CRC check

[Dan777]

I'm changing a JL to a JMP in OLLY by using the Binary edit. The program runs when using the F* key. Once I close Olly the exe don't work anymore. It goes back to the orginal Binary before I edited it.

The program has a CRC check and does not allow the code to be changed. Is there a way around this using Olly? I used HEIW to edit but I just get a system error.


Thanks in advance,
Dan

[coz]

It probably doesn't have a CRC check because a CRC check will not change the byte you modified back to the original. You most likely did not save the modification you made. Once you make the modification right click anywhere in the code and select "Copy to executable" and a box will pop up with all your modifications. Right click on it and select "Save file". That's about it, just don't save over the original.

Hope that helps.:D

[Dan777]

It really wasn't changing back, it just wasn't saving the changes I've made. I should of explained more clearly. The instructions you given is a allot simplier way of saving changes than the way I was...Thanks!

Unfortantly I've gotten the same results as I did with Hiew. I get a Windows
Error window.

I know the program has a CRC check because it's from a turtorial for Softice. I just used Olly to crack it. The turtorial didn't bother explaining how to find the CRC check since it was a turtorial on finding serials. I was just trying to find it for my own experiance and knowledge.

Thanks,
Dan

[coz]

Ohhh ok. Sorry. I haven't had a lot of experience with this. I have kryptoanalyzer for peid to find crc algorithms but I have never had to use it.