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Changing the User Agent string in UWP WebView

2018 Oct 23, 9:32

There's no perfect way to change the user agent string for the UWP WebView (x-ms-webview in HTML, Windows.UI.Xaml.Controls.WebView in XAML, and Windows.Web.UI.Interop.WebViewControl in Win32) but there are two imperfect methods folks end up using.

The first is to call UrlMkSetSessionOption. This is an old public API that allows you to configure various arcane options including one that is the default user agent string for requests running through urlmon. This API is allowed by the Microsoft Store for UWP apps. The change it applies is process wide which has two potential drawbacks. If you want to be able to have different UA strings set for different requests from a WebView that's not really possible with this solution. The other drawback is if you're using out of process WebView, you need to ensure you're calling into UrlMkSetSessionOption in the WebView's process. You'll need to write third party WinRT that calls UrlMkSetSessionOption, create the out of proc WebView, navigate it to some trusted local page, use AddWebAllowedObject or provide that URI WinRT access, and call into your third party WinRT. You'll need to do that for any new WebView process you create.

The second less generally applicable solution is to use NavigateWithHttpRequestMessage and set the User-Agent HTTP header. In this case you get to control the scope of the user agent string changes but has the limitations that not all sub resource downloads will use this user agent string and for navigations you don't initiate you have to manually intercept and re-request being careful to transfer over all POST body state and HTTP headers correctly. That last part is not actually possible for iframes.

PermalinkCommentsuser-agent uwp webview

Windows.Web.UI.Interop.WebViewControl localhost access

2018 Jul 25, 5:34

If you're developing with the new Windows.Web.UI.Interop.WebViewControl you may have noticed you cannot navigate to localhost HTTP servers. This is because the WebViewControl's WebView process is a UWP process. All UWP processes by default cannot use the loopback adapter as a security precaution. For development purposes you can allow localhost access using the checknetisolation command line tool on the WebViewControl's package just as you can for any other UWP app. The command should be the following:

checknetisolation loopbackexempt -a -n=Microsoft.Win32WebViewHost_cw5n1h2txyewy

As a warning checknetisolation is not good on errors. If you attempt to add a package but get its package family name wrong, checknetisolation just says OK:

C:\Users\davris>checknetisolation LoopbackExempt -a -n=Microsoft.BingWeather_4.21.2492.0_x86__8wekyb3d8bbwe
OK.
And if you then list the result of the add with the bad name you'll see the following:
[1] -----------------------------------------------------------------
Name: AppContainer NOT FOUND
SID: S-1-15-...

There's also a UI tool for modifying loopback exemption for packages available on GitHub and also one available with Fiddler.

As an additional note, I mentioned above you can try this for development. Do not do this in shipping products as this turns off the security protection for any consumer of the WebViewControl.

PermalinkCommentschecknetisolation loopback security uwp webview win32webview

Application Content URI Rule effects

2017 Jun 30, 3:01

Previously I described Application Content URI Rules (ACUR) parsing and ACUR ordering. This post describes what you get from putting a URI in ACUR.

URIs in the ACUR gain the following which is otherwise unavailable:

  • Geoloc API usage
  • Audio and video capture API usage
  • Pointer lock API usage
  • Web notifications API usage
  • IndexedDB API usage
  • Clipboard API usage
  • window.external.notify access from within webview
  • window.close the primary window
  • Top level navigation in the primary window
  • Cross origin XHR and fetch to ms-appx(-web) scheme URIs
  • Cross origin dirtied canvas read access if dirtied by ms-appx(-web) scheme URIs
  • Cross origin text track for video element for tracks from ms-appx(-web) scheme URIs

URIs in the ACUR that also have full WinRT access additionally gain the following:

  • Cross origin XHR and fetch
  • Cross origin dirtied canvas read access
  • Cross origin text track for video element
  • Local audio and video WinRT plugins work with media elements
PermalinkCommentsapplication-content-uri-rules coding javascript programming windows-store

Retweet of codinghorror

2015 Mar 18, 12:02
it is so much faster to find things on the internet than it is to find things on my local computer. Has been for years
PermalinkComments

U.S. Marshals Seize Cops’ Spying Records to Keep Them From the ACLU | Threat Level | WIRED

2014 Jun 4, 6:08

"A routine request in Florida for records detailing the use of a surveillance tool known as stingray turned extraordinary Tuesday when the U.S. Marshals Service seized the documents before local police could release them."

Also what about the part where the PD reveals that its been using the stingray a bunch without telling any court and blames that on the manufacturer’s NDA.

