MemoryModule x86x64 内存加载DLL

by devseed，此篇教程同时发在论坛和我的博客上，完整源码见我的github。

0x0 前言

距离上次我写的SimpleDpack教程（为了理解加壳原理自己写的轻量级压缩壳），已经有一年多了。前几天修复x64的IAT载入序号问题，于是想着可以用这个原理自己重写一个解析PE和内存加载DLL的功能。虽然已有类似实现功能，如MemoryModule，但是这个项目还是有点复杂，模块间耦合度有些高，没法作为shellcode附加到EXE来引导DLL。

因此我决定重写一个低耦合，同时支持x86和x64，可以作为shellcode引导”附加到EXE区段上的DLL”的框架 。

0x1 MemoryModule 设计思路

(1) usage

本框架采取与windows加载DLL相似的名称来设计api，可以实现：

  • 将DLL按照内存对齐模式载入到内存中
  • 动态重定向DLL中的reloc地址，并载入IAT
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const char *dllpath = "test.dll";
size_t mempesize = 0;
void *memdll = NULL;

// load the pe file in memory and align it to memory align
void *mempe = winpe_memload_file(dllpath, &mempesize, TRUE); 

// memory loadlibrary
memdll = winpe_memLoadLibrary(mempe);
winpe_memFreeLibrary(memdll);

// memory loadlibrary at specific address
size_t targetaddr = sizeof(size_t) > 4 ? 0x140030000: 0x90000;
memdll = winpe_memLoadLibraryEx(mempe, targetaddr, 
    WINPE_LDFLAG_MEMALLOC, (PFN_LoadLibraryA)winpe_findloadlibrarya(), 
    (PFN_GetProcAddress)winpe_memGetProcAddress);
winpe_memFreeLibrary(memdll);
free(mempe);
  • 将DLL注入到EXE的附加区段，并且用shellcode引导该DLL
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win_injectmemdll.exe exepath dllpath [outpath]

(2) libwinpe.c

参考stb用XXX_IMPLEMENTATION宏控制代码实现，使得include单个头文件就能把模块功能全部引入的做法，有着单头文件结成非常容易实用的特点。于是我就用了一周多时间，自己写了个类似的低耦合单头文件winpe.h，用于解析与加载PE。为了便于shellcode引导，系统函数大多用函数指针传入参数，关键函数全部声明为inline。另外，我还用内联汇编写了从ldr中获取kernel32的基地址，从而减少对IAT硬编码的依赖。

libwinpe.c, 与libwinpe.def（引入def是因为stdcall编译后会被修改名称），把winpe.h的声明的导出函数编译为DLL，如下：

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#define WINPE_SHARED
#define WINPE_IMPLEMENTATION
#include "winpe.h"
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EXPORTS
    winpe_appendsecth
    winpe_findgetprocaddress
    winpe_findkernel32
    winpe_findloadlibrarya
    winpe_findspace
    winpe_findmodulea
    winpe_imagebaseval
    winpe_imagesizeval
    winpe_memFreeLibrary
    winpe_memFreeLibraryEx
    winpe_memGetProcAddress
    winpe_memLoadLibrary
    winpe_memLoadLibraryEx
    winpe_membindiat
    winpe_membindtls
    winpe_memfindexp
    winpe_memfindiat
    winpe_memforwardexp
    winpe_memload
    winpe_memload_file
    winpe_memreloc
    winpe_noaslr
    winpe_oepval
    winpe_overlayload_file
    winpe_overlayoffset

(3) win_injectmemdll.c

对于编写shellcode， 这里为了方便调试，采取用pyhton的keystone进行jit生成的机器码写入win_injectmemdll.c的全局变量里的做法， 如下：

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def inject_shellcodestubs(srcpath, libwinpepath, targetpath):
    pedll = lief.parse(libwinpepath)
    pedll_oph = pedll.optional_header

    # generate oepint shellcode
    if pedll_oph.magic == lief.PE.PE_TYPE.PE32_PLUS:
        oepinit_code = gen_oepinit_code64()
        pass
    elif pedll_oph.magic == lief.PE.PE_TYPE.PE32:
        oepinit_code = gen_oepinit_code32()
        pass
    else:
        print("error invalid pe magic!", pedll_oph.magic)
        return
    
