The Lan Manager authentication level must be set to send NTLMv2 response only, and to refuse LM and NTLM.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-1153	3.031	SV-25105r2_rule		High

Description
The Kerberos v5 authentication protocol is the default for authentication for domains. NTLM which is less secure, is retained in later Windows versions for compatibility with standalone systems as well as applications that may still use it. Earlier versions of the LM/NTLM protocol are particularly vulnerable to attack and must be prevented.

STIG	Date
Windows 7 Security Technical Implementation Guide	2018-02-12

Details

Check Text ( C-62063r2_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: LAN Manager authentication level" is not set to "Send NTLMv2 response only\refuse LM & NTLM" (Level 5), this is a finding. The policy referenced configures the following registry value: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SYSTEM\CurrentControlSet\Control\Lsa\ Value Name: LmCompatibilityLevel Value Type: REG_DWORD Value: 5

Check Text ( C-62063r2_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: LAN Manager authentication level" is not set to "Send NTLMv2 response only\refuse LM & NTLM" (Level 5), this is a finding.

The policy referenced configures the following registry value:

Registry Hive: HKEY_LOCAL_MACHINE
Registry Path: \SYSTEM\CurrentControlSet\Control\Lsa\

Value Name: LmCompatibilityLevel

Value Type: REG_DWORD
Value: 5

Fix Text (F-66961r1_fix)
Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "Network security: LAN Manager authentication level" to "Send NTLMv2 response only\refuse LM & NTLM".