Detections
Analytics
2.3.11.10 Ensure 'Network security: Minimum session security for NTLM SSP based (including secure RPC) servers' is set to 'Require NTLMv2 session security, Require 128-bit encryption'
Information
This policy setting determines which behaviors are allowed by servers 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 all of the 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. That is, 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. Server 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 via GP, set the following UI path to Require NTLMv2 session security, Require 128-bit encryption:Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options\Network security: Minimum session security for NTLM SSP based (including secure RPC) servers
Default Value:
On Windows Server 2008 (non-R2): No requirements.
On Windows Server 2008 R2 and newer: Require 128-bit encryption. (NTLM connections will fail if strong encryption (128-bit) is not negotiated.)
Additional Information:
Microsoft Windows Server 2019 Security Technical Implementation Guide:
Version 2, Release 1, Benchmark Date: November 13, 2020
Vul ID: V-205922
Rule ID: SV-205922r569188_rule
STIG ID: WN19-SO-000340
Severity: CAT II
See Also
Item Details
Category: ACCESS CONTROL, IDENTIFICATION AND AUTHENTICATION, SYSTEM AND COMMUNICATIONS PROTECTION
References: 800-53|AC-17(2), 800-53|IA-5, 800-53|IA-5(1), 800-53|SC-8, 800-53|SC-8(1), CSCv7|12.5
Plugin: Windows
Control ID: 23fa973e5219617784b6f6045b0a082e73fac72f4526a5740beebf6403a62eea