PermalinkCommentstechnical law security phone

JS NICE: Statistical renaming, Type inference and Deobfuscation

2014 Jun 3, 9:36

JS NICE | Software Reliability Lab in ETH

JS NICE has indexed over 10,000 JavaScript projects from GitHub and then probabilistically infers newly suggested names and types for all of the local variables and function parameters of new JS.

PermalinkCommentstechnical javascript js coding

FitBit and WebOC Application Compatibility Errors

2013 Aug 29, 7:17
I just got a FitBit One from my wife. Unfortunately I had issues running their app on my Windows 8.1 Preview machine. But I recognized the errors as IE compatibility issues, for instance an IE dialog popup from the FitBit app telling me about an error in the app's JavaScript. Given my previous post on WebOC versioning you may guess what I tried next. I went into the registry and tried out different browser mode and document mode versions until I got the FitBit software running without error. Ultimately I found the following registry value to work well ('FitBit connect.exe' set to DWORD decimal 8888).
Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION]
"Fitbit Connect.exe"=dword:000022b8

For those familiar with the Windows registry the above should be enough. For those not familiar, copy and paste the above into notepad, save as a file named "fitbit.reg", and then double click the reg file and say 'Yes' to the prompt. Hopefully in the final release of Windows 8.1 this won't be an issue.
PermalinkComments

Stripe CTF - Input validation (Levels 1 & 2)

2012 Sep 6, 5:00

Stripe's web security CTF's Level 1 and level 2 of the Stripe CTF had issues with missing input validation solutions described below.

Level 1

Code

          $filename = 'secret-combination.txt';
extract($_GET);
if (isset($attempt)) {
$combination = trim(file_get_contents($filename));
if ($attempt === $combination) {

Issue

The issue here is the usage of the extract php method which extracts name value pairs from the map input parameter and creates corresponding local variables. However this code uses $_GET which contains a map of name value pairs passed in the query of the URI. The expected behavior is to get an attempt variable out, but since no input validation is done I can provide a filename variable and overwrite the value of $filename. Providing an empty string gives an empty string $combination which I can match with an empty string $attempt. So without knowing the combination I can get past the combination check.

Notes

Code review red flag in this case was the direct use of $_GET with no validation. Instead of using extract the developer could try to extract specifically the attempt variable manually without using extract.

Level 2

Code

    $dest_dir = "uploads/";
$dest = $dest_dir . basename($_FILES["dispic"]["name"]);
$src = $_FILES["dispic"]["tmp_name"];
if (move_uploaded_file($src, $dest)) {
$_SESSION["dispic_url"] = $dest;
chmod($dest, 0644);
echo "

Successfully uploaded your display picture.

";
}

Issue

This code accepts POST uploads of images but with no validation to ensure it is not an arbitrary file. And even though it uses chmod to ensure the file is not executable, things like PHP don't require a file to be executable in order to run them. Accordingly, one can upload a PHP script, then navigate to that script to run it. My PHP script dumped out the contents of the file we're interested in for this level:

Notes

Code review red flags include manual file management, chmod, and use of file and filename inputs without any kind of validation. If this code controlled the filename and ensured that the extension was one of a set of image extensions, this would solve this issue. Due to browser mime sniffing its additionally a good idea to serve a content-type that starts with "image/" for these uploads to ensure browsers treat these as images and not sniff for script or HTML.

PermalinkCommentsinput-validation php security technical

Changing System Environment Variables on Windows

2012 Mar 16, 3:13

Is this really the right way to do this? Feels icky:

To programmatically add or modify system environment variables, add them to the HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Environment registry key, then broadcast a WM_SETTINGCHANGE message with lParam set to the string “Environment”.

PermalinkCommentsprogramming techncial registry environment-variable windows

Thread Local Storage, part 1: Overview « Nynaeve

2011 Aug 6, 1:53Description of the inner workings of both of Window's TLS options, the Win32 APIs like TlsAlloc as well as __declspec(thread). I didn't know that the max number of TLS indices is now 1088.PermalinkCommentsblog programming development windows debug tls thread-local-storage

Using client-side storage, today. ✩ Mozilla Hacks – the Web developer blog

2011 Apr 5, 5:14A JS wrapper script that lets you use storage in IE6/7 via userData or localStorage every where else.PermalinkCommentsjavascript html web webbrowser storage technical userdata localstorage

Area Man Suddenly Realizes He's The One Who's Been Killing Off World's Bee Population | The Onion - America's Finest News Source

2010 Sep 8, 2:16'Following a news update on the depopulation of honeybees across North America and much of the world, it suddenly dawned on local bank teller Keith Orlander Tuesday that he, personally, was responsible for the dramatic and theretofore unexplained disappearance of the insects. "Boy, come to think of it, I guess I have been killing millions of bees lately,"'PermalinkCommentsbee bees humor onion

DVD Ripping and Viewing in Windows Media Center

2010 Aug 17, 3:05

I've just got a new media center PC connected directly to my television with lots of HD space and so I'm ripping a bunch of my DVDs to the PC so I don't have to fuss with the physical media. I'm ripping with DVD Rip, viewing the results in Windows 7's Windows Media Center after turning on the WMC DVD Library, and using a powershell script I wrote to copy over cover art and metadata.

