The Windows Server 2025 setting Microsoft network server: Digitally sign communications (if client agrees) 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 server will negotiate SMB packet signing as requested by the client.

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\LanManServer\Parameters\

Value Name: EnableSecuritySignature

Value Type: REG_DWORD Value: 0x00000001 (1)

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