pinvoke.net: Edit: kernel32.IsDebuggerPresent

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Summary: The IsDebuggerPresent API

!!!!VB.Net Signature:
 Private Declare Function IsDebuggerPresent Lib "kernel32" () As Integer
!!!!C# Signature:
 [DllImport("kernel32.dll")]
 static extern bool IsDebuggerPresent();
!!!!Boo Signature:
 [DllImport("kernel32.dll", SetLastError : true)]
 def IsDebuggerPresent() as bool:
     pass
!!!!User-Defined Types:
None.

VB Usage:

Private Declare Function IsDebuggerPresent Lib "kernel32" () As Integer

Try

If IsDebuggerPresent = 1 Then

MsgBox("Debugger is present!") 'Debugger was detected

Else

MsgBox("Debugger isn't present!") Debugger was not detected

End If

Catch ex As Exception

MsgBox(ex.Message)

End Try

!!!!Notes:
This is a quick way to help protect your applications from being reverse engineered at runtime. Call this when your application starts and exit if it returns true.

!!!!Tips & Tricks:
Call this before your application starts to protect it from runtime analysis. This is a weak form of protection, and is trivially bypassed. For a more robust mechanism, use a .NET obfuscator tool.

!!!!Sample Code:

// debug checking in debug builds would make it impossible to debug in Visual Studio
 #if !DEBUG
   if (IsDebuggerPresent() == true) {
      Application.Exit();
   }
 #endif
!!!!Alternative Managed API:
Do you know one?  Please contribute it!

Documentation: IsDebuggerPresent@msdn on MSDN