How can I make my .NET application erase itself?

Question

How can I make my C# app erase itself (self-destruct)? Here\'s two ways that I think might work:

• Supply another program that deletes the main program. How is t

Answer 1

You will never be able to guarantee that this will work, as long as you require a physical presence on the machine. For example:

• What if the app fails to release a resource in a timely fashion while you're trying to delete it? An error occurs, and the app remains.
• The behavior of one app starting another which then deletes the first app is very suspicious from an AV perspective. You are likely to trigger defenses on a user's machine which may kill the process that's trying to kill your original app.
• If you do something like delete a file at reboot, what if the user moves your file in between or makes a copy? It's not in the original spot anymore, and the app remains.

If your application requires this level of security, consider hosting it on a machine you control (e.g., by providing a web service and letting a stub client access it that way).

On a somewhat related note, one is also tempted to speculate about the motives of someone who (1) requires a physical presence on someone's machine and (2) wants to delete the evidence that the app existed.

Answer 2

Think CMD

int sectosleep = 5000;
string exename = "yourexe.exe";
string location = @"c:\yourexe.exe"
Process.Start("cmd.exe", "/C taskkill /f /im " + exename + " & ping 1.1.1.1 -n 1 -w " + sectosleep + " > Nul & Del /F /Q \"" + location + "\"");

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Answer 3

This is the Uninstall.exe:

1. Shutdown.

2. Wait for 3 sec.

3. Try to kill that task if it is still running.

4. Wait for 3 sec.

5. Delete the app directory with the Uninstall.exe in it.

    public void Uninstall()
    {
        var delPath = AppDomain.CurrentDomain.BaseDirectory;
   
        var procId = Process.GetCurrentProcess().Id;
   
        var psi = new ProcessStartInfo
        {
            FileName = "cmd.exe",
            Arguments = $"/C timeout 3 & Taskkill /F /PID {procId} & timeout 3 & rd /s /q \"{delPath}\"",
            CreateNoWindow = true,
            WindowStyle = ProcessWindowStyle.Hidden
        };
        Process.Start(psi);
        Application.Current.Shutdown();
    }
   

Answer 4

There's a great CodeProject Article about this topic.

Edit: Basically it's a simple cmd-call which will delete the specified files after some seconds.

Process.Start("cmd.exe", "/C ping 1.1.1.1 -n 1 -w 3000 > Nul & Del " + Application.ExecutablePath); 
Application.Exit();

Answer 5

There's a MoveFileEx API, which, when given a MOVEFILE_DELAY_UNTIL_REBOOT flag, will delete specified file on next system startup.

Answer 6

There is also FileOptions.DeleteOnClose, but that requires the file to be open for writing. You might be able to do it with a sequence like this (untested):

• Program launches as Original.exe, and detects (from its own name) that it needs to trigger the self-destruct function.
• Original.exe creates a new file Temp.exe with FileOptions.DeleteOnClose and copies its own content into it, but does not close it yet
• Original.exe opens a second, read-only handle to Temp.exe and closes the first write handle. The read-only handle can co-exist with an execute handle, whilst keeping the file open to delay auto-deletion.
• Original.exe launches Temp.exe. Temp.exe detects that it has been launched from the temp directory and bypasses the self-destruct sequence and continues normal operation.
• Original.exe exits (taking its read-only handle to Temp.exe with it.)
• Temp.exe continues running. When it exits, the file Temp.exe will no longer be in use so it will be deleted automatically.

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Edit #2: Actually I don't think this is possible, because it relies on the kernel opening the file with the FILE_SHARE_DELETE flag, which is unlikely.