xp_cmdshell is an extended stored procedure provided by Microsoft and stored in the master database. This procedure allows you to issue operating system commands directly to the Windows command shell via T-SQL code.

By default, the xp_cmdshell option is disabled on new installations. Along with other unwanted behavior malicious users can elevate their privileges with the use of xp_cmdshell. For this reason it is generally recommend to leave xp_cmdshell disabled. It can be enabled by using the Policy-Based Management or by running the sp_configure system stored procedure as shown in the following code example:

Use Master
GO

EXEC master.dbo.sp_configure 'show advanced options', 1
RECONFIGURE WITH OVERRIDE
GO

EXEC master.dbo.sp_configure 'xp_cmdshell', 1
RECONFIGURE WITH OVERRIDE
GO

To disable xp_cmdshell use the following code example. Note: The following example also sets show advanced options server configuration option to 0. It is best practice to leave this option in the default state of 0 to stop the enabling of features.

Use Master
GO

EXEC master.dbo.sp_configure 'xp_cmdshell', 0
RECONFIGURE WITH OVERRIDE
GO

EXEC master.dbo.sp_configure 'show advanced options', 0
RECONFIGURE WITH OVERRIDE
GO