Microsoft began 2025 with a hefty patch release this month, addressing eight zero-days with 159 patches for Windows, Microsoft Office and Visual Studio. Both Windows and Microsoft Office have Patch Now recommendations (with no browser or Exchange patches) for January.Microsoft also released a significant servicing stack update (SSU) that changes how desktop and server platforms are updated, requiring additional testing on how MSI Installer, MSIX and AppX packages are installed, updated, and uninstalled.To navigate these changes, the Readiness team has providedthis useful infographicdetailing the risks of deploying the updates.Known issuesReadiness worked with both Citrix and Microsoft to detail the more serious update issues affecting enterprise desktops, including:Windows 10/11: Following the installation of the October 2024 security update, some customers report that theOpenSSH(Open Secure Shell) service fails to start, preventingSSHconnections. The service fails without detailed logging; manual intervention is required to run the sshd.exe process. Microsoft is investigating the issue with no (as of now) published schedule for either mitigations or a resolution.Citrix reported significant issues with its Session Recording Agent (SRA), causing the January update to fail to complete successfully. Microsoft published a security bulletin (KB5050009) that says: Affected devices might initially download and apply the January 2025 Windows security update correctly, such as via the Windows Update page in Settings. Once this situation occurs, however, the update process stops and proceeds to rollback to the original state.In short, if you have the Citrix SRA installed, your device was (likely) not updated this month.Major revisionsFor this Patch Tuesday, we have the following revisions to previously released updates:CVE-2025-21311: Windows Installer Elevation of Privilege Vulnerability. Microsoft has released an updated group policy (SkuSiPolicy.p7b) to better handle security related issues with VBS scripts included in the knowledge note, Guidance for blocking rollback of Virtualization-based Security (VBS).CVE-2025-21308: Windows Themes Spoofing Vulnerability. Microsoft recommends disablingNTLMfor desktop systems to address this vulnerability. Guidance on theprocess can be found here:Restrict NTLM: Outgoing NTLM traffic to remote servers.Microsoft also releasedCVE-2025-21224to address two memory related security vulnerabilities in the legacy line printer daemon (LPD), a Windows feature that has been deprecated for 15 years. I cant see things improving for these print-related functions (given the problems weve seen for the past decade). Maybe now is the time to start removing these legacy features from your platform.Windows lifecycle and enforcement updatesThe following Microsoft products will beretiredthis year:Microsoft Genomics: Jan. 6, 2025Visual Studio App Center: March 31, 2025SAP HANA Large Instances (HLI): June 30, 2025Of course, we dont need to mention the elephant in the room. Microsoft will end support for Windows 10 in October.Each month, we analyze Microsofts updates across key product families Windows, Office, and developer tools to help you prioritize patching efforts. This prescriptive, actionable, guidance is based on assessing a large application portfolio and a detailed analysis of the Microsoft patches and their potential impact on the Windows platforms and apps.For this release cycle from Microsoft, we have grouped the critical updates and required testing efforts into different functional areas including:Remote desktopJanuary has a heavy focus on Remote Desktop Gateway (RD Gateway) and network protocols, with the following testing guidance:RD Gateway Connections: Ensure RD Gateway (RDG) continues to facilitate both UDP and TCP traffic seamlessly without performance degradation. Try disconnecting RDG from an existing/established connection.VPN, Wi-Fi, and Bluetooth Scenarios: test end-to-end configurations and nearby sharing functionality.DNS Management for Operators: Verify that users in the Network Configuration Operators group can manage DNS client settings effortlessly.Local Windows file system and storageFile system and storage components also get minor updates. Desktop and server file system testing efforts should focus on:Offline Files and Mapped Drives: Test mapped network drives under both online and offline conditions. Pay close attention toSync Centerstatus updates.BitLocker: Validate drive locking and unlocking, BitLocker-native boot scenarios, and post-hibernation states with BitLocker enabled.Virtualization and Microsoft Hyper-VHyper-Vand virtual machines receive lightweight updates:Traffic Testing: Install the Hyper-V feature and restart systems. Monitor network performance and ensure no regressions in virtual network traffic or virtual machine management.Security and authenticationKey areas for security-related testing include:Digest Authentication Stress Testing: Simulate heavy loads while using Digest authentication to uncover potential issues.SPNEGONegotiations: Verify Secure Negotiation Protocol (SPNEGO) functionalities in cross-domain or multi-forest Active Directory setups.Authentication Scenarios: Test applications relying onLSASSprocesses and ensure that protocols like Kerberos, NTLM, and certificate-based authentication remain stable under load.Other critical updatesThere are some additional testing priorities for this release:App Deployment Scenarios: Install and updateMSIX/Appxpackages with and without packaged services, confirming admin-only requirements for updates.WebSocket Connections: Establish and monitor secureWebSocketconnections, ensuring proper encryption and handshake results.Graphics and Themes: TestGDI+-based apps and workflows involving theme files to ensure UI elements render correctly across different view modes. Some suggestions include foreign language applications that rely on Input Method Editors (IMEs).Januarys updates maintain a medium-risk profile for most systems, but testing remains essential especially for networking, authentication, and file system scenarios. We recommend prioritizing remote network traffic validation, with light testing for storage and virtualization environments. If you have a large MSIX/Appx package portfolio, theres a lot of work to do to ensure that your package installs, updates and uninstalls successfully.Each month, we break down the update cycle into product families (as defined by Microsoft) with the following basic groupings:Browsers (Microsoft IE and Edge)Microsoft Windows (both desktop and server)Microsoft OfficeMicrosoft Exchange and SQL ServerMicrosoft Developer Tools (Visual Studio and .NET)Adobe (if you get this far)BrowsersThere were no Microsoft browser updates for Patch Tuesday this month. Expect Chromium updates that will affect Microsoft Edge in the coming week. (You can find the enterprise release schedule for Chromiumhere.)Microsoft WindowsThis is a pretty large update for the Windows ecosystem, with 124 patches for both desktops and servers, covering over 50 product/feature groups. Weve highlighted some of the major areas of interest:Fax/TelephonyMSI/AppX/Installer and the Windows update mechanismsWindows COM/DCOM/OLENetworking, Remote DesktopKerberos, Digital Certificates, BitLocker, Windows Boot ManagerWindows graphics (GDI) and Kernel driversUnfortunately, Windows security vulnerabilitiesCVE-2025-21275andCVE-2025-21308both affect core application functionality and have been publicly disclosed. Add these Windows updates to your Patch Now release schedule.Microsoft OfficeMicrosoft Office gets three critical updates, and a further 17 patches rated important. Unusually, three Microsoft Office updates affecting Microsoft Access fall into the zero-day category withCVE-2025-21366,CVE-2025-21395andCVE-2025-21186publicly disclosed. Add these Microsoft updates to your Patch Now calendar.Microsoft Exchange and SQL ServerThere were no updates from Microsoft for SQL Server or Microsoft Exchange servers this month.Microsoft Developer Tools (Visual Studio and .NET)Microsoft has released seven updates rated as important affecting Microsoft .NET and Visual Studio. Given the urgent attention required for Office and Windows this month, you can add these standard, low-profile patches to your standard developer release schedule.Adobe and third-party updatesNo Adobe related patches were released by Microsoft this month. However, two third-party, development related updates were published; they affect GitHub (CVE-2024-50338) andCERTCC patch (CVE-2024-7344). Both updates can be added to the standard developer release schedule.