Security Basics mailing list archives
RE: Linux hacked
From: "Matt Arntsen" <Matt.Arntsen () FranklinCovey com>
Date: Thu, 21 Oct 2004 11:01:05 -0600
I would also suggest using a simple script in the future that alerts when a file is changed, like passwd or shadow. I just wrote a simple script that performs an MD5 hash on certain files and then compares the hash every few minutes to a master hash and alerts me via page or email when the two hashes don't match. The important thing to remember when doing this is to have the master MD5 hash results on a read-only medium, like a cd and have it in your cd drive where, when the scripts is run, is mounted, hashes compared and then unmounted. This may draw some criticism from more advanced users but it is a good start in ensuring you know when something has changed. It does not prevent things from changing. Maybe setting the immutable bit might slow them down a bit. Good luck. matt -----Original Message----- From: Casper the Friendly Ghost [mailto:casper () camelot homelinux com] Sent: Wednesday, October 20, 2004 9:05 PM To: security-basics () securityfocus com Subject: Re: Linux hacked 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 !
Current thread:
- Linux hacked Nicholson, Dale (Oct 20)
- Re: Linux hacked Casper the Friendly Ghost (Oct 21)
- Re: Linux hacked Jonathan Loh (Oct 21)
- Message not available
- Re: Linux hacked xyberpix (Oct 21)
- RE: Linux hacked Randori (Oct 21)
- Re: Linux hacked xyberpix (Oct 21)
- Re: Linux hacked Barrie Dempster (Oct 21)
- Re: Linux hacked Miles Stevenson (Oct 21)
- Re: Linux hacked xyberpix (Oct 25)
- <Possible follow-ups>
- RE: Linux hacked Conlan Adams (Oct 21)
- RE: Linux hacked mike (Oct 21)
- RE: Linux hacked Matt Arntsen (Oct 21)
- RE: Linux hacked Jonathan Loh (Oct 22)
- RE: Linux hacked xyberpix (Oct 25)
- RE: Linux hacked Nicholson, Dale (Oct 25)
- RE: Linux hacked Leif Ericksen (Oct 25)
- RE: Linux hacked Randori (Oct 25)
- RSA SecurID Training in Tokyo ? momotaro (Oct 26)
- Re: Linux hacked Andy Paton (Oct 27)
- Re: Linux hacked Shyam Mani (Oct 27)