IsDebuggerPresent

Created the Monday 18 March 2019. Updated 3 years, 6 months ago.

This function checks specific flag in the Process Environment Block (PEB) for the field IsDebugged which will return zero if the process is not running into a debugger or a nonzero if a debugger is attached.

If you want to understand the underlying process of IsDebuggerPresent API you can check the code snippet section for the following method: IsDebugged Flag.


Technique Identifier

U0122

Technique Tag

isdebuggerpresent


Code Snippets

#include <windows.h>
#include <stdio.h>

int main(int argc, char** argv)
{
	if (IsDebuggerPresent())
	{
            printf("Debugger detected!!\n");
	}
	else
	{
	    printf("No debugger detected!!\n");
	}
	system("pause");
	return 0;
}
program IsDebuggerPresent;

{$APPTYPE CONSOLE}

uses
  WinAPI.Windows, System.SysUtils;

begin
  try
    if IsDebuggerPresent() then
      WriteLn('Process is currently getting debugged.')
    else
      WriteLn('Process is not likely getting debugged.');

    readln;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.

Detection Rules

rule Detect_IsDebuggerPresent : AntiDebug {
    meta:
        author = "naxonez"
        reference = "https://github.com/naxonez/yaraRules/blob/master/AntiDebugging.yara"
    strings:
	$ ="IsDebugged"
    condition:
        uint16(0) == 0x5A4D and filesize < 1000KB and any of them
}

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