Local Security Authority Subsystem Service

Local Security Authority Subsystem Service (LSASS) is a process in Microsoft Windows operating systems that is responsible for enforcing the security policy on the system. It verifies users logging on to a Windows computer or server, handles password changes, and creates access tokens. It also writes to the Windows Security Log.
Forcible termination of will result in the system losing access to any account, including NT AUTHORITY, prompting a restart of the machine.
Because is a crucial system file, its name is often faked by malware. The file used by Windows is located in the directory . If it is running from any other location, that is most likely a virus, spyware, trojan or worm. Due to the way some systems display fonts, malicious developers may name the file something like (capital "i" instead of a lowercase "L") in efforts to trick users into installing or executing a malicious file instead of the trusted system file. Sasser (computer worm) spreads by exploiting a buffer overflow in the LSASS on Windows XP and Windows 2000 operating systems.