Hacked - FreeBSD 7.1-Release

[Matthew Seaman]

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 at 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 at 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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