Virus writers have created a Linux worm which uses a recently discovered vulnerability in XML-RPC for PHP, a popular open source component used in many applications, to attack vulnerable systems.
XML-RPC for PHP features in many web application including PostNuke, Drupal, b2evolution, Xoops, WordPress, PHPGroupWare and TikiWiki. Most of these applications have been updated to address the security flaw.
If you use any of the listed programs, you should definitely be updating now. There may be other programs affected as well, so don’t take the risk with your site. Check out the full posting at The Register.