NtDetours

NTSTATUS NTAPI TrInit(PVOID ImageBase = &__ImageBase);

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hacer que la IAT sea escribible.

busca simple.cpp

TimedSleepEx llama a la API SleepEx real a través del puntero de función TrueSleepEx.``` static DWORD (WINAPI * TrueSleepEx)(DWORD dwMilliseconds, BOOL bAlertable) = SleepEx;

DWORD WINAPI TimedSleepEx(DWORD dwMilliseconds, BOOL bAlertable) { ... DWORD ret = TrueSleepEx(dwMilliseconds, bAlertable); ... }

**_no hagas esto !_** linker ya definido```
EXTERN_C PVOID __imp_SleepEx = SleepEx;

variable ( para x86 esto será __imp__SleepEx@8 y necesita usar``` __pragma(comment(linker, "/alternatename:___imp_SleepEx=__imp__SleepEx@8"))

así que usa ***__imp_SleepEx*** en lugar de ***TrueSleepEx*** y simplemente llama a api de la manera habitual y conveniente.

cualquier api importada SomeApi invocada mediante el puntero ***__imp_SomeApi*** ( carga diferida mediante ***__imp_load_SomeApi*** ). ¡úsalo!

ejemplo```
//EXTERN_C extern PVOID __imp_SleepEx;
DECLARE_T_HOOK(SleepEx, 8)

DWORD WINAPI hook_SleepEx( _In_ DWORD dwMilliseconds, _In_ BOOL bAlertable )
{
	ULONG ret = SleepEx(dwMilliseconds, bAlertable);

	DbgPrint("%s(%x, %x) = %x\n", __FUNCTION__, dwMilliseconds, bAlertable, ret);

	return ret;
}

void DetoursDemo()
{
	DBG_PRINT_ON();

	if (0 <= TrInit())
	{
		ThreadInfo* pti;
		SuspendAll(&pti);

		DbgPrint("before: SleepEx = 0x%p\n", SleepEx);

		TrHook(&__imp_SleepEx, hook_SleepEx, pti);

		DbgPrint("after: SleepEx = 0x%p\n", SleepEx);

		ResumeAndFree(pti);

		union {
			PVOID pv;
			DWORD (WINAPI * fn_SleepEx)( _In_ DWORD dwMilliseconds, _In_ BOOL bAlertable );
		};

		if (pv = GetProcAddress(GetModuleHandleW(L"kernel32"), "SleepEx"))
		{
			if (QueueUserAPC((PAPCFUNC)OutputDebugStringA, GetCurrentThread(), (ULONG_PTR)"asynchronous procedure call...\n"))
			{
				fn_SleepEx(INFINITE, TRUE);
			}
		}
	}
}

salida típica de depuración:``` NT::ThreadInfo::ThreadInfo<000002196427D6A0>(0000000000000814) NT::ThreadInfo::ThreadInfo<000002196427DBC0>(0000000000000128) NT::ThreadInfo::ThreadInfo<000002196427E0E0>(00000000000023D0) before: SleepEx = 0x00007FFED3DB06B0 0x00007FFED3DB06B0 -> 0x00007FF78BEB06C0 -> 0x00007FFE5394FFB8 [0x00007FFE5394FF98] after: SleepEx = 0x00007FFE5394FFB8 NT::ThreadInfo::~ThreadInfo<000002196427E0E0>(00000000000023D0) NT::ThreadInfo::~ThreadInfo<000002196427DBC0>(0000000000000128) NT::ThreadInfo::~ThreadInfo<000002196427D6A0>(0000000000000814) asynchronous procedure call... NT::hook_SleepEx(ffffffff, 1) = c0

otro ejemplo, con unhook:```
DWORD WINAPI hook_SleepEx( _In_ DWORD dwMilliseconds, _In_ BOOL bAlertable )
{
	// don't use any [TrueSleepEx](https://github.com/microsoft/Detours/blob/main/samples/simple/simple.cpp#L23) !! 
	ULONG ret = SleepEx(dwMilliseconds, bAlertable);

	DbgPrint("%s(%x, %x) = %x\n", __FUNCTION__, dwMilliseconds, bAlertable, ret);

	return ret;
}

int
WINAPI
hook_MessageBoxW(
				 _In_opt_ HWND hWnd,
				 _In_opt_ PCWSTR lpText,
				 _In_opt_ PCWSTR lpCaption,
				 _In_ UINT uType)
{
	// don't use any [Real_MessageBoxW](https://raw.githubusercontent.com/microsoft/Detours/main/samples/traceapi/_win32.cpp) !! 
	
	int ret = MessageBoxW(hWnd, lpText, __FUNCTIONW__, uType);

	DbgPrint("%s(\"%S\", \"%S\") = %x\n", __FUNCTION__, lpText, lpCaption, ret);

	return ret;
}

DECLARE_T_HOOK(SleepEx, 8)
DECLARE_T_HOOK(MessageBoxW, 16)

