone is used to steer the car by tilting it to swerve around a gradually-narrowing weaving road. It’s pretty fun, but what really makes it interesting to me is the combination of moderately-new technologies I’ve woven together to make it possible, specifically:

  • The Device Orientation API, which enables a web application to detect the angle at which you’re holding your mobile phone
  • Websockets as a mechanism to send that data in near-real-time from the phone to the browser, via a web server: for the fastest, laziest possible development, I used Firebase for this, but I’m aware that I could probably get better performance by running a local server on the LAN shared by both devices
  • The Canvas API to draw the output to the screen

Infographic showing how Steer! works. Phone accelerometer determines orientation, pushes to Firebase (up to 60 times/sec), which pushes to browser (via Websocket), which updates screen.

The desktop browser does all of the real work: it takes the orientation of the device and uses that, and the car’s current speed, to determine how it’s position changes over the time that’s elapsed since the screen was last refreshed: we’re aiming for 60 frames a second, of course, but we don’t want the car to travel slower when the game is played on a slower computer, so we use requestAnimationFrame to get the fastest rate possible and calculate the time between renderings to work out how much of a change has occurred this ‘tick’. We leave the car’s sprite close to the bottom of the screen at all times but change how much it rotates from side to side, and we use it’s rotated to decide how much of its motion is lateral versus the amount that’s “along the track”. The latter value determines how much track we move down the screen “behind” it.

The track is generated very simply by the addition of three sine waves of different offset and frequency – a form of very basic procedural generation. Despite the predictability of mathematical curves, this results in a moderately organic-feeling road because the player only sees a fraction of the resulting curve at any given time: the illustration below shows how these three curves combine to make the resulting road. The difficulty is ramped up the further the player has travelled by increasing the amplitude of the resulting wave (i.e. making the curves gradually more-agressive) and by making the road itself gradually narrower. The same mathematics are used to determine whether the car is mostly on the tarmac or mostly on the grass and adjust its maximum speed accordingly.

Sum of sine waves as used to generate the track for Steer!

In order to help provide a visual sense of the player’s speed, I added dashed lines down the road (dividing it into three lanes to begin with and two later on) which zip past the car and provide a sense of acceleration, deceleration, overall speed, and the impact of turning ‘sideways’ (which of course reduces the forward momentum to nothing).

This isn’t meant to be a finished game: it’s an experimental prototype to help explore some technologies that I’d not had time to look seriously at before now. However, you’re welcome to take a copy – it’s all open source – and adapt or expand it. Particular ways in which it’d be fun to improve it might include:

  • Allowing the player more control, e.g. over their accelerator and brakes
  • Adding hazards (trees, lamp posts, and others cars) which must be avoided
  • Adding bonuses like speed boosts
  • Making it challenging, e.g. giving time limits to get through checkpoints
  • Day and night cycles (with headlights!)
  • Multiplayer capability, like a real race?
  • Smarter handling of multiple simultaneous users: right now they’d share control of the car (which is the major reason I haven’t given you a live online version to play with and you have to download it yourself!), but it’d be better if they could “queue” until it was their turn, or else each play in their own split-screen view or something
  • Improving the graphics with textures
  • Increasing the entropy of the curves used to generate the road, and perhaps adding pre-scripted scenery or points of interest on a mathematically-different procedural generation algorithm
  • Switching to a local LAN websocket server, allowing better performance than the dog-leg via Firebase
  • Greater compatibility: I haven’t tried it on an iPhone, but I gather than iOS devices report their orientation differently from Android ones… and I’ve done nothing to try to make Steer! handle more-unusual screen sizes and shapes
  • Anything else? (Don’t expect me to have time to enhance it, though: but if you do so, I’d love to hear about it!)

Tomorrow’s Web, Today

Maybe it’s because I was at Render Conf at the end of last month or perhaps it’s because Three Rings DevCamp – which always gets me inspired – was earlier this month, but I’ve been particularly excited lately to get the chance to play with some of the more “cutting edge” (or at least, relatively-new) web technologies that are appearing on the horizon. It feels like the Web is having a bit of a renaissance of development, spearheaded by the fact that it’s no longer Microsoft that are holding development back (but increasingly Apple) and, perhaps for the first time, the fact that the W3C are churning out standards “ahead” of where the browser vendors are managing to implement technical features, rather than simply reflecting what’s already happening in the world.

Ben Foxall at Render Conf 2017 discusses the accompanying JSOxford Hackathon.
Ben Foxall at Render Conf 2017 discusses the accompanying JSOxford Hackathon. Hey, who’s that near the top-right?

