Defensive Technology: Windows Filtering Platform

Last November, I wrote a post about the basics of security software. In that post, I laid out how security software is composed of sensors and throttles controlled by threat intelligence. In today’s post, we’ll look at the Windows Filtering Platform, a fundamental platform technology introduced in Windows Vista that provides the core sensor andContinue reading “Defensive Technology: Windows Filtering Platform”

Debugging Chromium

A customer recently complained that after changing the Windows Security Zone Zone configuration to Disable launching apps and unsafe files: … trying to right-click and “Save As” on a Text file loaded in Chrome fails in a weird way. Specifically, Chrome’s download manager claims it saved the file (with an incorrect “size” that’s actually theContinue reading “Debugging Chromium”

Authenticode in 2025 – Azure Trusted Signing

I’ve written about signing your code using Authenticode a lot over the years, from a post in 2015 about my first hardware token to a 2024 post about signing using a Digicert HSM. Recently, Azure opened their Trusted Signing Service preview program up for individual users and I decided to try it out. The documentationContinue reading “Authenticode in 2025 – Azure Trusted Signing”

Guidelines for Secure Filename Display

Many years ago, I wrote the first drafts of Chromium’s Guidelines for Secure URL Display. These guidelines were designed to help feature teams avoid security bugs whereby a user might misinterpret a URL when making a security decision. From a security standpoint, URLs are tricky because they consist of a mix of security-critical information (theContinue reading “Guidelines for Secure Filename Display”

Mark-of-the-Web: Real-World Protection

Two years ago, I wrote up some best practices for developers who want to take a file’s security origin into account when deciding how to handle it. That post was an update of a post I’d written six years prior explaining how internet clients (e.g. browsers) mark a file to indicate that it originated fromContinue reading “Mark-of-the-Web: Real-World Protection”