It looks like all EXE files begin with MZ when they are opened in ASCII mode, is there an ASCII identified for vbs, com and bat files as well? i can't seem to find a pattern...
Or maybe there's another way to identify them? aside from just the extension...
TrID seems to have a "standalone" application you could probably use and pass the file in and read the contents out and see what file it is. It prides itself on the ability to pass it a generic file (extension or without) and it uses the headers of the file to discover what file type it actually is.
See if this tutorial is helpful (How to detect the types of executable files 3 part series). He has even presented a step by step algorithm on how to do this.
Also see this post: How to determine if a file is executable?
No, not really (Windows executables can have PE or PK at the beginning instead of MZ - see this for other possible formats).
For other types of files, there are certain heuristics you can use (e.g. GIF files start with "GIF89", Bash shell scripts usually start with #!/bin/bash, BAT files often execute @echo off at the beginning, VBS scripts use apostrophe at the start of line as a comment marker), but they aren't always 100% reliable (a file can be both a BAT script and a Bash shell script; or a file that's both a valid ZIP archive and a valid GIF image (like that stegosaurus image), for example).
See e.g. this article for further reading.
