IAT hook
一丶IAT
1.什麼是 IAT表.
熟悉PE結構的應該知道.IAT 是匯入表.
其IAT表如下:
typedef struct _IMAGE_IMPORT_DESCRIPTOR {
union {
DWORD Characteristics;
DWORD OriginalFirstThunk; 指向INT表 4個位元組一組.是RVA指向名字跟序號
} DUMMYUNIONNAME;
DWORD TimeDateStamp;
DWORD ForwarderChain;
DWORD Name;
DWORD FirstThunk; 在檔案中跟INT表一樣.這是IAT
} IMAGE_IMPORT_DESCRIPTOR;
typedef IMAGE_IMPORT_DESCRIPTOR UNALIGNED *PIMAGE_IMPORT_DESCRIPTOR;
我們知道PE有兩種狀態.第一種.在檔案中的狀態. 所以才有 VA 轉 FOA等等的互相轉換.
扯多了.
在檔案狀態. IAT表(firstThunk)跟 INT表一樣.都是指向一個很大的表.這個表裡面是4個位元組進行儲存.儲存的是Rva. 這些RVA分別指向 匯入序號以及以0結尾的字串.
如果在記憶體狀態.則INT表跟上面說的檔案狀態一樣指向 匯入序號.以及匯入的函式名字.
而IAT此時不同了.IAT此時就是儲存著INT指向的匯入函式的地址了.
如果還不理解.看下以前關於IAT部落格.
https://www.cnblogs.com/iBinary/p/9740757.html
如下圖所示:
其實IAT就是儲存函式地址.
2.怎麼進行HOOK
熟悉了IAT 那麼HOOK就很簡單了.首先你要會解析PE.
原理就是:
1.編寫DLL.注入到你想HOOK的程式中.
2.編寫DLL,DLL裡面獲取你HOOK程式的 ImageBase以及各種頭(DOS,NT,FILE,OPT)
3.DLL 裡面通過OPT的資料目錄第一項.得到匯入表RVA.加上ImageBase定位到匯入表
4.迴圈遍歷匯入表.匯入表是一行04個位元組.最後一項為0
5.通過匯入表找到IAT表.繼續遍歷IAT表.
6.判斷IAT中的函式地址,是否是你要進行HOOK的函式地址.
是: 則進行替換函式地址.比如替換為你的.一定要注入呼叫約定.
不是: 繼續迴圈.
在IAT表中沒找到.說明沒在這個匯入表中.匯入表+1(一個匯入表結構大小)
繼續迴圈 4 5 6步.
說的比較複雜,其實原理很簡單.
首先第一步.準備一個測試程式.測試程式呼叫MessageBoxA.
且載入我們的DLL(當然你編寫的DLL一般是注入的別的程式中.我這裡演示就直接載入自己進行HOOK自己).
測試程式如下:
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
int main()
{
getchar();
::MessageBoxA(NULL, "沒有HOOK", NULL, NULL);
LoadLibrary("IAThook.dll"); //載入HOOK的DLL
getchar();
//HOOK後進行測試的程式.
__asm
{
push 0
push 0
push 0
push 0
call dword ptr ds : [MessageBoxA] ;
}
__asm
{
push 0
push 0
push 0
push 0
call dword ptr ds : [MessageBoxA] ;
}
__asm
{
push 0
push 0
push 0
push 0
call dword ptr ds : [MessageBoxA] ;
}
}上面的內斂彙編是因為我自己HOOK自己了可以.但是都在第一次呼叫MessageBox函式的時候編譯器會儲存這個MessageBox函式的地址.就算我HOOK完畢了.它再次呼叫還是呼叫的以前的.所以我先改成下面這樣.
HOOK的DLL
// dllmain.cpp : 定義 DLL 應用程式的入口點。
#include "framework.h"
#include <windows.h>
//建立相同函式指標.
typedef int (WINAPI *PfnMsgA)(
_In_opt_ HWND hWnd,
_In_opt_ LPCSTR lpText,
_In_opt_ LPCSTR lpCaption,
_In_ UINT uType);
PfnMsgA g_OldPfnMsgA = nullptr;
int WINAPI MyMessageBox(_In_opt_ HWND hWnd,_In_opt_ LPCSTR lpText,_In_opt_ LPCSTR lpCaption,_In_ UINT uType)
{
char szHookText[] = "IBinary -> Iat Hook";
if (g_OldPfnMsgA != nullptr)
{
return g_OldPfnMsgA(hWnd, szHookText, lpCaption, uType);//呼叫以前的
}
return 0;
}
void SetIatHook()
{
MessageBoxA(NULL, "開始進行HOOK", NULL, NULL);
PVOID pHookAddress = nullptr;
pHookAddress = GetProcAddress(GetModuleHandleA("user32.dll"), "MessageBoxA"); //你要HOOK的函式.
if (nullptr == pHookAddress)
{
OutputDebugString(TEXT("獲取函式地址失敗"));
MessageBoxA(NULL, "獲取函式地址失敗HOOK", NULL, NULL);
return;
}
g_OldPfnMsgA =(PfnMsgA) pHookAddress; //儲存舊的函式指標.
//解析PE頭.尋找IAT.
