I was reading about Metamorphic & polymorphic viruses ..
to what i understood ; they both uses mutation engines to avoid detection by anti-viruses, as the polymorphic encrypts\decrypts its code , and the metamorphic generates a logical equivalent code.
According to what i know , viruses are parasitic male-ware. i.e. it needs a host to produce copies of itself and cannot act independently like worms .
So my question is , during the virus's typical life cycle (infection - duplications- activating payload- etc ) , where is the mutation engine in all this ? And when a virus moves from its host to another PC what happens to the engine ? And what happens at the next host in the first cycle , how can it achieve its mutation ?