Let's talk about shellcode for a bit, shall we?

It used to be that back in the day, it was difficult to write YARA signatures for shellcode

This was before the xor keyword or anything like that It was very common for malware authors to encode their shellcode payloads using trivial transforms

Single-byte XOR was extremely common, and relatively effective (still is, truth be told)

Writing signatures for XOR encoded payloads sucked quite a bit

If you want to get into reversing

Download a copy of IDA Free

Open up a program you run frequently

And figure out how it works Find a crackme and try it

Find some shellcode and learn the techniques

Write your own software and analyze it

Compile software for multiple architectures and look for the differences