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ImportRebuilder.cpp
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ImportRebuilder.cpp
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#include "ImportRebuilder.h"
#include "Scylla.h"
#include "StringConversion.h"
//#define DEBUG_COMMENTS
bool ImportRebuilder::rebuildImportTable(const WCHAR * newFilePath, std::map<DWORD_PTR, ImportModuleThunk> & moduleList)
{
bool retValue = false;
if (isValidPeFile())
{
if (readPeSectionsFromFile())
{
setDefaultFileAlignment();
retValue = buildNewImportTable(moduleList);
if (retValue)
{
alignAllSectionHeaders();
fixPeHeader();
if (newIatInSection)
{
patchFileForNewIatLocation();
}
retValue = savePeFileToDisk(newFilePath);
}
}
}
return retValue;
}
bool ImportRebuilder::buildNewImportTable(std::map<DWORD_PTR, ImportModuleThunk> & moduleList)
{
createNewImportSection(moduleList);
importSectionIndex = listPeSection.size() - 1;
if (newIatInSection)
{
changeIatBaseAddress(moduleList);
}
DWORD dwSize = fillImportSection(moduleList);
if (!dwSize)
{
return false;
}
setFlagToIATSection((*moduleList.begin()).second.firstThunk);
DWORD vaImportAddress = listPeSection[importSectionIndex].sectionHeader.VirtualAddress;
if (useOFT)
{
//OFT array is at the beginning of the import section
vaImportAddress += (DWORD)sizeOfOFTArray;
}
if (newIatInSection)
{
vaImportAddress += (DWORD)IatSize;
}
if (isPE32())
{
pNTHeader32->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress = vaImportAddress;
pNTHeader32->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].Size = (DWORD)(numberOfImportDescriptors * sizeof(IMAGE_IMPORT_DESCRIPTOR));
}
else
{
pNTHeader64->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress = vaImportAddress;
pNTHeader64->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].Size = (DWORD)(numberOfImportDescriptors * sizeof(IMAGE_IMPORT_DESCRIPTOR));
}
return true;
}
bool ImportRebuilder::createNewImportSection(std::map<DWORD_PTR, ImportModuleThunk> & moduleList)
{
char sectionName[IMAGE_SIZEOF_SHORT_NAME + 1] = {0};
const WCHAR * sectionNameW = Scylla::config[IAT_SECTION_NAME].getString();
calculateImportSizes(moduleList);
if (wcslen(sectionNameW) > IMAGE_SIZEOF_SHORT_NAME)
{
strcpy_s(sectionName, ".SCY");
}
else
{
StringConversion::ToASCII(sectionNameW, sectionName, _countof(sectionName));
}
if (newIatInSection)
{
sizeOfImportSection += IatSize;
}
return addNewLastSection(sectionName, (DWORD)sizeOfImportSection, 0);
}
void ImportRebuilder::setFlagToIATSection(DWORD_PTR iatAddress)
{
for (size_t i = 0; i < listPeSection.size(); i++)
{
if ((listPeSection[i].sectionHeader.VirtualAddress <= iatAddress) && ((listPeSection[i].sectionHeader.VirtualAddress + listPeSection[i].sectionHeader.Misc.VirtualSize) > iatAddress))
{
//section must be read and writeable
listPeSection[i].sectionHeader.Characteristics |= IMAGE_SCN_MEM_READ|IMAGE_SCN_MEM_WRITE;
}
}
}
DWORD ImportRebuilder::fillImportSection(std::map<DWORD_PTR, ImportModuleThunk> & moduleList)
{
std::map<DWORD_PTR, ImportModuleThunk>::iterator mapIt;
std::map<DWORD_PTR, ImportThunk>::iterator mapIt2;
PIMAGE_IMPORT_DESCRIPTOR pImportDesc = 0;
