Microsoft Vulnerable Driver Blocklist: Securing Windows Kernel Against BYOVD

Microsoft’s Windows already runs dozens of security checks before a program touches the kernel, but one of the least obvious — and quietly powerful — defenses is the Microsoft Vulnerable Driver Blocklist, a managed list that stops known-weak or malicious drivers from loading and protects the kernel from Bring-Your-Own-Vulnerable-Driver (BYOVD) and related exploitation techniques.

Background / Overview​

Drivers are special pieces of software that give hardware components — cameras, microphones, network adapters, storage controllers, and more — direct pathways into the Windows kernel. 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 answer to that risk is a layered strategy: code signing requirements, kernel integrity checks, virtualization-based protections, and a managed driver blocklist that prevents known-problem drivers from ever being loaded on protected systems. The blocklist is part of the broader Core Isolation and Windows Defender Application Control (WDAC) toolset and is designed to be applied automatically to systems that have the appropriate protections enabled.
Across the Windows ecosystem, Microsoft and hardware partners (IHVs/OEMs) collaborate to identify drivers that present a high risk to kernel integrity — drivers with known CVEs, those signed with certificates used by malware, or drivers that deliberately circumvent Windows security expectations. When risk and compatibility considerations align, Microsoft places vulnerable driver entries into a managed block policy that is distributed to endpoints.

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How the Vulnerable Driver Blocklist works​

The enforcement stack: HVCI, WDAC and Core Isolation​

The blocklist is enforced through a combination of features:

• Hypervisor-Protected Code Integrity (HVCI) — also called Memory Integrity — uses virtualization to verify kernel code before execution, making it much harder for unsigned or tampered drivers to run.
• Windows Defender Application Control (WDAC) — implements driver block and allow rules as a signed policy (SiPolicy) that the OS enforces.
• Core Isolation — the Windows Security surface where the blocklist setting is surfaced to end users (Device Security > Core isolation).

On supported systems, the Microsoft-managed blocklist becomes active and prevents drivers matching the block rules from loading into the kernel. The block rules can target drivers by SHA256 hash, file attributes (such as filename or version), and code signing certificate attributes — which gives Microsoft multiple lever points to block entire signer families or specific bad builds. BleepingComputer’s technical coverage and Microsoft documentation both describe these rule types.

Where the policy lives (and how it’s delivered)​

Microsoft publishes the managed block policy as an App Control policy that can be deployed in two forms:

• The binary policy used by the OS: often seen as a SiPolicy.p7b file and installed under %windir%\System32\CodeIntegrity.
• A downloadable “recommended driver block rules” package for enterprises that want the most up-to-date enforcement, which administrators can apply through App Control for Business. Microsoft documents the steps to download/extract a policy, rename the file to SiPolicy.p7b, copy it to the CodeIntegrity folder, and refresh App Control policies to activate it.

Microsoft historically ships blocklist updates as part of Windows Feature releases and periodic Windows Update servicing. The company states the managed blocklist is typically updated with each major Windows release and roughly one to two times per year, and it also occasionally publishes updates via regular Windows servicing channels. For organizations that require the latest rules, Microsoft recommends applying the downloadable policy with WDAC/App Control instead of waiting for OS-servicing cadence.

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Why this matters: The BYOVD threat and real-world context​

Attackers have steadily exploited the kernel attack surface using compromised or poorly implemented third‑party drivers. The BYOVD (Bring Your Own Vulnerable Driver) technique works by dropping a signed, legitimate driver with a known kernel flaw onto a target machine; because many drivers run in kernel mode and have privileged hooks, exploiting them can provide attackers durable, powerful access.
Microsoft’s vulnerable driver blocklist is a pragmatic countermeasure: rather than trying to police every possible code path, the blocklist prevents specific catalogued drivers from loading, removing a practical vector attackers use to get into the kernel. The security community and vendors feed driver vulnerability information into Microsoft’s process, allowing the blocklist to be informed by multiple sources including the Microsoft Vulnerable and Malicious Driver Reporting Center.
But the blocklist isn’t a silver bullet. History shows realistic limitations: in 2022 researchers discovered synchronization problems where the on-device blocklist on older Windows installations lagged behind Microsoft’s recommended list, leaving many systems exposed despite Microsoft publishing updated rules. Microsoft acknowledged the gap and patched the servicing process, but the episode underlines two themes: distribution timing matters, and enterprises should consider applying the latest blocklist via App Control if they need immediate parity with Microsoft’s recommended rules.

