Since the Conficker/Downadup worm’s discovery in November 2008, it has infected millions of PCs worldwide (estimates of the number infected vary greatly across sources). On April 1, security officials are expecting the worm to get an update, the details of which are unknown.
The worm can download malware from randomly generated domains, and can be transmitted without the presence of a server, in a peer-to-peer fashion or over a USB port. The April 1 update is expected to double the number of domains the worm polls each day in order to download updates. Conficker also creates thousands of false domains on a daily basis to throw off investigators.
Having already gone through three updates, the worm is no doubt growing in strength. Only already-infected computers stand to be harmed by the impending update; and while April 1 is the suspected update day, there is no way to know whether the update will be made before or after April 1.