简介
windows默认会用异常处理程序包含SetTimer的回调函数TimerProc,所以可以利用这一点给远程注入代码加上异常处理过程,防止注入代码导致远程程序异常崩溃。并且异常处理过程由windows自动处理,不需要编写额外代码,非常方便。
微软文档所述:
Windows 会将其对 TimerProc 的 调用括起来,其中包含使用和放弃所有异常的异常处理程序。 这是自 Windows 2000 以来的默认行为,但在 Windows 的未来版本中,这一行为可能会更改。 https://learn.microsoft.com/zh-cn/windows/win32/api/winuser/nf-winuser-setuserobjectinformationw
验证SetTimer函数自带异常处理
首先必须知道的是由windows消息队列来调用TimerProc函数。具体的说是SetTimer函数带回调函数时,由DispatchMessage函数调用TimerProc函数,且触发异常后,异常以后的代码不会被执行。
新建VS工程,选windows控制台程序,完整代码如下。
#include <windows.h>
#include <iostream>
using namespace std;
// 计时器回调函数
VOID CALLBACK Timerproc(
HWND hwnd, // handle to window for timer messages
UINT message, // WM_TIMER message
UINT idTimer, // timer identifier
DWORD dwTime) // current system time
{
cout << "Timerproc" << endl;
int a = 1, b = 0, c = 0;
c = a / b; // 这句代码会引发异常,除数为零
cout << c << endl;
}
int main() {
//const HWND hwnd = GetConsoleWindow(); // 获取本进程句柄
const UINT_PTR timer_id = SetTimer(nullptr, // 绑定的窗口句柄
0, // timer ID
0x0, // 倒计时数,毫秒
Timerproc); // 回调函数
int Counter = 0;
MSG msg;
while (GetMessage(&msg, nullptr, 0, 0)) {
++Counter;
cout << "Counter: " << Counter << "; message: " << msg.message << '\n';
DispatchMessage(&msg);
}
return 0;
}
调试运行,VS输出标签里重复提示除数为零异常,但程序仍然正常运行,没有显示cout << c << endl;这句代码,说明异常处理程序确实包含了TimerProc函数。
新线程内执行TimerProc函数
控制台程序
远程注入的代码是通过CreateRemoteThread函数执行,也就是新建一个线程。所以先来模拟本地新线程执行情景。
#include <windows.h>
#include <iostream>
#include <process.h>
using namespace std;
HANDLE hEvent;
// 计时器回调函数
VOID CALLBACK Timerproc(
HWND hwnd, // handle to window for timer messages
UINT message, // WM_TIMER message
UINT idTimer, // timer identifier
DWORD dwTime) // current system time
{
cout << "Timerproc" << endl;
KillTimer(hwnd, idTimer);
int a = 1, b = 0, c = 0;
c = a / b; // 这句代码会引发异常,除数为零
cout << c << endl;
SetEvent(hEvent);
}
DWORD WINAPI thread(_In_ LPVOID lpParameter) {
HWND process_hwnd = *(HWND*)lpParameter;
cout << "process_hwnd=" << process_hwnd << endl;
cout << "thread start PID=" << GetCurrentThreadId() << endl;
UINT_PTR timer_id;
const HANDLE thread_hwnd = GetCurrentThread();
timer_id = SetTimer(nullptr, 0, 0, nullptr);
timer_id = SetTimer(process_hwnd, // 绑定的窗口句柄
timer_id, // timer ID
0x0, // 倒计时数,毫秒
Timerproc); // 回调函数
hEvent = CreateEvent(nullptr, FALSE, FALSE, nullptr);
WaitForSingleObject(hEvent, 5000);
cout << "WaitForSingleObject end" << endl;
CloseHandle(hEvent);
return 0;
}
int main() {
//HANDLE process_handle = OpenProcess(PROCESS_ALL_ACCESS, FALSE, GetCurrentProcessId());
//cout << "process_handle=" << process_handle << endl;
HWND process_hwnd = GetConsoleWindow();
cout << "process_hwnd=" << process_hwnd << endl;
const HANDLE thread_handle = CreateThread(nullptr, 0, thread, &process_hwnd, 0, nullptr);
