Must read by every wordpress blog owner, now a days security is main issue...

In the past, the goal of web hackers was simply to disable websites. These criminals, however, discovered that taking a website down did not produce any benefits. Today, their new mode of attack is to hijack websites for their own gain. WordPress hackers accomplish this primarily through link injection. They hack into the user's web files and insert lines of code that attach unwanted links to practically every web page.
100% True, some sites affected by that(i know some sites too).

or you can easily use this
http://wordpress.org/extend/plugins/...roof-security/
Yes, installed

Note:
sorry this is old, but i read today only and posted my comment, also it is useful for most, because most of guys have Wordpress blog
torrfriend Reviewed by torrfriend on . How to Protect Your WordPress Blog As many users are probably aware, WordPress is one of the premier open source blog software available on the internet. It has gone far beyond the standard weblog and is now an excellent foundation for just about any type of website. However, the internet itself is fraught with inherent dangers which leave users open to attack by unscrupulous hackers. http://uuom.com/?di=112956447203 It must be understood that it is impossible to prevent every attack, but there are many steps that can be Rating: 5