The worm was programmed to start a SYN flood against port 80 of windowsupdate.com if the system date is after August 15 and before December 31 and after the 15th day of other months, thereby creating a distributed denial of service attack (DDoS) against the site. The damage to Microsoft was minimal as the site targeted was windowsupdate.com, rather than windowsupdate.microsoft.com, to which the former was redirected. Microsoft temporarily shut down the targeted site to minimize potential effects from the worm.