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2.3.11.5 Ensure 'Network security: Minimum session security for NTLM SSP based (including secure RPC) clients' is set to 'Require NTLMv2 session security, Require 128-bit encryption'

Information

This policy setting determines which behaviors are allowed by clients for applications using the NTLM Security Support Provider (SSP). The SSP Interface (SSPI) is used by applications that need authentication services. The setting does not modify how the authentication sequence works but instead require certain behaviors in applications that use the SSPI.

The recommended state for this setting is: Require NTLMv2 session security, Require 128-bit encryption.

Note: These values are dependent on the Network security: LAN Manager Authentication Level (Rule 2.3.11.7) security setting value.

Rationale:

You can enable both options for this policy setting to help protect network traffic that uses the NTLM Security Support Provider (NTLM SSP) from being exposed or tampered with by an attacker who has gained access to the same network. In other words, these options help protect against man-in-the-middle attacks.

Impact:

NTLM connections will fail if NTLMv2 protocol and strong encryption (128-bit) are not both negotiated. Client applications that are enforcing these settings will be unable to communicate with older servers that do not support them. This setting could impact Windows Clustering when applied to servers running Windows Server 2003, see Microsoft Knowledge Base article 890761: You receive an 'Error 0x8007042b' error message when you add or join a node to a cluster if you use NTLM version 2 in Windows Server 2003 for more information on possible issues and how to resolve them.

Solution

To establish the recommended configuration, set the following Device Configuration Policy to NTLMv2 and 128-bit encryption:

To access the Device Configuration Policy from the Intune Home page:

Click Devices

Click Configuration profiles

Click Create profile

Select the platform (Windows 10 and later)

Select the profile (Endpoint protection)

Click Create

Enter a Name

Click Next

Configure the following Setting

Path: Endpoint protection/Local device security options/Network access and security
Setting Name: Minimum Session Security For NTLM SSP Based Clients
Configuration: NTLMv2 and 128-bit encryption

Select OK

Continue through the Wizard to complete the creation of the profile (profile assignments, applicability etc.)

Note: More than one configuration setting from each of the Configuration profiles (ex: Administrative Templates, Custom etc.) can be added to each Device Configuration Policy.

Note #2: This setting can also be created via a Custom Configuration Profile using the following OMA-URI:

Name: <Enter name>
Description: <Enter Description>
OMA-URI: ./Device/Vendor/MSFT/Policy/Config/LocalPoliciesSecurityOptions/NetworkSecurity_MinimumSessionSecurityForNTLMSSPBasedClients
Data type: Integer
Value: 537395200

Select OK

Continue through the Wizard to complete the creation of the profile (profile assignments, applicability etc.)

Default Value:

Require 128-bit encryption. (NTLM connections will fail if strong encryption (128-bit) is not negotiated.)

See Also

https://workbench.cisecurity.org/files/4161

Item Details

References: CSCv7|12.5

Plugin: Windows

Control ID: eea902c39693efd54fb30f4dccf5714c86595a5b7a17f21d15f36ec21e34627a