Title

The Server Message Block (SMB) v1 protocol must be disabled on the SMB client. (Cat II impact)

Discussion

SMBv1 is a legacy protocol that uses the MD5 algorithm as part of SMB. MD5 is known to be vulnerable to a number of attacks such as collision and preimage attacks as well as not being FIPS compliant. Disabling SMBv1 support may prevent access to file or print sharing resources with systems or devices that only support SMBv1. File shares and print services hosted on Windows Server 2003 are an example, however Windows Server 2003 is no longer a supported operating system. Some older network attached devices may only support SMBv1.

Check Content

This requirement specifically applies to Windows 2012 but can also be used for Windows 2012 R2. Different methods are available to disable SMBv1 on Windows 2012 R2, if V-73805 is configured on Windows 2012 R2, this is NA. If the following registry value is not configured as specified, this is a finding: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SYSTEM\CurrentControlSet\Services\mrxsmb10\ Value Name: Start Type: REG_DWORD Value: 0x00000004 (4) If the following registry value includes MRxSmb10, this is a finding: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SYSTEM\CurrentControlSet\Services\LanmanWorkstation\ Value Name: DependOnService Type: REG_MULTI_SZ Value: Default values after removing MRxSmb10 include the following, which are not a finding: Bowser MRxSmb20 NSI

Fix Text

Configure the policy value for Computer Configuration >> Administrative Templates >> MS Security Guide >> "Configure SMBv1 client driver" to "Enabled" with "Disable driver (recommended)" selected for "Configure MrxSmb10 driver". Configure the policy value for Computer Configuration >> Administrative Templates >> MS Security Guide >> "Configure SMBv1 client (extra setting needed for pre-Win8.1/2012R2)" to "Enabled" with the following three lines of text entered for "Configure LanmanWorkstation Dependencies": Bowser MRxSmb20 NSI The system must be restarted for the changes to take effect. These policy settings requires the installation of the SecGuide custom templates included with the STIG package. "SecGuide.admx" and "SecGuide.adml" must be copied to the \Windows\PolicyDefinitions and \Windows\PolicyDefinitions\en-US directories respectively.

Additional Identifiers

Rule ID: SV-226051r794766_rule

Vulnerability ID: V-226051

Group Title: SRG-OS-000095-GPOS-00049

Expert Comments

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