    # find necessary functions
    FUNC_SIZE =0x400
    codes = {"winpe_memreloc": 0, 
        "winpe_membindiat": 0, 
        "winpe_membindtls": 0,
        "winpe_findloadlibrarya": 0, 
        "winpe_findgetprocaddress": 0}
    for k in codes.keys():
        func = next(filter(lambda e : e.name == k, 
            pedll.exported_functions))
        codes[k] = pedll.get_content_from_virtual_address(
            func.address, FUNC_SIZE)
    codes['winpe_oepinit'] = oepinit_code

    # write shellcode to c source file
    with open(srcpath, "rb") as fp:
        srctext = fp.read().decode('utf8')
    for k, v in codes.items():
        k = k.replace("winpe_", "")
        _codetext = ",".join([hex(x) for x in v])
        srctext = re.sub("g_" + k + r"_code(.+?)(\{0x90\})", 
            "g_" + k  +  r"_code\1{" + _codetext +"}", srctext)
    with open(targetpath, "wb") as fp:
        fp.write(srctext.encode('utf8'))

详见win_injectmemdll_shellcodestub.py

0x2 内存加载DLL

(1) windows dll加载机制

参考https://bbs.pediy.com/thread-252260.htm， windows对于加载DLL调用如下：

a) 当调用LoadLibrary时首先打开文件并将按照PE文件格式解析数据，并以IMAGE方式将PE各段内容

逐块映射到内存中,如果需要并修复重定位：

kernel32!LoadlibraryA

->kernel32!LoadLibraryExA

​ ->kernel32!LoadLibraryExW

​ ->ntdll!LdrLoadDll

​ ->ntdll!LdrpLoadDll

​ ->ntdll!LdrpMapDll

​ ->ntdll!LdrpCreateDllSection

​ ->ntdll!NtOpenFile //打开目标文件*

​ ->ntdll!NtCreateSection //创建映射*

​ ->ntdll!NtMapViewOfSection //映射*

​ ->LdrRelocateImageWithBias //修复重定位

b) 接着处理调入表等，然后调用TLS回调函数和DLLMAN入口函数；

kernel32!LoadlibraryA

->kernel32!LoadLibraryExA

->kernel32!LoadLibraryExW

​ ->ntdll!LdrLoadDll

​ ->ntdll!LdrpLoadDll

​ ->ntdll!LdrpMapDll

​ ->ntdll!LdrpWalkImportDescriptor //处理导入表等

​ ->LdrpRunInitializeRoutines //调用DLLMAN

​ ->LdrpCallTlsInitializers

​ ->LdrpCallInitRoutine

总结为如下流程：

  1. 载入DLL到内存上，将DLL进行memory align对齐
  2. 通过reloc段重定向硬编码地址
  3. 逐一扫码IAT表OFT的模块和函数名，加载对于模块，将地址填入FT中
  4. 调用DllMain函数（即DLL的OEP），fdwReason参数为DLL_PROCESS_ATTACH
  5. 初始化TLS, reason 为DLL_PROCESS_ATTACH

(2) 模拟Windows加载DLL

.1 载入DLL到内存上，将DLL进行memory align对齐

这里为了降低耦合，没有用系统的memset和memcpy，自己用inline实现的。

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inline size_t STDCALL winpe_memload(
    const void *rawpe, size_t rawsize, 
    void *mempe, size_t memsize, 
    bool_t same_align)
{
    // load rawpe to memalign
    PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER)rawpe;
    PIMAGE_NT_HEADERS  pNtHeader = (PIMAGE_NT_HEADERS)
        ((void*)rawpe + pDosHeader->e_lfanew);
    PIMAGE_FILE_HEADER pFileHeader = &pNtHeader->FileHeader;
    PIMAGE_OPTIONAL_HEADER pOptHeader = &pNtHeader->OptionalHeader;
    PIMAGE_SECTION_HEADER pSectHeader = (PIMAGE_SECTION_HEADER)
        ((void *)pOptHeader + pFileHeader->SizeOfOptionalHeader);
    WORD sectNum = pFileHeader->NumberOfSections;
    size_t imagesize = pOptHeader->SizeOfImage;
    if(!mempe) return imagesize;
    else if(memsize!=0 && memsize<imagesize) return 0;

    _inl_memset(mempe, 0, imagesize);
    _inl_memcpy(mempe, rawpe, pOptHeader->SizeOfHeaders);
    
    for(WORD i=0;i<sectNum;i++)
    {
        _inl_memcpy(mempe+pSectHeader[i].VirtualAddress, 
            rawpe+pSectHeader[i].PointerToRawData,
            pSectHeader[i].SizeOfRawData);
    }

    // adjust all to mem align
    if(same_align)
    {
        pDosHeader = (PIMAGE_DOS_HEADER)mempe;
        pNtHeader = (PIMAGE_NT_HEADERS)((void*)mempe + pDosHeader->e_lfanew);
        pFileHeader = &pNtHeader->FileHeader;
        pOptHeader = &pNtHeader->OptionalHeader;
        pSectHeader = (PIMAGE_SECTION_HEADER)
            ((void *)pOptHeader + pFileHeader->SizeOfOptionalHeader);
        sectNum = pFileHeader->NumberOfSections;

        pOptHeader->FileAlignment = pOptHeader->SectionAlignment;

        for(WORD i=0;i<sectNum;i++)
        {
            pSectHeader[i].PointerToRawData = pSectHeader[i].VirtualAddress;
        }
    }
    return imagesize;
}

.2 通过reloc段重定向硬编码地址

手动将以imagebase为基准的va重定向到目标imagebase的va。

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inline size_t STDCALL winpe_memreloc(
    void *mempe, size_t newimagebase)
{
    PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER)mempe;
    PIMAGE_NT_HEADERS  pNtHeader = (PIMAGE_NT_HEADERS)
        ((void*)mempe + pDosHeader->e_lfanew);
    PIMAGE_FILE_HEADER pFileHeader = &pNtHeader->FileHeader;
    PIMAGE_OPTIONAL_HEADER pOptHeader = &pNtHeader->OptionalHeader;
    PIMAGE_DATA_DIRECTORY pDataDirectory = pOptHeader->DataDirectory;
    PIMAGE_DATA_DIRECTORY pRelocEntry = &pDataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC];
	
    DWORD reloc_count = 0;
	DWORD reloc_offset = 0;
    int64_t shift = (int64_t)newimagebase - 
        (int64_t)pOptHeader->ImageBase;
	while (reloc_offset < pRelocEntry->Size)
	{
		PIMAGE_BASE_RELOCATION pBaseReloc = (PIMAGE_BASE_RELOCATION)
            ((void*)mempe + pRelocEntry->VirtualAddress + reloc_offset);
        PRELOCOFFSET pRelocOffset = (PRELOCOFFSET)((void*)pBaseReloc 
            + sizeof(IMAGE_BASE_RELOCATION));
        // RELOCOFFSET block num
		DWORD item_num = (pBaseReloc->SizeOfBlock - 
			sizeof(IMAGE_BASE_RELOCATION)) / sizeof(RELOCOFFSET);
		for (size_t i = 0; i < item_num; i++)
		{
			if (!pRelocOffset[i].type && 
                !pRelocOffset[i].offset) continue;
			DWORD targetoffset = pBaseReloc->VirtualAddress + 
                    pRelocOffset[i].offset;
            size_t *paddr = (size_t *)((void*)mempe + targetoffset);
            size_t relocaddr = (size_t)((int64_t)*paddr + shift);
            *paddr = relocaddr;
		}
		reloc_offset += sizeof(IMAGE_BASE_RELOCATION) + 
            sizeof(RELOCOFFSET) * item_num;
		reloc_count += item_num;
	}
    pOptHeader->ImageBase = newimagebase;
	return reloc_count;
}

