It is certainly not a false alert based on the VT results.
It is fine in the chest, it can do no harm in there and if it were a true system file you would know about it.
lsass.exe is a system process of the Microsoft Windows security mechanisms. It specifically deals with local security and login policies. This program is important for the stable and secure running of your computer and should not be terminated.
You don't mention the path to this particular lsass.exe, e.g. (C:\windows\system32\infected-file-name.xxx) ?
Check the avast! Log Viewer (right click the avast 'a' icon), Warning section, this contains information on all avast detections.
It is a common trick to use the name of a valid system file but put it in a different location, so you see why I ask about its location.
Because of the malware names of the VT results and the quotes below, it would be wise to do some other scans.
Note: lsass.exe is a process which is registered as a trojan. This Trojan allows attackers to access your computer from remote locations, stealing passwords, Internet banking and personal data. This process is a security risk and should be removed from your system.
Note: lsass.exe is registered as a downloader. This process usually comes bundled with a virus or spyware and its main role is to do nothing other than download other viruses/spyware to your computer. This process is a security risk and should be removed from your system.
If you haven't already got this software (freeware), download, install, update and run it, preferably in safe mode and report the findings (it should product a log file).
1.
SUPERantispyware On-Demand only in free version.
2. MalwareBytes Anti-Malware freeware version
http://download.bleepingcomputer.com/malwarebytes/mbam-setup.exe, right click on the link and select Save As or Save File (As depending on your browser), save it to a location where you can find it easily later.
Run the first and report the findings (hopefully we can check it and see if you need to do anything else) then running the second and report the findings.