PIMAGE_IMPORT_BY_NAME pImportByName = 0;
PIMAGE_THUNK_DATA pThunk = 0;
ImportModuleThunk * importModuleThunk = 0;
ImportThunk * importThunk = 0;
size_t stringLength = 0;
DWORD_PTR lastRVA = 0;
BYTE * sectionData = listPeSection[importSectionIndex].data;
DWORD offset = 0;
DWORD offsetOFTArray = 0;
if (useOFT)
{
//OFT Array is always at the beginning of the import section
offset = (DWORD)sizeOfOFTArray; //size includes null termination
}
if (newIatInSection)
{
offset += IatSize; //new iat at the beginning
}
pImportDescriptor = (PIMAGE_IMPORT_DESCRIPTOR)((DWORD_PTR)sectionData + offset);
//skip the IMAGE_IMPORT_DESCRIPTOR
offset += (DWORD)(numberOfImportDescriptors * sizeof(IMAGE_IMPORT_DESCRIPTOR));
for ( mapIt = moduleList.begin() ; mapIt != moduleList.end(); mapIt++ )
{
importModuleThunk = &((*mapIt).second);
stringLength = addImportDescriptor(importModuleThunk, offset, offsetOFTArray);
#ifdef DEBUG_COMMENTS
Scylla::debugLog.log(L"fillImportSection :: importDesc.Name %X", pImportDescriptor->Name);
#endif
offset += (DWORD)stringLength; //stringLength has null termination char
pImportByName = (PIMAGE_IMPORT_BY_NAME)((DWORD_PTR)sectionData + offset);
//pThunk = (PIMAGE_THUNK_DATA)(getMemoryPointerFromRVA(importModuleThunk->firstThunk));
lastRVA = importModuleThunk->firstThunk - sizeof(DWORD_PTR);
for ( mapIt2 = (*mapIt).second.thunkList.begin() ; mapIt2 != (*mapIt).second.thunkList.end(); mapIt2++ )
{
importThunk = &((*mapIt2).second);
if (useOFT)
{
//OFT Array is always at the beginning of the import section
pThunk = (PIMAGE_THUNK_DATA)((DWORD_PTR)sectionData + offsetOFTArray);
offsetOFTArray += sizeof(DWORD_PTR); //increase OFT array index
}
else
{
pThunk = (PIMAGE_THUNK_DATA)(getMemoryPointerFromRVA(importThunk->rva));
}
//check wrong iat pointer
if (!pThunk)
{
#ifdef DEBUG_COMMENTS
Scylla::debugLog.log(L"fillImportSection :: Failed to get pThunk RVA: %X", importThunk->rva);
#endif
return 0;
}
if ((lastRVA + sizeof(DWORD_PTR)) != importThunk->rva)
{
//add additional import desc
addSpecialImportDescriptor(importThunk->rva, offsetOFTArray);
if (useOFT)
{
pThunk = (PIMAGE_THUNK_DATA)((DWORD_PTR)sectionData + offsetOFTArray);
offsetOFTArray += sizeof(DWORD_PTR); //increase OFT array index, next module
}
}
lastRVA = importThunk->rva;
#ifdef DEBUG_COMMENTS
Scylla::debugLog.log(L"fillImportSection :: importThunk %X pThunk %X pImportByName %X offset %X", importThunk,pThunk,pImportByName,offset);
#endif
stringLength = addImportToImportTable(importThunk, pThunk, pImportByName, offset);
offset += (DWORD)stringLength; //is 0 bei import by ordinal
pImportByName = (PIMAGE_IMPORT_BY_NAME)((DWORD_PTR)pImportByName + stringLength);
}
offsetOFTArray += sizeof(DWORD_PTR); //increase OFT array index, next module
pImportDescriptor++;
}
return offset;
}
size_t ImportRebuilder::addImportDescriptor(ImportModuleThunk * pImportModule, DWORD sectionOffset, DWORD sectionOffsetOFTArray)
{
char dllName[MAX_PATH];
StringConversion::ToASCII(pImportModule->moduleName, dllName, _countof(dllName));
size_t stringLength = strlen(dllName) + 1;
/*
Warning: stringLength MUST include null termination char
