The New Technology LAN Manager (NTLM) authentication protocol is nearing its end and will no longer be enabled in the next version of Windows Server, Microsoft says.
The legacy protocol has been present in Windows for over three decades, but it is susceptible to various types of attacks, including relay, replay, and man-in-the-middle attacks, and Microsoft deprecated NTLM in favor of stronger, Kerberos-based alternatives.
Although it no longer receives updates or enhancements, NTLM is still used, exposing organizations to attacks due to the lack of authentication, weak cryptography, and limited diagnostic data.
“Despite its deprecated status, NTLM continues to be prevalent in environments where modern protocols, such as Kerberos, are not feasible due to legacy dependencies, network limitations, or ingrained application logic,” Microsoft notes.
The tech giant’s goal is to completely remove NTLM, and it is taking a three-phase approach to disable it by default on Windows Server and Windows clients.
Now, organizations can use the enhanced NTLM auditing features of Windows Server 2025 and Windows 11, versions 24H2 and later, to understand where and why the protocol is still used in their environments.
The next phase will involve overcoming hurdles faced when eliminating NTLM, related to domain controllers, local account authentication, and the hardcoded NTLM usage. The solutions will be released in the second half of the year, for Windows Server 2025 or Windows 11, version 24H2 and later.
Administrators will have IAKerb and local Key Distribution Center (KDC) (pre-release) for Kerberos authentication without NTLM fallback and Microsoft will update core Windows features to negotiate Kerberos first, thus reducing NTLM’s usage.
The next major releases of Windows Server and associated Windows client will still have NTLM, but it will be disabled by default and will require explicit re-enablement through new policy controls. Built-in support for NTLM only cases will also be included.
“Disabling NTLM by default does not mean completely removing NTLM from Windows yet. Instead, it means that Windows will be delivered in a secure-by-default state where network NTLM authentication is blocked and no longer used automatically,” Microsoft explains.
According to the tech giant, disabling NTLM represents a major step toward a passwordless, phishing-resistant future, but requires that organizations begin or accelerate their NTLM reduction efforts through audits, dependency mapping, migration to Kerberos, NTLM-off configurations testing, and enabling Kerberos upgrades as they become available.
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