It seems to me that HTML5 may well be the final version of HTML. Rather than making grand new releases to the core technology, we’re now – at last! – in a position where it’s possible to iteratively add new techniques in a resilient, progressive manner. We don’t need “HTML6” to deliver us any particular new feature, because the modern web is more-modular and is capable of having additional features bolted on. We’re in a world where browser detection has been replaced with feature detection, to the extent that you can even do non-hacky feature detection in pure CSS, now, and this (thanks to the nature of the Web as a loosely-coupled, resilient platform) means that it’s genuinely possible to progressively-enhance content and get on board with each hot new technology that comes along, if you want, while still delivering content to users on older browsers.

And that’s the dream! A web of progressive-enhancement stays true to Sir Tim’s dream of universal interoperability while still moving forward technologically. I’ve no doubt that there’ll always be people who want to break the Web – even Google do it, sometimes – with single-page Javascript-only web apps, “app shell” websites, mobile-only or desktop-only experiences and “apps” that really ought to have been websites (and perhaps PWAs) to begin with… but the fact that the tools to make a genuinely “progressively-enhanced” web, and those tools are mainstream, is a big deal. If you don’t think we’re at that point yet, I invite you to watch Rachel Andrews‘ fantastic presentation, “Start Using CSS Grid Layout Today”.

Three Rings DevCamp 2017
Three Rings’ developers hard at work at this year’s DevCamp.

Some of the things I’ve been playing with recently include:

Intersection Observers

Only really supported in Chrome, but there’s a great polyfill, the Intersection Observer API is one of those technologies that make you say “why didn’t we have that already?” It’s very simple: all an Intersection Observer does is to provide event hooks for target objects entering or leaving the viewport, without resorting to polling or hacky code on scroll event captures.

Intersection Observer example (animated GIF)

What’s it for? Well the single most-obvious use case is lazy-loading images, a-la Medium or Google Image Search: delivering users a placeholder image or a low-resolution copy until they scroll far enough for the image to come into view (or almost into view) and then downloading the full-resolution version and dynamically replacing it. My first foray into Intersection Observers was to take Medium’s approach and then improve it with a Service Worker in order to make it behave nicely even if the user’s Internet connection was unreliable, but I’ve since applied it to my Reddit browser plugin MegaMegaMonitor: rather than hammering the browser with Javascript the plugin now waits until relevant content enters the viewport before performing resource-intensive tasks.

Web Workers

I’d briefly played with Service Workers before and indeed we’re adding a Service Worker to the next version of Three Rings, which, in conjunction with a manifest.json and the service’s (ongoing) delivery over HTTPS (over H2, where available, since last year), technically makes it a Progressive Web App… and I’ve been looking for opportunities to make use of Service Workers elsewhere in my work, too… but my first dive in to Web Workers was in introducing one to the next upcoming version of MegaMegaMonitor.

MegaMegaMonitor v155a Lists feature
MegaMegaMonitor’s processor-intensive “Lists” feature sees the most benefit from Web Workers

Web Workers add true multithreading to Javascript, and in the case of MegaMegaMonitor this means the possibility of pushing the more-intensive work that the plugin has to do out of the main thread and into the background, allowing the user to enjoy an uninterrupted browsing experience while the heavy-lifting goes on in the background. Because I don’t control the domain on which this Web Worker runs (it’s reddit.com, of course!), I’ve also had the opportunity to play with Blobs, which provided a convenient way for me to inject Worker code onto somebody else’s website from within a userscript. This has also lead me to the discovery that it ought to be possible to implement userscripts that inject Service Workers onto websites, which could be used to mashup additional functionality into websites far in advance of that which is typically possible with a userscript… more on that if I get around to implementing such a thing.

Fetch

The final of the new technologies I’ve been playing with this month is the Fetch API. I’m not pulling any punches when I say that the Fetch API is exactly what XMLHttpRequests should have been from the very beginning. Understanding them properly has finally given me the confidence to stop using jQuery for the one thing for which I always seemed to have had to depend on it for – that is, simplifying Ajax requests! I mean, look at this elegant code:

fetch('posts.json')
.then(function(response) {
  return response.json();
})
.then(function(json) {
  console.log(json.something.otherThing);
});

Whether or not you’re a fan of Javascript, you’ve got to admit that that’s infinitely more readable than XMLHttpRequest hackery (at least, without the help of a heavyweight library like jQuery).

Laser Duck Hunt at Render Conf 2017
Other things I’ve been up to include Laser Duck Hunt, but that’s another story.

So that’s some of the stuff I’ve been playing with lately: Intersection Observers, Web Workers, Blobs, and the Fetch API. And I feel all full of optimism on behalf of the Web.