*/
memcpy((listPeSection[importSectionIndex].data + sectionOffset), dllName, stringLength); //copy module name to section
pImportDescriptor->FirstThunk = (DWORD)pImportModule->firstThunk;
pImportDescriptor->Name = (DWORD)convertOffsetToRVAVector(listPeSection[importSectionIndex].sectionHeader.PointerToRawData + sectionOffset);
if (useOFT)
{
pImportDescriptor->OriginalFirstThunk = (DWORD)convertOffsetToRVAVector(listPeSection[importSectionIndex].sectionHeader.PointerToRawData + sectionOffsetOFTArray);
}
return stringLength;
}
void ImportRebuilder::addSpecialImportDescriptor(DWORD_PTR rvaFirstThunk, DWORD sectionOffsetOFTArray)
{
PIMAGE_IMPORT_DESCRIPTOR oldID = pImportDescriptor;
pImportDescriptor++;
pImportDescriptor->FirstThunk = (DWORD)rvaFirstThunk;
pImportDescriptor->Name = oldID->Name;
if (useOFT)
{
pImportDescriptor->OriginalFirstThunk = (DWORD)convertOffsetToRVAVector(listPeSection[importSectionIndex].sectionHeader.PointerToRawData + sectionOffsetOFTArray);
}
}
void ImportRebuilder::calculateImportSizes(std::map<DWORD_PTR, ImportModuleThunk> & moduleList)
{
std::map<DWORD_PTR, ImportModuleThunk>::iterator mapIt;
std::map<DWORD_PTR, ImportThunk>::iterator mapIt2;
DWORD_PTR lastRVA = 0;
sizeOfImportSection = 0;
sizeOfApiAndModuleNames = 0;
sizeOfOFTArray = 0;
numberOfImportDescriptors = moduleList.size() + 1; //last is zero'd
for ( mapIt = moduleList.begin() ; mapIt != moduleList.end(); mapIt++ )
{
lastRVA = (*mapIt).second.firstThunk - sizeof(DWORD_PTR);
sizeOfApiAndModuleNames += (DWORD)(wcslen((*mapIt).second.moduleName) + 1);
for ( mapIt2 = (*mapIt).second.thunkList.begin() ; mapIt2 != (*mapIt).second.thunkList.end(); mapIt2++ )
{
if ((lastRVA + sizeof(DWORD_PTR)) != (*mapIt2).second.rva)
{
numberOfImportDescriptors++; //add additional import desc
sizeOfOFTArray += sizeof(DWORD_PTR) + sizeof(DWORD_PTR);
}
if((*mapIt2).second.name[0] != '\0')
{
sizeOfApiAndModuleNames += sizeof(WORD); //Hint from IMAGE_IMPORT_BY_NAME
sizeOfApiAndModuleNames += (DWORD)(strlen((*mapIt2).second.name) + 1);
}
//OriginalFirstThunk Array in Import Section: value
sizeOfOFTArray += sizeof(DWORD_PTR);
lastRVA = (*mapIt2).second.rva;
}
//OriginalFirstThunk Array in Import Section: NULL termination
sizeOfOFTArray += sizeof(DWORD_PTR);
}
sizeOfImportSection = sizeOfOFTArray + sizeOfApiAndModuleNames + (numberOfImportDescriptors * sizeof(IMAGE_IMPORT_DESCRIPTOR));
}
size_t ImportRebuilder::addImportToImportTable( ImportThunk * pImport, PIMAGE_THUNK_DATA pThunk, PIMAGE_IMPORT_BY_NAME pImportByName, DWORD sectionOffset)
{
size_t stringLength = 0;
if(pImport->name[0] == '\0')
{
pThunk->u1.AddressOfData = (IMAGE_ORDINAL(pImport->ordinal) | IMAGE_ORDINAL_FLAG);
}
else
{
pImportByName->Hint = pImport->hint;
stringLength = strlen(pImport->name) + 1;
memcpy(pImportByName->Name, pImport->name, stringLength);
pThunk->u1.AddressOfData = convertOffsetToRVAVector(listPeSection[importSectionIndex].sectionHeader.PointerToRawData + sectionOffset);
if (!pThunk->u1.AddressOfData)
{
#ifdef DEBUG_COMMENTS
Scylla::debugLog.log(L"addImportToImportTable :: failed to get AddressOfData %X %X", listPeSection[importSectionIndex].sectionHeader.PointerToRawData, sectionOffset);
