How to open Windows .sys files? Keyboard Drivers Configuration

Question

I'm trying to configure my keyboard drivers files on a Windows Server 2008 (Virtualbox), in order to understand how it is made.

Why? To solve this problem : How to enable Alt Gr or Alt keys on a Telnet Server

The file I want to open is for example kbdclass.sys. When I open it with Notepad ++ , I have this : http://image.noelshack.com/fichiers/2019/31/2/1564474290-kbdsys.jpg

I've been looking for some softwares on Internet, but I didn't find anything that opened my file. I know it is discouraged to touch to these files, but I need to understand how it works, because I don't see any other solutions to my problem.

Do you know how I could open it?

Answer 1

Drivers are exactly like .exe or .dll files; they contain instructions for the CPU. They do not contain text that you could directly edit. They were originally compiled from text, i.e. C source code, but only Microsoft has the original sources for Windows files and they are not public.

If all you have is the compiled executable file but not its original source code, the tools you could use are either a "hex editor" (which merely shows the bytes that are already there) or a "disassembler" (which translates the CPU instructions to textual assembly language) or a "decompiler" (which tries to translate the CPU instructions into something resembling C source code).

(While .exe/.dll files aren't limited to just code and can have attached "resources" such as images or text, which could be browsed using ResHacker, you won't find any of that in a kernel driver.)

Finally, note that kbdclass.sys deals with keyboard devices, and Telnet servers completely bypass that. They don't pretend that they're receiving physical keypresses; they mostly just receive already processed text.