.3 逐一扫码IAT表OFT的模块和函数名，加载对于模块，将地址填入FT中

用LoadLibraryA和GetProcAddress实现，考虑到shellcode，不能直接调用，应该通过传入函数指针调用。

另外还要考虑OFT中会出现用序号的情况，x86和x64判断表中不同，用sizeof(size_t)区分。

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WINPEDEF WINPE_EXPORT 
inline size_t STDCALL winpe_membindiat(void *mempe, 
    PFN_LoadLibraryA pfnLoadLibraryA, 
    PFN_GetProcAddress pfnGetProcAddress)
{
    PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER)mempe;
    PIMAGE_NT_HEADERS  pNtHeader = (PIMAGE_NT_HEADERS)
        ((void*)mempe + pDosHeader->e_lfanew);
    PIMAGE_FILE_HEADER pFileHeader = &pNtHeader->FileHeader;
    PIMAGE_OPTIONAL_HEADER pOptHeader = &pNtHeader->OptionalHeader;
    PIMAGE_DATA_DIRECTORY pDataDirectory = pOptHeader->DataDirectory;
    PIMAGE_DATA_DIRECTORY pImpEntry =  
        &pDataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT];
    PIMAGE_IMPORT_DESCRIPTOR pImpDescriptor =  
        (PIMAGE_IMPORT_DESCRIPTOR)(mempe + pImpEntry->VirtualAddress);

    PIMAGE_THUNK_DATA pFtThunk = NULL;
    PIMAGE_THUNK_DATA pOftThunk = NULL;
    LPCSTR pDllName = NULL;
    PIMAGE_IMPORT_BY_NAME pImpByName = NULL;
    size_t funcva = 0;
    char *funcname = NULL;

    // origin GetProcAddress will crash at InitializeSListHead 
    if(!pfnLoadLibraryA) pfnLoadLibraryA = 
        (PFN_LoadLibraryA)winpe_findloadlibrarya();
    if(!pfnGetProcAddress) pfnGetProcAddress = 
        (PFN_GetProcAddress)winpe_findgetprocaddress();

    DWORD iat_count = 0;
    for (; pImpDescriptor->Name; pImpDescriptor++) 
    {
        pDllName = (LPCSTR)(mempe + pImpDescriptor->Name);
        pFtThunk = (PIMAGE_THUNK_DATA)
            (mempe + pImpDescriptor->FirstThunk);
        pOftThunk = (PIMAGE_THUNK_DATA)
            (mempe + pImpDescriptor->OriginalFirstThunk);
        size_t dllbase = (size_t)pfnLoadLibraryA(pDllName);
        if(!dllbase) return 0;

        for (int j=0; pFtThunk[j].u1.Function 
            &&  pOftThunk[j].u1.Function; j++) 
        {
            size_t _addr = (size_t)(mempe + pOftThunk[j].u1.AddressOfData);
            if(sizeof(size_t)>4) // x64
            {
                if((_addr>>63) == 1)
                {
                    funcname = (char *)(_addr & 0xffff);
                }
                else
                {
                    pImpByName=(PIMAGE_IMPORT_BY_NAME)_addr;
                    funcname = pImpByName->Name;
                }
            }
            else
            {
                if(((size_t)pImpByName>>31) == 1)
                {
                    funcname = (char *)(_addr & 0xffff);
                }
                else
                {
                    pImpByName=(PIMAGE_IMPORT_BY_NAME)_addr;
                    funcname = pImpByName->Name;
                }
            }

            funcva = (size_t)pfnGetProcAddress(
                (HMODULE)dllbase, funcname);
            if(!funcva) continue;
            pFtThunk[j].u1.Function = funcva;
            assert(funcva == (size_t)GetProcAddress(
                (HMODULE)dllbase, funcname));
            iat_count++;
        }
    }
    return iat_count;
}

.4 调用DllMain函数（即DLL的OEP），fdwReason参数为DLL_PROCESS_ATTACH

前三步都完成后可以来通过DllMain来引导了。

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// initial memory module
if(!winpe_memreloc((void*)imagebase, imagebase))
    return NULL;
if(!winpe_membindiat((void*)imagebase, 
    pfnLoadLibraryA, pfnGetProcAddress)) return NULL;
winpe_membindtls(mempe, DLL_PROCESS_ATTACH);
PFN_DllMain pfnDllMain = (PFN_DllMain)
    (imagebase + winpe_oepval((void*)imagebase, 0));
pfnDllMain((HINSTANCE)imagebase, DLL_PROCESS_ATTACH, NULL);
return (void*)imagebase;

