Infections can likewise be made to fill moral needs. Welchia or the Nachi worm is one of those.
It was intended to fight and kill the Blaster worm on clients' laptops (assuming there was one), and forestall further Blaster contamination by downloading and introducing security patches from Microsoft. When the task was finished - Welchia brought itself down.
However, it had a point of weakness: the moral infection dialed PCs back. Thus, Welchia caused a nine-hour postpone in handling and giving visas by the US State Office. It additionally consumed 3/4 of Naval force Marine Corps limit, delivering it futile for quite a while.