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

From Windows Server 2008 R2 Member Server Security Technical Implementation Guide

Associated with: CCI-000366

SV-32446r1_rule NTLM will be prevented from falling back to a Null session.

Vulnerability discussion

This setting prevents NTLM from falling back to a Null (unauthenticated) session.

Check content

Analyze the system using the Security Configuration and Analysis snap-in. Expand the Security Configuration and Analysis tree view. Navigate to Local Policies -> Security Options. If the value for “Network Security: Allow LocalSystem NULL session fallback” is not set to “Disabled”, then this is a finding. The policy referenced configures the following registry value: Registry Hive: HKEY_LOCAL_MACHINE Subkey: \System\CurrentControlSet\Control\LSA\MSV1_0\ Value Name: allownullsessionfallback Type: REG_DWORD Value: 0

Fix text

Configure the policy value for Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> “Network Security: Allow LocalSystem NULL session fallback” to “Disabled”.

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