It’s always good to do a regular rootkitcheckup on your system. A nice tool for doing so is rkhunter.
1.1) What is Rootkit Hunter?
Rootkit Hunter (RKH) is an easy-to-use tool which checks
computers running UNIX (clones) for the presence of rootkits
and other unwanted tools.
1.2) What are rootkits?
Most times they are self-hiding toolkits used by blackhats,
crackers and scriptkiddies, to avoid the eye of the sysadmin.
Installing rkhunter (thru apt)
sudo apt-get install rkhunter
Running a rkhunter report
The most common “errors” you’ll encounter with Feisty will be for the following files:
You can let rkhunter ignore these files bye simply adjusting your rkhunter.conf file.
kvaes@ubuntu:~$ grep -i allowhidden /etc/rkhunter.conf
# One directory per line (use multiple ALLOWHIDDENDIR lines)