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Strengths: What the blocklist gets right​

• Managed, centrally curated protection for kernel risk: The blocklist leverages Microsoft’s global telemetry, partner reports, and security analysis to block drivers that are actively known to be dangerous. For organizations that enable HVCI or adopt WDAC, this delivers a near-zero administration path for that specific class of risk.
• Multiple blocking mechanisms: Rules based on hashes, file attributes, and signing certificates make policy resilient: Microsoft can block a single malicious build or an entire family signed by an abused certificate. This flexibility helps respond to threat patterns quickly.
• Integration with existing Windows security features: The blocklist works with HVCI, Smart App Control, and S Mode enforcement — helping tasks like device hardening become more straightforward for administrators and end users who accept Microsoft defaults.
• Enterprise deployment options: Organizations that require the most current rules can apply the downloadable WDAC policy and test it in audit mode prior to enforcement. Microsoft supplies tools and guidance so admins can verify policy application via Event Viewer and App Control logs.

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Limitations and risks you must understand​

• Compatibility vs. coverage tradeoff: Microsoft candidly acknowledges the blocklist is not exhaustive. Blocking a driver without careful consideration can cause device malfunctions and, rarely, stop errors (BSOD). For that reason, Microsoft balances blocking with compatibility concerns and may hold back some entries from on-device distributions to avoid widespread breakage. This means the managed endpoint list is often intentionally conservative compared to the fuller “recommended” list Microsoft offers to admins.
• Update cadence and synchronization issues: Because the policy is often updated around major Windows releases, there can be temporal gaps between when Microsoft identifies a dangerous driver and when every device receives the updated block rules. Enterprises that need tighter parity should apply the downloadable policy and use App Control to get updates immediately. The October 2022 synchronization bug — where older Windows versions were receiving outdated blocklists — illustrates the real impact of servicing gaps. Microsoft fixed that issue, but the event remains a cautionary tale.
• Dependence on HVCI or WDAC for full enforcement: Some blocking semantics are designed around systems with HVCI enabled. On systems without virtualization‑based protections, certain blocklist rule flavors may not behave identically, and Microsoft’s guidance is for non‑HVCI environments to rely on App Control. Recent community disclosures and advisories have documented nuanced enforcement differences that administrators should review before deploying a merged or custom policy. Administrators must audit and test policies in their environments rather than assuming identical behavior across all Windows builds.
• Potential bypasses and policy complexities: Security tooling and policy systems are not immune to misconfigurations or implementation gaps. Public advisories have discussed scenarios where certain WDAC rule qualifiers may not block drivers as expected on endpoints that lack HVCI; Microsoft’s guidance emphasizes that the blocklist is intended to be used in combination with HVCI and App Control best practices for full effect. Where unusual enforcement patterns matter (for example, on legacy server hardware or specialized appliances), administrators should validate behavior and consult Microsoft’s updated guidance.

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Deployment details for administrators and IT teams​

If you’re responsible for endpoint security, here’s what to know and do.

Quick checklist (high-level)​

• Ensure systems that require broad kernel protection have HVCI (Memory Integrity) enabled where hardware supports it.
• Apply the Microsoft recommended driver block rules via App Control for Business if you need the most current, aggressive list.
• Test any new block policy in audit mode before enforcing it in production.
• Monitor Event Viewer: CodeIntegrity operational logs expose policy application and block events (Event ID 3099 is one of the useful filters Microsoft documents).

Step-by-step: Applying the recommended blocklist (summary of Microsoft guidance)​

• Download the App Control policy refresh tool from Microsoft’s distribution channel.
• Download and extract the vulnerable driver blocklist binary package.
• Choose the audit-only or enforced version; rename it to SiPolicy.p7b.
• Copy SiPolicy.p7b to %windir%\System32\CodeIntegrity on the target device.
• Run the App Control policy refresh tool to activate and refresh policies.
• Reboot systems where drivers are already loaded to ensure blocked drivers are prevented on subsequent kernel loads.
• Verify via Event Viewer: Applications and Services Logs → Microsoft → Windows → CodeIntegrity → Operational and filter for relevant event IDs (such as 3099).

Testing and mitigation best practices​

• Start in audit mode to collect data on any drivers the policy would block without enforcing those blocks. Review logs and partner with IHVs to obtain patched driver builds for any critical devices.
• Use the Attack Surface Reduction (ASR) rule “Block abuse of exploited vulnerable signed drivers” in parallel for prevention of new vulnerable driver files being written to disk. The ASR rule complements the driver blocklist but does not replace it: ASR prevents new writes of exploit-prone drivers, whereas the blocklist prevents loaded drivers that match known-bad rules.

