Lsass is a windows running process-
Process File: lsass or lsass.exe
Process Name: Local Security Authority Service
Description: Windows Local Security Authority Server Process handles Windows security mechanisms. It verifies the validity of user logons to your computer or server. Technically, the software generates the process that is responsible for authenticating users for the Winlogon service.
Company: Microsoft Corp.
System Process: Yes
Security Risk ( Virus/Trojan/Worm/Adware/Spyware ): No
Common Errors: N/A
It's possible that yours is infected.
More info
http://securityresponse.symantec.com/avcenter/sec...Content/10108.html
Removal tool
http://securityresponse.symantec.com/avcenter/FxSasser.exe.