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NTLM must be prevented from falling back to a Null session.


Overview

Finding ID Version Rule ID IA Controls Severity
V-226325 WN12-SO-000062 SV-226325r794603_rule Medium
Description
NTLM sessions that are allowed to fall back to Null (unauthenticated) sessions may gain unauthorized access.
STIG Date
Microsoft Windows Server 2012/2012 R2 Domain Controller Security Technical Implementation Guide 2022-03-01

Details

Check Text ( C-28027r476819_chk )
If the following registry value does not exist or is not configured as specified, this is a finding:

Registry Hive: HKEY_LOCAL_MACHINE
Registry Path: \System\CurrentControlSet\Control\LSA\MSV1_0\

Value Name: allownullsessionfallback

Type: REG_DWORD
Value: 0
Fix Text (F-28015r476820_fix)
Configure the policy value for Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> "Network security: Allow LocalSystem NULL session fallback" to "Disabled".