Fileless SQL Server CLR-based Custom Stored Procedure Command Execution
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This techinque will allow for the execution of commands on a comprompised Microsoft SQL Server in a novel, fileless manner. The PowerShell module consists of two cmdlets:
- New-CLRProcedure - This cmdlet enables CLR stored procedures on the SQL Server, reconfigures it, loads the Dot Net assembly into memory, then creates a stored procedure from the loaded assembly.
- Invoke-CmdExec - This cmdlet passes a specified command to the previously created stored procedure, where it is then executed.
First, import the module:
Next, use the New-CLRProcedure cmdlet to create a custom stored procedure on the target SQL Server:
Add-CLRProcedure -Server MSSQL
Finally, use the Invoke-CmdExec cmdlet to execute commands on the target server:
Invoke-CmdExec -Server MSSQL -Command "mkdir c:\temp"
- Create another cmdlet to remove the custom stored procedure from the SQL Server
- Allow for the name of the assembly and the stored procedure to be changed via paramaters.