Tuesday, April 25, 2017

Set Windows Service Permission to Non-Administrator Accounts

Service related operations such as start/stop/restart windows services are usually assigned to Administrators. Sometimes, you might need to delegate these tasks to non-admin users. In this article, I will show the 4 methods to set the service's permission to any user account/service account. I will use SQL service (MSSQLSERVER) in domain environment.Method-1: Using Powershell Module (from TechNet Script Repository, easiest but modules are not trusted by Microsoft)
Method-2: Using subinacl.exe (from Official Microsoft Download, need to install executable locally on computer, an easy method)
Method-3: Using built-in security configuration template in MMC console (do not need to install executable, easy with GUI but more steps are needed)
Method-4: Using built-in service control manager command line (difficult, prone-to-errors if manually configured)


Method-1: Using Powershell Module
You can download PowershellAccessControl Module from here. It is easy to use, but these modules are not officially trusted by Microsoft.
As you can see, SQL service start/stop/restart option is gray-out for 'myuser'. See Fig-1.
Fig-1: Normal user can't start/stop the service
Open the powershell & load the module. Then check the current service permission for 'myuser'. To do this, make get-service and pipeline into Get-EffectiveAccess.
Get-Service MSSQLSERVER | Get-EffectiveAccess -Principal contoso\myuser
You can also check the service permission for domain admin account.
Get-Service MSSQLSERVER | Get-EffectiveAccess -Principal contoso\administrator
See Fig-2.
Fig-2: Check the users permissions on SQL service
Now, give the user start/stop permission of MSSQLSERVER. See Fig-3.
Get-Service MSSQLSERVER | Add-AccessControlEntry -ServiceAccessRights Start,Stop -Principal contoso\myuser
Fig-3: Assign start/stop permission to 'myuser' in powershell
You can see that the 'myuser' now has the start/stop/restart permission on SQL service. See Fig-4.
Fig-4: SQL service can now be stopped
Method-2: Using subinacl.exe
subinacl.exe is a command-line tool that is included in Server 2003 Resource kit. You can separately download it from Microsoft website here.
Install the subinacl.msi. See Fig-5.
Fig-5: Install subinacl.exe
After install is completed, go to the install directory and use subinacl.exe. For help, type subinacl.exe /?. See Fig-6.
Fig-7: Getting help with subinacl.exe

Since we are going to check/assign/revoke permission to sql service. We will use only these commands:
subinacl.exe /service <myservice> /accesscheck=<username>
subinacl.exe /service <myservice> /<grant/revoke>=<username>=<access>

Fig-8 shows how to check the current permission of sql service for 'myuser' and 'contoso\administrator' by using this command.
subinacl.exe  /service mssqlserver /accesscheck=contoso\myuser
Fig-8: Check the sql permission for 'myuser' and 'contoso\administrator'
Since we're going to give start/stop permission. Use /grant parameter with username. See fig-9.
We also re-check if the permission is correctly assigned.
subinacl.exe /service mssqlserver /grant=contoso\myuser=TO
Fig-9: Assign start/stop permission & re-check the permissions
From table, we can see that we have use TO alias in <access> parameter for starting & stopping the service. A full list of ACE aliases can be found here.
Alias
Description
F
Full Control
R
Generic Read
W
Generic Write
X
Generic eXecute
L
Read controL
Q
Query Service Configuration
S
Query Service Status
E
Enumerate Dependent Services
C
Service Change Configuration
T
Start Service
O
Stop Service
P
Pause/Continue Service
I
Interrogate Service
U
Service User-Defined Control Commands
Now, you can start/stop the SQL service !
If you want to revoke the permission. You can use with the subinacl.exe command with /revoke switch. See Fig-10.
subinacl.exe /service mssqlserver /revoke=contoso\myuser
Fig-10: Revoke service permission

Method-3: Using built-in security configuration template in MMC console
You can also use local security configuration to assign necessary permissions. These are steps:
  1. Create new security template (in which security settings of service is defined)
  2. Create new security database with newly created security template
  3. Analysis the current configuration with the security database and find the conflicts
  4. Apply the security configuration

