Api攔截并不是一個(gè)新的技術(shù)，很多商業(yè)軟件都采用這種技術(shù)。對(duì)windows的Api函數(shù)的攔截，不外乎兩種方法，第一種是Mr. Jeffrey Richter 的修改exe文件的模塊輸入節(jié)，種方法，很安全，但很復(fù)雜，而且有些exe文件，沒有Dll的輸入符號(hào)的列表，有可能出現(xiàn)攔截不到的情況。第二種方法就是常用的JMP XXX的方法，雖然很古老，卻很簡(jiǎn)單實(shí)用。
本文一介紹第二種方法在Win2k下的使用。第二種方法，Win98/me 下因?yàn)檫M(jìn)入Ring0級(jí)的方法很多，有LDT,IDT,Vxd等方法，很容易在內(nèi)存中動(dòng)態(tài)修改代碼，但在Win2k下，這些方法都不能用，寫WDM太過復(fù)雜，表面上看來很難實(shí)現(xiàn)，其實(shí)不然。Win2k為我們提供了一個(gè)強(qiáng)大的內(nèi)存Api操作函數(shù)---VirtualProtectEx，WriteProcessMemeory,ReadProcessMemeory，有了它們我們就能在內(nèi)存中動(dòng)態(tài)修改代碼了，其原型為：
BOOL VirtualProtectEx(
HANDLE hProcess, // 要修改內(nèi)存的進(jìn)程句柄
LPVOID lpAddress, // 要修改內(nèi)存的起始地址
DWORD dwSize, // 修改內(nèi)存的字節(jié)
DWORD flNewProtect, // 修改后的內(nèi)存屬性
PDWORD lpflOldProtect // 修改前的內(nèi)存屬性的地址
);
BOOL WriteProcessMemory(
HANDLE hProcess, // 要寫進(jìn)程的句柄
LPVOID lpBaseAddress, // 寫內(nèi)存的起始地址
LPVOID lpBuffer, // 寫入數(shù)據(jù)的地址
DWORD nSize, // 要寫的字節(jié)數(shù)
LPDWORD lpNumberOfBytesWritten // 實(shí)際寫入的子節(jié)數(shù)
);
BOOL ReadProcessMemory(
HANDLE hProcess, // 要讀進(jìn)程的句柄
LPCVOID lpBaseAddress, // 讀內(nèi)存的起始地址
LPVOID lpBuffer, // 讀入數(shù)據(jù)的地址
DWORD nSize, // 要讀入的字節(jié)數(shù)
LPDWORD lpNumberOfBytesRead // 實(shí)際讀入的子節(jié)數(shù)
);
具體的參數(shù)請(qǐng)參看MSDN幫助。在Win2k下因?yàn)镈ll和所屬進(jìn)程在同一地址空間，這點(diǎn)又和Win9x/me存在所有進(jìn)程存在共享的地址空間不同，
因此，必須通過鉤子函數(shù)和遠(yuǎn)程注入進(jìn)程的方法，現(xiàn)以一個(gè)簡(jiǎn)單采用鉤子函數(shù)對(duì)MessageBoxA進(jìn)行攔截例子來說明：
其中Dll文件為：
//---------------------------------------------------------------------------
#include
//---------------------------------------------------------------------------
// Important note about DLL memory management when your DLL uses the
// static version of the RunTime Library:
//
// If your DLL exports any functions that pass String objects (or structs/
// classes containing nested Strings) as parameter or function results,
// you will need to add the library MEMMGR.LIB to both the DLL project and
// any other projects that use the DLL. You will also need to use MEMMGR.LIB
// if any other projects which use the DLL will be performing new or delete
// operations on any non-TObject-derived classes which are exported from the
// DLL. Adding MEMMGR.LIB to your project will change the DLL and its calling
// EXE's to use the BORLNDMM.DLL as their memory manager. In these cases,
// the file BORLNDMM.DLL should be deployed along with your DLL.
//
// To avoid using BORLNDMM.DLL, pass string information using "char *" or
// ShortString parameters.
