понедельник, 11 ноября 2013 г.

Расширение крайней секции PE файла

Пример техники расширения крайней секции исполняемого файла. Демонстрируются следующие фитчи:
- Растягивание последней секции и внесение в неё данных из файла
- Пересчёт PE checksum (IMAGE_OPTIONAL_HEADER.Checksum)
- Сдвиг оверлея
- Поддержка PE и PE+(x64)

TODO:
- Выравнивание согласно  IMAGE_OPTIONAL_HEADER.FileAligment

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// --------------------------------------------------------------
// This is example, how to inject data to the last PE section,
// supported PE and PE+(x64)
// by JKornev <c> http://k0rnev.blogspot.com
// --------------------------------------------------------------
#include <stdio.h>
#include <Windows.h>
#include <ImageHlp.h>

#pragma comment(lib, "ImageHlp")


UINT Aligment(UINT size, UINT aligm_base)
{
    UINT new_size = size;
    if (size % aligm_base != 0) {
        new_size += aligm_base - (size % aligm_base);
    }
    return new_size;
}

void OutputSection(PIMAGE_SECTION_HEADER psect)
{
    char name[IMAGE_SIZEOF_SHORT_NAME + 1] = {0};
    memcpy(name, psect->Name, IMAGE_SIZEOF_SHORT_NAME);
    printf(" Name:%s\n"
        " Virual adress: 0x%08X\n"
        " Virual size: 0x%08X\n"
        " Raw adress: 0x%08X\n"
        " Raw size: 0x%08X\n"
        " Characteristics: 0x%08X\n",
        name, psect->VirtualAddress, psect->Misc.VirtualSize, psect->PointerToRawData, 
        psect->SizeOfRawData, psect->Characteristics);
}

int main(int argc, char *argv[])
{
    enum { PE_DEFAULT_HEADER_SIZE = 0x400 };//usually PE header raw size is 0x400
    char *phead, *pdata, *poverl;
    HANDLE hfile, hfile2, hmap;
    DWORD readed, written, offset, pe_size, data_size, overl_size, 
        roffset, old_checksum, new_checksum;
    PIMAGE_DOS_HEADER pdos;
    PIMAGE_FILE_HEADER pimg;
    PIMAGE_SECTION_HEADER psect;
    PIMAGE_OPTIONAL_HEADER32 popt32;
    PIMAGE_OPTIONAL_HEADER64 popt64;
    PIMAGE_NT_HEADERS32 pnt32;
    PIMAGE_NT_HEADERS64 pnt64;
    BOOL is_x64, have_checksum;
    PVOID pview;
    
    if (argc < 3) {
        printf("Error, incorrect arguments!\n"
            "Format: inject.exe \"pe file name\" \"data file name\"\n");
        return 1;
    }

    // Read PE header
    phead = (char *)malloc(PE_DEFAULT_HEADER_SIZE);
    if (!phead) {
        printf("Error, can't allocate buffer!\n");
        return 1;
    }

    hfile = CreateFileA(argv[1], GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);
    if (hfile == INVALID_HANDLE_VALUE) {
        printf("Error, can't open PE file '%s'!\n", argv[1]);
        return 1;
    }

    pe_size = GetFileSize(hfile, NULL);
    
    if (!ReadFile(hfile, phead, PE_DEFAULT_HEADER_SIZE, &readed, NULL)) {
        printf("Error, reading PE file failed!\n");
        return 1;
    }

    // Check DOS header
    offset = 0;
    pdos = (PIMAGE_DOS_HEADER)phead;
    if (pdos->e_magic != IMAGE_DOS_SIGNATURE) {
        printf("Error, '%s' isn't PE file!\n", argv[1]);
        return 1;
    }
    offset = pdos->e_lfanew + sizeof(DWORD)/*PE signature*/;

    pimg = (PIMAGE_FILE_HEADER)(phead + offset);
    offset += sizeof(IMAGE_FILE_HEADER);

    // Check architecture
    if (pimg->Machine == IMAGE_FILE_MACHINE_I386) {
        is_x64 = FALSE;
        popt32 = (PIMAGE_OPTIONAL_HEADER32)(phead + offset);
        offset += sizeof(IMAGE_OPTIONAL_HEADER32);
    } else if (pimg->Machine == IMAGE_FILE_MACHINE_AMD64) {
        is_x64 = TRUE;
        popt64 = (PIMAGE_OPTIONAL_HEADER64)(phead + offset);
        offset += sizeof(IMAGE_OPTIONAL_HEADER64);
    } else {
        printf("Error, architecture not supported!\n");
        return 1;
    }

    // Get pointer to the last section
    psect = (PIMAGE_SECTION_HEADER)(phead + offset);
    psect = &psect[pimg->NumberOfSections - 1];
    if (!psect->SizeOfRawData) {
        //maybe this section contains uninitialized data
        printf("Error, can't resize last section!\n");
        return 1;
    }

    printf("Resizable section, before:\n");
    OutputSection(psect);

