In 2012, the Dutch National Research and Education Network, SURFnet, observed a multitude of Distributed Denial of Service (DDoS) attacks against educational institutions. These attacks were effective enough to cause the online exams of hundreds of students to be cancelled. Surprisingly, these attacks were purchased by students from websites, known as Booters. These sites provide DDoS attacks as a paid service (DDoS-as-a-Service) at costs starting from 1 USD. Since this problem was first identified by SURFnet, Booters have been used repeatedly to perform attacks on schools in SURFnet’s constituency. Very little is known, however, about the characteristics of Booters, and particularly how their attacks are structure. This is vital information needed to mitigate these attacks. In this paper we analyse the characteristics of 14 distinct Booters based on more than 250 GB of network data from real attacks. Our findings show that Booters pose a real threat that should not be underestimated, especially since our analysis suggests that they can easily increase their firepower based on their current infrastructure.