The recent WannaCry ransomware outbreak spread because of a vulnerability in one of the internet’s most ancient networking protocols, Server Message Block version 1 (aka SMBv1 / SMB 1).
Barry Feigenbaum originally designed SMB at IBM. Microsoft has made considerable modifications to the most commonly used version. Microsoft merged the SMB protocol with the LAN Manager product.
The original SMB1 protocol is nearly 30 years old, and like much of the software made in the 80’s, it was designed for the world that no longer exists. The world without malicious actors, without vast sets of important data, without near-universal computer usage. Frankly, its naivete is staggering when viewed through modern eyes.
The Server Message Block, or SMB, protocol is a file sharing protocol that allows operating systems and applications to read and write data to a system. It also allows a system to request services from a server.
This is the protocol mainly used for providing shared access to files, printers, and serial ports and miscellaneous communications between nodes on a network.
In computer networking, Server Message Block (SMB), one version of which was also known as Common Internet File System (CIFS) operates as an application-layer network protocol.
There have been numerous vulnerabilities tied to the use of Windows SMB v1, including remote code execution and denial-of-service exploits. These two vulnerabilities can leave a system crippled, or allow attackers to compromise a system using this vulnerable protocol.
| Protocol Version |
Windows OS |
| SMB 1 |
Windows 2000, Windows 2003, Windows XP |
| SMB 2 |
Windows Server 2008 and Windows Vista SP1 |
| SMB 2.1 |
Windows Server 2008 R2 and Windows 7 |
| SMB 3.0 |
Windows Server 2012 and Windows 8 |
| SMB 3.0.2 |
Windows Server 2012 R2 and Windows 8.1 |
| SMB 3.1.1 |
Windows Server 2016 and Windows 10 |
SMB 1 protocol permits man-in-the-middle exploits and it “isn’t safe” to use. An attacker can use SMB 2 to pull information from the insecure SMB 1 protocol if it exists in a network.
The nasty bit is that no matter how you secure all these things if
your clients use SMB1, then a man-in-the-middle can tell your client
to ignore all the above. All they need to do is block SMB2+ on
themselves and answer to your server's name or IP.Your client will
happily derp away on SMB1 and share all its darkest secrets unless
you required encryption on that share to prevent SMB1 in the first
place. This is not theoretical-- we've seen it.
~ Ned Pyle, a Principal Program Manager, Microsoft
How to remove SMB V1 /SMB 1 in Windows OS?
Windows 8.1 and Windows 10:
Method-1: Open Control Panel (just start typing Control in the search box to find its shortcut quickly). Click Programs, and then click Turn Windows features on or off (under the Programs heading). Or
Start –> Run –> Type appwiz.cpl –> press enter –> Click Turn Windows features on or off
Clear the check box for SMB 1.0/CIFS File Sharing Support, as shown here. That’s it; you’re protected.
Method-2: open a Windows PowerShell prompt with administrative privileges. In the Windows 10 Creators Update, version 1703, right-click the Start button and choose Windows PowerShell (Admin) from the Quick Link menu.) If you’re running an earlier Windows 10 version, enter Windows PowerShell in the search box, then right-click the Windows PowerShell shortcut and click Run as administrator. From that elevated PowerShell prompt, type the following command:
Disable-WindowsOptionalFeature -Online -FeatureName smb1protocol
Press Enter and you’re done.
Note You must restart the computer after you make these changes.
Windows 2012 R2, and Windows Server 2016:
Method-1: Launch Server Manager from Command Line.
Press the Windows key + R to open the Run box, or open the Command Prompt. Type ServerManager and press Enter.
Or Launch Server Manager from Taskbar
On Server, the Server Manager approach:
Method-2: On Server, the PowerShell approach (Remove-WindowsFeature FS-SMB1):
Remove-WindowsFeature Name FS-SMB1
On legacy operating systems:
When using operating systems older than Windows 8.1 and Windows Server 2012 R2, you can’t remove SMB1 – but you can disable it.
Windows 8 and Windows Server 2012:
Windows 8 and Windows Server 2012 introduce 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. (A cmdlet is a lightweight command that is used in the Windows PowerShell environment.)
- To disable SMBv1 on the SMB server, run the following cmdlet:
Set-SmbServerConfiguration -EnableSMB1Protocol $false
- To enable SMBv1 on the SMB server, run the following cmdlet:
Set-SmbServerConfiguration -EnableSMB1Protocol $true
Windows Server 2008 R2 and Windows Server 2008:
To enable or disable SMB protocols on an SMB Server that is running Windows 7, Windows Server 2008 R2, Windows Vista, or Windows Server 2008, use Windows PowerShell or Registry Editor.
Windows PowerShell 2.0 or a later version of PowerShell
- To disable SMBv1 on the SMB server, run the following cmdlet:
Set-ItemProperty -Path “HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters” SMB1 -Type DWORD -Value 0 -Force
- To enable SMBv1 on the SMB server, run the following cmdlet:
Set-ItemProperty -Path “HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters” SMB1 -Type DWORD -Value 1 -Force
Note You must restart the computer after you make these changes.
Registry Editor:
Important
This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to backup, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base: 322756 How to backup and restore the registry in Windows
To enable or disable SMBv1 on the SMB server, configure the following registry key:
Registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\ParametersRegistry entry: SMB1
REG_DWORD: 0 = Disabled
REG_DWORD: 1 = Enabled
Default: 1 = Enabled
Windows Vista, Windows 7, and Windows 8:
- To disable SMBv1 on the SMB client, run the following commands:
sc.exe config lanmanworkstation depend= bowser/mrxsmb20/nsi
sc.exe config mrxsmb10 start= disabled
- To enable SMBv1 on the SMB client, run the following commands:
sc.exe config lanmanworkstation depend= bowser/mrxsmb10/mrxsmb20/nsi
sc.exe config mrxsmb10 start= auto
Source: Microsoft, zdnet, technet.microsoft, redmondmag, top-password, techtarget, windowsitpro
, click All Programs, click Accessories, right-click Notepad, and then click Run as administrator.
If you are prompted for an administrator password or for a confirmation, type the password, or click Allow or Yes.
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