Re: Linux hacked

[Casper the Friendly Ghost <casper () camelot homelinux com>]

To get back into your account you want to use, at the boot manager prompt 
(lilo/grub)
init=/bin/bash

For example, if you use lilo and have 'lin' as the name to access your linux 
you would have to press ESC and then write at the prompt 

lin init=/bin/bash

In grub you would have to edit the command and add init=/bin/bash after the 
kernel option

After it boots up (it will be really fast - no services) you want to do

mount -o remount,rw /dev/hd* (whichever your / partition is)

then you can just do passwd root
enter the new password
confirm

do umount /dev/hd* (the one you just mounted above)

hit the 3 magic buttons (Ctrl+Alt+Del)

boot normally and you should be able to login as root with your new password

My suggestion for a good rootkit finder is chkrootkit. It's the one I used for 
testing different rootkits and it found ~90% of them

As for what else he changed, there's no easy way to see. First thing you could 
do is a 

netstat -ap -A inet

this will show you all your open ports and the daemons listening to them. If 
you see anything suspicious do some more research.

Also, make copies of your logs, preferably on a different machine, and look 
into them deeply. Also do a lastlog and last -20 (or more) root to see if you 
find anybody connected from a supsicious place or anything else suspicious.

Make sure you do an emerge sync and emerge -avuU world to be up-to-date with 
all the packages (chances of a script kiddie to get in would be less likely 
with newer/patched software).

Also since you have more than a few users make sure your system wasn't 
compromised through THEM. A lot of times users have weak password and 
crackers break in their account and from there they do more damage.

Good luck!

-cos

P.S. To find out which kernel you're running do uname -r


On Wednesday 20 October 2004 12:52, Nicholson, Dale wrote:
> First let me say I'm a security novice.  Please bear with me.
>
> My home linux (gentoo) machine was hacked last Thursday.  Installed active
> on the box was ssh, apache, php 5, and a squirl mail.  Iptables was set up
> for a firewall.  The box was set up as a web server with a number of
> websites and about 35 email accounts (separate passwords for the mail than
> the user accounts on the box).
>
> I'm guessing it was some sort of script kiddie if the names taking credit
> for the hack in the hidden folders I found are any indication.  I did some
> research on the person taking credit and found all kinds of information on
> him, he's an 18yr old kid in Germany.  I doubt he is very knowledgeable or
> he would not have alerted me to the intrusion by somehow locking out all
> accounts from the machine.
>
> To get in I have to boot from cd and chroot in.  Everything I've tried has
> been unsuccessful in getting root back.
>
> I found a hidden directory /var/tmp/.tmp that has a bunch of directories
> under it with names like +_01_+++++++HaXorEd by ... and
> +_05_++++++++++Movies++++++....
>
> I unplugged the machine from the internet shortly after the hack and can
> find no evidence of any uploads.  I do see that the person somehow was able
> to break root.  I was only able to find the hidden directories because the
> person forgot to clean up root's history file where I found the command
> used to create the them.  The box was set up to not allow remote login of
> root via ssh but you could su in once logged in as one of three users.
>
> I'm a novice at security and had been depending on my system admin to keep
> the box up to date.  He tells me he's been doing an emerge world every week
> but I don't know how to tell.
>
> Can someone help me with where to get a listing of everything I have
> installed and the versions?  I can't remember if the kernel is a 2.4 or 2.6
> but I think it's 2.6.  Plus I know there have been problems with ssh in the
> past but I don't know which versions have problems and I'm not sure how to
> find out what version I'm running.  I'm kind of stuck as my sys-admin
> normally handles these things but he cannot ssh in to the box without me
> first fixing the problem since he lives 13 hours from me (the box is in my
> basement).
>
> Also, I need something that can detect root kits etc. on linux.  I've heard
> knoppix mentioned as having good tools on this list for an example, but I
> wouldn't know what tools to use for this particular case.
>
> This is what I tried so far:
> I logged in using a boot CD, mounted the hard disks, chrooted in, blanked
> out the root password in the /etc/shadow file, changed the root password,
> rebooted and tried to log in normally.  This did not work.  I also checked
> that the correct users were in both /etc/passwd and /etc/shadow.
>
> Note that both the email and websites were still working despite not being
> able to log in, although not now of course since I unplugged the ethernet
> cable.
>
> Any comments/assistance will be greatly appreciated.

-- 
In Linux We TrUsT !