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


Overview

Finding ID Version Rule ID IA Controls Severity
V-3666 3.089 SV-15981r1_rule 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 2017-01-30

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.
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).