During recent weeks, a worm has been affecting corporate, educational and public computer networks all throughout the world, leaving computer security experts searching for the person(s) responsible for the attacks and trying to determine what the virus would do next.

The worm, known as Conficker or Downadup, has worked his way into computers through a Windows operating system vulnerability that was detected not long ago, by hacking network passwords or by devices such as USB keys.

Experts have revealed that Conficker was the worst infection since the Slammer worm had spread across the Internet in January 2003, adding that the former had affected approximately nine million personal computers worldwide.

Even though back in October, Microsoft Corporation issued an emergency patch to protect the Windows OS from the vulnerability, the worm continued to attack computers.

This week, security researchers at  Silicon Valley security firm Qualys said that they had estimated that about 30 percent of Windows-based computers connected to the Internet had remained vulnerable to Conficker because they had not been updated with the patch.

The Conficker worm uses an intricate algorithm in order to draw up a list that changes on a daily basis of 250 domains that the infected systems attempt to make contact with. Consequently, hackers only have to register one of these domains so as to establish contact with the botnet that Conficker has set up, which results in security watchers’ efforts to take down the command to turn out to be to no avail.