cout << "CreateThread thread_handle=" << thread_handle << endl;
BOOL bRet;
int Counter = 0;
MSG msg;
while ((bRet = GetMessage(&msg, nullptr, 0, 0)) != 0) {
if (bRet == -1) {
// handle the error and possibly exit
}
else {
++Counter;
cout << "Counter: " << Counter << "; message: " << msg.message << '\n';
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return 0;
}
上面的代码无法运行成功,原因是TimeProc函数并未执行。没有执行是因为消息队列没有消息,那么GetMessage就会阻塞进程,不执行while循环体。不进入循环体,DispatchMessage函数就无法调用TimeProc函数。
至于为什么这里SetTimer函数没有触发消息……我也不知道。
窗口程序
控制台程序无法成功运行,但是换窗口程序却可以成功运行。
代码流程:
- WinMain函数是主函数,主函数中创建新线程执行thread函数。
- thread函数中创建事件,新建空计时器。新建空计时器是为了避免覆盖注入进程中已有的计时器(当SetTimer函数的第1、2参数为0时,windows会自动在当前进程创建新的计时器ID)。然后再次设置计时器,传入注入进程句柄、新建空计时器ID、Timerproc回调函数。最后执行WaitForSingleObject函数阻塞等待事件信号,如果Timerproc函数触发异常了,则会超时指定时间后继续执行。
- Timerproc函数可以自动处理异常,需要注意的是触发异常后的代码不会被执行。函数首先关闭计时器,接着直接插入注入代码或调用call函数,最后设置信号为有状态,以便让WaitForSingleObject函数接收信号。
- call函数有没有都可以,单独的call函数方便编程和调试。
改进的代码如下:
#include <iostream>
#include <windows.h>
using namespace std;
static const TCHAR gc_szClassName[] = TEXT("Test");
static const TCHAR gc_szWindowTitle[] = TEXT("Test");
HANDLE hEvent;
void call() {
int a = 1, b = 0, c = 0;
c = a / b; // 这句代码会引发异常,除数为零
cout << c << endl;
}
// 计时器回调函数
VOID CALLBACK Timerproc(
HWND hwnd, // handle to window for timer messages
UINT message, // WM_TIMER message
UINT idTimer, // timer identifier
DWORD dwTime) // current system time
{
cout << "Timerproc" << endl;
if (KillTimer(hwnd, idTimer))
cout << "KillTimer done" << endl;
else
cout << "KillTimer error" << endl;
call(); // 如果函数内异常导致退出,则不会执行下面的代码
SetEvent(hEvent);
}
DWORD WINAPI thread(_In_ LPVOID lpParameter) {
HWND process_hwnd = *(HWND*)lpParameter;
cout << "process_hwnd=" << process_hwnd << endl;
cout << "thread start PID=" << GetCurrentThreadId() << endl;
UINT_PTR timer_id;
const HANDLE thread_hwnd = GetCurrentThread();
hEvent = CreateEvent(nullptr, FALSE, FALSE, nullptr);
timer_id = SetTimer(nullptr, 0, 0, nullptr);
timer_id = SetTimer(process_hwnd, // 绑定的窗口句柄
timer_id, // timer ID
0x0, // 倒计时数,毫秒
Timerproc); // 回调函数
cout << "timer_id=" << timer_id << endl;
WaitForSingleObject(hEvent, 5000);
cout << "WaitForSingleObject end" << endl;
CloseHandle(hEvent);
return 0;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT uMessage, WPARAM wParam, LPARAM lParam) {
switch (uMessage) {
case WM_CREATE:
break;
case WM_CLOSE:
DestroyWindow(hWnd);
break;
case WM_DESTROY:
PostQuitMessage(EXIT_SUCCESS);
break;
default:;
}
return DefWindowProc(hWnd, uMessage, wParam, lParam);
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpszCommandLine, int nShowCommand) {
// define variables
HWND hWnd;
WNDCLASS wc;
MSG msg;
// unused parameters
UNREFERENCED_PARAMETER(hPrevInstance);
