Title

The Windows SMB server must be configured to always perform SMB packet signing. (Cat II impact)

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.

Check Content

Analyze the system using the Security Configuration and Analysis snap-in. (See "Performing Analysis with the Security Configuration and Analysis Snap-in" in the STIG Overview document.) Expand the Security Configuration and Analysis tree view. Navigate to Local Policies -> Security Options. If the value for "Microsoft Network Server: Digitally sign communications (always)" is not set to "Enabled", this is a finding. The policy referenced configures the following registry value: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \System\CurrentControlSet\Services\LanManServer\Parameters\ Value Name: RequireSecuritySignature 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 (always)" to "Enabled".

Additional Identifiers

Rule ID: SV-48133r1_rule

Vulnerability ID: V-6833

Group Title: SMB Server Packet Signing (Always)

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.