My powershell script follows. To use it you must do the following:

  1. Run Windows Media Center with the DVD in the drive and view the disc's metadata info.
  2. Rip each DVD to its own subdirectory of a common directory.
  3. The name of the subdirectory to which the DVD is ripped must have the same name as the DVD name in the metadata. An exception to this are characters that aren't allowed in Windows paths (e.g. <, >, ?, *, etc)
  4. Run the script and pass the path to the common directory containing the DVD rips as the first parameter.
Running WMC and viewing the DVD's metadata forces WMC to copy the metadata off the Internet and cache it locally. After playing with Fiddler and reading this blog post on WMC metadata I made the following script that copies metadata and cover art from the WMC cache to the corresponding DVD rip directory.

Download copydvdinfo.ps1

PermalinkCommentspowershell wmc technical tv dvd windows-media-center

RFC 5987 - Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters

2010 Aug 13, 11:47Other characters sets for HTTP headers: "By default, message header field parameters in Hypertext Transfer Protocol (HTTP) messages cannot carry characters outside the ISO-8859-1 character set. RFC 2231 defines an encoding mechanism for use in Multipurpose Internet Mail Extensions (MIME) headers. This document specifies an encoding suitable for use in HTTP header fields that is compatible with a profile of the encoding defined in RFC 2231."PermalinkCommentsrfc language localization charset http technical reference http-header

Damn, Tourists! « Burrito Justice

2010 Jun 7, 2:40Maps of where tourists vs locals take photos in major cities like New York, San Francisco, etc. based on geotagged photos on Flickr.
PermalinkCommentsgeolocation geo geography map flickr photo tourist technical visualization

Why the internet will fail (from 1995) « Three Word Chant!

2010 Feb 26, 8:50Did I read this already on Paleo-Future? Anyway still an awesome 1995 rant on why the Internet will fail. "Then there’s cyberbusiness. We’re promised instant catalog shopping–just point and click for great deals. We’ll order airline tickets over the network, make restaurant reservations and negotiate sales contracts. Stores will become obselete. So how come my local mall does more business in an afternoon than the entire Internet handles in a month? Even if there were a trustworthy way to send money over the Internet–which there isn’t–the network is missing a most essential ingredient of capitalism: salespeople."PermalinkCommentshumor internet fail article history

Official Google Blog: Unicode nearing 50% of the web

2010 Jan 28, 4:20Graph of encodings used by documents on the web. Unicode based encodings are thankfully on the rise.PermalinkCommentsunicode encoding web internationalization localization utf8 text html technical

Official Google Blog: Go thataway: Google Maps India learns to navigate like a local

2009 Dec 18, 2:27"...this week we launched an improvement to Google Maps India that describes routes in terms of easy-to-follow landmarks and businesses that are visible along the way. We gathered feedback from users around the world to spark this improvement to our technology, and we thought we'd give you a glimpse at our thinking behind this launch."PermalinkCommentsgoogle map geography geo india

Sprint fed customer GPS data to cops over 8 million times

2009 Dec 1, 9:40Wow: 'The fact that federal, state, and local law enforcement can obtain communications "metadata"—URLs of sites visited, e-mail message headers, numbers dialed, GPS locations, etc.—without any real oversight or reporting requirements should be shocking, but it isn't. The courts ruled in 2005 that law enforcement doesn't need to show probable cause to obtain your physical location via the cell phone grid. All of the aforementioned metadata can be accessed with an easy-to-obtain pen register/trap & trace order. But given the volume of requests, it's hard to imagine that the courts are involved in all of these.'PermalinkCommentsprivacy security gps phone cellphone government politics

I Love Local Commercials - Sponsored by MicroBilt Corporation

2009 Nov 5, 2:07Two guys sponsored by MicroBilt to travel around the country and make totally awesome commercials for local companies. Includes such gems as Salt Lake Community Barbering & Cosmetology School: "Your hairdo is only limited by your immagination. And how far along we are in the semester.", as well as Cullman Liquidation: "They're used. Some of them have stains. We cover that up."PermalinkCommentsvia:boingboing video advertising commercial tv monthly
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