Re: one of my servers has been compromized

[Dan Ballance <tzewang.dorje () gmail com>]

Thanks for the heads-up on rkhunter Gage.

Is there anything else out there atm that works as a reasonable root kit
detector or is such a thing considered impossible now? I realise a skilled
attack will be able to bury itself without a trace, but I'm thinking of
something that can be used in less skilled breaches such as the one thought
to have been identified in this thread. Sometimes something imperfect is
still better than nothing I think.

Also, am I correct to think that using something like tripwire is the best
way to detect root kits properly, but that it obviously needs installing
when the box is fresh and before it has been physically connected to a
network?

thanks to everyone for their valuable contributions here - much appreciated!

dan :)

On 5 December 2011 11:13, Gage Bystrom <themadichib0d () gmail com> wrote:

> If it was a rootkit then trying to run the outdated rkhunter would be a
> moot point. Whatever seizes the kernel first wins, hands down.
>
> Fortunately for him, since the bot was so easy to find in the first place
> and such a simple way of maintaining it, the box was clearly seized by
> someone who didn't give a rats ass about it. Probably a skiddie or an
> automated attack to begin with.
>
> As for plugging any security holes, check your httpd error logs. If you
> noted down the time of the bot files creation date you would look around
> the same time for suspicious log entries. If they were as careless in
> scrubbing the logs as they were holding the box it would give you a look
> into how it may have been compromised. If you're getting things like
> ../.../../../../etc/passwd then some sort of lfi vuln was likely exploited,
> start grepping your php files for stuff like include(), or if you're
> getting something like into outfile then check your mysql user permissions
> and don't let it have file perms, and then start grepping down for sql
> vulns.
>
> If it comes down to being too much of a hassle to get all the obvious
> vulns at least then go to your boss, admit there is an issue and that time
> needs to be taken to remove such legacy code as this could have been a far
> worse incident if it had been more targetted and the end goal wasn't a
> botnet.
>  On Dec 5, 2011 3:02 AM, "Dan Ballance" <tzewang.dorje () gmail com> wrote:
>
> > I'm no expert, but here's something to get you started while you wait for
> > more experienced replies. Check for root kits:
> >
> > sudo apt-get install rkhunter
> > sudo rkhunter --update
> > sudo rkhunter --check
> >
> > On 5 December 2011 10:44, Lucio Crusca <lucio () sulweb org> wrote:
> >
> > > Hello *,
> > >
> > > I'm not new here, but I've mostly lurked all the time through gmane. I
> > > never
> > > believed it could happen to me until it actually happened: they
> > > compromized
> > > one of my servers. It's a Ubuntu 10.04 server with all security patches
> > > regularly applied. I'm inclined to believe they used some hole in the web
> > > application, which is a old customized Virtuemart version (1.1.3), which
> > > is
> > > not upgradable because of the invasive code customizations (I'm not the
> > > author of that code, so I have no clue about what had been changed back
> > > then).
> > >
> > > Now the problem for me is to track down the security hole. Here is the
> > > email
> > > my provider received and forwarded to me:
> > >
> > > > Subject: ISP Report; botnet activity on irc.undernet.org
> > > > [...]
> > > >
> > > > Hello, I am an operator on the irc chat network,
> > > > irc.undernet.org and i would like you to investigate the
> > > > owner of the Ip addresses that are listed at the foot of this
> > > > email.
> > > >
> > > > This/These host(s) have likely been compromised, and had an
> > > > altered/rogue process installed on it, and was part of a botnet
> > > > that was found on our network.
> > > >
> > > > The exploit or compromise running on this system is likely
> > > > to be an irc bot. Can you please alert the person who is
> > > > responsible, for its security to patch/upgrade, remove the
> > > > irc process and secure their system.
> > > >
> > > > = Unix System owners =
> > > > A favourite place for hiding the bot(s) is in tmp
> > > > and in /var/tmp/ or /dev/shm/ or in a users home directory
> > > > sometimes it may be hidden like /tmp/".  ."/ or similar.
> > > >
> > > > The bot files can usually be found by running these one line
> > > > commands as the root user.
> > > >
> > > > find / -exec grep -l "undernet" {} +
> > > > find / -exec grep -l "sybnc" {} +
> > > > find / -name "*.set" | perl -pe 's/.\/\w+-(\w+)-.*/$1/' | sort | uniq
> > > > find / -name "inst" | perl -pe 's/.\/\w+-(\w+)-.*/$1/' | sort | uniq
> > > >
> > > > netstat -tanp
> > > > lsof -i tcp:<Port number>
> > > >
> > > > *netstat looking for connections to remote port 6667 or the
> > > > range of ports between 6660-7000 once you find the port you
> > > > can use the command, lsof -i tcp:portnumber to determine
> > > > which process/user it is running under, and terminate it.
> > > >
> > > > = Windows System Owners =
> > > > most windows bots are mIRC scripted bots and generally
> > > > need a file called mirc.ini to run, you should search for
> > > > this file. Run a good antivirus scanner and firewall.
> > > >
> > > > This Ip/host may be removed from our Irc network due to the
> > > > risks it presents to our users.
> > > >
> > > > Should you need any help with removing the files or bot
> > > > process, feel free to contact me by mail or on our network,
> > > > which you connect to using any irc client and issuing
> > > > /server irc.undernet.org
> > > >
> > > > I look forward to your reply
> > > > Scot
> > > >
> > > > * Affected host/IPs, capture time is GMT+1: United kingdom
> > > > and servers they were connected to.
> > > >
> > > > Please note: when resolving server names to IP Addresses
> > > > that all our servers end with .undernet.org (for example)
> > > > Tampa.FL.US. is actually  Tampa.FL.US.undernet.org
> > > >
> > > > Important: If you reply to this mail needing further
> > > > information, please leave this mail intact, or supply us
> > > > with the IP Address(es) in question, as we reference these
> > > > mails by the unique IP Address
> > > >
> > > > Time of Capture: DECEMBER 3, 2011 10:03:48 PM
> > > >
> > > > List of IP address(es) and server it connected to:
> > > > my.server.ip.address (CHICAGO.IL.US
> > > >
> > > > BUDAPEST.HU.EU
> > > >
> > > > MONTREAL.QC.CA.undernet.org)
> > >
> > > I've run the "find" commands and found a number of file with the first
> > > "find", under /tmp/.m
> > >
> > > Deleted them, looked up remote connections with netstat, killed perl
> > > processes that where trying to connect to port 6959 (only trying because
> > > I've now set up iptables so that they actually can't), but those
> > > processes
> > > kept spawning. Checked crontab of www-data, found the launcher, removed
> > > it.
> > >
> > > Now the problem is: how do I pervent further abuse? What should I search
> > > in
> > > the logs (if anything) to spot the security hole?
> > >
> > > TIA
> > > Lucio.
> > >
> > >
> > >
> > >
> > >
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