"which ‘evil IPv6 worms’ are you talking about? "

Why, the ones that require AirPort Extreme to ship from the factory with the packet filter turned on by default to prevent them from getting a foothold on your local network from which they can freely make outbound connections. You know, the ones that made the V6OPS working group in the IETF decide that, even though draft-ietf-nap is informational and explicitly calls out that it isn't making policy recommendations, stateful packet filters should nevertheless be widely deployed at residential IPv6 gateways to prevent inbound connections from being made, and that these filters should be turned on by default and require explicit user intervention to disable them.

Those darned IPv6 worms are extremely pernicious, aren't they? Why, they're so evil nobody even knows where they are or what they're doing! But, we know THEY MUST BE STOPPED! TURN ON YOUR FIREWALLS!!!

p.s. There are actually ways that IPv6 worms could propagate over IPv6 more readily without randomly generating addresses to probe, but those mechanisms are easily interdicted by widely deploying RFC 3041 private addressing to prevent addresses from usable beyond the necessary intervals of time in which they're used.