Things you probably didn’t know you could do with Chrome’s Developer Console

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Chrome comes with built-in developer tools. This comes with a wide variety of features, such as Elements, Network, and Security. Today, we’ll focus 100% on its JavaScript console.

When I started coding, I only used the JavaScript console for logging values like responses from the server, or the value of variables. But over time, and with the help of tutorials, I discovered that the console can do way more than I ever imagined…

History of the browser user-agent string

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In the beginning there was NCSA Mosaic, and Mosaic called itself NCSA_Mosaic/2.0 (Windows 3.1), and Mosaic displayed pictures along with text, and there was much rejoicing…

Have you ever wondered why every major web browser identifies itself as “Mozilla”? Wonder no longer…

Anatomy of Cookie XSS

A cross-site scripting vulnerability (shortened to XSS, because CSS already means other things) occurs when a website can be tricked into showing a visitor unsafe content that came from another site visitor. Typically when we talk about an XSS attack, we’re talking about tricking a website into sending Javascript code to the user: that Javascript code can then be used to steal cookies and credentials, vandalise content, and more.

Good web developers know to sanitise input – making anything given to their pages by a user safe before ever displaying it on a page – but even the best can forget quite how many things really are “user input”.

"Who Am I?" page provided by University of Oxford IT Services.
This page outputs a variety of your inputs right back at you.

Recently, I reported a vulnerability in a the University of Oxford’s IT Services‘ web pages that’s a great example of this.  The page (which isn’t accessible from the public Internet, and now fixed) is designed to help network users diagnose problems. When you connect to it, it tells you a lot of information about your connection: what browser you’re using, your reverse DNS lookup and IP address, etc.. The developer clearly understood that XSS was a risk, because if you pass a query string to the page, it’s escaped before it’s returned back to you. But unfortunately, the developer didn’t consider the fact that virtually anything given to you by the browser can’t be trusted.

My Perl program, injecting XSS code into the user's cookie and then redirecting them.
To demonstrate this vulnerability, I had the option of writing Perl or Javascript. For some reason, I chose Perl.

In this case, I noticed that the page would output any cookies that you had from the .ox.ac.uk domain, without escaping them. .ox.ac.uk cookies can be manipulated by anybody who has access to write pages on the domain, which – thanks to the users.ox.ac.uk webspace – means any staff or students at the University (or, in an escalation attack, anybody’s who’s already compromised the account of any staff member or student). The attacker can then set up a web page that sets up such a “poisoned” cookie and then redirects the user to the affected page and from there, do whatever they want. In my case, I experimented with showing a fake single sign-on login page, almost indistinguishable from the real thing (it even has a legitimate-looking .ox.ac.uk domain name served over a HTTPS connection, padlock and all). At this stage, a real attacker could use a spear phishing scam to trick users into clicking a link to their page and start stealing credentials.

A fake SSO login page, delivered from a legitimate-looking https URL.
The padlock, the HTTPS url, and the convincing form make this page look legitimate. But it’s actually spoofed.

I’m sure that I didn’t need to explain why XSS vulnerabilities are dangerous. But I wanted to remind you all that truly anything that comes from the user’s web browser, even if you think that you probably put it there yourself, can’t be trusted. When you’re defending against XSS attacks, your aim isn’t just to sanitise obvious user input like GET and POST parameters but also anything that comes from a browser header including cookies and referer headers, especially if your domain name carries websites managed by many different people. In an ideal world, Content Security Policy would mitigate all these kinds of attacks: but in our real world – sanitise those inputs!

DRY: Do Repeat Yourself

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I am increasingly of the opinion that the general software engineering adage “Don’t Repeat Yourself” does not always apply to web development. Also, I found that web development classes in CS academia are not very realistic. These two problems turn out to have the same root cause: a lack of appreciation of what browsers do…

Zopfli Optimization: Literally Free Bandwidth

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In 2007 I wrote about using PNGout to produce amazingly small PNG images. I still refer to this topic frequently, as seven years later, the average PNG I encounter on the Internet is very unlikely to be optimized.

For example, consider this recent Perry Bible Fellowship cartoon

Non-Rails Frameworks in Ruby: Cuba, Sinatra, Padrino, Lotus

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It’s common for a Ruby developer to describe themselves as a Rails developer. It’s also common for someone’s entire Ruby experience to be through Rails. Rails began in 2003 by David Heinemeier Hansson, quickly becoming the most popular web framework and also serving as an introduction to Ruby for many developers.

Rails is great. I use it every day for my job, it was my introduction to Ruby, and this is the most fun I’ve ever had as a developer. That being said, there are a number of great framework options out there that aren’t Rails.

