Windows 11 24H2 Sec Baseline → Broken SSO to on‑prem (Root cause: PKINIT SHA‑1 baseline)
Hi all, I ran into an issue with Entra-joined devices using Windows Hello for Business (Cloud Kerberos Trust) that might help others working with Windows 11 24H2 security baselines. Scenario Windows 11 25H2 devices Entra-joined (not hybrid) Intune-managed Windows Hello for Business (WHfB) enabled Cloud Kerberos Trust configured On-prem AD (Windows Server 2019/2022 DCs) Access to SMB shares / on-prem applications Symptoms SSO to on-prem resources fails Users get credential/PIN prompt instead of SSO Error message: “The system cannot contact a domain controller to service the authentication request” Client-side observations: klist → no tickets (initially) After enabling Cloud Kerberos Trust: klist get krbtgt → works klist get cifs/server.domain → fails Error: 0xc000a100 / 0x3bc4 Hash generation for the specified version and hash type is not enabled on server Root Cause The issue was caused by a Windows 11 24H2 security baseline setting related to Kerberos/PKINIT. The 24H2 baseline introduces a policy for configuring hash algorithms for certificate-based Kerberos authentication (PKINIT). This setting allows environments to disable SHA-1 and require SHA-2 algorithms. [applepie.se] Important detail: This configuration only works if the domain controllers fully support PKINIT with SHA-2, which effectively requires Windows Server 2025 domain controllers across the environment. If SHA-1 is disabled while running: Windows Server 2019 or 2022 DCs Mixed environments then PKINIT authentication fails, which directly impacts: Windows Hello for Business Cloud Kerberos Trust Any passwordless Kerberos-based authentication Why this is difficult to troubleshoot Cloud Kerberos Trust appears correctly configured AzureADKerberos object exists PRT is valid Network connectivity is fine However: Kerberos tickets are not issued correctly Service tickets (CIFS, HTTP, etc.) fail Errors are misleading and point to KDC/hash issues No explicit warning is provided in baseline guidance that mixed environments will break Resolution Revert the baseline change and allow SHA-1 for PKINIT again. Policy location: Computer Configuration → System → Kerberos / KDC → Configure hash algorithms for certificate logon Ensure: SHA-1 is set to Allowed/Default After reverting: Kerberos ticket issuance works SSO to on-prem resources is restored Recommendation Do not disable SHA-1 for PKINIT unless: All domain controllers are Windows Server 2025, and PKINIT SHA-2 support has been fully validated Treat this setting as future hardening, not production-safe for mixed environments today. Takeaway If you experience: WHfB + Cloud Kerberos Trust SSO failures klist get errors with hash generation issues Missing or failing Kerberos service tickets check the PKINIT hash configuration from the 24H2 security baseline first.Security Review for Microsoft Edge version 149
We have reviewed the new settings in Microsoft Edge version 149 and determined that there are no additional security settings that require enforcement. The Microsoft Edge version 139 security baseline continues to be our recommended configuration which can be downloaded from the Microsoft Security Compliance Toolkit. Microsoft Edge version 149 introduced 7 new Computer and User settings; we have included a spreadsheet listing the new settings to make it easier for you to find. As a friendly reminder, all available settings for Microsoft Edge are documented here, and all available settings for Microsoft Edge Update are documented here. Please continue to give us feedback through the Security Baselines Discussion site or this post.Security Review for Microsoft Edge version 148
We have reviewed the new settings in Microsoft Edge version 148 and determined that there are no additional security settings that require enforcement. The Microsoft Edge version 139 security baseline continues to be our recommended configuration which can be downloaded from the Microsoft Security Compliance Toolkit. Microsoft Edge version 148 introduced 16 new Computer and User settings; we have included a spreadsheet listing the new settings to make it easier for you to find. As a friendly reminder, all available settings for Microsoft Edge are documented here, and all available settings for Microsoft Edge Update are documented here. Please continue to give us feedback through the Security Baselines Discussion site or this post.Security Review for Microsoft Edge version 147
We have reviewed the new settings in Microsoft Edge version 147 and determined that there are no additional security settings that require enforcement. The Microsoft Edge version 139 security baseline continues to be our recommended configuration which can be downloaded from the Microsoft Security Compliance Toolkit. Microsoft Edge version 147 introduced 9 new Computer and User settings; we have included a spreadsheet listing the new settings to make it easier for you to find. Version 147 introduced the Control the availability of the XSLT feature policy (XSLTEnabled). This policy exists to support enterprise testing and transition scenarios while the Chromium project works toward deprecating and removing XSLT support from the browser due to security concerns associated with this legacy feature. XSLT support in modern browsers represents a disproportionate attack surface, and upstream Chromium has announced plans to disable and ultimately remove XSLT in a future release. As a result, organizations should treat continued reliance on client‑side XSLT as technical debt and plan migration accordingly. Additional details can be found here. Organizations are encouraged to proactively test setting XSLTEnabled = Disabled to identify application dependencies and remediation requirements ahead of any future default changes or removal of the feature. As a friendly reminder, all available settings for Microsoft Edge are documented here, and all available settings for Microsoft Edge Update are documented here. Please continue to give us feedback through the Security Baselines Discussion site or this post.Security Review for Microsoft Edge version 146
