Unable to Capture Output When Running as Other User

Question

I am making an application which allows a client to list all their running processes in a dialog box. I currently have the below code, and I can't work out why it isn't working.

I am not seeing any output whatsoever, be it sderr or stdout. Can someone please point me in the right direction?

private void button1_Click(object sender, EventArgs e)
{            
    string test = " ";

    var ss = new SecureString();
    ss.AppendChar('T');
    ss.AppendChar('a');
    ss.AppendChar('k');
    ss.AppendChar('e');
    ss.AppendChar('c');
    ss.AppendChar('a');
    ss.AppendChar('r');
    ss.AppendChar('e');
    ss.AppendChar('9');
    ss.AppendChar('9');
    ss.MakeReadOnly();

    var serverName = "SERVER-NAME";
    var sessionID = "2";
    var PID = "6816";

    var startInfo = new ProcessStartInfo("cmd", "/C tasklist /S " + serverName + " /FI \"SESSION eq " + sessionID + "\" >C:\\users\\test.account\\desktop\\NEWEWE.txt")
    {
        WorkingDirectory = @"C:\windows\system32",
        Verb = "runas",
        Domain = "BARDOM1",
        UserName = "XATest",
        Password = ss,

        WindowStyle = ProcessWindowStyle.Hidden,
        UseShellExecute = false,
        RedirectStandardOutput = true,
        CreateNoWindow = true
    };

    var proc = Process.Start(startInfo);
    proc.OutputDataReceived += (x, y) => test += (y.Data);
    proc.BeginOutputReadLine();
    proc.WaitForExit();

    MessageBox.Show(test);
    MessageBox.Show("done");
}

I have tried redirect output set to true and false, and I have tried setting the >c:\... in the CMD command with various properties, but can't see any output at all.

Cliffordclift

There's probably no output because the command is redirected to a file. If you change it to new ProcessStartInfo("cmd", "/C tasklist /S " + serverName + " /FI \"SESSION eq " + sessionID) does it work? – Touchwood

Hi theB ,Not only are you correct, but the server also needed to be reset so that XAtest could regain their admin rights! – Cliffordclift

I'm going to expand that comment into an actual answer in a couple min. – Touchwood

As an aside: Verb = "runas" (requesting elevation) has no effect here, because of UseShellExecute = false. In fact, you cannot both run as a different user and request elevation. – Sarver

Answer 1

The problem is that the command line specifies that the output should go to a file. I'd also recommend the use of a StringBuilder for collecting the output. It's a lot more efficient than concatenating strings with +=.

Here's an example that shows the working version, followed by a version that exhibits the behavior you were seeing.

StringBuilder test = new StringBuilder();

// Not redirected
ProcessStartInfo psi = new ProcessStartInfo("cmd", "/c echo yes")
{
    UseShellExecute = false,
    RedirectStandardOutput = true,
    CreateNoWindow = true
};

Process proc = Process.Start(psi);
proc.OutputDataReceived += (x, y) => test.Append(y.Data);
proc.BeginOutputReadLine();
proc.WaitForExit();

Console.WriteLine(test.ToString()); // Output: yes

test.Clear();

// Redirected
psi = new ProcessStartInfo("cmd", "/c echo yes > NUL")
{
    UseShellExecute = false,
    RedirectStandardOutput = true,
    CreateNoWindow = true
};

proc = Process.Start(psi);
proc.OutputDataReceived += (x, y) => test.Append(y.Data);
proc.BeginOutputReadLine();
proc.WaitForExit();

Console.WriteLine(test.ToString()); // Blank line

Touchwood