The Sasser worm, discovered on May 1, 2004, is a computer worm that affects computers running vulnerable versions of Microsoft Windows XP and Windows 2000. Created by a German student, the worm spreads by exploiting a vulnerability in the Local Security Authority Subsystem Service (LSASS). Sasser does not require user intervention to spread and can infect computers via the internet. The worm caused widespread disruption by causing computers to continually crash and reboot, affecting millions of machines and critical systems worldwide.