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What consumers and small business users should know​

• In most consumer installs of Windows 11 (post‑22H2), the blocklist is on by default where appropriate protections are present; average users should not need to take action beyond keeping Windows Update enabled. Microsoft surfaces a toggle in the Windows Security app under Device Security > Core isolation, but that toggle’s availability depends on your exact OS build and HVCI/Smart App Control configuration. If you see a banner about a blocked driver, check for a driver update via Windows Update or the device manufacturer.
• If a user experiences a device malfunction after a driver block, the recommended path is to update the driver from the vendor or roll back to a known-good driver supplied by the hardware manufacturer; disabling HVCI to circumvent a block is not recommended for security reasons unless you have no other option. Microsoft’s documentation warns that disabling the blocklist can be done via settings or registry tweaks on some builds, but this is discouraged unless necessary and done with full understanding of the risk.

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Case studies and historical notes​

• October 2022 sync issue: Researchers revealed that Windows 10 devices were receiving an outdated blocklist while Microsoft’s recommended online list had been updated. Microsoft corrected the servicing process and released a fix in an October 2022 preview update so the on‑endpoint list matched Microsoft’s recommended rules again. The episode demonstrated that distribution logistics matter: a perfect policy is only useful if devices actually receive it in a timely way.
• Ongoing vigilance: Microsoft continues to refine how the blocklist is curated and distributed. The company publishes the recommended driver block rules and provides a channel for driver submissions and dispute resolution through its Security Intelligence portal. Enterprises are advised to use the downloadable policy if they need stricter, faster protection than standard servicing provides.
• Reported implementation nuance (CVE advisory): Public advisories have highlighted nuanced enforcement differences in the WDAC implementation for driver block rules on systems that do not have HVCI enabled, indicating some rule qualifiers may not behave identically in such environments. Microsoft’s guidance is to use HVCI and App Control together and to verify behavior in target environments. Administrators should treat these advisories as prompts to validate policy behavior, particularly on heterogeneous or legacy endpoints.

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A clear-eyed security appraisal​

The Vulnerable Driver Blocklist is an important and pragmatic layer in Microsoft’s kernel protection architecture. It reduces attack surface by denying known dangerous drivers an entry point to the kernel — a capability that matters because exploitation of kernel-mode drivers remains one of the most reliable pathways for advanced threat actors to gain persistent control.
That said, it is neither comprehensive nor infallible. The list’s conservative distribution to avoid wide-scale compatibility regressions, its dependency on HVCI/WDAC for full effect, and past synchronization hiccups mean administrators must treat the blocklist as one critical control among several — not the final word on kernel security. Enterprises seeking maximum protection should:

• Enable HVCI and apply WDAC/App Control policies where hardware and workflows permit.
• Deploy Microsoft’s recommended driver block rules via App Control if they require the most current protections.
• Test policies in audit mode, work closely with IHVs for patched drivers, and maintain robust logging and alerting around CodeIntegrity events.

For consumers, the default protections on modern Windows 11 devices are a practical improvement: they raise the bar against common BYOVD tactics and make it harder for commodity and even some advanced attacks to succeed. Users should keep Windows Update and device drivers current and be cautious about manually installing third‑party drivers from unknown sources.

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Practical recommendations — checklist you can act on today​

• For home users:
• Keep Windows Update enabled and install recommended updates.
• Check Windows Security → Device Security → Core isolation to confirm Memory Integrity (HVCI) is enabled if your device supports it.
• If you see a blocked-driver banner, look for a vendor-supplied driver update before disabling protections.
• For IT administrators:
• Evaluate hardware compatibility and enable HVCI on supported fleets.
• Download the Microsoft recommended driver block rules and run them in audit mode across representative endpoints.
• Address any blocked drivers by coordinating with vendors and testing patched drivers before enforcing the policy.
• Use central management (Intune/Group Policy/endpoint management tooling) to roll the policy out and to gather CodeIntegrity logs centrally.
• Do not merge the Microsoft policy blindly with an explicit allowlist policy; remove “Allow All” rules if you plan to make a strict allowlist enforcement policy.

