我正在尝试使用 C 解析 PE 文件。导入解析很好,但导出解析有问题。这是我为了解析导出而编写的代码:
void PrintExports(DWORD imageBase) {
// Get the export section.
PIMAGE_DOS_HEADER ptrDosHeader = (PIMAGE_DOS_HEADER)imageBase;
PIMAGE_NT_HEADERS32 ptrNtHeaders = (PIMAGE_NT_HEADERS32)(ptrDosHeader->e_lfanew + imageBase);
DWORD exportsStartRVA = ptrNtHeaders->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress;
DWORD exportsEndRVA = exportsStartRVA + ptrNtHeaders->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].Size;
PIMAGE_SECTION_HEADER ptrExportsHeader = GetSectionHeaderByRVA(exportsStartRVA, ptrNtHeaders);
// Check it's not null..
if (!ptrExportsHeader)
return;
PIMAGE_EXPORT_DIRECTORY ptrExportsDirectory = (PIMAGE_EXPORT_DIRECTORY)(imageBase + exportsStartRVA );
printf("Exports\n");
printf(" Exports.section: %s\n", ptrExportsHeader->Name);
printf(" Exports.ordinalBase: %x\n", ptrExportsDirectory->Base);
printf(" Exports.NumberOfFunctions: %x (hex)\n", ptrExportsDirectory->NumberOfFunctions);
printf(" Exports.NumberOfNames: %x (hex)\n", ptrExportsDirectory->NumberOfNames);
PDWORD ptrExportsFunctions = (PDWORD)((DWORD)ptrExportsDirectory->AddressOfFunctions + imageBase);
PDWORD ptrExportsNamesOrdinals = (PDWORD)((DWORD)ptrExportsDirectory->AddressOfNameOrdinals + imageBase);
PDWORD * ptrExportsNames = (PDWORD *)((DWORD)ptrExportsDirectory->AddressOfNames + imageBase);
printf(" Exports.functions:\n");
printf(" EntryPoint Ordinal Name\n");
for (int i = 0; i < ptrExportsDirectory->NumberOfFunctions; i++) {
if (ptrExportsFunctions[i] == 0)
continue;
printf(" %010x %07x", ptrExportsFunctions[i], i + ptrExportsDirectory->Base);
if ((ptrExportsFunctions[i] >= exportsStartRVA) && (ptrExportsFunctions[i] <= exportsEndRVA))
printf(" (forwarder -> %s)", ptrExportsFunctions[i] + imageBase);
printf("\n");
}
return;
}
作为运行此代码的结果,我获得了导出的序号和地址。当我尝试使用下面的代码获取名称时,问题就开始了(此代码应该在“for”循环内)。发生的情况是我得到了访问冲突异常(我在这个例子中试图解析的 PE 是 shell32.dll):
for (int j = 0; j < ptrExportsDirectory->NumberOfNames; j++) {
if (ptrExportsNamesOrdinals[j] == i + ptrExportsDirectory->Base) {
printf(" %s", ptrExportsNames[j]);
}
}
此外,在某些情况下(例如,如果我尝试解析的 PE 是 user32.dll),ptrExportsNamesOrdinal[j] 的值永远不会等于i + ptrExportsDirectory->Base。你可以看到下面的截图:
我做了什么来修复它:
PDWORD ptrExportsFunctions = (PDWORD)(imageBase + ptrExportsDirectory->AddressOfFunctions);
PDWORD ptrExportsNames = (PDWORD)(imageBase + ptrExportsDirectory->AddressOfNames);
PWORD ptrExportsNamesOrdinals = (PWORD)(imageBase + ptrExportsDirectory->AddressOfNameOrdinals);
而不是在循环中:
for (DWORD j = 0; j < ptrExportsDirectory->NumberOfNames; j++)
{
if(ptrExportsNamesOrdinals[j] == i){
printf("%s", (char*)imageBase + ptrExportsNames[j]);
}
}
现在一切正常。
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