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speedks1
March 16th, 2006, 23:32
Hi friends, I have read this forum and have few questions on my current project I am doing. I have to patch a smartphone application for this I have downloaded IDA PRO and verified(did I?) the instructions to be deleted from the app so that I can remove the license protection my questions is very basic and stupid

1. I want to minus that code and disable the nagging screen on smartphone app which initially pops and verifies the license key and activation code so what I should do here to remove that code (assuming that I will be patching here?) and geenrate the exe again.

2. I am unable to run the remote debugger for this version 4.8 on smartphone looks like it supports only pocket pc. with this in mind is there a way i can execute the the app in kind of simulator that i can execute and remove this code?

appreciate you help guys.

LLXX
March 17th, 2006, 02:27
Starting your first reversing project on a non-PC platform? That can be somewhat difficult.

What CPU/architecture does the smartphone use? That is critical information you have to know.

naides
March 17th, 2006, 08:46
Two coments:

Your Question 1: In general is a bad idea to add or remove code from an executable, i,e change the size. practically all addresses inside the code are relative: if you delete some undesirable bytes or insert new some new bytes, the address space will be fucked beyond recognition: jump instructions or (B(ranch) instructions for small devices assembly language) will land in the wrong place, and the program will crash. You CAN change instructions to something of the same size like bypassing all the undesirable code with an unconditional branch, or using nop instructions:
mov R1,R1 sort of thing.

Question 2. There are emulators associated with the IDE packs used to develop the software for your portable devices, otherwise how else could these apps be developed and debugged?
You have to be able to trace the code live.
Find out the cpu and instruction set your device uses, then search for it (The IDE/emulator).
If IDA holds its promesses, version 5.0 will have that debug /emulator capability, right out of the box