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Conclusion​

Stopping kernel‑level exploitation requires multiple layers and rigorous operational practices. Microsoft’s Vulnerable Driver Blocklist is a solid, pragmatic layer — a managed, evidence-driven list that takes the most dangerous known driver builds out of circulation on protected systems. It is especially effective when combined with HVCI and WDAC policies and when organizations proactively use Microsoft’s downloadable policy to keep pace with threats.
But it is not a substitute for good operational hygiene: testing, driver lifecycle management, vendor coordination, and thoughtful policy rollout are still essential. The blocklist raises the security baseline for millions of Windows devices, but its true value is realized only when administrators, hardware partners, and end users treat it as part of a wider, continuously maintained defense-in-depth strategy.

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Source: Neowin This Windows security feature blocks dangerous drivers before they strike

 

[ChatGPT]

Microsoft’s quietly powerful Vulnerable Driver Blocklist now sits among the least flashy — but most consequential — defenses in Windows, preventing known‑weak kernel drivers from loading before they can be abused to escalate privileges, disable security software, or crash systems. m]

Background​

Drivers are the glue between hardware and the Windows kernel: cameras, microphones, USB audio devices, virtualization helpers and low-level system utilities all run kernel‑mode drivers to perform privileged actions. That privilege, however, is a double‑edged sword. A signed driver with a latent vulnerability can be reused by attackers — a tactic known as Bring‑Your‑Own‑Vulnerable‑Driver (BYOVD) — to gain kernel access and evade user‑mode defenses. Security researchers and vendors have documented multiple BYOVD campaigns in recent years, and Microsoft built the Vulnerable Driver Blocklist as a systemic countermeasure.
Introduced as an optional capability in Windows 10 and progressively hardened since, the blocklist is now part of the Core Isolation family of protections and, beginning with Windows 11 version 22H2, enabled by default on many devices. It’s managed as a signed Code Integrity (CI) policy and enforced by the operating system when certain protections — notably Hypervisor‑Protected Code Integrity (HVCI, also known as Memory Integrity), Smart App Control, or S Mode — are active. Microsoft updates the blocklist through Windows Update and publishes a more complete policy package for administrators who need to apply it manually.

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What the Vulnerable Driver Blocklist actually is​

The short definition​

• What: A Microsoft‑maintained list of kernel drivers (specific file hashes, file names, or driver versions) that are disallowed from loading because they contain known, exploitable vulnerabilities.
• Where it lives: As a signed Code Integrity policy binary (SiPolicy.p7b/DriverSiPolicy.p7b) in the OS CodeIntegrity folder and delivered via Windows Update or the Microsoft Download Center.
• When it runs: The kernel consults the policy during driver load and denies matching drivers from loading; if a driver is already loaded, a reboot is required for denial to take effect.

Why Microsoft created it​

Kernel drivers run with the highest privileges. Historically, attackers have abused signed drivers with vulnerabilities to perform actions that ordinary unsigned malware cannot: tamper with EDRs and antivirus products, intercept or modify kernel data structures, or create persistent, stealthy footholds. The blocklist aims to eliminate that attack surface by preventing known‑weak drivers from ever executing on protected systems. Microsoft also works with independent hardware vendors (IHVs) and OEMs to coordinate fixes and mitigate compatibility problems before blocking entries are enforced broadly.

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How it works — a technical walkthrough​

Policy format and delivery​

The blocklist is distributed as a Code Integrity policy. Administrators can:

• Download an XML policy (recommended blocklist) and convert it to a binary SiPolicy.p7b.
• Copy the binary into the system CodeIntegrity folder and run Microsoft’s App Control policy refresh tool to activate it.
• Use audit mode first to observe what would be blocked before enforcing rules.

When Windows starts and when drivers are loaded, the kernel checks the active CI policies. If a driver matches a deny rule in the Vulnerable Driver Blocklist, the OS prevents the binary from mapping into kernel memory. For drivers already present in memory at activation time, a restart is required to finish enforcement. Eventing lives under the CodeIntegrity logs in Event Viewer (Applications and Services Logs → Microsoft → Windows → CodeIntegrity → Operational), and Event ID 3099 indicates policy application details.

Integration with other Windows protections​

The blocklist complements several other layers:

• HVCI / Memory Integrity: HVCI enforces code integrity in a hypervisor‑protected environment; the blocklist is enforced when HVCI is active.
• Smart App Control and S Mode: These modes expand enforcement surfaces and, when active, cause the blocklist to be applied more strictly.
• Attack Surface Reduction (ASR): Microsoft recommends enabling the ASR rule “Block abuse of exploited vulnerable signed drivers” as a prevention layer for write‑to‑disk scenarios; note that ASR prevents writing vulnerable drivers to disk but does not by itself block an already‑installed driver from loading.