UNREFERENCED_PARAMETER(lpszCommandLine);
UNREFERENCED_PARAMETER(nShowCommand);
// initialize WNDCLASS structure
ZeroMemory(&wc, sizeof(wc));
wc.lpfnWndProc = WndProc;
wc.hInstance = hInstance;
wc.lpszClassName = gc_szClassName;
// attempt to register the class
if (RegisterClass(&wc) != 0) {
// show console
AllocConsole();
std::ignore = freopen_s((FILE**)stdout, "CONOUT$", "w", stdout);
std::ignore = freopen_s((FILE**)stdout, "CONOUT$", "w", stderr);
std::ignore = freopen_s((FILE**)stdout, "CONIN$", "r", stdin);
std::cout.clear();
std::clog.clear();
std::cerr.clear();
std::cin.clear();
// attempt to create the window
hWnd = CreateWindow(gc_szClassName, gc_szWindowTitle, WS_CAPTION | WS_SYSMENU | WS_VISIBLE, 100, 100, 100, 100, NULL, NULL, hInstance, NULL);
cout << "window hwnd=" << hWnd << endl;
const HANDLE thread_handle = CreateThread(nullptr, 0, thread, &hWnd, 0, nullptr);
int Counter = 0;
// retrieve messages
while (GetMessage(&msg, NULL, 0, 0) > 0) {
++Counter;
std::cout << "Counter: " << Counter << "; message: " << msg.message << '\n';
TranslateMessage(&msg);
DispatchMessage(&msg);
}
// use the return-code from the window
return (int)msg.wParam;
}
return EXIT_FAILURE;
}
将注入函数转为汇编语言
转为汇编语言这一步骤我卡住好几天。转为汇编语言本进程执行很简单,但如果要把thread()、timerproc()、call()三个函数在远程进程运行则有难度。主要难度为注入到远程进程后,由于没有基址重定位,无法执行call系统函数语句CALL KillTimer,也无法执行call自有函数语句CALL call。
研究了几天之后发现受限于内联汇编的功能局限性,不能用内联汇编完成目的。所以简单学习了一下asmjit,改用asmjit汇编引擎实现功能。
本进程执行代码
接下来需要将thread()、Timerproc()、call()函数转换为汇编语言。转换后的完整代码如下:
#include <iostream>
#include <windows.h>
using namespace std;
HANDLE hEvent;
void call() {
//cout << "func call start" << endl;
//int a = 1, b = 0, c = 0;
//c = a / b; // 这句代码会引发异常,除数为零
//cout << "func call end" << endl;
char start[] = "func call start\n";
char end[] = "func call end\n";
__asm {
lea eax, start
push eax
call printf
xor eax, eax
div eax // 0除以0 异常语句
lea eax, end
push eax
call printf
}
}
// 计时器回调函数
VOID CALLBACK Timerproc(
HWND hwnd, // handle to window for timer messages
UINT message, // WM_TIMER message
UINT idTimer, // timer identifier
DWORD dwTime) // current system time
{
//cout << "Timerproc" << endl;
//if (KillTimer(hwnd, idTimer))
// cout << "KillTimer done" << endl;
//else
// cout << "KillTimer error" << endl;
//call(); // 如果函数内异常导致退出,则不会执行下面的代码
//SetEvent(hEvent);
__asm {
push idTimer
push hwnd
call KillTimer
call call
//mov dword ptr ds : [0x12345678] , eax; // 把call函数的返回值结果存放到指定的内存地址
push hEvent
call SetEvent
}
}
DWORD WINAPI thread(_In_ LPVOID lpParameter) {
HWND process_hwnd = *(HWND*)lpParameter;
UINT_PTR timer_id;
//cout << "process_hwnd=" << process_hwnd << endl;
//cout << "thread start PID=" << GetCurrentThreadId() << endl;
//const HANDLE thread_hwnd = GetCurrentThread();
