ISIS sympathizers are targeting WordPress sites and communication platforms of commercial entities, news organizations, federal/state/local governments, religious institutions, foreign governments, and a number of other domestic and international websites. The FBI is warning WordPress users to patch vulnerable plugins for the popular content management system before ISIS exploit them to display pro-ISIS messages. The attackers are sympathizers and supporters of ISIS (also known as ISIL), not actual members of the terrorist organization. They are mostly unskilled people and are not doing much hard work.
Source: https://thehackernews.com/2015/04/hacking-wordpress-isis.html