By John Leyden
Posted in Anti-Virus, 3rd April 2009 10:54 GMT

The "activation" of Windows machines infected with the latest variant of the Conficker worm has allowed security watchers to come up with a far more accurate estimate of how many machines are infected.

Early versions of Conficker called home to 250 different domain names every day to check for updates. Since Wednesday, machines infected by with the latest version of the worm (Conficker-C) began using a sample of 500 out of pre-programmed 50,000 domains a day to search for upgrades.

The unknown virus writers who created the worm are yet to publish any such update, but the call-back behaviour has allowed anti-virus firms to come up with an estimate of how many machines are infected by Conficker-C for the first time.

Continued @ The Register