I have a .Net app that i install and set to run at Startup. The installer also creates a user that has write permissions to the appropriate application folders and registry sections, preventing the currently running user from modifying the restricted areas.
However, i am unable to figure out how to run the application under a different user. It's not a Service (although that is a possibility). I'm really trying to figure out how to do the following:
Start an application on boot as a different user.
Install a service to start on boot, as a different user.
Can anyone point me in the right direction?
Regards
Tris
With respect to services, you specify the user they run as when you install one.
To start an app as someone else, you could create a batch script that launches your app with the RUNAS command, though I believe you are prompted for a password so it may not be what you're after.
Related
I am new to building Windows Services, As a learning exercise I am following the template provided by Visual Studio in order to write a service which will block specific users from using the CD drive and logging attempts to a file. I haven't been able to find documentation that would allow me to 1) prevent non-elevated users from stopping or restarting the service and 2) force the service to run as NT Authority\SYSTEM and prevent the user from changng the 'run as' user. Any tips would be appreciated. I have searched the internet and stack overflowbut perhaps I just dont know enough about services or the relevant terminology to find what I need. Thanks in advance!
I rewrote my project to take advantage of PSService a PowerShell script by JFLarvoire (available on GitHub) which dynamically generates a customizable Windows Service executable. You can reconfigure PSService to specify what user the service should run as but by default it runs as the SYSTEM account which met my needs perfectly. Further research has also shown that unprivileged Windows users can start a system service but cannot stop them unless they have been granted permission to do so.
I wrote a .NET console application that needs to be scheduled trough Windows scheduler. Such console performs some network and database activities and write a logfile. The application work if run on Desktop/Command prompt but if I try to run it trough the scheduler it refuse to start. Another issue I faced is the write access to the app folder. Even if I set permissions to the folder containing application binaries to be wrote by 'Everyone' the app seems unable to create the log file and/or append data to it. The problem fixes if I run the application with Administrator priviledges (on desktop) but if I define the Activity in the scheduler to Run with higher privildegs this will not fix it anyway.
Best course of action is to create a Service account with admin privileges and schedule the task under such account and select the option to run whether the user is logged on or off.
This approach is even more relevant where Active Directory is in place.
Hope this helps,
Apex
I found the issue... http://support.microsoft.com/kb/2452723
It seems that the "Start In" parameter of the Action should not contain quotes.
Of course the folder should be 'writetable' for the user assigned to the task.
I've been wrestling with this issue for a few days and can't find any posts that solve it for me. Maybe what I want isn't possible.
We have developed a WinForms application for internal use at our company.
Most employees do not have admin access in windows.
Our application requires admin access to the machine and needs to automatically start when the user logs on.
Here's what I've tried:
1) Putting a Shortcut in the Startup folder
I can get the app to automatically launch (using a relauncher), but it still requires an admin to be at the computer on every restart (to enter the password).
2) Registry Key
I created a Software\Microsoft\Windows\CurrentVersion\Run registry key to automatically start the application. Whether I run the relauncher or the app itself, UAC demands a password on every restart (or relogin).
3) Scheduled Task
I created a scheduled task to automatically start the app on logon using admin permissions on the machine (under use the following account). I also checked the 'Run with highest privileges' box. UAC still pops up on every restart.
4) Windows Service
I tried to run the app as a windows service, but it has a user interface (which is disabled by windows services).
5) Disable UAC for Specific Program
It looks like you can disable UAC for a specific program but that involves downloading the Application Compatibility Toolkit, creating some kind of database, etc. I'd very much prefer that our IT staff wouldn't have to do that at every machine. At this point, it's probably my only option.
It seems like an admin should be able to install an application so that it runs automatically without a prompt. Am I missing a way to do this?
You should make split your program into a non-admin UI, which runs on user startup, and an admin service, which performs the administrative tasks.
To run admin-requiring code from the UI, use WCF to ask the service to do it.
Beware that hostile parties may impersonate the UI and ask the service to do malicious things; you need to carefully figure out what the service should be able to do in response to IPC calls.
Your problem is not a UAC problem, it is a security problem.
