Security Software – An Overview

Last Update: 8 September 2026 I’ve spent nearly my entire professional career in software security: designing software to prevent abuse by bad actors. I’ve been battling the bad guys for over two decades now, from hunting security bugs in Microsoft Office (I once won an Xbox for finding a vulnerability that allowed malicious clipart takeContinue reading “Security Software – An Overview”

Best Practices for SmartScreen AppRep

Last Updated: September 9, 2026 Last year, I wrote about how Windows integrates SmartScreen Application Reputation to help ensure users have a secure and smooth experience when running downloaded software. tl;dr: When a user runs a downloaded program, Windows/Edge call SmartScreen web-based reputation service. There are four possible outcomes: As a software developer, it’s naturalContinue reading “Best Practices for SmartScreen AppRep”

Defensive Technology: Controlled Folder Access

Most client software’s threat models (e.g. Edge, Chrome) explicitly exclude threats where the local computer was compromised by malware. That’s because, without a trusted computing base, it’s basically impossible to be secure against attackers. This concept was immortalized decades ago in the Ten Immutable Laws of Security: In the intervening years, new technologies (like SecureContinue reading “Defensive Technology: Controlled Folder Access”

Defensive Technology: Antimalware Scan Interface (AMSI)

Endpoint security software faces a tough challenge — it needs to be able to rapidly distinguish between desired and unwanted behavior with few false positives and false negatives, and attackers work hard to obfuscate (or cloak) their malicious code to prevent detection by security scanners. To maximize protection, security software wants visibility into attack chainsContinue reading “Defensive Technology: Antimalware Scan Interface (AMSI)”