Today, most browsers integrate security services that attempt to protect users from phishing attacks: for Microsoft’s Edge, the service is Defender SmartScreen, and for Chrome, Firefox, and many derivatives, it’s Google’s Safe Browsing. URL Reputation services do what you’d guess — they return a reputation based on the URL, and the browser will warn/block loadingContinue reading “Cloaking, Detonation, and Client-side Phishing Detection”
Tag Archives: SmartScreen
ServiceWorkers vs. Network Filtering
In a recent post, I explored how the design of network security features impact the tradeoffs of the system. In that post, I noted that integrating a URL check directly into the browser provides the security check with the best context, because it allows the client to see the full URL being checked and ifContinue reading “ServiceWorkers vs. Network Filtering”
The Challenge of IP Reputation
When protecting clients and servers against network-based threats, it’s tempting to consider the peer’s network address when deciding whether that peer is trustworthy. Unfortunately, while IP addresses can be a valuable signal, attempts to treat traffic as trustworthy or untrustworthy based on IP address alone can be very prone to mistakes. Background Most clients andContinue reading “The Challenge of IP Reputation”
SmartScreen Application Reputation, with Pictures
Last Update: September 8, 2026 I’ve previously explained how Chromium-based browsers assign a “danger level” based on the type of the file, as determined from its extension. Depending on the Danger Level, the browser may warn the user before a file download begins in order to confirm that the user really wanted a potentially-dangerous file.Continue reading “SmartScreen Application Reputation, with Pictures”
Enforcing SmartScreen with Policy
Microsoft Defender SmartScreen provides protection against the most common forms of attack: phishing, malware, and tech scams. SmartScreen support is built-in to Microsoft Edge and the Windows 8+ shell. The SmartScreen web service also powers the Microsoft Defender Browser Protection extension for Chromium-derived browsers. While SmartScreen provides powerful controls to block attacks, the user remainsContinue reading “Enforcing SmartScreen with Policy”