The system will be configured to meet the minimum session security requirement for NTLM SSP based servers.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-3666	3.089	SV-32352r1_rule		Medium

Description
Windows has implemented a variety of security support providers for use with RPC sessions. In a homogenous Windows environment, all of the options should be enabled and testing should be performed in a heterogeneous environment to determine the maximum-security level that provides reliable functionality.

STIG	Date
Windows Server 2008 R2 Domain Controller Security Technical Implementation Guide	2019-06-18

Details

Check Text ( C-32752r1_chk )
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: Minimum session security for NTLM SSP based (including secure RPC) servers” is not set to “Require NTLMv2 session security” and “Require 128-bit encryption”, then this is a finding. Warning: Microsoft warns that setting these may prevent the client from communicating with legacy servers that do not support them. The policy referenced configures the following registry value: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \System\CurrentControlSet\Control\Lsa\MSV1_0\ Value Name: NTLMMinServerSec Value Type: REG_DWORD Value: 0x20080000 (537395200) Warning: “Require NTLMv2 session security” will prevent authentication, if the “Network security: LAN Manager Authentication level” is set to permit NTLM or LM authentication. Documentable Explanation: If the required settings must be modified to support operation in a mixed Windows environment, then this should be documented with the IAO.

Check Text ( C-32752r1_chk )

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: Minimum session security for NTLM SSP based (including secure RPC) servers” is not set to “Require NTLMv2 session security” and “Require 128-bit encryption”, then this is a finding.

Warning: Microsoft warns that setting these may prevent the client from communicating with legacy servers that do not support them.

The policy referenced configures the following registry value:

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

Value Name: NTLMMinServerSec

Value Type: REG_DWORD
Value: 0x20080000 (537395200)

Warning: “Require NTLMv2 session security” will prevent authentication, if the “Network security: LAN Manager Authentication level” is set to permit NTLM or LM authentication.

Documentable Explanation: If the required settings must be modified to support operation in a mixed Windows environment, then this should be documented with the IAO.

Fix Text (F-28830r1_fix)
Configure the policy value for Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> “Network security: Minimum session security for NTLM SSP based (including secure RPC) servers” to “Require NTLMv2 session security”, ”Require 128-bit encryption (all options selected).