////hEvent = CreateEvent(nullptr, FALSE, FALSE, nullptr);
//timer_id = SetTimer(nullptr, 0, 0, nullptr);
//timer_id = SetTimer(process_hwnd, // 绑定的窗口句柄
// timer_id, // timer ID
// 0x0, // 倒计时数,毫秒
// Timerproc); // 回调函数
//cout << "timer_id=" << timer_id << endl;
//WaitForSingleObject(hEvent, 5000);
//cout << "WaitForSingleObject end" << endl;
//CloseHandle(hEvent);
char start[] = "func thread start\n";
char end[] = "func thread end\n";
__asm {
lea eax, start
push eax
call printf
push 0
push 0
push 0
push 0
call CreateEvent
mov hEvent, eax
push 0
push 0
push 0
push 0
call SetTimer
push Timerproc
push 0
push eax
push process_hwnd
call SetTimer
mov timer_id, eax
push 0x1388; 5000毫秒
push hEvent
call WaitForSingleObject
push hEvent
call CloseHandle
lea eax, end
push eax
call printf
}
return 0;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT uMessage, WPARAM wParam, LPARAM lParam) {
switch (uMessage) {
case WM_CREATE:
break;
case WM_CLOSE:
DestroyWindow(hWnd);
break;
case WM_DESTROY:
PostQuitMessage(EXIT_SUCCESS);
break;
default:;
}
return DefWindowProc(hWnd, uMessage, wParam, lParam);
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpszCommandLine, int nShowCommand) {
// define variables
HWND hWnd;
WNDCLASS wc;
MSG msg;
// unused parameters
UNREFERENCED_PARAMETER(hPrevInstance);
UNREFERENCED_PARAMETER(lpszCommandLine);
UNREFERENCED_PARAMETER(nShowCommand);
// initialize WNDCLASS structure
ZeroMemory(&wc, sizeof(wc));
wc.lpfnWndProc = WndProc;
wc.hInstance = hInstance;
wc.lpszClassName = TEXT("class name");
// attempt to register the class
if (RegisterClass(&wc) != 0) {
AllocConsole();
std::ignore = freopen_s((FILE**)stdout, "CONOUT$", "w", stdout);
std::ignore = freopen_s((FILE**)stdout, "CONOUT$", "w", stderr);
std::ignore = freopen_s((FILE**)stdout, "CONIN$", "r", stdin);
std::cout.clear();
std::clog.clear();
std::cerr.clear();
std::cin.clear();
// attempt to create the window
hWnd = CreateWindow(TEXT("class name"), TEXT("window title"), WS_CAPTION | WS_SYSMENU | WS_VISIBLE, 1100, 600, 100, 100, NULL, NULL, hInstance, NULL);
cout << "window hwnd=" << hWnd << endl;
const HANDLE thread_handle = CreateThread(nullptr, 0, thread, &hWnd, 0, nullptr);
int Counter = 0;
// retrieve messages
while (GetMessage(&msg, NULL, 0, 0) > 0) {
++Counter;
std::cout << "Counter: " << Counter << "; message: " << msg.message << '\n';
TranslateMessage(&msg);
DispatchMessage(&msg);
}
// use the return-code from the window
return (int)msg.wParam;
}
return EXIT_FAILURE;
}
运行成功。实际应用时可以把call函数里的两个调试printf语句删了。
远程进程执行代码
代码只适用于x86程序,如果你系统是64位系统,测试用的笔记本程序需要使用c:\windows\SysWOW64\notepad.exe
#include <algorithm>
#include <format>
#include <iomanip>
#include <windows.h>
#include <iostream>
