RPC command to initiate a software install

Question

I was recently working with a product from Symantech called Norton EndPoint protection. It consists of a server console application and a deployment application and I would like to incorporate their deployment method into a future version of one of my products.

The deployment application allows you to select computer workstations running Win2K, WinXP, or Win7. The selection of workstations is provided from either AD (Active Directory) or NT Domain (WINs/DNS NetBIOS lookup). From the list, one can click and choose which workstations to deploy the end point software which is Symantech's virus & spyware protection suite.

Then, after selecting which workstations should receive the package, the software copies the setup.exe program to each workstation (presumable over the administrative share \pcname\c$) and then commands the workstation to execute setup.exe resulting in the workstation installing the software.

I really like how their product works but not sure what they are doing to accomplish all the steps. I've not done any deep investigations into this such as sniffing the network, etc... and wanted to check here to see if anyone is familiar with what I'm talking about and if you know how it's accomplished or have ideas how it could be accomplished.

My thinking is that they are using the admin share to copy the software to the selected workstations and then issuing an RPC call to command the workstation to do the install.

What's interesting is that the workstations do this without any of the logged in users knowing what's going on until the very end where a reboot is necessary. At which point, the user gets a pop-up asking to reboot now or later, etc... My hunch is that the setup.exe program is popping this message.

To the point: I'm looking to find out the mechanism by which one Windows based machine can tell another to do some action or run some program.

My programming language is C/C++

Any thoughts/suggestions appreciated.

Answer 1

This sort of functionality is also available with products LANDesk and Altiris. You need a daemonized listener on the client side that will listen for instructions/connections from the server. Once a connection is made any number of things can happen: you can transfer files, kick on installation scripts, etc. usually transparently to any users on that box.

I've used the Twisted Framework (http://twistedmatrix.com) to do this with a small handful of Linux machines. It's Python and Linux, not Windows, but the premise is the same: a listening client accepts instructions from a server and executes them. Very simple.

This functionality can also be accomplished with VB/Powershell scripts in a Windows-based domain.

Answer 2

I was also looking into this, since I too want to remote deploy software. I chose to packet sniff pstools since it has proven itself quite reliable in such remote admin tasks.

I must admit I was definitely over-thinking this challenge. You have probably done your packet sniff by now and discovered the same things I have. I hope by leaving this post behind we can assist other developers.

This is how pstools accomplishes execution of arbitrary code:

It copies a system service executable to \\server\admin$ (you either have to already have local admin on the remote machine, or supply credentials). Once the file is copied, it uses the Service Control Manager API to make the copied file a system service and start it.

Obviously, this system service can now do whatever it wants, including binding to an RPC named pipe. In our case, the system service would install an msi. To get confirmation of successful installation you could either remote poll a registry key, or an rpc function. Either way, you should remove the system service when you are done and delete the file (psexec does not do this, I guess they don't want it to be used surreptitiously, and in that case leaving the service behind would at least give an admin a fighting chance of realizing someone had compromised their box.) This method does not require any preconfiguration of the remote machine, simply that you have admin creds and that file sharing and rpc are open in the firewall.

I've seen demos in C# using WMI, but I don't like those solutions. File sharing and RPC are most likely to be open in firewalls. If they aren't, file sharing and remote MMC management of the remote server wouldn't work. WMI can be blocked and still leave these functional.

I've worked with a lot of software that does remote installations, and a lot of them are not as reliable as pstools. My guess is that this is because those developers are using other methods that are not as likely to be open at the firewall level.

The simple solution is often the most elusive. As always, my hat is off to the SysInternals folks. They are true hackers in the positive, old school meaning of the word!