//
// If your DLL uses the dynamic version of the RTL, you do not need to
// explicitly add MEMMGR.LIB as this will be done implicitly for you
//---------------------------------------------------------------------------
#pragma argsused
HHOOK g_hHook;
HINSTANCE g_hinstDll;
FARPROC fpMessageBoxA;
HMODULE hModule ;
BYTE OldMessageBoxACode[5], NewMessageBoxACode[5];
DWORD dwIdOld, dwIdNew;
BOOL bHook = false;
void HookOn();
void HookOff();
BOOL Init();
int WINAPI MyMessageBoxA(HWND hWnd, LPCTSTR lpText, LPCTSTR lpCaption, UINT uType);
//---------------------------------------------------------------------------
// 空的鉤子函數(shù)
LRESULT WINAPI Hook(int nCode, WPARAM wParam, LPARAM lParam)
{
return(CallNextHookEx(g_hHook, nCode, wParam, lParam));
}
//---------------------------------------------------------------------------
// 輸出,安裝空的鉤子函數(shù)
extern "C" __declspec(dllexport) __stdcall
BOOL InstallHook()
{
g_hinstDll = LoadLibrary("project1.dll"); // 這里的文件名為Dll本身的文件名
g_hHook = SetWindowsHookEx(WH_GETMESSAGE, (HOOKPROC)Hook, g_hinstDll, 0);
if (!g_hHook)
{
MessageBoxA(NULL, "SET ERROR", "ERROR", MB_OK);
return(false);
}
return(true);
}
//---------------------------------------------------------------------------
本文一介紹第二種方法在Win2k下的使用。第二種方法，Win98/me 下因?yàn)檫M(jìn)入Ring0級(jí)的方法很多，有LDT,IDT,Vxd等方法，很容易在內(nèi)存中動(dòng)態(tài)修改代碼，但在Win2k下，這些方法都不能用，寫WDM太過復(fù)雜，表面上看來很難實(shí)現(xiàn)，其實(shí)不然。Win2k為我們提供了一個(gè)強(qiáng)大的內(nèi)存Api操作函數(shù)---VirtualProtectEx，WriteProcessMemeory,ReadProcessMemeory，有了它們我們就能在內(nèi)存中動(dòng)態(tài)修改代碼了，其原型為：
BOOL VirtualProtectEx(
HANDLE hProcess, // 要修改內(nèi)存的進(jìn)程句柄
LPVOID lpAddress, // 要修改內(nèi)存的起始地址
DWORD dwSize, // 修改內(nèi)存的字節(jié)
DWORD flNewProtect, // 修改后的內(nèi)存屬性
PDWORD lpflOldProtect // 修改前的內(nèi)存屬性的地址
);
BOOL WriteProcessMemory(
HANDLE hProcess, // 要寫進(jìn)程的句柄
LPVOID lpBaseAddress, // 寫內(nèi)存的起始地址
LPVOID lpBuffer, // 寫入數(shù)據(jù)的地址
DWORD nSize, // 要寫的字節(jié)數(shù)
LPDWORD lpNumberOfBytesWritten // 實(shí)際寫入的子節(jié)數(shù)
);
BOOL ReadProcessMemory(
HANDLE hProcess, // 要讀進(jìn)程的句柄
LPCVOID lpBaseAddress, // 讀內(nèi)存的起始地址
LPVOID lpBuffer, // 讀入數(shù)據(jù)的地址
DWORD nSize, // 要讀入的字節(jié)數(shù)
LPDWORD lpNumberOfBytesRead // 實(shí)際讀入的子節(jié)數(shù)
);
具體的參數(shù)請(qǐng)參看MSDN幫助。在Win2k下因?yàn)镈ll和所屬進(jìn)程在同一地址空間，這點(diǎn)又和Win9x/me存在所有進(jìn)程存在共享的地址空間不同，
因此，必須通過鉤子函數(shù)和遠(yuǎn)程注入進(jìn)程的方法，現(xiàn)以一個(gè)簡(jiǎn)單采用鉤子函數(shù)對(duì)MessageBoxA進(jìn)行攔截例子來說明：
其中Dll文件為：
//---------------------------------------------------------------------------
#include
//---------------------------------------------------------------------------
// Important note about DLL memory management when your DLL uses the
// static version of the RunTime Library:
//
// If your DLL exports any functions that pass String objects (or structs/
// classes containing nested Strings) as parameter or function results,
// you will need to add the library MEMMGR.LIB to both the DLL project and
// any other projects that use the DLL. You will also need to use MEMMGR.LIB
// if any other projects which use the DLL will be performing new or delete
// operations on any non-TObject-derived classes which are exported from the
// DLL. Adding MEMMGR.LIB to your project will change the DLL and its calling
// EXE's to use the BORLNDMM.DLL as their memory manager. In these cases,
// the file BORLNDMM.DLL should be deployed along with your DLL.
//
// To avoid using BORLNDMM.DLL, pass string information using "char *" or
// ShortString parameters.
//
// If your DLL uses the dynamic version of the RTL, you do not need to
// explicitly add MEMMGR.LIB as this will be done implicitly for you
//---------------------------------------------------------------------------
#pragma argsused
HHOOK g_hHook;
HINSTANCE g_hinstDll;
FARPROC fpMessageBoxA;
HMODULE hModule ;
BYTE OldMessageBoxACode[5], NewMessageBoxACode[5];
DWORD dwIdOld, dwIdNew;
BOOL bHook = false;
void HookOn();
void HookOff();
BOOL Init();
int WINAPI MyMessageBoxA(HWND hWnd, LPCTSTR lpText, LPCTSTR lpCaption, UINT uType);
//---------------------------------------------------------------------------
// 空的鉤子函數(shù)
LRESULT WINAPI Hook(int nCode, WPARAM wParam, LPARAM lParam)
{
return(CallNextHookEx(g_hHook, nCode, wParam, lParam));
}
//---------------------------------------------------------------------------
// 輸出,安裝空的鉤子函數(shù)
extern "C" __declspec(dllexport) __stdcall
BOOL InstallHook()
{
g_hinstDll = LoadLibrary("project1.dll"); // 這里的文件名為Dll本身的文件名
g_hHook = SetWindowsHookEx(WH_GETMESSAGE, (HOOKPROC)Hook, g_hinstDll, 0);
if (!g_hHook)
{
MessageBoxA(NULL, "SET ERROR", "ERROR", MB_OK);
return(false);
}
return(true);
}
//---------------------------------------------------------------------------