abatishchev abatishchev - 21 days ago 12
C# Question

Elevating privileges doesn't work with UseShellExecute=false

I want to start a child process (indeed the same, console app) with elevated privileges but with hidden window.

I do next:

var info = new ProcessStartInfo(Assembly.GetEntryAssembly().Location)
{
UseShellExecute = true, // !
Verb = "runas",
};

var process = new Process
{
StartInfo = info
};

process.Start();


and this works:

var identity = new WindowsPrincipal(WindowsIdentity.GetCurrent());
identity.IsInRole(WindowsBuiltInRole.Administrator); // returns true


But
UseShellExecute = true
creates a new window and I also I can't redirect output.

So when I do next:

var info = new ProcessStartInfo(Assembly.GetEntryAssembly().Location)
{
RedirectStandardError = true,
RedirectStandardOutput = true,
UseShellExecute = false, // !
Verb = "runas"
};

var process = new Process
{
EnableRaisingEvents = true,
StartInfo = info
};

DataReceivedEventHandler actionWrite = (sender, e) =>
{
Console.WriteLine(e.Data);
};

process.ErrorDataReceived += actionWrite;
process.OutputDataReceived += actionWrite;

process.Start();
process.BeginOutputReadLine();
process.BeginErrorReadLine();
process.WaitForExit();


This doesn't elevate privileges and code above returns false. Why??

Answer

ProcessStartInfo.Verb will only have an effect if the process is started by ShellExecuteEx(). Which requires UseShellExecute = true. Redirecting I/O and hiding the window can only work if the process is started by CreateProcess(). Which requires UseShellExecute = false.

Well, that's why it doesn't work. Not sure if forbidding to start a hidden process that bypasses UAC was intentional. Probably. Very probably.

Check this Q+A for the manifest you need to display the UAC elevation prompt.

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