T_HOOKS_BEGIN(gHooks)
	T_HOOK(SleepEx),
	T_HOOK(MessageBoxW),
T_HOOKS_END()

void DemoApiCalls()
{
	union {
		PVOID pv;
		DWORD (WINAPI * fn_SleepEx)( _In_ DWORD dwMilliseconds, _In_ BOOL bAlertable );
		int (WINAPI * fn_MessageBoxW)( _In_opt_ HWND hWnd, _In_opt_ LPCWSTR lpText, _In_opt_ LPCWSTR lpCaption, _In_ UINT uType);
	};

	if (pv = GetProcAddress(GetModuleHandleW(L"kernel32"), "SleepEx"))
	{
		if (QueueUserAPC((PAPCFUNC)OutputDebugStringA, GetCurrentThread(), (ULONG_PTR)"asynchronous procedure call...\n"))
		{
			fn_SleepEx(INFINITE, TRUE);
		}
	}

	if (pv = GetProcAddress(GetModuleHandleW(L"user32"), "MessageBoxW"))
	{
		fn_MessageBoxW(0, L"[some text]", 0, MB_ICONINFORMATION);
	}
}

void DetoursDemo()
{
	DBG_PRINT_ON();

	if (0 <= TrInit())
	{
		ThreadInfo* pti;
		SuspendAll(&pti);
		TrHook(gHooks, _countof(gHooks), pti);
		ResumeAndFree(pti);

		DemoApiCalls();

		SuspendAll(&pti);
		TrUnHook(gHooks, _countof(gHooks), pti);
		ResumeAndFree(pti);

		DemoApiCalls();
	}
}

NT::ThreadInfo::ThreadInfo<0000026DEA5AD6D0>(00000000000017E8)
NT::ThreadInfo::ThreadInfo<0000026DEA5ADBF0>(00000000000013E0)
NT::ThreadInfo::ThreadInfo<0000026DEA5AE110>(00000000000002D4)
0x00007FFED3DB06B0 -> 0x00007FF693E10790 -> 0x00007FFE5394FFB8 [0x00007FFE5394FF98]
0x00007FFED41CA160 -> 0x00007FF693E10720 -> 0x00007FFE5430FFB8 [0x00007FFE5430FF98]
NT::ThreadInfo::~ThreadInfo<0000026DEA5AE110>(00000000000002D4)
NT::ThreadInfo::~ThreadInfo<0000026DEA5ADBF0>(00000000000013E0)
NT::ThreadInfo::~ThreadInfo<0000026DEA5AD6D0>(00000000000017E8)
asynchronous procedure call...
NT::hook_SleepEx(ffffffff, 1) = c0


---------------------------
NT::hook_MessageBoxW
---------------------------
[some text]
---------------------------
OK   
---------------------------

NT::hook_MessageBoxW("[some text]", "(null)") = 1

NT::ThreadInfo::ThreadInfo<0000026DEA5C7370>(0000000000001A84)
NT::ThreadInfo::ThreadInfo<0000026DEA5C7890>(0000000000000D1C)
NT::ThreadInfo::ThreadInfo<0000026DEA5E2950>(00000000000020C8)
NT::ThreadInfo::ThreadInfo<0000026DEA5E2E70>(0000000000000D18)
NT::ThreadInfo::ThreadInfo<0000026DEA5E3390>(0000000000001974)
NT::ThreadInfo::ThreadInfo<0000026DEA5DD3D0>(00000000000023E0)
NT::ThreadInfo::ThreadInfo<0000026DEA5DD8F0>(0000000000001C58)
NT::ThreadInfo::~ThreadInfo<0000026DEA5DD8F0>(0000000000001C58)
NT::ThreadInfo::~ThreadInfo<0000026DEA5DD3D0>(00000000000023E0)
NT::ThreadInfo::~ThreadInfo<0000026DEA5E3390>(0000000000001974)
NT::ThreadInfo::~ThreadInfo<0000026DEA5E2E70>(0000000000000D18)
NT::ThreadInfo::~ThreadInfo<0000026DEA5E2950>(00000000000020C8)
NT::ThreadInfo::~ThreadInfo<0000026DEA5C7890>(0000000000000D1C)
NT::ThreadInfo::~ThreadInfo<0000026DEA5C7370>(0000000000001A84)

asynchronous procedure call...

---------------------------
Error
---------------------------
[some text]
---------------------------
OK   
---------------------------

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DBG_PRINT_ON() / DBG_PRINT_OFF()

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habilitar / deshabilitar salida de depuración (por defecto deshabilitada)

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NTSTATUS NTAPI SuspendAll(Out ThreadInfo** ppti);

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enumerar hilos en el proceso mediante NtGetNextThread comprobar si es el hilo actual ( ZwQueryInformationThread(ThreadBasicInformation) ) suspender el hilo ZwSuspendThread guardar su contexto ZwGetContextThread vincular la información del hilo (handle/context) a la lista

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void NTAPI ResumeAndFree(In ThreadInfo* pti);

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recorrer la lista de hilos ( pti ) reanudar el hilo cerrar su handle liberar memoria