Local Security Authority Subsystem Service

Local Security Authority Subsystem Service, abbreviated LSASS, is a process in Microsoft Windows operating systems that verifies the user logging on to a Windows computer or server.

The Sasser worm exploited a vulnerability in LSASS to spread via buffer overflow in computers running the recent Microsoft operating systems Windows XP and Windows 2000. The worm is particularly potent in that it can spread without the help of the user; it does not 'travel by email' like many other worms.