NtQueryInformationProcess

This function retrieves information about a running process. Malware are able to detect if the process is currently being attached to a debugger using the ProcessDebugPort (0x7) information class.

A nonzero value returned by the call indicates that the process is being debugged.

Technique Identifiers

U0120 B0001.012

Technique Tag

NtQueryInformationProcess

Evasion Categories

Anti-Debugging

Code Snippets

program NtQueryProcessInformation;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  Winapi.Windows,
  System.SysUtils;

function NtQueryInformationProcess(
  ProcessHandle : THandle;
  ProcessInformationClass : DWORD;
  ProcessInformation : Pointer;
  ProcessInformationLength : ULONG;
  ReturnLength : PULONG
): LongInt; stdcall; external 'ntdll.dll';

// https://docs.microsoft.com/en-gb/windows/win32/api/winternl/nf-winternl-ntqueryinformationprocess
function isDebuggerPresent(): Boolean;
var hProcess : THandle;
    APortNumber : DWORD;
    ARetLen : Cardinal;

const ProcessDebugPort = 7;
begin
  hProcess := GetCurrentProcess();
  if hProcess = 0 then
    Exit();
  ///

  if NtQueryInformationProcess(hProcess, ProcessDebugPort, @APortNumber, sizeOf(DWORD), @ARetLen) <> ERROR_SUCCESS then
    Exit();

  result := APortNumber <> 0;
end;

begin
  try
    if isDebuggerPresent() then
      raise Exception.Create('Debugger Detected !');

    WriteLn('No Debugger Detected :)');
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;

  WriteLn('Press a return key to close application.');
  ReadLn;
end.

About Author Open Snippet

Author: Jean-Pierre LESUEUR (DarkCoderSc) / Target Platform: Windows

using System;
using System.Runtime.InteropServices;

[DllImport("ntdll.dll", SetLastError = true)]
static extern int NtQueryInformationProcess(
    IntPtr processHandle,
    int processInformationClass,
    ref IntPtr processInformation,
    uint processInformationLength,
    ref IntPtr returnLength
);

[DllImport("kernel32.dll", SetLastError = true)]
static extern IntPtr GetCurrentProcess();

bool isBeingDebugged()
{
    var ERROR_SUCCESS = 0x0;
    var ProcessDebugPort = 0x7;

    IntPtr currProcessHandle = GetCurrentProcess();
    if (currProcessHandle == IntPtr.Zero)
    {
        throw new Exception("Could not retrieve current process handle.");
    }

    IntPtr returnLength = IntPtr.Zero;
    IntPtr portNumber = IntPtr.Zero;

    int ntStatus = NtQueryInformationProcess(currProcessHandle, ProcessDebugPort, ref portNumber, (uint)IntPtr.Size, ref returnLength);        
    if (ntStatus != ERROR_SUCCESS)
    {
        throw new Exception("Could not query information process.");
    }

    return (portNumber != IntPtr.Zero);
}

if (isBeingDebugged())
{
    throw new Exception("Debugger Detected !");
}

Console.WriteLine("No Debugger Detected :)");

About Author Open Snippet

Author: Jean-Pierre LESUEUR (DarkCoderSc) / Target Platform: Windows

Detection Rules

rule Detect_NtQueryInformationProcess: AntiDebug {
    meta: 
        description = "Detect NtQueryInformationProcess as anti-debug"
        author = "Unprotect"
        comment = "Experimental rule"
    strings:
        $1 = "NtQueryInformationProcess" fullword ascii
    condition:   
       uint16(0) == 0x5A4D and filesize < 1000KB and $1
}

rule:
  meta:
    name: check process job object
    namespace: anti-analysis/anti-debugging/debugger-detection
    authors:
      - michael.hunhoff@mandiant.com
    scope: function
    mbc:
      - Anti-Behavioral Analysis::Debugger Detection [B0001]
    references:
      - https://github.com/LordNoteworthy/al-khaser/blob/master/al-khaser/AntiDebug/ProcessJob.cpp
    examples:
      - al-khaser_x86.exe_:0x426730
  features:
    - and:
      - match: contain loop
      - basic block:
        - and:
          - api: kernel32.QueryInformationJobObject
          - number: 0x3 = JobObjectBasicProcessIdList
      - basic block:
        - and:
          - api: kernel32.OpenProcess
          - number: 0x400 = PROCESS_QUERY_INFORMATION

Additional Resources

External Links

The resources provided below are associated links that will give you even more detailed information and research on current evasion technique. It is important to note that, while these resources may be helpful, it is important to exercise caution when following external links. As always, be careful when clicking on links from unknown sources, as they may lead to malicious content.

NtQueryInformationProcess function (winternl.h) - Win32 apps | Microsoft Docs

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Created

March 18, 2019

Last Revised

March 24, 2026