.5 初始化TLS, reason 为DLL_PROCESS_ATTACH

这部分我没有找到有TLS的DLL，所以没法进一步测试了。这部分代码直接借鉴的MemoryModule的相关函数。

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inline size_t STDCALL winpe_membindtls(void *mempe, DWORD resaon)
{
    PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER)mempe;
    PIMAGE_NT_HEADERS  pNtHeader = (PIMAGE_NT_HEADERS)
        ((void*)mempe + pDosHeader->e_lfanew);
    PIMAGE_FILE_HEADER pFileHeader = &pNtHeader->FileHeader;
    PIMAGE_OPTIONAL_HEADER pOptHeader = &pNtHeader->OptionalHeader;
    PIMAGE_DATA_DIRECTORY pDataDirectory = pOptHeader->DataDirectory;
    PIMAGE_DATA_DIRECTORY pTlsDirectory = 
        &pDataDirectory[IMAGE_DIRECTORY_ENTRY_TLS];
    if(!pTlsDirectory->VirtualAddress) return 0;

    size_t tls_count = 0;
    PIMAGE_TLS_DIRECTORY pTlsEntry = (PIMAGE_TLS_DIRECTORY)
        (mempe + pTlsDirectory->VirtualAddress);
    PIMAGE_TLS_CALLBACK *tlscb= (PIMAGE_TLS_CALLBACK*)
        pTlsEntry->AddressOfCallBacks;
    if(tlscb)
    {
        while(*tlscb)
        {
            (*tlscb)(mempe, reason, NULL);
            tlscb++;
            tls_count++;
        }
    }
    return tls_count;
}

0x3 DLL附加到EXE区段与shellcode编写

(1) EXE区段扩容

首先需要修改exe的区段头，在后面增加一个区段。这里要特别注意区段的对齐，之后还要修正SizeOfImage。

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inline size_t STDCALL winpe_appendsecth(void *pe, 
    PIMAGE_SECTION_HEADER psecth)
{
    PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER)pe;
    PIMAGE_NT_HEADERS  pNtHeader = (PIMAGE_NT_HEADERS)
        ((void*)pe + pDosHeader->e_lfanew);
    PIMAGE_FILE_HEADER pFileHeader = &pNtHeader->FileHeader;
    PIMAGE_OPTIONAL_HEADER pOptHeader = &pNtHeader->OptionalHeader;
    PIMAGE_SECTION_HEADER pSectHeader = (PIMAGE_SECTION_HEADER)
        ((void*)pOptHeader + pFileHeader->SizeOfOptionalHeader);
    WORD sectNum = pFileHeader->NumberOfSections;
    PIMAGE_SECTION_HEADER pLastSectHeader = &pSectHeader[sectNum-1];
    DWORD addr, align;

    // check the space to append section
    if(pFileHeader->SizeOfOptionalHeader 
        + sizeof(IMAGE_SECTION_HEADER)
     > pSectHeader[0].PointerToRawData) return 0;

    // fill rva addr
    align = pOptHeader->SectionAlignment;
    addr = pLastSectHeader->VirtualAddress + pLastSectHeader->Misc.VirtualSize;
    if(addr % align) addr += align - addr%align;
    psecth->VirtualAddress = addr;

    // fill file offset
    align = pOptHeader->FileAlignment;
    addr =  pLastSectHeader->PointerToRawData+ pLastSectHeader->SizeOfRawData;
    if(addr % align) addr += align - addr%align;
    psecth->PointerToRawData = addr;

    // adjust the section and imagesize 
    pFileHeader->NumberOfSections++;
    _inl_memcpy(&pSectHeader[sectNum], psecth, sizeof(IMAGE_SECTION_HEADER));
    align = pOptHeader->SectionAlignment;
    addr = psecth->VirtualAddress + psecth->Misc.VirtualSize;
    if(addr % align) addr += align - addr%align;
    pOptHeader->SizeOfImage = addr; 
    return pOptHeader->SizeOfImage;
}

(2) 引导DLL的shellcode编写

这部分内容和winpe_memLoadLibrary函数实现的方式类似，只不过要用汇编来写shellcode，引导完成后跳转到原来exe的oep。 关键地址可以先留空，在注入时候填入对位置。对于相应的函数的shellcode，由win_injectmemdll_shellcodestub.py读取对应的libpe32.dll函数，填入对应的全局变量。下面代码以x86为例：

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def gen_oepinit_code32():
    ks = Ks(KS_ARCH_X86, KS_MODE_32)
    code_str = f"""
    // for relative address, get the base of addr
    call getip; 
    lea ebx, [eax-5];
    
