Network security: Minimum session security for NTLM SSP based (including secure RPC) clients
Applies to
- Windows 11
- Windows 10
Describes the best practices, location, values, policy management and security considerations for the Network security: Minimum session security for NTLM SSP based (including secure RPC) clients security policy setting.
Reference
This policy setting allows a client device to require the negotiation of 128-bit encryption or NTLMv2 session security. These values are dependent on the Network security: LAN Manager Authentication Level policy setting value.
Possible values
Require NTLMv2 session security
The connection fails if the NTLMv2 protocol is not negotiated.
Require 128-bit encryption
The connection fails if strong encryption (128-bit) is not negotiated.
Best practices
Practices in setting this policy are dependent on your security requirements.
Location
Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options
Default values
The following table lists the actual and effective default values for this policy. Default values are also listed on the policy’s property page.
| Server type or GPO | Default value |
|---|---|
| Default Domain Policy | Not defined |
| Default Domain Controller Policy | Not defined |
| Stand-Alone Server Default Settings | Require 128-bit encryption |
| DC Effective Default Settings | Require 128-bit encryption |
| Member Server Effective Default Settings | Require 128-bit encryption |
| Client Computer Effective Default Settings | Require 128-bit encryption |
Policy management
This section describes features and tools that are available to help you manage this policy.
Restart requirement
None. Changes to this policy become effective without a device restart when they are saved locally or distributed through Group Policy.
Policy conflicts
The settings for this security policy are dependent on the Network security: LAN Manager Authentication Level policy setting value. For info about this policy, see Network security: LAN Manager authentication level.
Security considerations
This section describes how an attacker might exploit a feature or its configuration, how to implement the countermeasure, and the possible negative consequences of countermeasure implementation.
Vulnerability
Network traffic that uses the NTLM Security Support Provider (NTLM SSP) could be exposed such that an attacker who has gained access to the network can create man-in-the-middle attacks.
Countermeasure
Enable all options that are available for the Network security: Minimum session security for NTLM SSP based (including secure RPC) clients policy setting.
Potential impact
Client devices that enforce these settings cannot communicate with older servers that do not support them.