Mass attacks on the Internet pose a serious threat to online services. With the help of hijacked computers or servers, cyber criminals can steer millions of enquiries to websites in a very short time and thus paralyse them. The competence centre for IT security CISPA has managed to beat hackers at their own game: together with Japanese colleagues, the computer scientists laid novel digital bait, so-called honeypots, and used it to study the hackers' methods. Their willingness to take new paths paid off: the scientists not only tracked down the sources of the attacks, but also developed an innovative early warning system.