    // get the imagebase
    mov eax, 0x30; // to avoid relative addressing
    mov edi, dword ptr fs:[eax]; //peb
    mov edi, [edi + 0ch]; //ldr
    mov edi, [edi + 14h]; //InMemoryOrderLoadList, this
    mov edi, [edi -8h + 18h]; //this.DllBase
    
    // get loadlibrarya, getprocaddress
    mov eax, [ebx + findloadlibrarya];
    add eax, edi;
    call eax;
    mov [ebx + findloadlibrarya], eax;
    mov eax, [ebx + findgetprocaddress];
    add eax, edi;
    call eax;
    mov [ebx + findgetprocaddress], eax;
    
    // reloc
    mov eax, [ebx + dllrva];
    add eax, edi;
    push eax;
    push eax;
    mov eax, [ebx + memrelocrva];
    add eax, edi;
    call eax;
    
    // bind iat
    mov eax, [ebx + findgetprocaddress]; 
    push eax; // arg3, getprocaddress
    mov eax, [ebx + findloadlibrarya]; 
    push eax; // arg2, loadlibraryas
    mov eax, [ebx + dllrva]; 
    add eax, edi; 
    push eax; // arg1, dllbase value
    mov eax, [ebx + membindiatrva];
    add eax, edi
    call eax;
    
    // bind tls
    xor eax, eax;
    inc eax; 
    push eax; // arg2, reason for tls
    mov eax, [ebx + dllrva] 
    add eax, edi; 
    push eax; // arg1, dllbase
    mov eax, [ebx + membindtlsrva];
    add eax, edi;
    call eax;
    
    // call dll oep, for dll entry
    xor eax, eax; 
    push eax; // lpvReserved
    inc eax; 
    push eax; // fdwReason, DLL_PROCESS_ATTACH
    mov eax, [ebx + dllrva]; 
    add eax, edi; 
    push eax; // hinstDLL
    mov eax, [ebx + dlloeprva];
    add eax, edi; 
    call eax;
    
    // jmp to origin oep
    mov eax, [ebx+exeoeprva];
    add eax, edi;
    jmp eax;
    getip:
    mov eax, [esp]
    ret
    exeoeprva: nop;nop;nop;nop;
    dllrva: nop;nop;nop;nop;
    dlloeprva: nop;nop;nop;nop;
    memrelocrva: nop;nop;nop;nop;
    membindiatrva: nop;nop;nop;nop;
    membindtlsrva: nop;nop;nop;nop;
    findloadlibrarya: nop;nop;nop;nop;
    findgetprocaddress: nop;nop;nop;nop;
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// these functions are stub function, will be filled by python
#define FUNC_SIZE 0x400
#define SHELLCODE_SIZE 0X2000
unsigned char g_oepinit_code[] = {0x90};
unsigned char g_memreloc_code[] = {0x90};
unsigned char g_membindiat_code[] = {0x90};
unsigned char g_membindtls_code[] = {0x90};
unsigned char g_findloadlibrarya_code[] = {0x90};
unsigned char g_findgetprocaddress_code[] = {0x90};

void _makeoepcode(void *shellcode, 
    size_t shellcoderva, size_t dllrva, 
    DWORD orgexeoeprva, DWORD orgdlloeprva)
{
    // bind the pointer to buffer
    size_t oepinit_end = sizeof(g_oepinit_code);
    size_t memreloc_start = FUNC_SIZE;
    size_t membindiat_start = memreloc_start + FUNC_SIZE;
    size_t membindtls_start = membindiat_start + FUNC_SIZE;
    size_t findloadlibrarya_start = membindtls_start + FUNC_SIZE;
    size_t findgetprocaddress_start = findloadlibrarya_start + FUNC_SIZE;

