I learned basis of assembly language with, both, AT&T and Intel style. After that I gone through buffer overflow and how to use shellcode with it. Should I go for Metasploit now?
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Metasploit can generate some malicious files, such as PDFs. Malware analysis isn't necessarily just Windows PE files so it might be a good idea to look into other file formats. Metaploit could be useful to generate your own samples to analyze.
Msfvenom might be interesting to you as well. It is a tool that generates shellcode given a payload. Generated shellcode might not always be the best though.
You may find other people code useful and metasplot is good to test and understand how things can be exploited.
For reversing there are alot of videos and sildes that other people have released explaining how they achieved there goals