#include <psapi.h>
#include <string>
#include <asmjit/asmjit.h>
using namespace std;
using namespace asmjit;
using namespace x86;
struct THREAD_PARAM {
DWORD ret_value; // alloc_addr + 0x0
FARPROC settimer; // alloc_addr + 0x4
FARPROC killtimer; // alloc_addr + 0x8
HWND remote_hwnd; // alloc_addr + 0xC
DWORD timerproc; // alloc_addr + 0x10
DWORD timer_id; // alloc_addr + 0x14
DWORD custom_call; // alloc_addr + 0x18
};
/**
* \brief 获取指定进程中的模块函数句柄
* \param hRemoteProcess 指定进程句柄
* \param lpModuleName 指定函数名所在的模块名,大小写任意
* \param lpProcName 指定要获取的函数名,大小写必须匹配
* \return 成功则返回指定的函数地址,未找到返回空指针
* \note 可至微软learn网站查询函数所在的模块
*/
FARPROC GetRemoteModule(_In_ const HANDLE hRemoteProcess, _In_ const LPCWSTR lpModuleName, _In_ const LPCSTR lpProcName) {
// https://learn.microsoft.com/zh-cn/windows/win32/psapi/enumerating-all-modules-for-a-process
// 获取远程模块信息
HMODULE hModule[MAX_PATH];
DWORD cbNeeded;
if (!EnumProcessModules(hRemoteProcess, hModule, MAX_PATH, &cbNeeded))
return nullptr;
// 遍历枚举到的模块
for (size_t i = 0; i < cbNeeded / sizeof(HMODULE); i++) {
TCHAR szModName[MAX_PATH];
// Get the full path to the module's file.
if (GetModuleFileNameEx(hRemoteProcess, hModule[i], szModName,
sizeof(szModName) / sizeof(TCHAR))) {
// 转为wstring字符串,并全部转换为小写以便比较
wstring ModName(szModName);
wstring ModuleName(lpModuleName);
ranges::transform(ModName, ModName.begin(), ::tolower);
ranges::transform(ModuleName, ModuleName.begin(), ::tolower);
//wcout << format(L"\t0x{:08X} {}\n", (DWORD)hModule[i], ModName);
// 如果是要找的模块
if (ModName.find(ModuleName) != wstring::npos)
// 如果GetProcAddress函数成功,则返回值是导出的函数或变量的地址。如果GetProcAddress函数失败,则返回值为 NULL。 要获得更多的错误信息,请调用 GetLastError。
return GetProcAddress(hModule[i], lpProcName);
}
}
return nullptr;
}
int main() {
const HWND remote_hwnd =
FindWindow(L"Notepad", nullptr);
cout << "remote_hwnd=" << remote_hwnd << endl;
DWORD remote_pid = 0;
GetWindowThreadProcessId(remote_hwnd, &remote_pid);
cout << "remote_pid=" << remote_pid << endl;
const HANDLE remote_handle = OpenProcess(PROCESS_ALL_ACCESS, false, remote_pid);
if (!remote_handle)
return 0;
// 获取远程进程模块函数信息
auto settimer = GetRemoteModule(remote_handle, TEXT("User32.dll"), "SetTimer");
auto killtimer = GetRemoteModule(remote_handle, TEXT("User32.dll"), "KillTimer");
//cout << format("SetTimer addr=0x{:08X}\n", (DWORD)settimer);
//cout << format("KillTimer addr=0x{:08X}\n", (DWORD)killtimer);
// 申请远程空间,写入和执行权限
DWORD alloc_addr = (DWORD)VirtualAllocEx(remote_handle, nullptr, MAX_PATH, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
if (!alloc_addr) {
cout << "GetLastError()=" << GetLastError() << endl;
return 0;
}
cout << setw(8) << setfill('0') << hex << "VirtualAlloc addr=0x" << alloc_addr << endl;
DWORD addr_param = alloc_addr; // 参数内存地址
