WDAC

Winsage
April 13, 2026
Microsoft will enforce a new mandate requiring all hardware drivers to comply with the Windows Hardware Compatibility Program (WHCP) standards starting April 1, 2026. This change will eliminate the "cross-signing" system that allowed older drivers with expired certificates to remain trusted. The enforcement of WHCP certification will apply to various versions of Windows 11 and Windows Server 2025. Users may face blocks when installing older drivers on new systems, but existing installations will not be immediately disrupted. Microsoft plans to introduce an "allow list" for vetted legacy drivers to ensure essential equipment remains operational during the transition. The initial rollout will occur in "evaluation mode," allowing Microsoft to monitor driver behavior without blocking software. For corporate environments, Microsoft offers "Application Control for Business" to allow specific software while maintaining security measures.
Winsage
March 31, 2026
Microsoft will eliminate default trust for kernel drivers signed through the outdated cross-signed root program with the April 2026 Windows update. All new kernel drivers must be certified via the Windows Hardware Compatibility Program (WHCP). This change will affect Windows 11 builds 24H2, 25H2, and 26H1, as well as Windows Server 2025, with future versions following the same standards. The update will begin in evaluation mode, monitoring driver loads for compliance before transitioning to enforcement mode. An allow list of reputable drivers will be maintained for legacy hardware, and enterprises can use Application Control for Business policies to authorize specific drivers. Users with older hardware may face compatibility issues if their drivers are not WHCP-certified.
Winsage
March 12, 2026
In March, Microsoft released cumulative security updates for Windows 10 and Windows 11, with support for certain versions continuing until March 2026. The updates include KB5079466 for Windows 11 version 26H1, KB5079473 for versions 24H2 and 25H2, KB5078883 for version 23H2, and KB5078885 for Windows 10 version 22H2. These updates will be distributed via Windows Update, the Microsoft Update Catalog, and WSUS for enterprise environments. This month, Microsoft combined the Servicing Stack Update (SSU) with the Latest Cumulative Update, simplifying the update process. Key enhancements include improvements to Secure Boot, with expanded device target data for new certificates, and security enhancements for Explorer’s search functionality in Windows 11 versions 24H2 and 25H2. A fix for Windows Defender Application Control (WDAC) was also implemented, addressing issues with COM objects under certain policy configurations. The Windows System Image Manager received a new warning dialog for confirming the trustworthiness of catalog files, which is important for enterprise environments. Updates for Windows 10 22H2, despite its end-of-life status, included fixes for secure boot issues and improvements for file version history in the Control Panel. An SSU for Windows 11 (KB5077869) was also released to maintain update stability. Microsoft's updates scheduled for March 2026 will address vulnerabilities in components like the Windows App Installer, SQL Server, and Microsoft Office. The Security Update Guide provides detailed information on specific vulnerabilities and affected components.
Winsage
September 1, 2025
Cybercriminals are using Windows Defender Application Control (WDAC) policies to disable Endpoint Detection and Response (EDR) agents, creating vulnerabilities in corporate security. Ransomware groups like Black Basta have adopted this method, which evolved from a proof-of-concept tool called "Krueger" into real malware named "DreamDemon." Attackers manipulate the C:WindowsSystem32CodeIntegritySiPolicy.p7b file to implement malicious WDAC policies that block EDR executables during system startup. The technique involves a four-step process: loading the policy, placing it in the CodeIntegrity directory, hiding the policy file, and creating decoy log files. DreamDemon samples, written in C++, exhibit enhanced stealth and target major EDR vendors. Detection efforts focus on monitoring specific registry keys and analyzing file signatures. Despite awareness of this threat, EDR vendors have not implemented sufficient preventative measures, leaving systems exposed.
Winsage
April 22, 2025
A security vulnerability identified as CVE-2025-21204 has been discovered in the Windows Update Stack, allowing local attackers to execute unauthorized code and escalate privileges to SYSTEM-level access. This vulnerability, with a CVSS score of 7.8 (High), affects Windows 10 versions 1507, 1607, and 1809, among likely other supported Windows 10/11 and Windows Server versions. The flaw arises from a design issue where Windows Update processes do not properly follow directory junctions, enabling attackers with limited user privileges to redirect trusted paths to locations containing malicious code. Microsoft has introduced a mitigation strategy in its April 2025 cumulative update, which includes creating a new folder at the root of system drives and implementing detection rules for suspicious junction creations. Organizations are advised to apply the April 2025 security updates, restrict ACLs on specific directories, prevent symbolic link creation, and monitor file creation activities in certain directories.
Tech Optimizer
April 16, 2025
Windows Defender Application Control (WDAC) is a built-in security feature on Windows PCs that restricts the execution of unauthorized software by allowing only trusted applications. However, hackers have discovered multiple methods to bypass WDAC, exposing systems to malware and cyber threats. Techniques for bypassing WDAC include using Living-off-the-Land Binaries (LOLBins), DLL sideloading, and exploiting misconfigurations in WDAC policies. Attackers can execute unauthorized code without triggering alerts from traditional security solutions, enabling them to install ransomware or create backdoors. Microsoft operates a bug bounty program to address vulnerabilities in WDAC, but some bypass techniques remain unpatched for long periods. Users can mitigate risks by keeping Windows updated, being cautious with software downloads, and using strong antivirus software.
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