We have reviewed the new settings in Microsoft Edge version 146 and determined that there are no additional security settings that require enforcement. The Microsoft Edge version 139 security baseline continues to be our recommended configuration which can be downloaded from the Microsoft Security Compliance Toolkit. Microsoft Edge version 146 introduced 9 new Computer and User settings; we have included a spreadsheet listing the new settings to make it easier for you to find. As a friendly reminder, all available settings for Microsoft Edge are documented here, and all available settings for Microsoft Edge Update are documented here. Please continue to give us feedback through the Security Baselines Discussion site or this post.Security baseline for Windows Server 2025, version 2602
Microsoft is pleased to announce the February 2026 Revision (v2602) of the security baseline package for Windows Server 2025! You can download the baseline package from the Microsoft Security Compliance Toolkit, test the recommended configurations in your environment, and customize / implement them as appropriate. Summary of Changes in This Release This release includes several changes made since the Security baseline for Windows Server 2025, version 2506 to further assist in the security of enterprise customers along with better aligning with the latest capabilities and standards. The changes include what is now depicted in the table below. Security Policy Change Summary Configure the behavior of the sudo command Configured as Enabled: Disabled on both MS and DC Configure Validation of ROCA-vulnerable WHfB keys during authentication Configured as Enabled: Block on DC to block Windows Hello for Business (WHfB) keys that are vulnerable to the Return of Coppersmith's attack (ROCA) Disable Internet Explorer 11 Launch Via COM Automation Configured as Enabled to prevent legacy scripts and applications from programmatically launching Internet Explorer 11 using COM automation interfaces Do not apply the Mark of the Web tag to files copied from insecure sources Configured as Disabled on both MS and DC Network security: Restrict NTLM: Audit Incoming NTLM Traffic Configured as Enable auditing for all accounts on both MS and DC Network security: Restrict NTLM: Audit NTLM authentication in this domain Configured as Enable all on DC Network security: Restrict NTLM: Outgoing NTLM traffic to remote servers Configured as Audit all on both MS and DC NTLM Auditing Enhancements Already enabled by default to improve visibility into NTLM usage within your environment Prevent downloading of enclosures Remove from the baseline as it is not applicable for Windows Server 2025. It depends on IE – RSS feed Printer: Configure RPC connection settings Enforce the default, RPC over TCP with Authentication Enabled, on both MS and DC Printer: Configure RPC listener settings Configure as RPC over TCP | Kerberos on MS Printer: Impersonate a client after authentication Add RESTRICTED SERVICES\PrintSpoolerService to allow the Print Spooler’s restricted service identity to impersonate clients securely Configure the behavior of the sudo command Sudo for Windows can be used as a potential escalation of privilege vector when enabled in certain configurations. It may allow attackers or malicious insiders to run commands with elevated privileges, bypassing traditional UAC prompts. This is especially concerning in environments with Active Directory or domain controllers. We recommend to configuring the policy Configure the behavior of the sudo command (System) as Enabled with the maximum allowed sudo mode as Disabled to prevent the sudo command from being used. Configure Validation of ROCA-vulnerable WHfB keys during authentication To mitigate Windows Hello for Business (WHfB) keys that are vulnerable to the Return of Coppersmith's attack (ROCA), we recommend enabling the setting Configure Validation of ROCA-vulnerable WHfB keys during authentication (System\Security Account Manager) in a Block mode in domain controllers. To ensure there are no incompatible devices/orphaned/vulnerable keys in use that will break when blocked, please see Using WHfBTools PowerShell module for cleaning up orphaned Windows Hello for Business Keys - Microsoft Support. Note: A reboot is not required for changes to this setting to take effect. Disable Internet Explorer 11 Launch Via COM Automation Similar to the Windows 11 version 25H2 security baseline, we recommend disabling Internet Explorer 11 Launch Via COM Automation (Windows Components\Internet Explorer) to prevent legacy scripts and applications from programmatically launching Internet Explorer 11 using COM automation interfaces such as CreateObject("InternetExplorer.Application"). Allowing such behavior poses a significant risk by exposing systems to the legacy MSHTML and ActiveX components, which are vulnerable