This article intends to highlight the differences between Cuba, Sinatra, Padrino, Lotus, and how they compare to or differ from Rails. Let’s have a look at some Non-Rails Frameworks in Ruby.

Squiz CMS Easter Eggs (or: why do I keep seeing Greg’s name in my CAPTCHA?)

Anybody who has, like me, come into contact with the Squiz Matrix CMS for any length of time will have come across the reasonably easy-to-read but remarkably long CAPTCHA that it shows. These are especially-noticeable in its administrative interface, where it uses them as an exaggerated and somewhat painful “are you sure?” – restarting the CMS’s internal crontab manager, for example, requires that the administrator types a massive 25-letter CAPTCHA.

Four long CAPTCHA from the Squiz Matrix CMS.
Four long CAPTCHA from the Squiz Matrix CMS.

But there’s another interesting phenomenon that one begins to notice after seeing enough of the back-end CAPTCHA that appear. Strange patterns of letters that appear in sequence more-often than would be expected by chance. If you’re a fan of wordsearches, take a look at the composite screenshot above: can you find a person’s name in each of the four lines?

Four long CAPTCHA from the Squiz Matrix CMS, with the names Greg, Dom, Blair and Marc highlighted.
Four long CAPTCHA from the Squiz Matrix CMS, with the names Greg, Dom, Blair and Marc highlighted.

There are four names – GregDomBlair and Marc – which routinely appear in these CAPTCHA. Blair, being the longest name, was the first that I noticed, and at first I thought that it might represent a fault in the pseudorandom number generation being used that was resulting in a higher-than-normal frequency of this combination of letters. Another idea I toyed with was that the CAPTCHA text might be being entirely generated from a set of pronounceable syllables (which is a reasonable way to generate one-time passwords that resist entry errors resulting from reading difficulties: in fact, we do this at Three Rings), in which these four names also appear, but by now I’d have thought that I’d have noticed this in other patterns, and I hadn’t.

Instead, then, I had to conclude that these names were some variety of Easter Egg.

In software (and other media), "Easter Eggs" are undocumented  hidden features, often in the form of inside jokes.
Smiley decorated eggs. Picture courtesy Kate Ter Haar.

I was curious about where they were coming from, so I searched the source code, but while I found plenty of references to Greg Sherwood, Marc McIntyre, and Blair Robertson. I couldn’t find Dom, but I’ve since come to discover that he must be Dominic Wong – these four were, according to Greg’s blog – developers with Squiz in the early 2000s, and seemingly saw themselves as a dynamic foursome responsible for the majority of the CMS’s code (which, if the comment headers are to be believed, remains true).

Greg, Marc, Blair and Dom, as depicted in Greg's 2007 blog post.
Greg, Marc, Blair and Dom, as depicted in Greg’s 2007 blog post.

That still didn’t answer for me why searching for their names in the source didn’t find the responsible code. I started digging through the CMS’s source code, where I eventually found fudge/general/general.inc (a lot of Squiz CMS code is buried in a folder called “fudge”, and web addresses used internally sometimes contain this word, too: I’d like to believe that it’s being used as a noun and that the developers were just fans of the buttery sweet, but I have a horrible feeling that it was used in its popular verb form). In that file, I found this function definition:

/**
 * Generates a string to be used for a security key
 *
 * @param int            $key_len                the length of the random string to display in the image
 * @param boolean        $include_uppercase      include uppercase characters in the generated password
 * @param boolean        $include_numbers        include numbers in the generated password
 *
 * @return string
 * @access public
 */
function generate_security_key($key_len, $include_uppercase = FALSE, $include_numbers = FALSE) {
  $k = random_password($key_len, $include_uppercase, $include_numbers);
  if ($key_len > 10) {
    $gl = Array('YmxhaXI=', 'Z3JlZw==', 'bWFyYw==', 'ZG9t');
    $g = base64_decode($gl[rand(0, (count($gl) - 1)) ]);
    $pos = rand(1, ($key_len - strlen($g)));
    $k = substr($k, 0, $pos) . $g . substr($k, ($pos + strlen($g)));
  }
  return $k;
} //end generate_security_key()

For the benefit of those of you who don’t speak PHP, especially PHP that’s been made deliberately hard to decipher, here’s what’s happening when “generate_security_key” is being called:

  • A random password is being generated.
  • If that password is longer than 10 characters, a random part of it is being replaced with either “blair”, “greg”, “marc”, or “dom”. The reason that you can’t see these words in the code is that they’re trivially-encoded using a scheme called Base64 – YmxhaXI=Z3JlZw==, bWFyYw==, and ZG9t are Base64 representations of the four names.