DWORD addr_call = alloc_addr + 0x21; // 函数地址
// 构造和写入函数
THREAD_PARAM thread_param{};
thread_param.remote_hwnd = remote_hwnd;
thread_param.settimer = settimer;
thread_param.killtimer = killtimer;
// 生成代码
JitRuntime rt;
auto a = x86::Assembler();
CodeHolder code;
code.init(rt.environment(), rt.cpuFeatures());
code.attach(&a);
// 构造thread函数
a.push(0);
a.push(0);
a.push(0);
a.push(0);
a.call(dword_ptr(alloc_addr + 0x4)); // settimer
a.mov(dword_ptr(alloc_addr + 0x14), eax); //timer_id
a.push(dword_ptr(alloc_addr + 0x10)); // timerproc
a.push(0);
a.push(eax);
a.push(dword_ptr(alloc_addr + 0xC)); // remote_hwnd
a.call(dword_ptr(alloc_addr + 0x4)); // settimer
a.ret();
CodeBuffer& thread = code.textSection()->buffer(); // 获取对应的机器码
// 打印生成的机器码
//cout << "assembly=";
//for (auto& i : thread)
// cout << format("{:02X} ", i);
//cout << endl;
size_t nSize = thread.size();
cout << format("线程函数写入地址=0x{:08X} 大小=0x{:08X}\n", addr_call, nSize);
WriteProcessMemory(remote_handle, (LPVOID)addr_call, thread.data(), nSize, nullptr);
DWORD thread_addr = addr_call; // 记录线程函数地址
addr_call = addr_call + nSize + 0x8;
// 重置并复用CodeHolder变量code
code.reset();
code.init(rt.environment(), rt.cpuFeatures());
code.attach(&a);
// 构造timerproc
a.push(dword_ptr(alloc_addr + 0x14)); // idTimer
a.push(dword_ptr(alloc_addr + 0xC)); // hwnd
a.call(dword_ptr(alloc_addr + 0x8)); // call KillTimer
a.call(dword_ptr(alloc_addr + 0x18)); // custom_call
a.ret();
CodeBuffer& timerproc = code.textSection()->buffer();
thread_param.timerproc = addr_call; // 记录therad地址
nSize = timerproc.size();
cout << format("回调函数写入地址=0x{:08X} 大小=0x{:08X}\n", addr_call, nSize);
WriteProcessMemory(remote_handle, (LPVOID)addr_call, timerproc.data(), nSize, nullptr);
addr_call = addr_call + nSize + 0x8;
// 重置并复用CodeHolder变量code
code.reset();
code.init(rt.environment(), rt.cpuFeatures());
code.attach(&a);
// 构造自定函数
a.xor_(eax, eax);
a.div(eax); // 异常语句
a.mov(dword_ptr(alloc_addr), eax); // 写入返回值到alloc_addr,程序读取alloc_addr地址的数值即可知道返回值
a.ret();
CodeBuffer& custom_call = code.textSection()->buffer();
thread_param.custom_call = addr_call; // 记录custom_call地址
nSize = custom_call.size();
cout << format("自定函数写入地址=0x{:08X} 大小=0x{:08X}\n", addr_call, nSize);
WriteProcessMemory(remote_handle, (LPVOID)addr_call, custom_call.data(), nSize, nullptr);
addr_call = addr_call + nSize + 0x8;
// 写入参数
cout << format("线程参数写入地址=0x{:08X} 大小=0x{:08X}\n", addr_param, sizeof(THREAD_PARAM));
WriteProcessMemory(remote_handle, (LPVOID)addr_param, &thread_param, sizeof(THREAD_PARAM), nullptr);
const HANDLE hRemoteThread = CreateRemoteThread(remote_handle, nullptr, 0, (LPTHREAD_START_ROUTINE)thread_addr, (LPVOID)addr_param, 0, nullptr);
//system("pause");
return 0;
}