1) Create new security template
Create "Security Template" folder under C:\ where we can save our own security templates.
Open MMC console >> Add/Remove Snap-in >> Choose Security Templates >> Add >> OK
Right-click and "New Template Search Path". See Fig-11. Select the location to our newly created folder(C:\Security Templates). The path will be listed in console as shown in Fig-12.
Fig-11: Set the new template search path
Then, right-click the new node and choose "New Template". See Fig-12.
Fig-12: Creating new security template
Give the new template name and click OK. See Fig-13.
Fig-13: Give the new template name
You will see a bunch of security options (the same one you see in Local Security Policy Editor). Since we want to modify the security setting of SQL service, right-click SQL Server (MSSQLSERVER) and click Properties. See Fig-14.
Enable the check box to define the policy. Click Edit Security for more options.
Fig-14: Browse for sql service to edit security settings
You can see that "System" and "Administrators" already have full permissions. Add 'myuser' as new user and select 'Start, stop and pause' permission. See Fig-15.
Fig-15: Add new user and set service permissions
You need to save this modified security template. Right-click the template node and save. And the file will be saved as .inf file in your template directory. See Fig-16.
Fig-16: Save the template
2) Create new security database with newly created security template
From current MMC console >> Add/Remove Snap-in >> Security Configuration and Analysis >> Add >>OK. See Fig-17.
Fig-17: Add Security Configuration & Analysis Snap-in
Right-Click the "Security Configuration and Analysis" node and click open database...
Choose the location you want to save the security database file (I use the default directory "C:\Users\<myusername>\Documents\Security\Database"). I give the name of the database as "ModifySQLServicePermission". See Fig-18.

Fig-18: Set location to save the security database & give the file name
Then you will need to import the template. Choose your saved template which is stored at C:\Security Template\Assign MSSQLSERVER Start_Stop Permission to MyUser. See Fig-19.
Fig-19: Import the security template to use with security database
3) Analysis the current configuration with the security database and find the conflicts
Now, we can analyze your computer security's setting whether it matches with our newly created security database.
Right-click the "Security Configuration and Analysis" and click Analyze Computer Now....See Fig-20.
Fig-20: Analyze if the current security setting matches with the security database
You will see the result tree after analysis is finished.
Go to SQL service and check the result and there you will see the red cross icon which indicates that it conflicts with your current (unmodified) security settings. See Fig-21.
Fig-21: The red-cross shows us the conflicted security settings
4) Apply the security configuration
You can now apply the security settings.
Click Configure Computer Now... as shown in Fig-22. You will see the progress status as in Fig-23.
Fig-22: Apply Security Settings
Fig-23: Apply Security settings in progress
Now, you can start/stop the SQL service with our normal user account.

Method-4: Using built-in service control manager command line
In this method, we edit the Security Descriptor of windows service in SDDL (Security Descriptor Definition Language) language. it is a bit difficult to understand if you're not already familiar to SDDL descriptions. But there is an easy method to do this, which will be explained here. (I have written the another blogpost to explain the details of modifying these access control lists with example).
Here, you need to use sc.exe to check/get/set the service permissions. Its syntax is:
sc.exe sdshow <myservice>        Find the current security settings
sc.exe sdset <myservice>  <securitySettingsInSDDLformat>      Set the security settings



So, we will check the current permission of SQL service by the following command.
sc sdshow myssqlserver

Fig-24: Check the initial service security stings
Then, you need to generate the new security descriptor using the same method as we do in previous method with MMC console.
  • Open MMC Console
  • Add "Security Templates" and "Security Configuration and Analysis" Snap-ins (Fig-11)
  • Set the template path, create new template with desired settings and save the template (Fig-12,13,14,15,16)
There is an .inf file in your saved location. Open the file and you will see entries as the below one. See Fig-25.

"MSSQLSERVER",2,"D:AR(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;SY)(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;BA)(A;;CCLCSWLOCRRC;;;IU)(A;;RPWPDTRC;;;S-1-5-21-2647241702-1957647361-952520019-1197)S:(AU;FA;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;WD)"
Fig-25: Contents of security template (.inf) file
You will see there is an extra entry compared to our initial result which I highlighted in red color. This is the added user permission to start/stop the SQL service followed by user's SID.

 Note: You can also get the user name back from this SID by the following command (optional, just for knowledge)
wmic useraccount where sid="S-1-5-21-2647241702-1957647361-952520019-1197" get name,sid


Now, I can set this new permission with sc.exe sdset <newSDDL> command. See Fig-26.
Fig-26: Set the new permission with sc.exe sdset
The command completes successfully. And user now has start/stop permission on SQL service. See Fig-27.
Fig-27: User can now start/stop the service









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