PE file - what's missing?

Question

I'm trying to generate an executable in PE format - Windows 7, 64 bit, initially a minimal file for testing purposes that does nothing more than

mov eax, 42
ret

I've got one that dumpbin seems happy with and contains apparently valid values for all the fields the various sources I can find say are actually used, but when I try to run it, Windows says 'not a valid Win32 application'. dumpbin output follows; can anyone see from this what I'm missing?

Dump of file a.exe

PE signature found

File Type: EXECUTABLE IMAGE

FILE HEADER VALUES
            8664 machine (x64)
               1 number of sections
               0 time date stamp Thu Jan 01 00:00:00 1970
               0 file pointer to symbol table
               0 number of symbols
              F0 size of optional header
              22 characteristics
                   Executable
                   Application can handle large (>2GB) addresses

OPTIONAL HEADER VALUES
             20B magic # (PE32+)
            2.05 linker version
               0 size of code
               0 size of initialized data
               0 size of uninitialized data
            1000 entry point (0000000140001000)
               0 base of code
       140000000 image base (0000000140000000 to 0000000140000FFF)
            1000 section alignment
             200 file alignment
            0.00 operating system version
            0.00 image version
            4.00 subsystem version
               0 Win32 version
            1000 size of image
             200 size of headers
               0 checksum
               3 subsystem (Windows CUI)
            8100 DLL characteristics
                   NX compatible
                   Terminal Server Aware
          100000 size of stack reserve
            1000 size of stack commit
          100000 size of heap reserve
            1000 size of heap commit
               0 loader flags
              10 number of directories
               0 [       0] RVA [size] of Export Directory
               0 [       0] RVA [size] of Import Directory
               0 [       0] RVA [size] of Resource Directory
               0 [       0] RVA [size] of Exception Directory
               0 [       0] RVA [size] of Certificates Directory
               0 [       0] RVA [size] of Base Relocation Directory
               0 [       0] RVA [size] of Debug Directory
               0 [       0] RVA [size] of Architecture Directory
               0 [       0] RVA [size] of Global Pointer Directory
               0 [       0] RVA [size] of Thread Storage Directory
               0 [       0] RVA [size] of Load Configuration Directory
               0 [       0] RVA [size] of Bound Import Directory
               0 [       0] RVA [size] of Import Address Table Directory
               0 [       0] RVA [size] of Delay Import Directory
               0 [       0] RVA [size] of COM Descriptor Directory
               0 [       0] RVA [size] of Reserved Directory


SECTION HEADER #1
   .text name
       6 virtual size
    1000 virtual address (0000000140001000 to 0000000140001005)
     200 size of raw data
     200 file pointer to raw data (00000200 to 000003FF)
       0 file pointer to relocation table
       0 file pointer to line numbers
       0 number of relocations
       0 number of line numbers
60000020 flags
         Code
         Execute Read

RAW DATA #1
  0000000140001000: B8 2A 00 00 00 C3                                ©*...+

  Summary

        1000 .text

Answer 1

Your "size of image" covers only the header area; the .text section and the entry point lies outside of it. Set it to at least 1006 and the file should work.

---

How I found it:

1. Made a minimal C program:

   int entry() { return 42; }

2. Compiled it without libraries and with custom entry:

   cl test.cpp /link /nodefaultlib /entry:entry /subsystem:console

3. Started editing the header to match your listing, and run the exe after each change. Once I changed the SizeOfImage to 1000, I got the "not a valid Win32 application" message.

Answer 2

I can't tell by looking at your dumpbin output but there's an excellent utility, CFF Explorer that you can use to inspect pretty much every detail of PE files. It's interactive and shows the various tables and you can also edit most of the values on the fly to experiment with it.

I found it easier in the past to compare values to the PE specs in CFF Explorer than using dumpbin.