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Is SMBv1 secure?
What's wrong with SMB V1?
What is SMB V1?
Is SMB V1 better than SMBv2?
Should I disable or remove SMBv1?
How secure is SMB v3?
Feb 5, 2021 · SMBv1 vulnerability is dangerous for larger networks. A modest home LAN should avoid SMBv1, but an old device disconnected from the internet cannot be used as an entry-point by an attacker. For more information, see : Microsoft's advisory Stop using SMB1.
- Overview
- Disabling SMBv2 or SMBv3 for troubleshooting
- How to remove SMBv1 via PowerShell
- How to detect status, enable, and disable SMB protocols
- Disable SMBv1 by using Group Policy
This article describes how to enable and disable Server Message Block (SMB) version 1 (SMBv1), SMB version 2 (SMBv2), and SMB version 3 (SMBv3) on the SMB client and server components.
While disabling or removing SMBv1 might cause some compatibility issues with old computers or software, SMBv1 has significant security vulnerabilities, and we strongly encourage you not to use it. SMB 1.0 isn't installed by default in any edition of Windows 11 or Windows Server 2019 and later. SMB 1.0 also isn't installed by default in Windows 10, except Home and Pro editions. We recommend that instead of reinstalling SMB 1.0, you update the SMB server that still requires it. For a list of third parties that require SMB 1.0 and their updates that remove the requirement, review the SMB1 Product Clearinghouse.
We recommend keeping SMBv2 and SMBv3 enabled, but you might find it useful to disable one temporarily for troubleshooting. For more information, see How to detect status, enable, and disable SMB protocols on the SMB Server.
In Windows 10, Windows 8.1, Windows Server 2019, Windows Server 2016, Windows Server 2012 R2, and Windows Server 2012, disabling SMBv3 deactivates the following functionality:
•Transparent Failover - clients reconnect without interruption to cluster nodes during maintenance or failover
•Scale Out - concurrent access to shared data on all file cluster nodes
•Multichannel - aggregation of network bandwidth and fault tolerance if multiple paths are available between client and server
•SMB Direct - adds RDMA networking support for high performance, with low latency and low CPU use
Windows Server 2012 Windows Server 2012 R2, Windows Server 2016, Windows Server 2019: Server Manager method
To remove SMBv1 from Windows Server: 1.On the Server Manager Dashboard of the server where you want to remove SMBv1, under Configure this local server, select Add roles and features. 2.On the Before you begin page, select Start the Remove Roles and Features Wizard, and then on the following page, select Next. 3.On the Select destination server page under Server Pool, ensure that the server you want to remove the feature from is selected, and then select Next. 4.On the Remove server roles page, select Next. 5.On the Remove features page, clear the check box for SMB 1.0/CIFS File Sharing Support and select Next. 6.On the Confirm removal selections page, confirm that the feature is listed, and then select Remove.
Windows 8.1, Windows 10, and Windows 11: Add or Remove Programs method
To disable SMBv1 for the mentioned operating systems: 1.In Control Panel, select Programs and Features. 2.Under Control Panel Home, select Turn Windows features on or off to open the Windows Features box. 3.In the Windows Features box, scroll down the list, clear the check box for SMB 1.0/CIFS File Sharing Support and select OK. 4.After Windows applies the change, on the confirmation page, select Restart now.
•Server
•Client
Windows 8 and Windows Server 2012 introduced the new Set-SMBServerConfiguration Windows PowerShell cmdlet. The cmdlet enables you to enable or disable the SMBv1, SMBv2, and SMBv3 protocols on the server component.
You don't have to restart the computer after you run the Set-SMBServerConfiguration cmdlet.
SMBv1
This procedure configures the following new item in the registry: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters •Registry entry: SMB1 •REG_DWORD: 0 = Disabled To use Group Policy to configure this, follow these steps: 1.Open the Group Policy Management Console. Right-click the Group Policy object (GPO) that should contain the new preference item, and then click Edit. 2.In the console tree under Computer Configuration, expand the Preferences folder, and then expand the Windows Settings folder. 3.Right-click the Registry node, point to New, and select Registry Item. In the New Registry Properties dialog box, select the following: •Action: Create •Hive: HKEY_LOCAL_MACHINE •Key Path: SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters •Value name: SMB1 •Value type: REG_DWORD •Value data: 0
SMB v1
To disable the SMBv1 client, the services registry key needs to be updated to disable the start of MRxSMB10, and then the dependency on MRxSMB10 needs to be removed from the entry for LanmanWorkstation so that it can start normally without requiring MRxSMB10 to first start. This guidance updates and replaces the default values in the following two items in the registry: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\mrxsmb10 Registry entry: Start REG_DWORD: 4= Disabled HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation Registry entry: DependOnService REG_MULTI_SZ: "Bowser","MRxSmb20″,"NSI" To configure this by using Group Policy, follow these steps: 1.Open the Group Policy Management Console. Right-click the GPO that should contain the new preference item, and then click Edit. 2.In the console tree under Computer Configuration, expand the Preferences folder, and then expand the Windows Settings folder. 3.Right-click the Registry node, point to New, and select Registry Item. 4.In the New Registry Properties dialog box, select the following: •Action: Update •Hive: HKEY_LOCAL_MACHINE •Key Path: SYSTEM\CurrentControlSet\services\mrxsmb10 •Value name: Start •Value type: REG_DWORD •Value data: 4 5.Then remove the dependency on the MRxSMB10 that was disabled. In the New Registry Properties dialog box, select the following: •Action: Replace •Hive: HKEY_LOCAL_MACHINE •Key Path: SYSTEM\CurrentControlSet\Services\LanmanWorkstation •Value name: DependOnService •Value type: REG_MULTI_SZ •Value data: •Bowser •MRxSmb20 •NSI 6.Restart the targeted systems to finish disabling SMB v1.
Auditing SMBv1 usage
To determine which clients are attempting to connect to an SMB server with SMBv1, you can enable auditing on Windows Server 2016, Windows 10, and Windows Server 2019. You can also audit on Windows 7 and Windows Server 2008 R2 if the May 2018 monthly update is installed, and on Windows 8.1 and Windows Server 2012 R2 if the July 2017 monthly update is installed. •Enable: •Disable: •Detect:
May 18, 2023 · By default, AES-128-GCM is negotiated with SMB 3.1.1, bringing the best balance of security and performance. Windows Server 2022 and Windows 11 SMB Direct now support encryption. Previously, enabling SMB encryption disabled direct data placement, making RDMA performance as slow as TCP.
Jun 8, 2020 · SMBv1, the original version of the protocol, suffers from a range of limitations and security vulnerabilities. Its inherently insecure design has led to high-profile attacks, like the WannaCry ransomware. Microsoft has since deprecated SMBv1 in favor of more secure and efficient versions.
Oct 26, 2018 · The problem with SMBv1 is SMB Relay Attacks and ultimately the attacker harvesting credentials using it. Windows provides a way to require digital signing of network communications, specifically related to SMB communications.
Mar 6, 2024 · As a defense in depth measure, you can use segmentation and isolation techniques to secure SMB traffic and reduce threats between devices on your network. SMB is used for file sharing, printing, and inter-process communication such as named pipes and RPC.
There are a few different versions – SMBv1, SMBv2, and SMBv3 – each with their own unique capabilities and security profiles. In this comprehensive guide, I‘ll give you the complete low-down on detecting which SMB editions you have enabled, turning them on or off, and optimizing your configurations for performance and safety.