     // fill the address table
    size_t *pexeoeprva = (size_t*)(g_oepinit_code + oepinit_end - 8*sizeof(size_t));
    size_t *pdllbrva = (size_t*)(g_oepinit_code + oepinit_end - 7*sizeof(size_t));
    size_t *pdlloeprva = (size_t*)(g_oepinit_code + oepinit_end - 6*sizeof(size_t));
    size_t *pmemrelocrva = (size_t*)(g_oepinit_code + oepinit_end - 5*sizeof(size_t));
    size_t *pmembindiatrva = (size_t*)(g_oepinit_code + oepinit_end - 4*sizeof(size_t));
    size_t *pmembindtlsrva = (size_t*)(g_oepinit_code + oepinit_end - 3*sizeof(size_t));
    size_t *pfindloadlibrarya = (size_t*)(g_oepinit_code + oepinit_end - 2*sizeof(size_t));
    size_t *pfindgetprocaddress = (size_t*)(g_oepinit_code + oepinit_end - 1*sizeof(size_t));
    *pexeoeprva = orgexeoeprva;
    *pdllbrva =  dllrva;
    *pdlloeprva = dllrva + orgdlloeprva;
    *pmemrelocrva = shellcoderva + memreloc_start;
    *pmembindiatrva = shellcoderva + membindiat_start;
    *pmembindtlsrva = shellcoderva + membindtls_start;
    *pfindloadlibrarya = shellcoderva + findloadlibrarya_start;
    *pfindgetprocaddress = shellcoderva + findgetprocaddress_start;

    // copy to the target
    memcpy(shellcode , 
        g_oepinit_code, sizeof(g_oepinit_code));
    memcpy(shellcode + memreloc_start, 
        g_memreloc_code, sizeof(g_memreloc_code));
    memcpy(shellcode + membindiat_start, 
        g_membindiat_code, sizeof(g_membindiat_code));
    memcpy(shellcode + membindtls_start, 
        g_membindtls_code, sizeof(g_membindtls_code));
    memcpy(shellcode + findloadlibrarya_start, 
        g_findloadlibrarya_code, sizeof(g_findloadlibrarya_code));
    memcpy(shellcode + findgetprocaddress_start, 
        g_findgetprocaddress_code, sizeof(g_findgetprocaddress_code));
}

0x4 技巧tips

(1) x64适配

由于大部分都用的size_t或void*等与cpu字长相关的变量，大部分代码不用修改就能编译。

其余的差异部分，可以用sizeof(size_t)>4区分，或者_WIN64宏。如下所示

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// append section header to exe
size_t align = sizeof(size_t) > 4 ? 0x10000: 0x1000; 
size_t padding = _sectpaddingsize(mempe_exe, mempe_dll, align);
secth.Characteristics = IMAGE_SCN_MEM_READ | 
    IMAGE_SCN_MEM_WRITE | IMAGE_SCN_MEM_EXECUTE;
secth.Misc.VirtualSize = SHELLCODE_SIZE + padding + mempe_dllsize;
secth.SizeOfRawData = SHELLCODE_SIZE + padding + mempe_dllsize;
strcpy((char*)secth.Name, ".module");
winpe_noaslr(mempe_exe);
winpe_appendsecth(mempe_exe, &secth);
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inline void* winpe_findkernel32()
{
    // return (void*)LoadLibrary("kernel32.dll");
    // TEB->PEB->Ldr->InMemoryOrderLoadList->curProgram->ntdll->kernel32
    void *kerenl32 = NULL;
#ifdef _WIN64
    __asm{
        mov rax, gs:[60h]; peb
        mov rax, [rax+18h]; ldr
        mov rax, [rax+20h]; InMemoryOrderLoadList, currentProgramEntry
        mov rax, [rax]; ntdllEntry, currentProgramEntry->->Flink
        mov rax, [rax]; kernel32Entry,  ntdllEntry->Flink
        mov rax, [rax-10h+30h]; kernel32.DllBase
        mov kerenl32, rax;
    }
#else
    __asm{
        mov eax, fs:[30h]; peb
        mov eax, [eax+0ch]; ldr
        mov eax, [eax+14h]; InMemoryOrderLoadList, currentProgramEntry
        mov eax, [eax]; ntdllEntry, currentProgramEntry->->Flink
        mov eax, [eax]; kernel32Entry,  ntdllEntry->Flink
        mov eax, [eax - 8h +18h]; kernel32.DllBase
        mov kerenl32, eax;
    }
#endif
    return kerenl32;
}

(2) 扫描export找到LoadLibrary和GetProcAddress

上面的代码我们可以获取kernel32的基址了，之后可以自己通过扫描export表来查找对应的导出函数了。

这里注意有个坑点，有的导出表项会forward到其他dll上，如kernel32!InitializeSListHead -> NTDLL!RtlInitializeSListHead，详见crashing-kernel32-initializeslisthead。通过DirRVA < FuncRVA < DirRVA + ExportSize来判断是否forward。

