The FBI has warned that ISIL is exploiting vulnerabilities in WordPress sites running out-of-date versions of WordPress or old versions of certain plugins or themes to deface the sites.
The FBI’s statement: http://www.ic3.gov/media/2015/150407-1.aspx
Sucuri’s writeup with mention of specific plugins to check: http://blog.sucuri.net/2015/04/fbi-public-service-annoucement-defacements-exploiting-wordpress-vulnerabilities.html
The current version of WordPress (as of 4/8/2015) is 4.1.1. If you are running any earlier version, you are vulnerable. If you need to upgrade, you can do so from your WordPress admin login or by downloading the latest version of WordPress from https://wordpress.org/ Don’t forget to update any out-of-date plugins or themes as well.
If you need help updating your HIS-hosted WordPress site, open a support request ticket at http://info.his.com/support/support.his.com.html