How Do I Stop An Application From Opening

Question

I want to write a small app that sits in my tray and that allows me to select an executable and prevent it from opening.

The UI of the app is easy to do using WinForms.

What I want to know is how to detect if a certain exe has been lauched and then how to stop it from running. I'm pretty sure I'll have to dig down into some Win32 stuff but I have no experience in that area, hence this post.

There is an existing app similar to this, but I can't for the life of me remember what it's called. It was written in VB6 and it's open source too.

Any help is much appreciated.

Answer 1

Rather than trying to kill the process when it runs, how about stopping it from running in the first place?

Changing what happens when the shell tries to launch an application is simple - add a new registry key to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options

To test this I added a registry key called notepad.exe and within this the string value Debugger with the value calc.exe. Now whenever I try and run notepad calc opens. The following is the exported registry key.

REGEDIT4

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\notepad.exe]
"Debugger"="calc.exe"

Having made this change I've not yet managed to open notepad, not bad for a no code solution. If you need to be 100% certain that the application never runs you could always add a "kill" solution too as detailed by others.