[mewpmewp2]

Computer viruses need to get an ability to mutate by themselves, improving the code overtime though.

[ben_w]

Simulated evolution is trivial to implement, but my guess is also a bit pointless from the point of view of most people writing viruses — the viruses might mutate to not give them money.

[scarmig]

Those mutations would probably be favored by evolution, if anything. They would attract less attention and allow more focus on reproduction.