Why would creating your own programming language for a virus be a good thing? If viruses are the only thing written in this language, wouldn't the language make it easier for the anti-virus companies to detect it without having to worry as much about false positives?
It also seems to me that a new language for this exact purpose is unlikely, however, it could very well be a proprietary or otherwise unknown language that may have been built for another purpose (internal company, domain-specific development, etc) and not often seen in this context.
Normally compilers compile each operation into a single destination machine code chunk. If you ignore efficiency, there are many ways to implement the same operation in machine code. A Cracker Compiler could contain multiple destination chunks and randomly choose one at compile time.
Writing a detector for a virus with infinite code representations would be difficult.
