RE: Linux hacked

From: Jonathan Loh (kj6loh_at_yahoo.com)
Date: 10/22/04

  • Next message: Andrew Shore: "RE: Is this normal?" 
    Date: Thu, 21 Oct 2004 22:47:01 -0700 (PDT)
To: Matt Arntsen <Matt.Arntsen@FranklinCovey.com>, security-basics@securityfocus.com

    Both AIDE and Tripwire will do that for you. The advantage of this is that you
    do not have to rely on your own code especially if you do not know how to
    program. Even if you know how to program this will prevent you from having to
    reinvent the wheel. But as with all security programs KNOW what they do before
    using them.
    --- Matt Arntsen <Matt.Arntsen@FranklinCovey.com> wrote:

    > 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 !
    >

                    
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  • Next message: Andrew Shore: "RE: Is this normal?"