Develop Reference

Can I get rid of UAC warning when autostart with Windows?

I have written a small program in c# that helps with switching between licenses for my company. It's a tray icon with a menu with the different choices.
It changes an environment variable and needs to have elevated rights in its manifest.
This means that the UAC warning shows up every time the program starts, which is not ideal because it would be really nice to have the program on autostart when Windows starts, without the warning showing up all the time.
Are there a good way to do this?
Is it possible to:
Run the program without elevated privileges and only get the UAC
warning when I call the function to change the variables.
Change the
environment variables without admin rights.
Add the program to a "white list" programmatically (although more realistic, add it manually)
I know the UAC is there to protect from malicious software, but it would be really nice to solve this in a way that enables me to start the program at Windows start.
I haven't been able to fine any silver bullet on this problem.
Any advise?

The normal way around this is you have a windows service that runs with system privileges that will set the environment variables for you.
You will need to have your installer install the service and set it to auto start. Then your tray application will need to communicate with the service with some kind of Inter-Process Communication (like WCF), the tray program can then send the requests to change the variable and the service can execute those changes.
Another way to handle this is start your program un-elevated then when you need to do something that requires UAC privileges you launch a new copy of your program as an administrator and pass in command line arguments that tell it to do the work you need done then exit. You also could have your program check to see if it is an admin, and if it already is elevated it could skip the step of starting the new copy.

What you need to do is move the license information to a location that all users can write to:
user's own environment variable
%CSIDL_COMMON_APPDATA% (e.g. C:\ProgramData, which all users can write to)
HKEY_CURRENT_USER
The ideal solution involves writing to a common machine-wide location:
%CSIDL_COMMON_APPDATA% (e.g. C:\ProgramData)
HKEY_LOCAL_MACHINE/Software/Contoso/License
C:\Program Files\Contoso\License\license.txt
Legacy software can't be changed
But assuming there are many existing unchangeable applications that cannot be altered to look anywhere else but an environment variable for license information you can (after you smack that guy who designed that):
write the license information to the user's own environment variable
Your switching tool will call:
SetEnvironmentVariable("ContosoLicenseInfo", "V2h5IGFyZSB5b3UgZGVjb2RpbmcgdGhpbmdzIHRoYXQgZG9uJ3QgYmVsb25nIHRvIHlvdT8=");
What would you have done under Windows XP
All this hand-wringing about UAC. You have to ask yourself:
What would I have done under Windows XP?
Without UAC, and the user running as a standard user, what will your license switching tool have done?
would have it crashed horribly on startup?
would it have crashed as soon as the user tried to use it?
would it have failed in a polite way?
would it show a message on startup saying: "Sorry, no."?
What would you have done under Windows 7?
Even better, you have to ask what you would have done for a user running under Windows 7? A standard user logs in, and you have a program in their startup group that claims to require administrative privileges.
The user needs to go get an administrator during login to run your tool? That's not going to fly.
If you're dead set against using a per-user location.
If you're dead set against using a common location that all users can write to
Then change your tool to run without needing user privileges.
Only when the user goes to do something do you need admin privileges.
Check if the user is an admin:
Boolean IsUserAnAdmin()
{
PSID administratorsGroup;
administratorsGroup = AllocateAndInitializeSid(SECURITY_NT_AUTHORITY, 2, SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS, 0, 0, 0, 0, 0, 0);
Boolean result = CheckTokenMembership(0, administratorsGroup);
FreeSid(administratorsGroup);
}
If they are an admin, you can perform the action as in.
If the user is not an admin, then you put the UAC shield on the Apply button.
You then re-launch your tool as an admin:
ShellExecute("runas", "C:\Program Files\Contoso\LicenseSwitcher.exe", ...); //the "runas" verb triggers elevation
But what would you do under Windows 7
None of the UAC stuff works if UAC is disabled. In that case: you are a standard user, and that's it.
In that case, it really is best to convert to:
machine wide location for the default license
per-user location if you want to choose your own

UAC is there to protect the Windows User by alerting them (and requiring an explicit action) that a particular application is requesting elevated permissions. If it was possible to bypass it from with the application itself them it would leave it a little pointless :)
I would assume that you are looking to change environment variables globally because I believe that you can change them for the current process without being elevated.

Auto Start WinForms Application With Admin Permissions On Non-Admin Account

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.

Run as Administrator vs. Administrator group

I have a C# app that needs to allow the user to change the Computer Name. This is a pretty privileged operation. I can only get it to work if the user runs the app as Administrator (Windows 7, right-click on executable, "Run as Administrator"). Fine, but the user IS an administrator, so why would they need to Run AS an Administrator? I've tried this several times. It always fails if the user--an administrator--tries to do it running the application normally. It always works if they run it as "Run as Administrator".
If the answer is, "It just works that way, you have to run as admin even if you are an admin," my question is how can I detect if they are running with super-duper admin privileges? I found this, but it just checks to see if the user is part of the Administrator user group which, I already pointed out, isn't sufficient (and throws a null pointer exception).
Am I missing something here? Do I need to approach it from another angle?

It's because of User Account Control (UAC). Introduced in Vista, this changes the way administrator user accounts operate.
When an user from the administrator group logs on, the user is allocated two tokens: a token with all privileges, and a token with reduced privileges. When that user creates a new process, the process is by default handed the reduced privilege token. So, although the user has administrator rights, she does not exercise them by default. This is a "Good Thing"™.
To exercise those rights the user must start the process with elevated rights. For example, by using the "Run as administrator" verb. When she does this, the full token is handed to the new process and the full range of rights can be exercised.
You almost certainly don't want to be detecting whether or not your process is running elevated. Best practise is to mark those parts of your program that require elevation and force the system to show UAC elevation dialogs when those parts of the program execute.
The bind is that elevation can only happen at process start. So if you need to split your app into parts that require elevation, and parts that don't, there need to be multiple processes. Whilst you could mark your entire app as requiring elevation, you should not do so if the only thing that needs elevation is the very rare scenario where the computer name is to be changed.
Your next step is to bone up on the details over at MSDN. For example:
http://msdn.microsoft.com/en-us/library/windows/desktop/bb756996.aspx
http://msdn.microsoft.com/en-us/library/windows/desktop/aa511445.aspx

I want run my function in limited account with administrator permission

I want run my program under a limited user account but with administrator privileges on windows XP.
I can't find an answer. I think I can use two ways:
Run my program by another way like a program or a service
Run my function with some method like PrincipalPermission space or something like this
But I can't solve this problem.

Have you looked at the "runas" command? For example:
C:\> runas /noprofile /netonly /user:MYCOMPUTER\testuser "C:\Program Files\My Special Program\Program.exe"

I want run my program under a
limited user account but with
administrator privileges.
This can't be done. A limited user doesn't have admin privileges. You need to run it as an admin user with, e.g. runas.

One way to solve this is to fragment your program into two parts. One part as a windows service and the one as a user app. You can set the service to run as a Network Service, Local Service or Local System depending the level of access you need. Anything that needs administrator privileges will be performed by the Windows service. The user app can be responsible for showing the user interface and other similar things. You need to have some kind of IPC (Inter process communication) between your applications to facilitate this as well.

Install program that has to be run as administrator

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.