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Edge browser and JavaScript UWP app security model comparison

2018 Nov 29, 2:21

There are two main differences in terms of security between a JavaScript UWP app and the Edge browser:

Process Model

A JavaScript UWP app has one process (technically not true with background tasks and other edge cases but ignoring that for the moment) that runs in the corresponding appcontainer defined by the app's appx manifest. This one process is where edgehtml is loaded and is rendering HTML, talking to the network, and executing script. Specifically, the UWP main UI thread is the one where your script is running and calling into WinRT.

In the Edge browser there is a browser process running in the same appcontainer defined by its appx manifest, but there are also tab processes. These tab processes are running in restricted app containers that have fewer appx capabilities. The browser process has XAML loaded and coordinates between tabs and handles some (non-WinRT) brokering from the tab processes. The tab processes load edgehtml and that is where they render HTML, talk to the network and execute script.

There is no way to configure the JavaScript UWP app's process model but using WebViews you can approximate it. You can create out of process WebViews and to some extent configure their capabilities, although not to the same extent as the browser. The WebView processes in this case are similar to the browser's tab processes. See the MSWebViewProcess object for configuring out of process WebView creation. I also implemented out of proc WebView tabs in my JSBrowser fork.

ApplicationContentUriRules

The ApplicationContentUriRules (ACUR) section of the appx manifest lets an application define what URIs are considered app code. See a previous post for the list of ACUR effects.

Notably app code is able to access WinRT APIs. Because of this, DOM security restrictions are loosended to match what is possible with WinRT.

Privileged DOM APIs like geolocation, camera, mic etc require a user prompt in the browser before use. App code does not show the same browser prompt. There still may be an OS prompt – the same prompt that applies to any UWP app, but that’s usually per app not per origin.

App code also gets to use XMLHttpRequest or fetch to access cross origin content. Because UWP apps have separate state, cross origin here might not mean much to an attacker unless your app also has the user login to Facebook or some other interesting cross origin target.

PermalinkCommentsedge javascript security uwp web-security wwa

Tweet from David_Risney

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2015 Nov 6, 12:26
Facebook's censoring me. Tried to post my @boingboing item re: http://tsu.co . Got blocked. http://boingboing.net/2015/11/06/facebook-is-censoring-links-to.html …
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Facebook Mangles Unicode URLs https://shkspr.mobi/blog/?p=20643 
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2015 Feb 26, 2:01
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2015 Feb 20, 4:19
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Claire Ayoub @intoosteep :
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Funny anecdote but also a how-to on creating a Facebook ad campaign that targets a single person.

PermalinkCommentshumor security ad facebook

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An interesting way to use the report-uri feature of CSP to detect if a user is logged into Google, Facebook etc.

PermalinkCommentstechnical security csp web

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2014 May 29, 4:03


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thefrogman: Poorly Drawn Lines by Reza...

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Will Arnett Explains the Origins of His Arrested Development Chicken Dance

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thebluthcompany:

To decide what Gob’s bad impression of a chicken might be, Arnett consulted on set in 2003 with series executive producers Mitch Hurwitz and James Vallely. They all tried out different versions for each other. “Jimmy started doing a little bit, then Mitch got up and did some, and then I began trying things,” remembers Arnett. “Picture three grown men hopping around, working out what it would be … They were pitching this really taunting dance, but I wanted to give it this very sharp, almost roosterlike, chest-sticking-out mannerism, like a real macho bravado dance.” And how did clapping get introduced to the move? “Because I wanted it to be only sort of threatening.”

Read More | Vulture

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Scumbag Steve's Advice for Annoying Facebook Girl

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Blake Boston of the Scumbag Steve meme writes an open letter to the woman in the Annoying Facebook Girl meme.

PermalinkCommentshumor meme scumbag-steve

Privacy through Obscurity

2012 Mar 9, 3:30

With Facebook changing its privacy policy and settings so frequently and just generally the huge amount of social sites out there, for many of us it is far too late to ensure our name doesn't show up with unfortunate results in web searches. Information is too easily copyable and archive-able to make removing these results a viable option, so clearly the solution is to create more data.

Create fake profiles on Facebook using your name but with a different photo, different date of birth, and different hometown. Create enough doppelgangers to add noise to the search results for your name. And have them share embarrassing stories on their blogs. The goal is to ensure that the din of your alternates drowns out anything embarrassing showing up for you.

Although it will look suspicious if you're the only name on Google with such chaff. So clearly you must also do this for your friends and family. Really you'll be doing them a favor.

PermalinkCommentstechnical facebook stupid internet privacy

Cursor:none abuse (trick users into clicking Facebook 'like') (co.uk)

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Cursor spoofing. Great job!

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Lessons of the Chewbacca Incident « Binary Bonsai

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