Category Archives: browsers

Practical Time Machines

Many “emergency” situations in our modern world would’ve been easy to fix had they been foreseen in advance. If only we’d known what was going to happen, the badness could’ve easily been prevented. Unfortunately, when problems are discovered only “as they happen” in production, everyone must race to minimize the damage and put out theContinue reading “Practical Time Machines”

Determining OS Platform Version

In general, you should not care what Operating System visitors are using to visit your website. If you attempt to be clever, you will often get it wrong and cause problems that are an annoyance for users and a hassle for me to debug. So avoid trying to be nosy/clever if at all possible. ThatContinue reading “Determining OS Platform Version”

Download Blocking by File Type

Last Updated: 20 May 2024 I’ve previously gushed about the magic of the File Type Policies component — a mechanism that allows files to be classified by their level of “dangerousness”, such that harmless files (e.g. .txt files) can be downloaded freely, whilst potentially-dangerous files (e.g. .dll files) are subjected to a higher degree ofContinue reading “Download Blocking by File Type”

Per-Site Permissions in Edge

Last year, I wrote about how the new Microsoft Edge browser mostly ignores Security Zones (except in very rare circumstances) to configure security and permissions decisions. Instead, in Chromium per-site permissions are controlled by settings and policies expressed using a simple syntax with limited wildcarding support. Settings Page’s Site Permissions and Group Policy Internet ExplorerContinue reading “Per-Site Permissions in Edge”

Specifying Per-Site Policy with Chromium’s URL Filter Format

Chromium-based browsers like Microsoft Edge make very limited use of Windows Security Zones. Instead, most permissions and features that offer administrators per-site configuration via policy rely on lists of rules in the URL Filter Format. Filters are expressed in a syntax (Chrome Doc, Edge Doc) that is similar to other types of globbing rules, butContinue reading “Specifying Per-Site Policy with Chromium’s URL Filter Format”

Web Proxy Authentication

Last year, I wrote about how the new Microsoft Edge’s adoption of the Chromium stack changed proxy determination away from the Windows Service (WinHTTP Proxy Service) to similar but not identical code in Chromium. This change mostly goes unnoticed, but it can have performance and functionality implications. In today’s post, I want to explore anotherContinue reading “Web Proxy Authentication”

window.close() Restrictions

Sometimes, Web Developers are surprised to find that the window.close() API doesn’t always close the browser window. When looking at the Developer Tools console, they’ll see a message like: Scripts may close only the windows that were opened by them. Why Do Browsers Limit close()? Before we dive into what factors govern what happens whenContinue reading “window.close() Restrictions”

Sandboxing vs. Elevated Browsing (As Administrator)

The Web Browser is the most security-critical application on most users’ systems– it accepts untrusted input from servers anywhere in the world, parses that input using dozens to hundreds of parsers, and renders the result locally as fast as it can. For performance reasons, almost all code in almost all browsers is written in memory-unsafeContinue reading “Sandboxing vs. Elevated Browsing (As Administrator)”

Simply Making Simple Fixes Simple for Chromium

Google recently introduced a cool web-based editing tool for Chromium source code, a very stripped down version of the Willy Wonka tooling Googlers get to use for non-Chromium projects. I’ve used this tool to submit two trivial change lists (CLs, aka PRs) to Chromium, but I was curious about whether this new feature would workContinue reading “Simply Making Simple Fixes Simple for Chromium”