to exploitation. Do not apply the Mark of the Web tag to files copied from insecure sources We have included the setting Do not apply the Mark of the Web tag to files copied from insecure sources (Windows Components\File Explorer) configured as Disabled, which is consistent with Windows 11 security baseline. When this configuration is set to Disabled, Windows applies the Mark of the Web (MotW) tag to files copied from locations classified as Internet or other untrusted zones. This tag helps enforce additional protections such as SmartScreen checks and Office macro blocking, reducing the risk of malicious content execution. NTLM Auditing As part of our ongoing effort to help customers transition away from NTLM and adopt Kerberos for a more secure environment, we introduce new recommendations to strengthen monitoring and prepare for future NTLM restrictions on Windows Server 2025. Configure Network security: Restrict NTLM: Audit Incoming NTLM Traffic (Security Options) to Enable auditing for all accounts on both member servers and domain controllers. When enabled, the server logs events for all NTLM authentication requests that would be blocked once incoming NTLM traffic restrictions are enforced. Configure Network security: Restrict NTLM: Audit NTLM authentication in this domain (Security Options) to Enable all on domain controllers. This setting logs NTLM pass-through authentication requests from servers and accounts that would be denied when NTLM authentication restrictions are applied at the domain level. Configure Outgoing NTLM traffic to remote servers (Security Options) to Audit all on both member servers and domain controllers to log an event for each NTLM authentication request sent to a remote server, helping identify servers that still receive NTLM traffic. In addition, there are two new NTLM auditing capabilities enabled by default that were recently introduced in Windows Server 2025 and Windows 11 version 25H2. These enhancements provide detailed audit logs to help security teams monitor and investigate authentication activity, identify insecure practices, and prepare for future NTLM restrictions. Since these auditing improvements are enabled by default, no additional configuration is required, and thus the baseline does not explicitly enforce them. For more details, see Overview of NTLM auditing enhancements in Windows 11 and Windows Server 2025. Prevent Downloading of Enclosures The policy Prevent downloading of enclosures (Windows Components\RSS Feeds) has been removed from the Windows Server 2025 security baseline. This setting is not applicable to Windows Server 2025 because it depends on Internet Explorer functionality for RSS feeds. Printer security enhancements There are two new policies in Windows Server 2025 designed to significantly improve security posture of printers: Require IPPS for IPP printers (Printers) Set TLS/SSL security policy for IPP printers (Printers) Enabling these policies may cause operational challenges in environments that still rely on IPP or use self-signed or locally issued certificates. For this reason, these policies are not ter enforced in the Windows Server 2025 security baseline. However, we do recommend customers transition out of IPP or self-signed certificates and restricting them for a more secure environment. In addition, there are some changes to printer security Added RESTRICTED SERVICES\PrintSpoolerServiceto the Impersonate a client after authentication (User Rights Assignments) policy for both member servers and domain controllers, consistent with security baseline for Windows 11 version 25H2. Enforced the default setting for Configure RPC connection settings (Printers) to always use RPC over TCP with Authentication Enabled on both member servers and domain controllers. This prevents misconfiguration that could introduce security risks. Raised the security bar of the policy Configure RPC listener settings (Printers) from Negotiate (default) to Kerberos on member servers. This change encourages customers to move away from NTLM and adopt Kerberos for a more secure environment. Secure Boot certificate update To help organizations deploy, manage, and monitor the Secure Boot certificate update, Windows includes several policy settings under Administrative Templates\Windows Components\Secure Boot. These settings are deployment controls and aids. Enable Secure Boot Certificate Deployment allows an organization to explicitly initiate certificate deployment on a device. When enabled, Windows begins the Secure Boot certificate update process the next time the Secure Boot task runs. This setting does not override firmware compatibility checks or force updates onto unsupported devices. Automatic Certificate Deployment via Updates controls whether Secure Boot certificate updates are applied automatically through monthly Windows security and non‑security updates. By default, devices that Microsoft has identified as capable of safely applying the updates will receive and apply them automatically as part of cumulative servicing. If this setting is disabled, automatic deployment is blocked and certificate updates must be initiated through other supported deployment methods. Certificate Deployment via Controlled Feature Rollout allows organizations to opt devices into a Microsoft‑managed Controlled Feature Rollout for Secure Boot certificate updates. When enabled, Microsoft assists with coordinating deployment across enrolled devices to reduce risk during rollout. Devices participating