The initial problem I see with something like this would be encryption. All the attacker would have to do is encrypt their virus which would get it past the an

The initial problem I see with something like this would be encryption. All the attacker would have to do is encrypt their virus which would get it past the antivirus gate keeper, then when it was decrypted on the local PCs there would be nothing to recognise it. The same problem would exist for anything running over https. That would be the first problem to solve, although I'm sure there would be ways of resolving this.