The system is not configured to meet the minimum requirement for session security for NTLM SSP based Clients.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-3382	3.076	SV-15980r1_rule	ECCT-2 ECCT-1	Medium

Description
Microsoft 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 Vista Security Technical Implementation Guide	2015-06-03

Details

Check Text ( C-32747r1_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) clients” is not set to “Require NTLMv2 session security” and “Require 128-bit encryption”, then this is a finding. The policy referenced configures the following registry value: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \System\CurrentControlSet\Control\Lsa\MSV1_0\ Value Name: NTLMMinClientSec Value Type: REG_DWORD Value: 0x20080000 (537395200) Warnings: Microsoft warns that setting these may prevent the client from communicating with legacy servers that do not support them. “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 these settings need to be modified in a mixed Windows environment, the changes should be documented with the IAO.

Check Text ( C-32747r1_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) clients” is not set to “Require NTLMv2 session security” and “Require 128-bit encryption”, then this is a finding.

The policy referenced configures the following registry value:

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

Value Name: NTLMMinClientSec

Value Type: REG_DWORD
Value: 0x20080000 (537395200)

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

“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 these settings need to be modified in a mixed Windows environment, the changes should be documented with the IAO.

Fix Text (F-28826r1_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) clients” to “Require NTLMv2 session security”, ”Require 128-bit encryption” (all options selected).