in a Controlled Feature Rollout must have diagnostic data enabled. Devices that are not enrolled will not participate. Secure Boot certificate updates depend on device firmware support. Some devices have known firmware limitations that can prevent updates from being applied safely. Organizations should test representative hardware, monitor Secure Boot event logs, and consult the deployment guidance at https://aka.ms/GetSecureBoot for detailed recommendations and troubleshooting information. SMB Server hardening feature SMB Server has been susceptible to relay attacks (e.g., CVE-2025-55234), and Microsoft has released multiple features to protect against the relay attacks including SMB Server signing, which can be enabled with the setting of Microsoft network server: Digitally sign communications (always) (Security Option) SMB Server extended protection for authentication (EPA), which can be enabled with the setting of Microsoft network server: Server SPN target name validation level (Security Option) To further support customers to adopt these SMB Server hardening features, in the September 2025 Security Updates, Microsoft has released support for Audit events, across all supported in-market platforms, to audit SMB client compatibility for SMB Server signing as well as SMB Server EPA. These audit capabilities can be controlled via the two policies located at Network\Lanman Server Audit client does not support signing Audit SMB client SPN support This allows you to identify any potential device or software incompatibility issues before deploying the hardening measures that are already supported by SMB Server. Our recommendation is For domain controllers, the SMB signing is already enabled by default so there is no action needed for hardening purposes. For member servers, first enabling the two new audit features to assess the environment and then decide whether SMB Server Signing or EPA should be used to mitigate the attack vector. Please let us know your thoughts by commenting on this post or through the Security Baseline Community.Security Review for Microsoft Edge version 145
We have reviewed the new settings in Microsoft Edge version 145 and determined that there are no additional security settings that require enforcement. The Microsoft Edge version 139 security baseline continues to be our recommended configuration which can be downloaded from the Microsoft Security Compliance Toolkit. Microsoft Edge version 145 introduced 11 new Computer and User settings; we have included a spreadsheet listing the new settings to make it easier for you to find. As a friendly reminder, all available settings for Microsoft Edge are documented here, and all available settings for Microsoft Edge Update are documented here. Please continue to give us feedback through the Security Baselines Discussion site or this post.Security Baseline for M365 Apps for enterprise v2512
Security baseline for Microsoft 365 Apps for enterprise (v2512, December 2025) Microsoft is pleased to announce the latest Security Baseline for Microsoft 365 Apps for enterprise, version 2512, is now available as part of the Microsoft Security Compliance Toolkit. This release builds on previous baselines and introduces updated, security‑hardened recommendations aligned with modern threat landscapes and the latest Office administrative templates. As with prior releases, this baseline is intended to help enterprise administrators quickly deploy Microsoft recommended security configurations, reduce configuration drift, and ensure consistent protection across user environments. Download the updated baseline today from the Microsoft Security Compliance Toolkit, test the recommended configurations, and implement as appropriate. This release introduces and updates several security focused policies designed to strengthen protections in Microsoft Excel, PowerPoint, and core Microsoft 365 Apps components. These changes reflect evolving attacker techniques, partner feedback, and Microsoft’s secure by design engineering standards. The recommended settings in this security baseline correspond with the administrative templates released in version 5516. Below are the updated settings included in this baseline: Excel: File Block Includes External Link Files Policy Path: User Configuration\Administrative Templates\Microsoft Excel 2016\Excel Options\Security\Trust Center\File Block Settings\File Block includes external link files The baseline will ensure that external links to workbooks blocked by File Block will no longer refresh. Attempts to create or update links to blocked files return an error. This prevents data ingestion from untrusted or potentially malicious sources. Block Insecure Protocols Across Microsoft 365 Apps Policy Path: User Configuration\Administrative Templates\Microsoft Office 2016\Security Settings\Block Insecure Protocols The baseline will block all non‑HTTPS protocols when opening documents, eliminating downgrade paths and unsafe connections. This aligns with Microsoft’s broader effort to enforce TLS‑secure communication across productivity and cloud services. Block OLE Graph Functionality Policy Path: User Configuration\Administrative Templates\Microsoft Office 2016\Security Settings\Block OLE Graph This setting will prevent MSGraph.Application and MSGraph.Chart (classic OLE Graph components) from executing. Microsoft 365 Apps will instead render a static image, mitigating a historically risky automation interface. Block OrgChart Add‑in Policy Path: User