Towards Intelligible Robust Anomaly Detection by Learning Interpretable Behavioural Models

Gudmund Grov, Wei Chen, Marc Sabate, David Aspinall

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Network anomaly detection for enterprise cyber security is challenging for a number of reasons. Network traffic is voluminous, noisy, and the notion of what traffic should be considered malicious changes over time as new malware appears. To be most useful, an anomaly detection algorithm should be robust in its performance as new types of malware appear: maintaining a low false positive rate but raising alarms at traffic patterns which correspond to malicious behaviour; and provide intelligible alarms that present their reasoning to support both the analysis of the alarms and necessary incident response. In this paper we investigate new methods for building anomaly detectors using interpretative behavioural models which, we argue, can capture “normal” behaviours at a suitable level of abstraction to provide robustness, in addition to being inherently intelligible as they are interpretable for the security analyst. We consider two such models: a simple Markov Chain model with minimal behavioural structure and a Finite State Automata (FSA) with more structure, and show how these can be learned from normal network traffic alone. Our results show that the FSA performs better than common classifier methods with comparable results to standard Botnet detection methods. The results also indicate that the additional structure in the FSA is important. The FSA shows promise for robustness, although further work (with more data) is needed to fully explore this.
Original languageEnglish
Title of host publicationVol. 12 (2019): NISK 2019; Proceedings of the 12th Norwegian Information Security Conference
PublisherAkademika
Number of pages16
Publication statusPublished - 20 Nov 2019
Event12th Norwegian Information Security Conference: Co-located with NIKT - Narvik, Norway
Duration: 25 Nov 201927 Nov 2019
https://nikt2019.uit.no/en/nisk-2019-call-for-papers/

Publication series

NameNISK
PublisherAkademika
Volume12
ISSN (Electronic)1894-7735

Conference

Conference12th Norwegian Information Security Conference
Abbreviated titleNISK 2019
Country/TerritoryNorway
CityNarvik
Period25/11/1927/11/19
Internet address

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