When i open task manager, and click "show processes from all users", i notice that many processes run under SYSTEM, LOCAL SERVICE, NETWORK SERVICE usernames. I wonder is it possible for virus to run on those system directories?
While I'm pretty sure it's possible, you most likely don't have anything to worry about. When you open things like Task Manager, or Activity Monitor, you typically see TONS of processes under system and other sort of foreign looking names you have never heard of. Most of the time, these are harmless. You can always run a virus scan.
Honestly though, unless you've been browsing sites that are out of the norm, or carelessly downloading stuff, chances are you're fine:)
Do you know how insanely complex an operating system is? And then windows is a bloody huge os too. It has processes running that handle you Internet access, program messaging, all your drivers for everything...
chances are if it says it's running in system you should leave it alone... a virus scan won't do any harm though, but don't go messing around not knowing
thats a terrible idea satsuma. first, he is just viewing processes from another user, which is poking around, but it cant do any harm. its important to know what are non vital programs that can be stopped to free up RAM. second, since an os is a complex thing, you should always go poking around to see how it works under the hood. one of the first things i did when i got my first ubuntu disk is sit down and go through every path I could think of.
There is no harm in poking around inside of an OS. IMHO one of the first things you should do when you install a new OS is to try and see what breaks it. If you're concerned about losing or corrupting your data that happens to be important enough to cause alarm, yet somehow not quite important enough for you to be making regular back-ups for, then use a VM; that's why they exist.
@ OP: I feel like I'm the only one here that read your question correctly. Yes, it is possible for a virus or any other application to be run under those accounts. The only difference between those accounts and say a regular administrative user is that the built in service accounts cannot be run in interactive session.
Okay fair enough littleBobby and computergeek, i understand that it's wise to try and educate yourself in such matters (and often quite interesting). But my main point was if you don't know what it does, try not to break it XD