While most Windows users focus on antivirus software and firewalls, a quiet but powerful security feature has been working in the background to protect systems against one of the most dangerous classes of cyberattacks: kernel-level driver exploits.
Microsoft’s Vulnerable Driver Blocklist, part of the Core Isolation security umbrella, operates silently to prevent known-dangerous drivers from ever executing on Windows systems.
How It Works
The Vulnerable Driver Blocklist is a collection of drivers that are restricted by default from running in Windows, preventing attackers from exploiting what’s known as Bring-Your-Own-Vulnerable-Driver (BYOVD) attacks.
Drivers are special pieces of software that give hardware components (cameras, microphones, network adapters, and storage controllers) direct pathways into the Windows kernel, and because kernel-mode drivers run with very high privileges, a single vulnerable or malicious driver can be used to bypass user-mode protections, disable security tooling, or escalate privileges to obtain full system control.
Microsoft’s Careful Balancing Act
The Vulnerable Driver Blocklist is the result of ongoing collaboration between Microsoft and independent hardware vendors (IHVs) and OEMs, and whenever a driver vulnerability is reported, Microsoft works with vendors to patch the security threat and add a driver version to the blocklist if the threat factor is significantly high and the risk of breaking compatibility is relatively low.
However, Microsoft’s Vulnerable Driver Blocklist doesn’t list all compromised drivers That is because sometimes blocking a driver without the user knowing about it can cause poor user experience on Windows, such as device malfunctions and the dreaded Blue Screen of Death (BSOD). The blocklist is updated through Windows Update during feature updates roughly 1-2 times per year.
Multiple Protection Layers
In most Windows installations, the Vulnerable Driver Blocklist is on by default and is enforced when hypervisor-protected code integrity (HVCI), Smart App Control, or S mode is active.
The blocklist operates through Windows Defender Application Control, and when a driver attempts to load, Windows checks its cryptographic hash against the regularly updated blocklist, if it matches a known vulnerable or malicious entry, the system prevents it from loading entirely.
User Control and Management
For regular consumers, the Vulnerable Driver Blocklist can be toggled through the Windows Security app or through the Settings app under Privacy & Security > Windows Security.
For IT administrators, Microsoft offers an offline XML policy file that can be downloaded and deployed across enterprise environments.
Limitations and Best Practices
The blocklist is not a silver bullet, as it turns out. Compatibility constraints, update cadence, and the sophistication of adversaries mean it must be paired with vigilant vendor coordination, proactive detection, and staged auditing in production.
Security experts recommend that users maintain updated drivers from trusted vendors, keep systems fully patched, and treat the blocklist as part of a wider, continuously maintained defense-in-depth strategy rather than as a standalone protective measure.