Configuration\Administrative Templates\Microsoft Office 2016\Security Settings\Block OrgChart The legacy OrgChart add‑in is disabled, preventing execution and replacing output with an image. This reduces exposure to outdated automation frameworks while maintaining visual fidelity. Restrict FPRPC Fallback in Microsoft 365 Apps Policy Path: User Configuration\Administrative Templates\Microsoft Office 2016\Security Settings\Restrict Apps from FPRPC Fallback The baseline disables the ability for Microsoft 365 Apps to fall back to FrontPage Server Extensions RPC which is an aging protocol not designed for modern security requirements. Avoiding fallback ensures consistent use of modern, authenticated file‑access methods. PowerPoint: OLE Active Content Controls Updated Policy Path: User Configuration\Administrative Templates\Microsoft PowerPoint 2016\PowerPoint Options\Security\OLE Active Content This baseline enforces disabling interactive OLE actions, no OLE content will be activate. The recommended baseline selection ensures secure‑by‑default OLE activation, reducing risk from embedded legacy objects. Deployment options for the baseline IT Admins can apply baseline settings in different ways. Depending on the method(s) chosen, different registry keys will be written, and they will be observed in order of precedence: Office cloud policies will override ADMX/Group Policies which will override end user settings in the Trust Center. Cloud policies may be deployed with the Office cloud policy service for policies in HKCU. Cloud policies apply to a user on any device accessing files in Office apps with their AAD account. In Office cloud policy service, you can create a filter for the Area column to display the current Security Baselines, and within each policy's context pane the recommended baseline setting is set by default. Learn more about Office cloud policy service. ADMX policies may be deployed with Microsoft Intune for both HKCU and HKLM policies. These settings are written to the same place as Group Policy, but managed from the cloud. There are two methods to create and deploy policy configurations: Administrative templates or the settings catalog. Group Policy may be deployed with on premise AD DS to deploy Group Policy Objects (GPO) to users and computers. The downloadable baseline package includes importable GPOs, a script to apply the GPOs to local policy, a script to import the GPOs into Active Directory Group Policy, updated custom administrative template (SecGuide.ADMX/L) file, all the recommended settings in spreadsheet form and a Policy Analyzer rules file. GPOs included in the baseline Most organizations can implement the baseline’s recommended settings without any problems. However, there are a few settings that will cause operational issues for some organizations. We've broken out related groups of such settings into their own GPOs to make it easier for organizations to add or remove these restrictions as a set. The local-policy script (Baseline-LocalInstall.ps1) offers command-line options to control whether these GPOs are installed. "MSFT Microsoft 365 Apps v2512" GPO set includes “Computer” and “User” GPOs that represent the “core” settings that should be trouble free, and each of these potentially challenging GPOs: “DDE Block - User” is a User Configuration GPO that blocks using DDE to search for existing DDE server processes or to start new ones. “Legacy File Block - User” is a User Configuration GPO that prevents Office applications from opening or saving legacy file formats. "Legacy JScript Block - Computer" disables the legacy JScript execution for websites in the Internet Zone and Restricted Sites Zone. “Require Macro Signing - User” is a User Configuration GPO that disables unsigned macros in each of the Office applications. If you have questions or issues, please let us know via the Security Baseline Community or this post. Related: Learn about Microsoft Baseline Security ModeSecurity Review for Microsoft Edge version 144
We have reviewed the new settings in Microsoft Edge version 144 and determined that there are no additional security settings that require enforcement. The Microsoft Edge version 139 security baseline continues to be our recommended configuration which can be downloaded from the Microsoft Security Compliance Toolkit. Microsoft Edge version 144 introduced 2 new Computer and User settings; we have included a spreadsheet listing the new settings to make it easier for you to find. As a friendly reminder, all available settings for Microsoft Edge are documented here, and all available settings for Microsoft Edge Update are documented here. Please continue to give us feedback through the Security Baselines Discussion site or this post.Security Review for Microsoft Edge version 143
We have reviewed the new settings in Microsoft Edge version 143 and determined that there are no additional security settings that require enforcement. The Microsoft Edge version 139 security baseline continues to be our recommended configuration which can be downloaded from the Microsoft Security Compliance Toolkit. Microsoft Edge version 143 introduced 3 new Computer and User settings; we have included a spreadsheet listing the new settings to make it easier for you to find. As a friendly reminder, all available settings for Microsoft Edge are documented here, and all available settings for Microsoft Edge Update are documented here. Please continue to give us feedback through the Security Baselines Discussion site or this post.
