Abstract. Dependable operation of the Internet is of crucial importance for our society. In recent years Distributed Denial of Service (DDoS) attacks have quickly become a major problem for the Internet. Most of these attacks are initiated by kids that target schools, ISPs, banks and web-shops; the Dutch NREN (SURFNet), for example, sees around 10 of such attacks per day. Performing attacks is extremely simple, since many websites offer "DDoS as a Service"; in fact it is easier to order a DDoS attack than to book a hotel! The websites that offer such DDoS attacks are called "Booters" or Stressers", and are able to perform attacks with a strength of many Gbps. Although current attempts to mitigate attacks seem promising, analysis of recent attacks learns that it is quite easy to build next generation attack tools that are able to generate DDoS attacks with a strength thousand to one million times higher than the ones we see today. If such tools are used by nation-states or, more likely, terrorists, it should be possible to completely stop the Internet. This paper argues that we should prepare for such novel attacks.
Current DDoS attacksCurrent DDoS attacks are often performed by youngsters via websites that offer "DDoS as a Service". Such websites, which are called "Booters" or Stressers", are able to generate attacks with strengths of many Gbps. A simple Google search shows that hundreds of such Booters are currently active; the costs to perform a series of attacks is typically a few dollars [1][2]. In general Booters do not attack their targets directly, but use one or two levels of intermediate systems to strengthen and anonymise the attacks. The first level is formed by botnets that start the attack once they receive specific commands from the Booter. The second level is used to amplify the attack and can, for example, involve a set of DNS or NTP servers that react upon the reception of relatively small requests by sending large response packets. The ratio between response and request message size is the amplification factor; in practice we find factors between ten and hundred. Particularly popular for amplification attacks are socalled open DNS resolvers, which are basically misconfigured DNS servers that answer DNS queries irrespective of their origin. To target a specific victim, the