Hacking the World with HTML

In my previous article Exploring the MS-DOS Stub I stated that after experimenting, the Windows loader only cares about the e_magic and the e_lfanew members from the _IMAGE_DOS_HEADER. Because the rest of the members of the DOS header is used by MS-DOS to execute the stub program. Check it out if you have not.

If you take a PE file and null out the MS-DOS header and the MS-DOS stub program leaving out the e_magic and the e_lfanew values, the PE will still work fine as the rest is not needed by the Windows PE loader. The e_lfanew address at offset 0x3c is important as it points to the beginning of the _IMAGE_NT_HEADERS structure which is the actual start of the PE file.

Since those values are not important we can insert an HTML comment from offset 0x2 which is the e_cblp value and begin an HTML comment and end the comment at the end of the PE and append our HTML/PHP/ASP/JSP file contents.

I wrote a simple program in C to automate this task. You can provide your PE file and the HTML/PHP/ASP/JSP file to inject and it will generate an HTML file. You can rename the file into the extension you desire.

Exploring the MS-DOS Stub

A long time ago when I got my first computer, I accidentally opened a 32-bit demo with a nice chiptune inside MS-DOS and it worked. I was surprised by how this happens. I was curious to find out how this works behind the scenes. Back in the time I was a little kid and had no clue about programming. This curiosity leads me to discover amazing things I never imagined.
First, let us have a look at the PE header. It starts with the MS-DOS header and contains a 16-bit MS-DOS executable (stub program).

(source: https://commons.wikimedia.org/wiki/File:Portable_Executable_32_bit_Structure.png)

Converting an EXE to a DLL

I’ve been doing some crazy experiments on running an EXE as a DLL. Here are some parts of my research.

Case #1

Let’s take a simple example like a MessageBox.

After compiling to an EXE we have to change the characteristics under NT Header->File Header to a DLL file. I will use the value 0x2000 | 0x2| 0x100 = 0x2102.