The Windows Server 2025 setting Microsoft network client: Digitally sign communications (always) must be configured to Enabled.

The server message block (SMB) protocol provides the basis for many network operations. Digitally signed SMB packets aid in preventing man-in-the-middle attacks. If this policy is enabled, the SMB client will only communicate with an SMB server that performs SMB packet signing.

Satisfies: SRG-OS-000423-GPOS-00187, SRG-OS-000424-GPOS-00188

If the following registry value does not exist or is not configured as specified, this is a finding:

Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters\

Value Name: RequireSecuritySignature

Value Type: REG_DWORD Value: 0x00000001 (1)

Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> Microsoft network client: Digitally sign communications (always) to "Enabled".