And the answer depends on what your application that "requires admin rights" needs to do.
If your application needs to be able to start, and stop services, then the User needs the ability to start and stop services. In which case you need to give the users that privilege.
If the user's need the ability to alter or delete files, then they need that privilege too. In that case it is easier to grant Full Control permissions to Everyone.
If your application needs the ability to modify registry keys in the HKLM tree then you can, again, grant Full Control to Everyone in the registry.
If you need your users to have the ability to modify items, then they need permissions to modify those locations. Granting them those NTFS permissions is not a bad thing; it is exactly what those permissions exist for - to control access.
But why
But then we ask why? What is it you're doing that users need all the rights of an administrator, and all capabilities of an administrator, all the power of an administrator, but you don't want to make them a member of the Administrator's group?
The answer is almost invariably that your internal use application doesn't need to run as an administrator.
What Would XP Do?
The question becomes:
What would you do on Windows XP?
A standard user on Windows XP didn't even have the UAC convenience feature. If a user wanted to run an application an administrator: they had to logout and login as an administrator. How did, or how would, the application work on a system with UAC disabled?
Presumably very little of your application needs to run as admin - the rest would be better running as the unprivileged user. This is very common (think self-updating browsers, for example).
The proper way to do this is to install a service to do the privileged bit, and have the UI communicate with the service.
Our application requires admin access to the machine ...
Why?
You cannot bypass the UAC prompt, and this is by design.
See FAQ: Why can’t I bypass the UAC prompt? for a good discussion of why. Excerpt:
If it were possible to mark an application to run with silently-elevated privileges, what would become of all those apps out there with LUA bugs? Answer: they'd all be marked to silently elevate. How would future software for Windows be written? Answer: To silently elevate. Nobody would actually fix their apps, and end-user applications will continue to require and run with full administrative permissions unnecessarily.
Background
I've written a small C#/.NET 4.0 application that syncs various settings from a game installed in Program Files to and from other copies of the same game on different machines (think Chrome bookmark sync, but for this game). The sync itself is a relatively simple affair, dealing with files stored inside the game's Program Files folder.
On my machine, this works fine without having to elevate my application through UAC. Windows 7 makes the game use Program Files virtualisation and my application works fine with that.
However, on a lot of tester's machines, I'm getting reports that the application either can't work with the files and in come cases can't even see the game's folder! Having the user right-click and "Run as Administrator" solves the problem in every case.
So, we just set the application's manifest to require admin privileges, right? That's fine (although not ideal) for when the user manually invokes the application or the sync process because they'll be interacting with the application and ready to accept a UAC request.
However, one of the features of my application is a "Sync Automatically" option, which allows the user to "set and forget" the application. With this set, the application puts itself into the registry at HKCU\Software\Microsoft\Windows\CurrentVersion\Run to be run at startup and sits in the system tray syncing the settings in the background as needed.
Obviously, I need to be smarter here. Presenting a UAC prompt as soon as the user logs in to their account or at random intervals afterwards isn't the way forwards.
So, my question!
What's the best way to approach a situation where I'd need to run an application at startup that needs administrator privileges? Is there a way to have the user authorise an installation that causes the system to automatically run the application with the correct privileges without a prompt at startup/login?
Update Just to be clear, this must be achievable in code.
You should consider making your Sync functionality exist within a Windows Service.
This is the preferred method for running 'background' functionality on Windows.
The Service can either run under the user's account (assuming they have permissions to modify the files), or you can use another account which does. Worst case, you can run as SYSTEM (although, this isn't best practice).
If you've already got your background process functionality working, then this should be a simple process to convert over to a Service.
There's a sample project here that will set you on the right path: http://www.codeproject.com/KB/dotnet/simplewindowsservice.aspx
Since you mentioned running at startup, why not use a scheduled task instead of what you're doing with the registry? You can set them up from code - there's a project on CodePlex that is basically a managed wrapper to save you having to do the PInvokes yourself. You run your little "set up the startup task" app elevated, and it specifies that the app should launch elevated, and the user won't even be prompted. I believe that's the answer to the question in your last paragraph.
