The LanMan authentication level will be set to Send NTLMv2 response only\refuse LM & NTLM.

From Windows Server 2008 R2 Domain Controller Security Technical Implementation Guide

Associated with IA controls: IAIA-2, IAIA-1

SV-32300r1_rule The LanMan authentication level will be set to Send NTLMv2 response only\refuse LM & NTLM.

Vulnerability discussion

The Kerberos v5 authentication protocol is the default for authentication of users who are logging on to domain accounts.The Windows NTLM protocol is retained in later Windows versions for compatibility with clients and servers that are running earlier versions. It is also used to authenticate logons to stand-alone computers that are running later versions.

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Configure the policy value for Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> “Network security: LAN Manager authentication level” to “Send NTLMv2 response only\refuse LM & NTLM”.

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