i4DM Security Bulletin | April 2026
WHAT HAPPENED?
A security researcher publicly leaked working exploit code for three Windows Defender vulnerabilities called BlueHammer, RedSun, and UnDefend.
What makes this dangerous is how these exploits work together. BlueHammer and RedSun allow bad actors to take full control of your system. Once inside, they use UnDefend to block Defender from updating its virus definitions, essentially blinding your antivirus while they operate freely. These attacks work on fully updated Windows 10 and 11 systems, meaning even machines that are current on patches are vulnerable right now.
THE BIGGER PICTURE: MYTHOS WILL LEAK
When it does, we are all in a lot of trouble. Anthropic’s Claude Mythos is an AI model that can autonomously discover zero-day vulnerabilities and build working exploits across every major operating system and browser. It recently chained four zero-days to escape a browser sandbox without human help. When this technology reaches the wrong hands, the speed and scale of cyberattacks will change dramatically. This is why we recommend revisiting BYOD policies and Azure Virtual Desktop (AVD) to keep company data off vulnerable endpoints.
HOW i4DM KEEPS YOU PROTECTED
Our clients trust us to keep them protected. Here’s how:
– We manage your patching. Critical updates are deployed across your systems so you don’t have to think about it.
– We don’t rely on Defender alone. Two of these three exploits specifically target Windows Defender. Our clients are protected with supplemental endpoint detection and response tools that go well beyond what Defender provides.
– We monitor for suspicious activity. Our team watches for privilege escalation, unauthorized access, and anomalies so threats are caught before they become incidents.
– We train your team. Most attacks still start with phishing or stolen credentials. We provide cybersecurity awareness training so your people recognize threats before they click.
– We enforce strong authentication. Enhanced multi-factor authentication and password management are standard across our managed environments.
– We help you plan for what’s next. With threats like Mythos on the horizon, now is the time to evaluate BYOD policies and Azure Virtual Desktop to keep company data off vulnerable endpoints.
Want to know how protected your business is? Call today: 410-995-8444 | [email protected]
Sources: BleepingComputer, Huntress Labs, SOCRadar, Help Net Security, The Hacker News