    // Unset 'discardable' flag
    if (psect->Characteristics & IMAGE_SCN_MEM_DISCARDABLE) {
        psect->Characteristics ^= IMAGE_SCN_MEM_DISCARDABLE;
    }

    // Read data
    hfile2 = CreateFileA(argv[2], GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
    if (hfile2 == INVALID_HANDLE_VALUE) {
        printf("Error, can't open data file '%s'!\n", argv[2]);
        return 1;
    }

    data_size = GetFileSize(hfile2, NULL);
    if (!data_size) {
        printf("Error, file '%s' is empty!\n", argv[2]);
        return 1;
    }

    pdata = (char *)malloc(data_size);
    if (!pdata) {
        printf("Error, can't allocate data buffer!\n");
        return 1;
    }

    if (!ReadFile(hfile2, pdata, data_size, &readed, NULL)) {
        printf("Error, reading data file failed!\n");
        return 1;
    }

    // Shift overlay
    roffset = psect->PointerToRawData + psect->SizeOfRawData;//raw(in file) offset to the end of last section data
    overl_size = pe_size - roffset;//calculate overlay size
    if (overl_size > 0) {
        poverl = (char *)malloc(overl_size);
        if (!poverl) {
            printf("Error, can't allocate temp buffer!\n");
            return 1;
        }

        SetFilePointer(hfile, roffset, 0, FILE_BEGIN);
        if (!ReadFile(hfile, poverl, overl_size, &readed, NULL)) {
            printf("Error, reading overlay failed!\n");
            return 1;
        }

        SetFilePointer(hfile, roffset + data_size, 0, FILE_BEGIN);
        if (!WriteFile(hfile, poverl, overl_size, &written, NULL)) {
            printf("Error, can't save overlay!\n");
            return 1;
        }
        free(poverl);
    }

    // Put data
    SetFilePointer(hfile, roffset, 0, FILE_BEGIN);
    if (!WriteFile(hfile, pdata, data_size, &written, NULL)) {
        printf("Error, can't save new data!\n");
        return 1;
    }

    // Change header info
    psect->SizeOfRawData += data_size;
    if (psect->SizeOfRawData > psect->Misc.VirtualSize) {
        if (is_x64) {
            //change size of image
            popt64->SizeOfImage += Aligment(psect->SizeOfRawData, popt64->SectionAlignment) - Aligment(psect->Misc.VirtualSize, popt64->SectionAlignment);
            //change section virtual size
            psect->Misc.VirtualSize = Aligment(psect->SizeOfRawData, popt64->SectionAlignment);
        } else {
            popt32->SizeOfImage += Aligment(psect->SizeOfRawData, popt32->SectionAlignment) - Aligment(psect->Misc.VirtualSize, popt32->SectionAlignment);
            psect->Misc.VirtualSize = Aligment(psect->SizeOfRawData, popt32->SectionAlignment);
        }
    }

    // Save header
    SetFilePointer(hfile, 0, 0, FILE_BEGIN);
    if (!WriteFile(hfile, phead, PE_DEFAULT_HEADER_SIZE, &written, NULL)) {
        printf("Error, can't save new header!\n");
        return 1;
    }
    FlushFileBuffers(hfile);

    // Recalculate checksum (optional feature)
    if (is_x64) {
        have_checksum = (popt64->CheckSum ? TRUE : FALSE);
    } else {
        have_checksum = (popt32->CheckSum ? TRUE : FALSE);
    }
    if (have_checksum) {
        hmap = CreateFileMapping(hfile, NULL, PAGE_READWRITE, 0, 0, NULL);
        pview = MapViewOfFile(hmap, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, 0);
        if (pview) {
            if (is_x64) {
                if (pnt64 = (PIMAGE_NT_HEADERS64)CheckSumMappedFile(pview, pe_size + data_size, &old_checksum, &new_checksum)) {
                    pnt64->OptionalHeader.CheckSum = new_checksum;
                } else {
                    printf("Warning, can't recalc header checksum!\n");
                }
            } else {
                if (pnt32 = (PIMAGE_NT_HEADERS32)CheckSumMappedFile(pview, pe_size + data_size, &old_checksum, &new_checksum)) {
                    pnt32->OptionalHeader.CheckSum = new_checksum;
                } else {
                    printf("Warning, can't recalc header checksum!\n");
                }
            }
            UnmapViewOfFile(pview);
        } else {
            printf("Warning, can't recalc header checksum!\n");
        }
        if (hmap) {
            CloseHandle(hmap);
        }
    }

    printf("\nResizable section, after:\n");
    OutputSection(psect);
    printf("Operation successful\n");

    free(pdata);
    free(phead);
    CloseHandle(hfile);
    CloseHandle(hfile2);
    return 0;
}

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