unix question: unknown user logged in? hacked?

[Aaron Konstam]

On Fri, 2007-04-20 at 13:42 -0700, Mike Wright wrote:
> Hi all,
> 
> There is a mystery user on a remote system that I can't identify.  I 
> want to be sure that it's not an uninvited guest :(  If anybody is 
> willing to help I'd be most appreciative.
> 
> Running fc6, but I don't thinks it's relevant, although it may be.
> 
> The box is at a remote location and I access it via ssh.  When I run 
> "top" it shows 2 users, but when I run "who" it shows only one, me, from 
> my remote location.
> 
> At first I thought it might have been a left open login on one of the 
> mingetty's so I disabled them all in inittab and changed runlevels from 
> 3 to 4 and saw that all the mingetty's were gone (I think that should 
> logout anybody on one of those), then returned to runlevel 3 and re-ran 
> "top".  Still 2 users.
> 
> I don't think it can be anybody left over from a previous runlevel 5.
> 
> I ran "ps auxf" and went over it line by line and couldn't find any 
> other bash sessions than my current remote login on pts/0.
> 
> Anybody know how to identify the second user shown by top?
> 
> I'm very paranoid about hackers/owners/skiddies and this definitely has 
> my ears perked up.
> 
> Thanks in advance for any tips or ideas,
> Mike Wright :m)
> 
My top says there are only one user. But does it identify a name for
this second user in top. That is do you find and programs listed in top
running by any other user except yourself and root?