Port scans are typically at the begin of a chain of events that will lead to the attack and exploitation of a host over a network. Since building an effective defense relies on information what kind of threat an organization is facing, threat intelligence outlining an actor’s modus operandi is a critical ingredient for network security. In this paper, we describe characteristic patterns in port scan packets that can be used to identify the tool chain used by an adversary. In an empirical analysis of scan traffic received by two /16 networks, we find that common open source port scan tools are adopted differently by communities across the globe, and that groups specializing to use a particular tool have also specialized to exploit particular services.@en

Denial of Service (DoS) attacks are a major threat currently observable in omputer networks and especially the Internet. In such an attack a malicious party tries to either break a service, running on a server, or exhaust the capacity or bandwidth of the victim to hinder customers to effectively use the service. Recent reports show that the total number of Distributed Denial of Service (DDoS) attacks is steadily growing with “mega-attacks” peaking at hundreds of gigabit/s (Gbps). In this paper, we will provide a quantification of DDoS attacks in size and duration beyond these outliers reported in the media. We find that these mega attacks do exist, but the bulk of attacks is in practice only a fraction of these frequently reported values. We further show that it is feasible to collect meaningful backscatter traces using surprisingly small telescopes, thereby enabling a broader audience to perform attack intelligence research.@en