Zmist

Zmist (also known as Z0mbie.Mistfall) is a metamorphic computer virus[1][2] created by the Russian virus writer known as Z0mbie. It was the first virus to use a technique known as "code integration". In the words of Ferrie and Ször:[3]

This virus supports a unique new technique: code integration. The Mistfall engine contained in it is capable of decompiling Portable Executable files to [their] smallest elements, requiring 32 MB of memory. Zmist will insert itself into the code: it moves code blocks out of the way, inserts itself, regenerates code and data references, including relocation information, and rebuilds the executable.