======================
Horde Security Notes
======================
:Last update: $Date: 2008/09/16 08:43:03 $
:Revision: $Revision: 1.9.10.3 $
:Contact: horde@lists.horde.org
.. contents:: Contents
.. section-numbering::
Temporary files
===============
Horde applications make extensive use of temporary files. In order to make
sure these files are secure, you should make sure your installation meets the
following criteria.
Sites may gain increased security by defining a temporary directory in the
Horde configuration which is writable by the web server, but not writable by
other users. Since the temporary files may contain sensitive information it
is best to also make these file unreadable by other users. That is, they can
be made readable and writable only by the web server user.
PHP Sessions
============
For the most security, you should enable PHP session cookies by enabling the
PHP setting ``session.use_cookies``. When doing so, be sure to set an
appropriate cookie path and cookie domain in the Horde configuration also to
secure your cookies. You should even force session cookie usage in the Horde
configuration, which is the default setting in all Horde versions now.
If you want to use HTTPS connections, consider forcing users to HTTPS in the
Horde setup. This will force cookies to be sent over secure connections only
and helps to prevent sidejacking.
If PHP sessions are set to use the ``files`` save_handler, then these files
should be secured properly. Sites can increase security by setting the PHP
setting ``session.save_path`` to a directory that is only readable and
writable by the web server process.
Sites with a large user base should consider setting the
``session.entropy_file`` and ``session.entropy_length`` to appropriate values.
Horde will encrypt the user credentials before storing them in the session.
However, this encryption can be improved if you have and enable the PHP
extension "mcrypt" which allows for stronger encryption than is otherwise
provided by Horde.
Default database passwords
==========================
The Horde documentation and sample database creation scripts create a default
user and password for accessing the horde database. Using this password in a
production environment is a security hole, since an attacker will easily guess
it.
It is very important that sites change at least the password to something
secure.
Prevent configuration file reading and writing
==============================================
The configuration files may contain sensitive data (such as database
passwords) that should not be read or written by local system users or remote
web users.
If you use a Unix system, one way to make the configuration files and
directories accessible only to the web server is as follows. Here we assume
that the web server runs as the user ``apache`` and the files are located in
``/home/httpd/html`` -- substitute the correct user or file path if needed::
$ chown -R apache /home/httpd/html/horde/config
$ chown -R apache /home/httpd/html/horde/*/config
$ chmod -R go-rwx /home/httpd/html/horde/config
$ chmod -R go-rwx /home/httpd/html/horde/*/config
For completely fascist permissions, you can make the entire Horde tree
inaccessible by anyone except the web server user (and root)::
$ chown -R apache /home/httpd/html/horde
$ chmod -R go-rwx /home/httpd/html/horde
$ chmod -R a-w /home/httpd/html/horde/
Note that the last line makes all files unwritable by any user (only root can
override this). This makes the site secure, but may make it more difficult to
administrate. In particular, it will defeat the Horde administrative
configuration interface, forcing you to update the Horde configuration files
manually (as per the INSTALL_ instructions).
The above will not secure the files if other user's on the same machine can
run scripts as the apache user. If you need to protect against this you
should make other user's scripts run under their own account with some
facility such as apache's suexec module. You need to watch out not only for
cgi scripts, but also for other modules like mod_php, mod_perl, mod_python,
etc. that may be in use on your server.
.. _INSTALL: ?f=INSTALL.html
Restricting test.php files
==========================
The ``test.php`` files provide a wealth of information that can be used
against the site by attackers. One you have confirmed that everything is
working, you should disable access to the test.php files. You can do this via
the web server, or via system file permissions. On a unix system, you might
issue a command such as::
$ chmod a-rwx /home/httpd/html/horde/test.php
$ chmod a-rwx /home/httpd/html/horde/*/test.php
Preventing Apache from serving configuration and source files
==============================================================
The Horde configuration files may contain sensitive data (such as database
passwords) that should not be served by the web server. Other directories
contain PHP source code that isn't intended for viewing by end-users. The
Horde group has provided ``.htaccess`` files in various directories to help
protect these files. However, that depends on your web server honoring
``.htacess`` files (which is a performance hit, and may not be available in
all web servers).
An Apache site can also prevent the web server from serving these
files by adding sections to ``httpd.conf`` such as the following::
<Directory "/home/httpd/html/horde/config">
order deny,allow
deny from all
</Directory>
<Directory "/home/httpd/html/horde/lib">
order deny,allow
deny from all
</Directory>
<Directory "/home/httpd/html/horde/locale">
order deny,allow
deny from all
</Directory>
<Directory "/home/httpd/html/horde/po">
order deny,allow
deny from all
</Directory>
<Directory "/home/httpd/html/horde/scripts">
order deny,allow
deny from all
</Directory>
<Directory "/home/httpd/html/horde/templates">
order deny,allow
deny from all
</Directory>
Repeat this pattern for each Horde application. For example, for IMP you
would then add::
<Directory "/home/httpd/html/horde/imp/config">
order deny,allow
deny from all
</Directory>
<Directory "/home/httpd/html/horde/imp/lib">
order deny,allow
deny from all
</Directory>
<Directory "/home/httpd/html/horde/imp/locale">
order deny,allow
deny from all
</Directory>
<Directory "/home/httpd/html/horde/imp/po">
order deny,allow
deny from all
</Directory>
<Directory "/home/httpd/html/horde/imp/scripts">
order deny,allow
deny from all
</Directory>
<Directory "/home/httpd/html/horde/imp/templates">
order deny,allow
deny from all
</Directory>
Setup scripts
=============
There are various scripts use to setup or configure Horde. If you allow other
users on the web server machine, you should protect these files from being
accessed by them. On a unix system, you might restrict these files to root
access by using the following type of commands::
$ chown -R root /home/httpd/html/horde/scripts
$ chown -R root /home/httpd/html/horde/*/scripts
$ chmod -R go-rwx /home/httpd/html/horde/scripts
$ chmod -R go-rwx /home/httpd/html/horde/*/scripts
Using a chroot web server setup
===============================
Unix users may want to consider using a chroot environment for their web
server. How to do this is beyond the scope of this document, but sufficient
information exists on the world wide web and/or in your server documentation
to complete this task.
Hiding PHP info from the user
=============================
You should consider setting the following PHP variables in your ``php.ini``
file to prevent information leak to the user, or global insertion by the
user::
expose_php = Off
display_errors = Off
log_errors = On
register_globals = Off
You should also set up error logging (using the PHP ``error_log`` variable)
to log to a file, syslog, or other log destination.
Using a secure web server
=========================
Horde depends on passing sensitive information (such as passwords and session
information) between the web server and the web client. Using a secure
(SSL-enabled) web server will help protect this information as it traversing
the network.
Using a secure POP3/IMAP server
===============================
If you are using a POP3/IMAP server with Horde (e.g. for authentication or for
IMP) then Horde is passing the user's login credentials between the web server
and the mail server.
If your web server and IMAP server are on the same host, you can increase
security by forcing all traffic over the loopback or localhost interface so
that it is not exposed to your network.
In cases where that is not possible, we recommend using a secure mail
connection such as IMAP-SSL or POP3-SSL to ensure that passwords remain safe.
LDAP Security
=============
LDAP security is similar to the above POP3/IMAP server security issue. If you
are using LDAP, you should make sure that you are not exposing ldap passwords
or any sensitive data in your LDAP database.
Database socket security
========================
If your database (e.g. MySQL or PostgreSQL) is on the same host as your web
server, you may use unix sockets rather than tcp connections to help improve
your security (and performance). If it doesn't support unix sockets, you can
achieve some better security by restricting the tcp support to the loopback or
localhost interface.
If the database keeps its socket file (e.g. ``mysql.sock``) in a directory
like ``/tmp`` or ``/var/tmp``, you should set permissions carefully to ensure
that local users (if you have any) can't delete the socket. The unix "sticky"
bit should already be sent on the temporary directory itself, but you also
need to make sure the socket itself isn't writable by "other" or users can
delete it.
You might consider moving the socket file to another location such as
``/var/run`` or the top-level directory of your database program (e.g.
``/var/lib/mysql`` or ``/var/lib/pgsql``).
Sendmail or SMTP considerations
===============================
In some cases, you can increase security by sending mail via the local
command-line sendmail program on your web server, rather than using SMTP.
However, there may be reasons to use SMTP instead, such as if your smtp server
does spam or virus checking which would be skipped using the local sendmail
program.
Additional Notes
================
This is by far not a complete security HOWTO. This is just a compiled list of
what people have contributed so far. If you have tips, ideas, suggestions or
anything else that you think could help others in securing their Horde
installation, please let us know.