meaning that they did gain root access after all but were able to hide this through a rootkit???

/Håkan


Jan Schaefer wrote:
Hi,

  
My question is:  They did not guess the root password, 
how did they manipulate files which are only writable 
by root???
    

The following articles at wikipedia should give you an idea what was
going on on your maschine:

http://en.wikipedia.org/wiki/Exploit_%28computer_security%29
http://en.wikipedia.org/wiki/Rootkit

Hope that helps,

Jan

P.S. I would recommend an clean re-install. You never know what things
are sleeping and hiding on your maschine now...