HMODULE hModImageBase = GetModuleHandle(NULL);//獲取當前的ImagBase
PIMAGE_DOS_HEADER pDosHead =(PIMAGE_DOS_HEADER)(DWORD)hModImageBase; //獲取DOS頭
DWORD dwTemp = (DWORD)pDosHead + (DWORD)pDosHead->e_lfanew;
PIMAGE_NT_HEADERS pNtHead = (PIMAGE_NT_HEADERS)dwTemp;
PIMAGE_FILE_HEADER pFileHead = (PIMAGE_FILE_HEADER)& pNtHead->FileHeader;
PIMAGE_OPTIONAL_HEADER pOptHead = (PIMAGE_OPTIONAL_HEADER)& pNtHead->OptionalHeader;
//尋找匯出表的位置.
DWORD dwExportLocal = pOptHead->DataDirectory[1].VirtualAddress; //找到匯出表偏移.
//定位到匯出表
dwTemp = (DWORD)GetModuleHandle(NULL) + dwExportLocal;
PIMAGE_IMPORT_DESCRIPTOR pImport = (PIMAGE_IMPORT_DESCRIPTOR)dwTemp;
PIMAGE_IMPORT_DESCRIPTOR pCurrent = pImport;
DWORD *pFirstThunk; //匯入表子表,也就是IAT儲存函式地址的表.
//遍歷匯入表
while (pCurrent->Characteristics && pCurrent->FirstThunk != NULL)
{
dwTemp = pCurrent->FirstThunk + (DWORD)GetModuleHandle(NULL);//找到匯入表
pFirstThunk = (DWORD *)dwTemp; //加上偏移才是真正的匯入表.
while (*(DWORD*)pFirstThunk != NULL)
{
//遍歷子表
if (*(DWORD*)pFirstThunk == (DWORD)g_OldPfnMsgA)
{
//找到要修改的匯入表了//修改記憶體保護屬性.寫入我們新的函式地址.
DWORD oldProtected;
VirtualProtect(pFirstThunk,0x1000, PAGE_EXECUTE_READWRITE,&oldProtected);
dwTemp = (DWORD)MyMessageBox;
memcpy(pFirstThunk, (DWORD *)&dwTemp,4); //將變數中儲存的函式地址拷貝到匯入表中.
VirtualProtect(pFirstThunk,0x1000,oldProtected,&oldProtected);
}
pFirstThunk++; //繼續遍歷.
}
pCurrent++; //每次是加一個匯入表結構.
}
}
void UnIatHook()
{
/*
1.遍歷匯入表.恢復匯入表即可.
*/
MessageBoxA(NULL, "開始進行HOOK", NULL, NULL);
PVOID pHookAddress = nullptr;
pHookAddress = MyMessageBox;
if (nullptr == pHookAddress)
{
OutputDebugString(TEXT("獲取函式地址失敗"));
MessageBoxA(NULL, "恢復函式地址失敗HOOK", NULL, NULL);
return;
}
//解析PE頭.尋找IAT.
HMODULE hModImageBase = GetModuleHandle(NULL);//獲取當前的ImagBase
PIMAGE_DOS_HEADER pDosHead = (PIMAGE_DOS_HEADER)(DWORD)hModImageBase; //獲取DOS頭
DWORD dwTemp = (DWORD)pDosHead + (DWORD)pDosHead->e_lfanew;
PIMAGE_NT_HEADERS pNtHead = (PIMAGE_NT_HEADERS)dwTemp;
PIMAGE_FILE_HEADER pFileHead = (PIMAGE_FILE_HEADER)& pNtHead->FileHeader;
PIMAGE_OPTIONAL_HEADER pOptHead = (PIMAGE_OPTIONAL_HEADER)& pNtHead->OptionalHeader;
//尋找匯出表的位置.
DWORD dwExportLocal = pOptHead->DataDirectory[1].VirtualAddress; //找到匯出表偏移.
//定位到匯出表
dwTemp = (DWORD)GetModuleHandle(NULL) + dwExportLocal;
PIMAGE_IMPORT_DESCRIPTOR pImport = (PIMAGE_IMPORT_DESCRIPTOR)dwTemp;
PIMAGE_IMPORT_DESCRIPTOR pCurrent = pImport;
DWORD* pFirstThunk; //匯入表子表
//遍歷匯入表
while (pCurrent->Characteristics && pCurrent->FirstThunk != NULL)
{
dwTemp = pCurrent->FirstThunk + (DWORD)GetModuleHandle(NULL);
pFirstThunk = (DWORD*)dwTemp; //加上偏移才是真正的匯入表.
while (*(DWORD*)pFirstThunk != NULL)
{
//遍歷子表
if (*(DWORD*)pFirstThunk == (DWORD)MyMessageBox) //如果是我們的函式地址.則進行恢復.
{
//找到要修改的匯入表了//修改記憶體保護屬性.寫入我們新的函式地址.
DWORD oldProtected;
VirtualProtect(pFirstThunk, 0x1000, PAGE_EXECUTE_READWRITE, &oldProtected);
dwTemp = (DWORD)GetProcAddress(GetModuleHandleA("user32.dll"), "MessageBoxA");
memcpy(pFirstThunk, (DWORD*)& dwTemp, 4); //將變數中儲存的函式地址拷貝到匯入表中.
VirtualProtect(pFirstThunk, 0x1000, oldProtected, &oldProtected);
}
pFirstThunk++; //繼續遍歷.
}
pCurrent++; //每次是加一個匯入表結構.
}
}
BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
SetIatHook();
break;
case DLL_THREAD_ATTACH:
break;
case DLL_THREAD_DETACH:
break;
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}
測試程式碼如下:
