Often times, when I stumble upon IDAPython scripts, I notice that they are using inefficient / incorrect IDAPython APIs to disassemble or decode instructions (for instance using idc.GetMnem() or idc.GetDisasm()). Therefore, in this blog post, I am going to illustrate how to use IDA’s instruction decoding functions from IDAPython in order to write a very simple x86 emulator. The goal is to demonstrate the correct use of instruction decoding IDAPython APIs. By the end of this post, you should be able to solve similar problems using IDAPython. Continue reading →