此处为了找到LoadLibraryA和GetProcAddress函数，不考虑forward情况，否则会引入递归问题。

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inline void* STDCALL winpe_memfindexp(
    void *mempe, LPCSTR funcname)
{
    PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER)mempe;
    PIMAGE_NT_HEADERS  pNtHeader = (PIMAGE_NT_HEADERS)
        ((void*)mempe + pDosHeader->e_lfanew);
    PIMAGE_FILE_HEADER pFileHeader = &pNtHeader->FileHeader;
    PIMAGE_OPTIONAL_HEADER pOptHeader = &pNtHeader->OptionalHeader;
    PIMAGE_DATA_DIRECTORY pDataDirectory = pOptHeader->DataDirectory;
    PIMAGE_DATA_DIRECTORY pExpEntry =  
        &pDataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT];
    PIMAGE_EXPORT_DIRECTORY  pExpDescriptor =  
        (PIMAGE_EXPORT_DIRECTORY)(mempe + pExpEntry->VirtualAddress);

    WORD *ordrva = mempe + pExpDescriptor->AddressOfNameOrdinals;
    DWORD *namerva = mempe + pExpDescriptor->AddressOfNames;
    DWORD *funcrva = mempe + pExpDescriptor->AddressOfFunctions;
    if((size_t)funcname <= MAXWORD) // find by ordnial
    {
        WORD ordbase = LOWORD(pExpDescriptor->Base) - 1;
        WORD funcord = LOWORD(funcname);
        return (void*)(mempe + funcrva[ordrva[funcord-ordbase]]);
    }
    else
    {
        for(int i=0;i<pExpDescriptor->NumberOfNames;i++)
        {
            LPCSTR curname = (LPCSTR)(mempe+namerva[i]);
            if(_inl_stricmp(curname, funcname)==0)
            {
                return (void*)(mempe + funcrva[ordrva[i]]);
            }       
        }
    }
    return NULL;
}

inline PROC winpe_findloadlibrarya()
{
    // return (PROC)LoadLibraryA;
    HMODULE hmod_kernel32 = (HMODULE)winpe_findkernel32();
    char name_LoadLibraryA[] = {'L', 'o', 'a', 'd', 'L', 'i', 'b', 'r', 'a', 'r', 'y', 'A', '\0'};
    return (PROC)winpe_memfindexp( // suppose exp no forward, to avoid recursive
        (void*)hmod_kernel32, name_LoadLibraryA);
}

inline PROC winpe_findgetprocaddress()
{
    // return (PROC)GetProcAddress;
    HMODULE hmod_kernel32 = (HMODULE)winpe_findkernel32();
    char name_GetProcAddress[] = {'G', 'e', 't', 'P', 'r', 'o', 'c', 'A', 'd', 'd', 'r', 'e', 's', 's', '\0'};
    return (PROC)winpe_memfindexp(hmod_kernel32, name_GetProcAddress);
}

0x5 后记

本项目是我实现不加壳vfs（即通过hook nt函数将文件和文件夹等读取重定向到zip文件中）的衍生产物，采取的是尽量单头文件法和内联函数减小耦合，方便集成到代码中的做法。与其他的MemoryModule最大的区别是支持从shellcode引导DLL。由于以前我有了自己写压缩壳的经验，整体上处理起来还算是顺利。强迫症，感觉好多时间都花在了怎么统一化命名api和代码风格规范上了。至于实现内存加载Resource方面，暂时不考虑实现，汉化游戏一般也用不到这方面内容。

另外，这里还有个坑卡了我好长时间，就是x64的堆栈必须要0x10对齐（即调用函数时要sub rsp, 0x28预留空间与对齐），才能在movaps指令上不报错。之前一直不知道这条指令需要对齐，一直以为是少了哪些初始化，走偏了好久。特别感谢@YeLikERs指出了这一点，同时在PEB，LDR相关内容上帮助了很多。

经测试兼容性还算不错，windows xp, windows 7, windows 10, windows 11测试example文件都通过了，甚至我连linux上的wine也测试了（即用我汉化的游戏测试shellcode引导附加到exe区段上的DLL）。最后，附上几张测试图：

memdll_x86winetestmemdll_x64test