I need a database of malicious code for MIPS processor Assembly or C to inject in Mibench and evaluate my detection mechanism at run time. Is there anything like this for MIPS? what about for other processors? I have shellcodes for MIPS and I want virus like codes for MIPS. Don't we have any attack benchmark for this purpose?
You are asking for a database of MIPS code for evaluating a detection technique, but I'm not sure that there are databases of embedded malware for public evaluation the same way that there are databases of desktop malware. If there are, I would love to know about them.
As an alternative (and I am sure you have done this), try searching for examples of MIPS shellcode and crafting exploits that work on your own framework. This is a lot of work, but there are definitely examples of MIPS shellcode and malicious embedded logic described in articles (like www.shell-storm.org/shellcode, metasploit, etc.) that you could use. They are just not in a unified database. Also, you may need to do some work to craft things that will exploit things in MiBench.