[gentoo-user] Rooted/compromised Gentoo, seeking advice

[Paul Hartman <paul.hartman+gentoo@gmail.com>]

Hi, today when working remotely I ran nethogs and noticed suspicious
network traffic coming from my home gentoo box. It was very low
traffic (less than 1KB/sec bandwidth usage) but according to nethogs
it was between a root user process and various suspicious-looking
ports on outside hosts in other countries that I have no business
with. netstat didn't show anything, however, but when I ran chkrootkit
told me that netstat was INFECTED. I immediately issued "shutdown -h
now" and now I won't be able to take a further look at it until I get
home and have physical access to the box. System uptime was a few
months. It was last updated for installation of a 2.6.33 kernel
(2.6.35 is out now).

I have 3 goals now:

1) Figure out what is running on my box and how long it has been there.
2) Find out how it got there.
3) Sanitizing, or most likely rebuilding the system from scratch.

I won't feel comfortable about doing item 3 until I learn the cause of
1 and 2. Since this is a home PC, it's not mission-critical and I have
other computers so I can afford to leave it offline while I
investigate this security breach, but at the same time it's worrisome
because I do banking etc from this machine. I'll obviously have to
check the status of any other computer on the same network.

My user account has sudo-without-password rights to any command. In
hindsight this risk may not be worth the extra convenience... A rogue
"sudo install-bad-stuff" anywhere over time could have done me in.

Alternatively I was running vulnerable/compromised software. My box
has sshd running, root login in ssh is not allowed, and pubkey only
logins (no passwords). It is behind a wireless router but port 22 is
open and pointing to this box, and a few others needed by other
applications. So I will check out which keys exist on the compromised
machine and make sure I recognize them all. I'll also need to check
the status of any other computer my key is stored on (a mix of linux &
windows, and my mobile phone). Sigh...

I am using ~amd64 and I update deep world about 3 times a week normally.

The computer is only a few months old, but it was created by cloning a
~2-years-old computer.  I did emerge -e world as part of the upgrade
process.

If anyone has advice on what I should look at forensically to
determine the cause of this, it is appreciated. I'll first dig into
the logs, bash history etc. and really hope that this very happened
recently.

Thanks for any tips and wish me good luck. :)