Tag Archives: MoTW

Mark-of-the-Web: Additional Guidance

I’ve been writing about Windows Security Zones and the Mark-of-the-Web (MotW) security primitive in Windows for decades now, with 2016’s Downloads and MoTW being one of my longer posts that I’ve updated intermittently over the last few years. If you haven’t read that post already, you should start there. Advice for Implementers At this point,Continue reading “Mark-of-the-Web: Additional Guidance”

MHTML in Chromium

The MHTML file format (aka “Webpage, single file”) allows a single file to contain the multiple resources that are used to load a webpage (script, css, images, etc). Edge (Chromium) has an option to use the format when saving the current page via Ctrl+S or the Save page as… menu command: … but the browser’sContinue reading “MHTML in Chromium”

Security Zones in Edge (and Chrome)

Last updated: 25 March 2025 Browsers As Decision Makers As a part of every page load, browsers have to make dozens, hundreds, or even thousands of decisions — should a particular API be available? Should a resource load be permitted? Should script be allowed to run? Should video be allowed to start playing automatically? ShouldContinue reading “Security Zones in Edge (and Chrome)”

Private Browsing Mode

Note: This blog post was originally written before the new Chromium-based Microsoft Edge was announced. As a consequence, it includes discussion of the behavior of the Legacy Microsoft Edge browser. The new Chromium-based Edge behaves largely the same way as Google Chrome. Last Update: 13 June 2025 InPrivate Mode was introduced in Internet Explorer 8Continue reading “Private Browsing Mode”

Downloads and the Mark-of-the-Web

Last update: October 28, 2025 Background To help protect the user and their device, Windows and its applications will often treat files originating from the Internet more cautiously than files generated locally. The Windows Security Zones determination process is most directly implemented by the MapURLToZone API; that API accepts a URL or a file pathContinue reading “Downloads and the Mark-of-the-Web”