Application will not open in Win7, IIS 7.5, ASP.NET4 environment when called via C# code

Question

I think I have a security issue here but can't seem to get around it. I am running IIS 7.5 with an application pool named "MyAppPool." I am then calling a program from C# code, PDFCreator.exe, which reads from C:\DWF and then writes C:\DWF\DWF.PDF.

I have given IIS AppPool\MyAppPool full rights to PDFCreator.exe as well as the C:\DWF directory. When C# creates the process and calls PDFCreator.exe, it simply starts a process showing MyAppPool as owner but never opens the application.

Can anyone chime in on anything security-related I may be missing?

ProcessStartInfo processStartInfo = new ProcessStartInfo(@"c:\program files (x86)\pdfcreator\pdfcreator.exe");
processStartInfo.Arguments = @"/PF""c:\dwf\dwf.dwf"" /NoStart";
processStartInfo.RedirectStandardInput = true;
processStartInfo.RedirectStandardOutput = true;
processStartInfo.RedirectStandardError = true;
processStartInfo.UseShellExecute = false;
Process process = Process.Start(processStartInfo);
// Read the output stream first and then wait
string output = process.StandardOutput.ReadToEnd();
string errors = process.StandardError.ReadToEnd();
Response.Write(output + errors);

Answer 1

That's a suboptimal design for an IIS application.

Desktop apps run interactively.

IIS apps run as a service - without displaying a user interface to the user.

You're essentially using IIS to kick off some background processing tasks (because there's no GUI visible to you) that think they're foreground processing tasks.

The "kind of crafty" bit you mentioned in your comments is exactly why you might have problems doing this. Just to pick one sentence:

"This app then prints to a PDF file using PDFCreator's printer driver and saves it to the desktop."

In the case of an IIS AppPool user, where's the desktop?

You could try using a specific user account (not an IIS AppPool\ThisIsAVirtualAccount virtual App Pool Identity account) which gives it a specific profile, and setting Load User Profile to True (App Pool properties) in order to ensure the profile folders (and the printer driver) are available for that user.

But this is all stuff that's going to be happening somewhere in the background on an IIS box, and if the app decides to pop an error dialog, that's it, it's broken until the box restarts. Like I said, suboptimal.