On High-Speed Flow-Based Intrusion Detection Using Snort-Compatible Signatures
Felix Erlacher, Falko Dressler
Abstract
Signature-based Network Intrusion Detection Systems (NIDS) have become state-of-the-art in modern network security solutions. However, most systems are not designed for modern high-speed network links. In the field of network monitoring, an alternative solution has become the choice for such high-speed networks. Flow-monitoring, typically based on the Internet Protocol Flow Information Export (IPFIX) standard, now goes well beyond collecting statistical information about network connections. Current solutions are even able to include selected parts of the payload in these Flows to be used in conjunction with NIDS. Recently, we extended this concept to application layer HTTP Flows. We now present our improved version of the IPFIX-based Signature-based Intrusion Detection System (FIXIDS). <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Fixids</small> makes use of HTTP intrusion detection signatures from the popular Snort system and applies them to incoming IPFIX-conforming HTTP Flows. Our evaluation shows that <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Fixids</small> can deal with four times higher network data rates without drops compared to Snort, while maintaining the same event detection rate. Furthermore, a substantial part of the data traffic can be outsourced to <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Fixids</small> so that Snort can be relieved of a significant portion of rules and traffic. This increases both the detection rate and the data rate the overall security appliance can handle.