IE 10, 'MoBro' tidbits leak ahead of Windows 8 CP launch

Internal Microsoft notes reveal new information about "MoBro" (Modern Browser) and a 64-bit only "Enhanced Protected Mode"

Yesterday, I stumbled upon what appears to be presentation notes from an undisclosed "IE readiness meeting" that took place between the IE leads and Eric Lawrence, Product Manager on the IE team, just weeks after the 2011 BUILD conference. The notes have been online for several months now, though no one seems to have either seen them or taken notice. They do contain mostly well-known IE features, but also at least one unknown feature of IE 10.

The notes are available here, though they are likely to be removed soon.

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While most of this was discussed at BUILD, the notes give some hints about lesser-known or even unknown performance improvements in WinInit (Windows Internet API), JavaScript and the limitations of the Metro-style Internet Explorer 10. Here are the highlights:

Mystery of the "Enhanced Protected Mode" (EPP) in IE 10 x64

One feature that struck me immediately is the implementation of a new feature dubbed "Enhanced Protected Mode" (EPP). The note reads:

New 64bit tabs will not execute 32bit plugins (e.g., <SL5). Can be enabled without Enhanced Protected Mode (EPP) which is for 64bit isolates tabs to AppContainers which further constrains reads and writes (ideal for high-security for example governments). ASLR = Address Space Layout Randomization and ForceASLR bit is true by default for added security.

"Protected Mode" has been introduced in IE 7 as a mechanism to prevent malware from writing to the registry and file system. However, "Enhanced Protected Mode" is something new. If I interpret these notes correctly, it simply uses the x64 version of IE 10 and isolates tabs in app containers, giving them the same restrictions that Metro-style apps have. Digging a bit further and checking back with friends from the IE team, I got an excerpt from the group policy which reveals:

Enhanced Protected Mode provides additional protection against malicious websites by using 64-bit processes on 64-bit versions of Windows. For computers running Windows 8 and above, Enhanced Protected Mode also limits the locations Internet Explorer can read from in the registry and the file system.

So, x64 IE 10.0 processes + AppContainer + ASLR + Protected Mode (which limits system access) = Enhanced Protected Mode? If so, this would mean an absolute locked-down browsing experience that would also lead to NO plug-ins, but maximum security. I'd enable that mode in a heartbeat.

IE 10 "MoBro" aka "Modern Immersive Browser" aka "MIB" limitations

As we know, Windows 8 ships with two separate versions of IE 10. The traditional, "classic" IE 10 and the Metro-style Internet Explorer app that the IE team refers to (mostly) internally as "MoBro/Modern Immersive Browser/MIB". The notes mention how the two browsers share settings and configurations, but operate "contextually" -- meaning that if you click on a URL in Outlook, the desktop IE 10 opens, while clicking on a URL in a Metro-style app causes MoBro to open.

Also, the note goes on to say how not just Plug-ins and Browser Helper Objects are unsupported in MoBro, but literally all third party interventions, including protocol handlers (think RSS readers). Unfortunately, the IE team is well aware that there is no supported method to determine which "mode" the user is currently in and seems to make no qualms about solving this scenario, which, in my opinion, is a mistake. At least give users the opportunity to switch to classic desktop, when the website includes non-supported content or content that requires plug-ins.

The same rigid restrictions apply to most video content: First of all, DRM (digital rights management) media is not supported and while DRM is pretty much hated across the board, some broadcasters still have no choice but to use it. Reading these notes, I was wondering how distributors of HD content are planning on targeting the Metro IE 10 if DRM isn't on board. Will everyone have their little app?

Windows Media Video V1-3 video format isn't on board, either. WEBGL 3D seems to have also been killed off in MoBro. I mean, I get it, as part of moving to an HTML5-powered web but forcing it this hard seems to really go a bit too far.

JavaScript and Browser Performance Enhancements

To offer improved performance, the JavaScript compiler seems to have undergone some optimization and a "plethora of new features" will be added to the onboard Javascript engine. Here's the note:

...such as the new html5 features and WebWorkers, JITing changes, etc.). Supports ECMA 5.0 -- see http://test262.ecmascript.org/. No multi-core in the roadmap, up to 100 WebWorkers supported, Watson (only for MoBro), new typed arrays use the native buffer, Strict mode is now supported which may break Javascript attempting to execute evals as they are not executed in strict mode (so the result below would be 10 instead of the expected 5).

To improve overall internet and browser responsiveness, Windows 8's "WinInet" (Windows Internet Application Programming Interface) seems to have undergone some under-the-hood changes. According to the internal presentation notes, site connections are now cached (and kept alive) and recycled for several "Get Requests" in one page, which reduces both traffic and improves performance. Since IE 10 isn't the only application making use of WinInet, other online applications benefit from it as well. Plus, the overhead of WinInet is being reduced since now all IE tabs/instances share only one WinInet service instead of creating a separate WinInet process.

We'll have more answers on those mysterious notes soon. Stay tuned.

This article, "IE 10, 'MoBro' tidbits leak ahead of Windows 8 CP launch," was originally published at ITworld. For the latest IT news, analysis and how-tos, follow ITworld on Twitter and Facebook.

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