#endif
}
//next import should be nulled
pThunk++;
pThunk->u1.AddressOfData = 0;
#ifdef DEBUG_COMMENTS
Scylla::debugLog.log(L"addImportToImportTable :: pThunk->u1.AddressOfData %X %X %X", pThunk->u1.AddressOfData, pThunk, listPeSection[importSectionIndex].sectionHeader.PointerToRawData + sectionOffset);
#endif
stringLength += sizeof(WORD);
}
return stringLength;
}
BYTE * ImportRebuilder::getMemoryPointerFromRVA(DWORD_PTR dwRVA)
{
int peSectionIndex = convertRVAToOffsetVectorIndex(dwRVA);
if (peSectionIndex == -1)
{
return 0;
}
DWORD rvaPointer = ((DWORD)dwRVA - listPeSection[peSectionIndex].sectionHeader.VirtualAddress);
DWORD minSectionSize = rvaPointer + (sizeof(DWORD_PTR) * 2); //add space for 1 IAT address
if (listPeSection[peSectionIndex].data == 0 || listPeSection[peSectionIndex].dataSize == 0)
{
listPeSection[peSectionIndex].dataSize = minSectionSize;
listPeSection[peSectionIndex].normalSize = minSectionSize;
listPeSection[peSectionIndex].data = new BYTE[listPeSection[peSectionIndex].dataSize];
listPeSection[peSectionIndex].sectionHeader.SizeOfRawData = listPeSection[peSectionIndex].dataSize;
}
else if(listPeSection[peSectionIndex].dataSize < minSectionSize)
{
BYTE * temp = new BYTE[minSectionSize];
memcpy(temp, listPeSection[peSectionIndex].data, listPeSection[peSectionIndex].dataSize);
delete [] listPeSection[peSectionIndex].data;
listPeSection[peSectionIndex].data = temp;
listPeSection[peSectionIndex].dataSize = minSectionSize;
listPeSection[peSectionIndex].normalSize = minSectionSize;
listPeSection[peSectionIndex].sectionHeader.SizeOfRawData = listPeSection[peSectionIndex].dataSize;
}
return (BYTE *)((DWORD_PTR)listPeSection[peSectionIndex].data + rvaPointer);
}
void ImportRebuilder::enableOFTSupport()
{
useOFT = true;
}
void ImportRebuilder::enableNewIatInSection(DWORD_PTR iatAddress, DWORD iatSize)
{
newIatInSection = true;
IatAddress = iatAddress;
IatSize = iatSize;
iatRefScan.ScanForDirectImports = false;
iatRefScan.ScanForNormalImports = true;
iatRefScan.startScan(ProcessAccessHelp::targetImageBase, (DWORD)ProcessAccessHelp::targetSizeOfImage, IatAddress, IatSize);
}
void ImportRebuilder::patchFileForNewIatLocation()
{
iatRefScan.patchNewIat(getStandardImagebase(), listPeSection[importSectionIndex].sectionHeader.VirtualAddress, (PeParser *)this);
}
void ImportRebuilder::changeIatBaseAddress( std::map<DWORD_PTR, ImportModuleThunk> & moduleList )
{
std::map<DWORD_PTR, ImportModuleThunk>::iterator mapIt;
std::map<DWORD_PTR, ImportThunk>::iterator mapIt2;
DWORD_PTR oldIatRva = IatAddress - ProcessAccessHelp::targetImageBase;
for ( mapIt = moduleList.begin() ; mapIt != moduleList.end(); mapIt++ )
{
(*mapIt).second.firstThunk = (*mapIt).second.firstThunk - oldIatRva + listPeSection[importSectionIndex].sectionHeader.VirtualAddress;
for ( mapIt2 = (*mapIt).second.thunkList.begin() ; mapIt2 != (*mapIt).second.thunkList.end(); mapIt2++ )
{
(*mapIt2).second.rva = (*mapIt2).second.rva - oldIatRva + listPeSection[importSectionIndex].sectionHeader.VirtualAddress;
}
}
}

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