Windows updating software for use with the website
Every time an update requiring a reboot was installed, Automatic Updates would prompt the user with a dialog box.
That allowed the user to restart immediately, or dismiss the dialog box, which would reappear in ten minutes, a behavior Jeff Atwood described as "perhaps the naggiest dialog box ever." in Windows XP would claim 100% of a computer's CPU capacity for extended periods of time (between ten minutes to two hours), making affected computers unusable.
If that one server got compromised one day, or an attacker cracks the [Microsoft] DNS server again, there could be millions of users installing trojans every hour. Unlike its predecessor, Automatic Updates can download and install updates.
The scope of this attack is big enough to attract crackers who actually know what they are doing..." Automatic Updates is the successor of the Critical Update Notification Utility. Instead of the five-minute schedule used by its predecessor, Automatic Updates checks the Windows Update servers once a day.
As the service has evolved over the years, so have its client software.
But the list grew so large that the performance impact of processing became a concern.
Arie Slob, writing for the newsletter in March 2003, noted that the size of the update list had exceeded Windows Update v4, released in 2001 in conjunction with Windows XP, changed this.
This version of the app makes an inventory of the system's hardware and Microsoft software and sends them to the service, thus offloading the processing burden to Microsoft servers.
Critical Update Notification Utility (initially Critical Update Notification Tool) is a background process that checks the Windows Update web site on a regular schedule for new updates that have been marked as "Critical". By default, this check occurs every five minutes, plus when Internet Explorer starts; however, the user could configure the next check to occur only at certain times of the day or on certain days of the week.