Date: Thu, 10 Dec 2009 07:24:34 +0000 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: squirrel@isot.com Cc: FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org> Subject: Re: Hacked - FreeBSD 7.1-Release Message-ID: <4B20A232.1010800@infracaninophile.co.uk> In-Reply-To: <70b530187d5c4ef4336260f6fdf72193@mail.isot.com>
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Squirrel wrote:
> I've just finished the rtld patch. Now in process of regenerating
> all the keys and certs. Next will look into php. But far as rtld
> vulnerability, doesn't it require at least a local user account?
> Looking at all the authentication, there wasn't any authenticated
> session during the time frame. So I'm leaning more towards php
> 5.2.9, and checking all my ports.
You don't necessarily need to have a login session (ie. recorded in wtmp)
to exploit the rtld bug -- just control over some process and the ability
to run commands through it. Although the rtld bug is "only" a local root
compromise, since it is so simple to exploit it is a lot more dangerous
than most, and in combination with just about any form of remote exploit
it means your box get rooted.
Upgrading PHP and all ports is a good move. portaudit(1) is a good idea
but it doesn't necessarily address the direct route your attackers used.
My suspicions (in the absence of any detailed forensic examination of
your machine) are that you are running some vulnerable PHP code. This
may be part of a well known application, or it may be something locally written.
In this case, I'd recommend a number of measures:
* Run a security scanner like nikto (ports: security/nikto)
against each of the websites on your server. Do this at
regular intervals, and take action to fix any problems it
discovers.
* Make sure that you only grant the minimum necessary permissions
on the filesystem to allow apache to run your applications. In
general, everything under your doc root should be *readable* by
uid www but not *writable* -- don't be seduced by the idea of
making the webroot owned by www:www --- root:wheel is a much
better idea, and files should be mode 644, directories mode 755
unless there's a good reason to have them otherwise.
* Refuse to run any PHP application that requires you to have
'register_globals = YES' or to similarly poke enormous holes
in security through php.ini. Any application developer that
has not modified their code to use the $GLOBALS array by now
is lazy and incompetent and their code is likely to have all
sorts of other holes.
* Similarly give your web application only the minimum necessary
permissions it needs to access any databases. You'll frequently
see instructions to do things like: 'GRANT ALL PRIVILEGES ON foo.*
TO www@localhost WITH GRANT OPTION;' This is way too much and should
be trimmed down. Web apps rarely have any need to make schema
changes, and creating other UIDs is right out, so
'GRANT SELECT,INSERT,UPDATE,DELETE ON foo.* TO www@localhost' is a
much more reasonable starting point.
* Where a web application has a legitimate reason to want to write
to the filesystem (eg. uploading files), preferably confine the
write access to a separate directory tree outside the web root --
/tmp or /var/tmp aren't bad choices, but it might be better to
create a specific location for a particular application.
* Where a web application has an administrative mode preferably
arrange to run this over HTTPS thus protecting any passwords
from snooping. If the administrative mode needs to have generic
read/write access to the web tree, then consider running it in a
completely separate Apache instance with different user credentials
than the generally accessible web server.
Making the last point work with some arbitrary web application is
frequently challenging, but usually at least possible by a combination
of mod_rewrite and mod_proxy functions in the Apache config.
Cheers,
Matthew
--
Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard
Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
Kent, CT11 9PW
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