Off topic - Modding .exe (sisx)

hello guys, Im just wondering if is there a way that I can decompile the exe file of a Symbian file extension(sisx), its a file on Nokia phone, it can be an application or game, I unpacked the sisx file, I messed up with HxD editing the exe file, and when I pack back the files, and install the sisx to a phone, it never run.

Can someone give some advice? Decompiling exe or efficient way of using HxD.

Thank you!

Theres really no easy way to do that, thats why its called closed source, but there is some possibilities.

I belive you can "decompile" .exe's with a disassembler. It wont break it down into a high level language like C++. instead you'll end up with assembler code. Assembler code is very low level and difficult to work with in large programs, and it also might not work in your specific case. There could be some sort of protection built into the phone to stop it from being modded, cause if I was a company I wouldn't want other companies reverse engineering my work.

also, this is all from a poor memory of an operating system I no longer use, so some of that could be inaccurate.

thank you stealth for the response, Im able to change some strings with HxD, but when I packed the sisx files, and have it install in a phone, it wont open, do I have to preserve the byte in that exe? How?

Correct me if I'm wrong, but generally when a Hex editor is being used, the modified executable must contain an equal amount of bytes as the original executable. If not, the executable file won't be able to run properly. I'm not an expert when it comes to reverse engineering, but I've experienced this problem several times when I first began using a Hex Editor. Hope this helps. ^_^

KVk, thank you for that info, can you post a link for a tutorial for the correct way of preserving the bytes using hex editor? Maybe there's a workaround in doing the editing.

You don't need a tutorial in order to be able to inject null values. Just replace overwritten bytes '00'. This should help in byte preservation.

—Before— markup4D 61 72 79 20

—After— markup4D 61 72 79 00

As I said before, I'm not an expert, so this may or may not be your problem, but if you are disregarding file size, it probably is.

If after this, you still want that tutorial… http://www.flexhex.com/docs/howtos/hex-editing.phtml

thank you KVk, I will check out your link. :thumbsup: