What is smss.exe?
Session Manager Subsystem (smss.exe), also referred to as Windows Session Manager of the Microsoft Windows Operating System, is a process that is part of the Windows NT operating system and is responsible for starting the user session.
The process, which runs in the background, is started when the Operating System starts. The process should not be removed from the PC as it is important for the stable running of the computer and should always be included in your Windows boot up list. Termination may lead to malfunction and is not recommended.
The process is started by a system thread that is also responsible for, among other things, launching winlogon as well as Win32 processing (csrss.exe) and setting of the system’s variables. If any of these processes terminate abnormally, the system may malfunction.
Malware
The smss.exe file is stored in the folder C:\Windows\System32 and usually occupies 50688 bytes and is classified as a Windows System file. Any other file that looks like smss.exe but is located in any other folder is most likely malware (which can be a virus, Trojan, worm and so on). These are dangerous files which can compromise your personal data and should be gotten rid of. One way of looking for malware is by checking your system for similar names that are stored in the computer. You can also check the task list to see the programs currently running on the computer. This is done by pressing the ctrl-alt-del keys at the same time to view the task manager and then clicking on the “Processes” tab. Any process that resembles the real thing, but is not, is a sign of trouble.
Many programs are registered as smss.exe and look legitimate but could turn up to be a Trojan. Some files that associate themselves with smss.exe include SMSS and IntelliSys. The first is a file that disguises itself as a system file and is created by the FLOOD.F Trojan, a malicious malware. The latter, IntelliSys is adware (it displays advertisements without your consent based on what it finds after spying on you) that hides in C:\Windows. Obviously, this would be a menace and the best way to deal with the problem is to arm yourself with the latest and updated anti-malware software. Some of these anti-spyware applications including Norton and McAfee are available online for free.
For more information on smss.exe read What is SMSS.exe?
http://www.tech-faq.com/smss.exe.shtml
http://www.rolo.org/smssexe.html