On Tue, 2010-02-16 at 14:37 -0700, JD Austin wrote:
> My 2 cents :)
> It may be a simple web form exploit or something more serious and they
> have no guarantee that it won't be exploited again and again.
> I'm not a security expert but used to hang out with hackers back when
> it was just starting to be illegal and have a good understanding of
> how they think and operate. I'm perfectly capable of doing such
> things but thankfully hacking never appealed to me :) Good hackers
> will patch your system in ways you would never detect... for that
> matter you'd never even know they were there... they won't show up in
> a process list, you won't find their files searching for them, they
> eliminate any trace of themselves in logs, and you probably won't find
> their back door unless they're amateur 'script kiddies'. Fortunately
> MOST hacker attacks are script kiddies. You'll usually find traces of
> their attack in logs and temp folders.
>
> The 'clean and recover' method will never give you 100% certainty that
> you've eliminated the exploit. The machine could have patched
> binaries all over the place. I have cleaned up such messes before; it
> can be very time consuming. Even if you find how they got in, how can
> you ever be completely sure you've stopped them from getting back in
> without building an new instance to replace it?
>
> The safest way to deal with it is to build a hardened server from
> scratch; before loading data:
> * change all passwords/etc on the new server
> * generate new ssh keys if they exist
> * install mod_ssl, intrusion detection, and fail2ban/denyhosts
> * re-write applications NOT to use register_globals in PHP and
> turn it off
> * turn up logging
> * migrate the applications/data to it after checking logs for
> clues of exploit and fix before migrating.
> The data center can probably give them some information to help them
> find where their server was exploited.
----
If the mandate is to clean in place and put back online, I myself would
not be interested because the predicate is one that I could never agree
to and hence, JD is right. You would surely spend more time fixing and
trying to locate and removing the exploits than backing up, clean
install and putting the data back and still, if it is not a clean
install, someone is going to have some sleepless nights.
I myself am an avid fan of denyhosts. It is of course, the curse for the
dyslexic's among us ;-)
Craig
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