Disable: 'Network security: Minimum session security for NTLM SSP based (including secure RPC) servers' for NTLMMinServerSec This policy setting determines which behaviors are allowed 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 possible values for the Network security: Minimum session security for NTLM SSP based (including secure RPC) servers setting are: - Require message confidentiality. This option is only available in Windows XP and Windows Server 2003, the connection will fail if encryption is not negotiated. Encryption converts data into a form that is not readable until decrypted. - Require message integrity. This option is only available in Windows XP and Windows Server 2003, the connection will fail if message integrity is not negotiated. The integrity of a message can be assessed through message signing. Message signing proves that the message has not been tampered with; it attaches a cryptographic signature that identifies the sender and is a numeric representation of the contents of the message. - Require 128-bit encryption. The connection will fail if strong encryption (128-bit) is not negotiated. - Require NTLMv2 session security. The connection will fail if the NTLMv2 protocol is not negotiated. - Not Defined. Counter Measure: Enable all available options for the Network security: Minimum session security for NTLM SSP based (including secure RPC) servers policy setting. Potential Impact: 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 "How to apply more restrictive security settings on a Windows Server 2003-based cluster server" at http://support.microsoft.com/en-us/kb/891597 and "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" at http://support.microsoft.com/kb/890761/ for more information on possible issues and how to resolve them."

[disable/require NTLMv2 session security/Require 128-bit encryption/require NTLMv2 session security and 128-bit encryption]

(1) GPO: Computer ConfigurationWindows SettingsSecurity SettingsLocal PoliciesSecurity OptionsNetwork security: Minimum session security for NTLM SSP based (including secure RPC) servers (2) REG: HKEY_LOCAL_MACHINESystemCurrentControlSetControlLsaMSV1_0NTLMMinServerSec