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The threat the blocklist addresses: BYOVD and real incidents​

Bring‑Your‑Own‑Vulnerable‑Driver is not academic. Multiple research reports and incident analyses have shown adversaries using legitimate signed drivers as a stepping stone to kernel‑level control. The Check Point Research analysis of the Silver Fox campaign — which abused a WatchDog Antimalware driver to terminate security processes and deploy the ValleyRAT backdoor — is one of the clearest, recent examples. Check Point’s findings underline two key points: drivers can be signed yet still exploitable, and attackers can modify binaries (e.g., tweak unauthenticated signature attributes) in ways that preserve signature validity while altering file hashes. That undermines simple hash‑based blocklists and demonstrates why Microsoft and responders must stay proactive.
Security reporting and mainstream outlets documented these tactics and urged administrators to monitor the driver blocklist closely, because such drivers can be weaponized to kill AV/EDR processes, disable telemetry and persistence controls, or conceal kernel rootkits. Tech publications and CERT agencies recommended applying Microsoft’s blocklist, but also supplemented it with YARA rules and behavior‑based detection where possible.

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Strengths: What the blocklist does well​

• Stops a high‑risk, high‑impact class of attacks before execution. Blocking known vulnerable drivers eliminates one of the most powerful primitives attackers enjoy: kernel execution using trusted artifacts. This reduces the attack surface available to adversaries attempting privilege escalation or EDR evasion.
• Integrated and OS‑level enforcement. Because the policy is enforced at boot and during driver load, it is harder for user‑mode malware to bypass than third‑party allow/block schemes.
• Administrable and auditable. Microsoft provides an offline XML policy for testing, and the platform supports audit mode so organizations can measure impact before enforcing blocks. Event logging provides a path to triage false positives or identify compatibility risk.
• Vendor collaboration model. Microsoft coordinates with IHVs/OEMs to patch drivers and to time the addition of blocklist entries to avoid unnecessary breakage — an important practical measure in heterogeneous hardware environments.

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Risks, caveats, and real‑world tradeoffs​

No protection is free of tradeoffs. The Vulnerable Driver Blocklist’s practical utility is tightly coupled to how Microsoft, IHVs and admins balance security with compatibility.

• Compatibility breakage: Blocking a driver can cause devices or software to malfunction — from cameras and USB audio devices to BIOS/flashing utilities. Community reports show that some Windows updates that added drivers to the blocklist were followed by user complaints of broken peripherals, error Code 10 states, or failures of firmware update tools. These are real pain points for end users and IT. These incidents illustrate why Microsoft holds back some blocks until vendor fixes and extensive testing are completed. Community reports and update notes referenced updates to DriverSiPolicy.p7b that correlated with device failures. These are credible user reports, but each case requires troubleshooting because many variables (driver versions, OS build, OEM utilities) can affect outcomes.
• Not exhaustive: Microsoft explicitly states the blocklist is not comprehensive. The company balances the need to prevent exploitation with the risk of breaking essential functionality; therefore, some known vulnerable drivers may not be blocked immediately if doing so would cause widespread compatibility issues. That means administrators and defenders should not rely solely on Microsoft’s list as the single source of truth.
• Delay between disclosure and blocking: Vendor coordination and testing take time. During that window, defenders must use detection and defense‑in‑depth strategies (EDR heuristics, ASR rules, monitoring for suspicious driver load events) to mitigate exploitation. Check Point researchers emphasized the need for YARA and behavior detection because some exploited drivers were not yet blocklisted.
• Hash/signature trickery: As Check Point documented, attackers may alter unauthenticated parts of a signed binary to change its hash while retaining signature validity, complicating hash‑based deny rules. This demonstrates the need for policy entries that include more than just file hashes where possible — for example, vendor/version constraints, or other attributes.

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Practical guidance: What admins and power users should do​

For IT administrators (enterprise)​

• Treat the Microsoft blocklist as a critical but not sole control. Combine it with ASR rules, EDR behavioral rules, and file integrity monitoring.
• Deploy in audit mode first. Use the provided XML policy and the App Control policy refresh tool to apply the blocklist in audit mode so you can observe Event ID 3099 and CodeIntegrity operational logs without breaking devices.
• Test on pilot groups. Roll the policy to a small subset of hardware variants to detect compatibility impact.
• Coordinate with IHVs/OEMs. When a driver is flagged as vulnerable, push vendors to supply patched drivers and coordinate rollout timing before moving from audit to enforced mode.
• Use multiple policy layers. If you operate WDAC/Device Guard policies, merge carefully and avoid KeepAll/Allow All rules that may inadvertently reopen the attack surface.
• Document rollback plans. Know how to remove policies or disable enforcement for affected fleets without hitting firmware locks that could prevent boot. (Microsoft warns about UEFI‑locked policies in other contexts; test recovery steps.)

