How can a C# program run another program with admin privileges?

Question

I have a problem with this situation: I made 2 programs:

The first one just print an output saying that was launched with admin provileges or not, and the second one, execute the first program with admin privileges and without use the UAC. The trouble is that the second program can't launch the first with admin privileges i don't know why. This is my code:

Code of the first program:

// This only prints if you start as administrator or not.
bool isElevated;
WindowsIdentity identity = WindowsIdentity.GetCurrent();
WindowsPrincipal principal = new WindowsPrincipal(identity);
isElevated = principal.IsInRole(WindowsBuiltInRole.Administrator);
Console.WriteLine("I got admin privileges?: "+isElevated);

Code of the second program:

// This execute the first program with admin privileges without UAC
string username = "myuser";
SecureString userpass = new SecureString();
userpass.AppendChar('m');
userpass.AppendChar('y');
userpass.AppendChar('p');
userpass.AppendChar('a');
userpass.AppendChar('s');
userpass.AppendChar('s');

Process program = new Process();
program.StartInfo.UserName = username;
program.StartInfo.Password = userpass;
program.StartInfo.FileName = "Path/First_program.exe";
program.StartInfo.UseShellExecute = false;
program.Start();

PD: I don't want the user to open the UAC, thats why i already insert the username and the password. Thanks in advance.

Answer 1

You have half of the answer. The other half is that the program must request to be executed with elevated privileges. By default, Windows programs run in a "Basic" trust level, regardless of the true level of permissions possible under the user. To gain access to administrative powers, the program must request elevation, which by definition will involve UAC.

Programs like yours can request elevation using the runas verb in the ProcessStartInfo, or by specifying requireAdministrator elevated permissions in the manifest of either application (assuming you control them). Either way, if UAC is enabled, the user will get a prompt.

The only way to circumvent this is to set up the program that would otherwise require elevated permissions as a Windows service, configured in services.msc to run with administrative permissions. You'll get one UAC prompt when installing/registering the service to run in this way, and from then on the service can perform that task without any further UAC action. You can then use various communication technologies, from named pipes to true network comms like TCP, to signal the service that it should do what you want.