  Intrusion Detection Systems (IDSs) can analyze network traffic for signs of
attacks and intrusions. However, encrypted communication limits their
visibility and sophisticated attackers additionally try to evade their
detection. To overcome these limitations, we extend the scope of Network IDSs
(NIDSs) with additional data from the hosts. For that, we propose the
integrated open-source zeek-osquery platform that combines the Zeek IDS with
the osquery host monitor. Our platform can collect, process, and correlate host
and network data at large scale, e.g., to attribute network flows to processes
and users. The platform can be flexibly extended with own detection scripts
using already correlated, but also additional and dynamically retrieved host
data. A distributed deployment enables it to scale with an arbitrary number of
osquery hosts. Our evaluation results indicate that a single Zeek instance can
manage more than 870 osquery hosts and can attribute more than 96% of TCP
connections to host-side applications and users in real-time.
