Code shows the example how to use external modules on-the-fly WITHOUT imports table.

The code does the following steps:

1. Finds out the KERNEL32.DLL base (see versions below),
2. finds out export table at KERNEL32.DLL module space (kernel32!ExportTable),
3. finds out the entry point of GetProcAddress in kernel32!ExportTable directly (in memory),
4. calls GetProcAddress to get entry point of LoadLibraryA routine,
5. calls LoadLibraryA and GetProcAddress to import desired module and symbols.

• 1536 bytes,
• 2 sections (code and data),
• NO imports table and other data directories,
• uses THREAD ENVIRONMENT BLOCK (TEB) to get KERNEL32.DLL base,
• reads entry point of GetAddressProc() directly from KERNEL32 exports,
• then calls it to get entry of LoadLibraryA() routine.

• 1536 bytes,
• 2 sections (code and data),
• NO imports table and other data directories,
• uses RETURN ADDRESS to get KERNEL32.DLL base,
• reads entry point of GetAddressProc() directly from KERNEL32 exports,
• then calls it to get entry of LoadLibraryA() routine.

• 268 bytes,
• no sections,
• NO imports table and other data directories,
• SIZE-OPTIMIZED to fits within 268 bytes,
• uses RETURN ADDRESS to get KERNEL32.DLL base,
• reads entry point of GetAddressProc() directly from KERNEL32 exports,
• then calls it to get entry of LoadLibraryA() routine.

• We assume that entry point in our application is called directly by KERNEL32.DLL,
• so the return address on app start-up should points somwhere in-the-middle of KERNEL32.DLL module,
• we scan memory pointed by return address backward until we found something, which looks like the PE header.

• GS register points to the Thread Environment Block (TEB) on x86-64 Windows (https://en.wikipedia.org/wiki/Win32_Thread_Information_Block),
• We search TEB.PEB.LoaderData.Modules for 'kernel32.dll' entry.

• Code works on x86-64 only (PE32+),
• Minimal version is size-optimized to fit wihin 268 bytes, due to this, literals are stored in the unused PE parts, which are not neccesery to run a program, but some disassemblers or debuggers may fail to load the file.

Based on codes samples from:

• https://stackoverflow.com/a/32820799
• https://hero.handmade.network/forums/code-discussion/t/129-howto_-_building_without_import_libraries
• https://stackoverflow.com/a/45528159