I would use Security namespace and check inline for the user roles.
using System.Threading;
using System.Security.Principal;
namespace StackOverflow_Demo
{
class Program
{
static void Main(string[] args)
{
AppDomain.CurrentDomain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal);
WindowsPrincipal currentPrincipal = (WindowsPrincipal) Thread.CurrentPrincipal;
if (currentPrincipal.IsInRole("Administrators"))
{
// continue programm
}
else
{
// throw exception/show errorMessage - exit programm
}
}
}
}
The currentUser may start your application and will get an info message if he is not member of admininistrator role!
Hope this may help!
Background: I am by no means a windows security / user permissions expert. I have an application (written in C#), that has to be able to write / delete files & folders in its root directory, write / delete files elsewhere on the disk, write/modify values in System Registry (Local Machine) and start & stop other applications and services. I figure that I need administrator privileges for at least some of those actions.
I tried running this and on computers with UAC turned off it works great without any additional settings. However on computers with UAC turned on (any level above 'never notify' in Windows 7) it will crash. I need it to work on all computers.
Up to now I would just manually check the "run this program as administrator" checkbox and everything would be fine. However now we have decided that we will allow customers to install this software on their own, and it needs to run "out of the box".
I have a deployment project in Visual Studio 2008 that installs everything and writes the necessary start up data in registry. What I need to do now is to set the "Run this program as Administrator" flag. I am guessing this isn't quite as simple as I'd like it to be.
So What is the proper way of doing this? This program is started on startup, and it would be irritating for our customers if UAC would pop up (and possibly dim the screen) every time they restart their computer.
Thank you for your help.
EDIT: Thank you for your replies. I realise that working around UAC would be frowned upon, and I can see that Microsoft does not support "white lists" so it would ask for permission only once. That's fine I can respect that, however I do have some follow up questions:
Can you provide me with a link that will show me how to properly elevate the program to correct elevated state? Is there any literature on what are the options, etc... Basicly I'd love a UAC 101 guide.
Is there a way to elevate the security status when I need the extra privileges (and only then prompt with UAC). Basicly this applications runs in the background, doing mostly nothing for most of the time. Every now and again it will check some files (at this point I will require to be able to write to disk and read the registry (read only is fine at this point), however since it's a temporary folder it wouldn't matter where I'd put it. If there is a location where the application can write without any privileges that would be perfect.)
However at some point I will need to preform all the rest of the tasks (user needs to confirm this action anyway) so if UAC would prompt at this point that would be no problem. Is there a way to elevate it just at this point, and then return it to default permissions?
Will such a solution work with older versions of Windows, including Vista and Xp (and perhaps older?) What would it take to make it work?
The proper way is to elevate when the program starts, with the UAC prompt (which you can set via the program's manifest) - attempting to be clever and bypass it is frowned upon.
Think about it - if you could install something which would elevate automatically without the UAC prompt ... what would be the point of UAC?
To add a UAC manifest to a program you simply add the manifest in a project and edit it. A sample manifest for UAC is here. If you want to elevate at the last possible moment then you need a spawn separate process - you cannot elevate an existing process. So separate that bit out and then start it using
Process.StartInfo.UseShellExecute = true;
Process.StartInfo.Verb = "runas";
You need to rethink how your application works. You're quite correct that it would be annoying to display an elevation prompt on login. So don't do it. On the other hand, you may well have tasks which you need to perform using administrative access.
So you have two choices:
Change your tasks so that they no longer require administrative elevation (e.g., write your files elsewhere).
Break your application into a Windows service component and a user interface component. The service component can run under an elevated account (hopefully the least-elevated account necessary to perform the tasks you need to do). The user interface component can talk to the service (via named pipes or similar) when necessary.
You can split your program into two components:
a user application running without elevation
a Windows service that is responsible for the tasks that require elevation
Since you're using .NET, communication between the components is probably easiest done using WCF.
And as a side note: Programmatically modifying files under C:\Program Files is not considered good practice and might lead to a number of other problems. Windows has dedicated places for storing configuration settings and other program data.