For home and power users​

• Check the toggle in Windows Security: Open Windows Security → Device Security → Core isolation details. The Vulnerable Driver Blocklist toggle should be visible on systems where the Windows Security app exposes it; if you don’t see it, the policy may still be present and active under the hood — check Windows Registry or the CodeIntegrity folder. Microsoft documentation explains how the toggle interacts with Memory Integrity and S Mode.
• If a peripheral stops working after an update: Before long troubleshooting, consider temporarily disabling the Vulnerable Driver Blocklist (only if you accept the risk) or rolling back the recent Windows update — but be mindful that disabling the blocklist may reduce protection against attacks that abuse vulnerable drivers. Always obtain driver updates from the vendor rather than relying on third‑party sources. Community threads show users recovering functionality by rolling back particular KBs that updated DriverSiPolicy.p7b, but this is a practical mitigation rather than a recommended long‑term solution. ([reddit.ct.com/r/Insta360/comments/1i59m4t)

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Operational checklist: Deploying the blocklist safely​

• Download the recommended blocklist XML from Microsoft’s Download Center.
• Convert XML to binary (SiPolicy.p7b) using ConvertFrom‑CIPolicy or the WDAC wizard.
• Apply the binary to a test device and run App Control policy refresh.
• Monitor Event Viewer: filter CodeIntegrity Operational for Event ID 3099 to verify policy application and identify candidate blocked drivers.
• Move to staged enforcement after confirming no critical devices are impacted. 6. Maintain a vendor escalation path and a driver‑update calendar to remediate blocked items.

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How to read signs of trouble — and what to avoid​

• Do not assume that a missing toggle means the blocklist is disabled. Microsoft’s UI availability and the Windows Security app version can vary; the presence of SiPolicy files under the CodeIntegrity folder or registry flags can indicate activity even if the UI element is absent. If you’re uncertain, check Event Viewer and the CodeIntegrity folder before toggling protections.
• Avoid disabling HVCI or the blocklist as a first step when something breaks. Instead, use audit logs to identify the blocked item, obtain an updated vendor driver where possible, or test removal of the offending driver in a controlled manner. Disabling the protection reduces your system’s resilience to BYOVD-style attacks.

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Critical observations and recommended improvements​

• Microsoft’s approach correctly balances security and compatibility, but the approach leaves a residual exposure window: drivers that are known vulnerable but withheld for compatibility reasons continue to present risk. Organizations should maintain an independent inventory of drivers used on their endpoints and proactively monitor third‑party advisories and CVEs relevant to those drivers.
• The blocklist relies on vendor cooperation and testing. Microsoft should continue to expand telemetry and vendor notification channels so high‑risk drivers are remediated faster and the need for blocking that impacts customers is minimized. The Check Point Silver Fox analysis underscores the need for rapid, automated sharing of detection rules — such as YARA signatures and behavior indicators — in addition to blocked hashes.
• Policy granularity can be improved. Relying on simple hash denies is fragile when adversaries can tweak unauthenticated signature attributes. Policies that include contextual signals — certificate chain attributes, file size ranges, or version constraints — reduce false negatives and raise attack cost for adversaries. Check Point’s research demonstrated attackers’ ability to change hashes while preserving signature validity.

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Conclusion​

The Vulnerable Driver Blocklist is an essential, pragmatic tool in Windows’ defense‑in‑depth architecture. It prevents a particularly dangerous class of kernel attacks and gives Microsoft and enterprise defenders a way to centrally deny known‑bad drivers. That said, it is not a silver bullet: compatibility constraints, update cadence, and the sophistication of adversaries mean the blocklist must be paired with vigilant vendor coordination, proactive detection, and staged auditing in production.
If you run Windows in a managed environment, treat the blocklist as a mandatory policy to test and deploy — but never as the only control. If you’re a home user, keep your system updated, check Windows Security’s Core Isolation settings, and always prefer vendor drivers updated to patch vulnerabilities. The attacker techniques the blocklist is designed to neutralize are real and evolving; layered defenses and active monitoring remain the most reliable path to safety.

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Source: Neowin This Windows security feature blocks dangerous drivers before they strike