Vulnerability Discussion

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 only communicate with an SMB client that performs SMB packet signing.

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

Check

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: RequireSecuritySignature

Value Type: REG_DWORD
Value: 0x00000001 (1)

Fix

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