There are widespread reports that older versions of WordPress blogs are under attack. To keep the WordPress blog installations safe all we need to do is to upgrade it to the latest version Immediately. Right Now. That much is the seriousness of the problem!!
With the recent versions of WordPress, upgrading to the latest version is just a click away. I’ve been using the Automatic Upgrade features and it’ works like a charm. Even though Automatic Upgrade works without any problems, it is always advised to take backup of the blog before you attempt any upgrades.
To read more information about the attack and the tips on how to respond to a WordPress attack read Lorelle post