The Windows SMB server must perform SMB packet signing when possible.

From Windows Server 2012/2012 R2 Member Server Security Technical Implementation Guide

Part of SMB Server Packet Signing (if client agrees)

SV-52870r2_rule The Windows SMB server must perform SMB packet signing when possible.

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 negotiate SMB packet signing as requested by the client.

Check content

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: 1

Fix text

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".

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