This seems like a strange choice of Easter Egg: immortalising the names of your developers in CAPTCHA. It seems like a strange choice especially because this somewhat weakens the (already-weak) CAPTCHA, because an attacking robot can quickly be configured to know that a 11+-letter codeword will always consist of letters and exactly one instance of one of these four names: in fact, knowing that a CAPTCHA will always contain one of these four and that I can refresh until I get one that I like, I can quickly turn an 11-letter CAPTCHA into a 6-letter one by simply refreshing until I get one with the longest name – Blair – in it!

A lot has been written about how Easter Eggs undermine software security (in exchange for a small boost to developer morale) – that’s a major part of why Microsoft has banned them from its operating systems (and, for the most part, Apple has too). Given that these particular CAPTCHA in Squiz CMS are often nothing more than awkward-looking “are you sure?” dialogs, I’m not concerned about the direct security implications, but it does make me worry a little about the developer culture that produced them.

I know that this Easter Egg might be harmless, but there’s no way for me to know (short of auditing the entire system) what other Easter Eggs might be hiding under the surface and what they do, especially if the developers have, as in this case, worked to cover their tracks! It’s certainly the kind of thing I’d worry about if I were, I don’t know, a major government who use Squiz software, especially their cloud-hosted variants which are harder to effectively audit. Just a thought.

Craziest Internet Explorer Bug Ever?

As web developers, we’re used to working around the bugs in Microsoft Internet Explorer. The older versions are worst, and I’m certainly glad to not have to write code that works in Internet Explorer 6 (or, increasingly, Internet Explorer 7) any more: even Microsoft are glad to see Internet Explorer 6 dying out, but even IE8 is pretty ropey too. And despite what Microsoft claim, I’m afraid IE9 isn’t really a “modern” browser either (although it is a huge step forwards over its predecessors).

But imagine my surprise when I this week found what I suspect might be a previously undiscovered bug in Internet Explorer 8 and below. Surely they’ve all been found (and some of them even fixed), but now? But no. It takes a very specific set of circumstances for the bug to manifest itself, but it’s not completely unbelievable – I ran into it by accident while refactoring parts of Three Rings.

A completely useless Internet Explorer error message.
A completely useless Internet Explorer error message. Thanks, IE.

Here’s the crux of it: if you’re –

  • Using Internet Explorer 8 or lower, and
  • You’re on a HTTPS (secure) website, and
  • You’re downloding one of a specific set of file types: Bitmap files, for example, are a problem, but JPEG files aren’t (Content-Type: image/bmp), and
  • The web server indicates that the file you’re downloading should be treated as something to be “saved”, rather than something to be viewed in your browser (Content-Disposition: attachment), and
  • The web server passes a particular header to ask that Internet Explorer does not cache a copy of the file (Cache-Control: no-cache),

Then you’ll see a dialog box like the one shown above. Switching any of the prerequistes in that list out makes the problem go away: even switching the header from a strict “no-cache” to a more-permissive “private” makes all the difference.

I’ve set up a test environment where you can see this for yourself: HTTP version; HTTPS version. The source code of my experiment (PHP) is also available. Of course, if you try it in a functional, normal web browser, it’ll all work fine. But if you’ve got access to a copy of Internet Explorer 8 on some old Windows XP box somewhere (IE8 is the last version of the browser made available for XP), then try it in that and see for yourself what a strange error you get.

KeePass for Opera

Opera 12 has been released, and brought with it a handful of new features. But there’s also been a feature removed – a little-known feature that allowed power users to have the web address appear in the title bar of the browser. I guess that the development team decided that, because the title bar is rarely seen nowadays (the space in which a title once occupied has for a long while now been used as a tab strip, in the style that Google Chrome and Mozilla Firefox eventually copied), this feature wasn’t needed.

But for users of the KeePass Password Safe, this has the knock-on effect of crippling the ability for this security tool to automatically type passwords and other form data into web pages, forcing users to take the long-winded route of manually copy-pasting them each time.

KeePass for Opera Plugin

To fix this problem, I’ve released the KeePass for Opera browser extension. It’s ludicrously simple: it injects a bit of Javascript (originally by Jean François) into every page you visit, which then appends the URL of the page to the title bar. This allows KeePass to detect what site you’re on, so the usual Global Auto-Type command (typically Left Ctrl + Alt + A) will work as normal.

[button link=”https://addons.opera.com/en-gb/extensions/details/keepass-auto-type/” align=”right” size=”medium” caption=”KeePass for Opera”]Install[/button]

Download KeePass for Opera (browser extension)

Open in Opera to install.

Further reading:

I’ve mentioned KeePass a few times before. See: