First, the good news: Matt & his brave crew of WordPress coders have just released version 2.6 of the Open Source award-winningly awesome content management system called WordPress (download it here). I’ve been using it since it was called b2, and love it. I recommend it for most of my clients, and they love the simplicity and ease of use. I also really like how easy it is to customize and extend, using the excellent theme and plugin system.
If you have a WordPress installation yourself, please upgrade it today. Why should you do it today? In short, not only does the latest version of WordPress have some awesome new features (like content change tracking, a new “Press this” browser bookmark, using Google’s Gears system to make it faster, and about 194 bug fixes) it also contains the latest SECURITY FIXES.
Why should you care about security fixes? Because older versions of WordPress are vulnerable to exploits. I know this for a fact, and have been working on cleaning out a number of older installations of WordPress that have been hacked. This isn’t a fun process, and if you stay up to date, you will have the best chance of not getting hacked yourself.
This isn’t a problem exclusive to WordPress, and they’ve done a really good job generally at fixing holes (the current release proactively fixes a number of potential issues), but it is an issue you should definitely look into.
On a Unix machine, one thing to look for is this pattern in any files:
You can do a search through all your hosting accounts by running this command (run as root):
# grep -R 'md5($_COOKIE' /home/
That will tell you if you have any infected files (for this particular exploit). If you find any, you need to clean out those files. If you are running your sites out of version control (like using
svn), this may be slightly easier.
$ svn st should tell you if any files were changed from the last time you checked them out. If you see unexpected files show up, you’ve been hacked.
To clean out your installation, not using version control method (done as root in this case):
- Copy your whole
public_htmldirectory to another location so you can do forensics on it and copy valid files back into your new installation:
# cd /home/USERNAME/
# mkdir public_html-hacked
# mv public_html/* public_html-hacked/
- Download a clean copy of WordPress into your
# cd /home/USERNAME/
# wget http://wordpress.org/latest.zip .
# unzip latest.zip
# cp -R wordpress/* public_html/
# chown -R USERNAME:USERNAME public_html/*
- Create a new
wp-config.phpfile. It’s probably a really good idea to first change your MySQL database password. To create your new config file:
# cp wp-config-sample.php wp-config.php
# vi wp-config.php
Enter the correct (new) values for your MySQL database name, username, password, and the (currently 3) authorization unique key values (go to http://api.wordpress.org/secret-key/1.1/ to automatically generate the 3 keys for you to copy/paste into your config file.
- Next, upgrade your WordPress database:
http://example.com/wp-admin/upgrade.php. You’ll have to sign in with your admin username and password. Once this is done (should go without a hitch, hopefully), examine your user table to see if there are any entries there that shouldn’t be. Delete any users that you didn’t create. Also, it would be a good idea to update the password for each user in the system.
- Go through all of your Settings, looking for any suspicious changes. Specifically notice what the Uploads directory is set to (in Settings->Miscellaneous). It should probably be set to something like
wp-content/uploads. If it says something like
../../../../../tmp/change it back. Also go look there to see if there are any left-over files that need to be investigated and removed.
- Make a local copy backup of your database and then clean out entries that don’t belong there. Check your raw database (using something like PHPMyAdmin or command line mysql tools) and examine the
wp_userstable. Look for a user called WordPress. Delete it! If you found it, also check the
wp_usermetatable and delete all entries associated with the bogus WordPress user ID. Next, check through your other MySQL tables to look for any suspicious entries (attached files, comments, posts, etc.) Delete anything that looks incorrect or wrong, but be sure not to delete your actual content.
As you can see, there are lots of things to check for if your installation of WordPress gets compromised. So, to save yourself a lot of pain and suffering, make sure you upgrade your WordPress installation(s) just as soon as you can.
More good info if you think your WordPress installation has been hacked:
- Has Your WordPress Been Hacked Recently?
- WordPress Support: Security issue, multiple sites
- Search the WordPress support forums for “exploit”
- Specific WordPress Codex information about this exploit
- Doncha’s excellent (and more recent) write-up of how to deal with a hacked WordPress installation
- WordPress Exploit Scanner plugin