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.
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